1
|
Bruhn D, Povlsen P, Gardner A, Mercado LM. Instantaneous Q 10 of night-time leaf respiratory CO 2 efflux - measurement and analytical protocol considerations. New Phytol 2024. [PMID: 38600045 DOI: 10.1111/nph.19753] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2024] [Accepted: 03/26/2024] [Indexed: 04/12/2024]
Abstract
The temperature sensitivity (e.g. Q10) of night-time leaf respiratory CO2 efflux (RCO2) is a fundamental aspect of leaf physiology. The Q10 typically exhibits a dependence on measurement temperature, and it is speculated that this is due to temperature-dependent shifts in the relative control of leaf RCO2. Two decades ago, a review hypothesized that this mechanistically caused change in values of Q10 is predictable across plant taxa and biomes. Here, we discuss the most appropriate measuring protocol among existing data and for future data collection, to form the foundation for a future mechanistic understanding of Q10 of leaf RCO2 at different temperature ranges. We do this primarily via a review of existing literature on Q10 of night-time RCO2 and only supplement to a lesser degree with own original data. Based on mechanistic considerations, we encourage that instantaneous Q10 of leaf RCO2 to represent night-time should be measured: only at night-time; only in response to short-term narrow temperature variation (e.g. max. 10°C) to represent a given midpoint temperature at a time; in response to as many temperatures as possible within the chosen temperature range; and on still attached leaves.
Collapse
Affiliation(s)
- Dan Bruhn
- Department of Chemistry and Bioscience, Aalborg University, Aalborg, 9220, Denmark
| | - Peter Povlsen
- Department of Chemistry and Bioscience, Aalborg University, Aalborg, 9220, Denmark
| | - Anna Gardner
- Faculty of Environment, Science and Economy, University of Exeter, EX4 4QE, Exeter, UK
- School of Biosciences, University of Birmingham, Birmingham, B14 2TT, UK
| | - Lina M Mercado
- Faculty of Environment, Science and Economy, University of Exeter, EX4 4QE, Exeter, UK
| |
Collapse
|
2
|
Kadam AH, Schnitzer JE. Insights into Disease Progression of Translational Preclinical Rat Model of Interstitial Pulmonary Fibrosis through Endpoint Analysis. Cells 2024; 13:515. [PMID: 38534359 DOI: 10.3390/cells13060515] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2023] [Revised: 02/06/2024] [Accepted: 03/13/2024] [Indexed: 03/28/2024] Open
Abstract
Idiopathic pulmonary fibrosis (IPF) is a devastating interstitial lung disease characterized by the relentless deposition of extracellular matrix (ECM), causing lung distortions and dysfunction. Animal models of human IPF can provide great insight into the mechanistic pathways underlying disease progression and a means for evaluating novel therapeutic approaches. In this study, we describe the effect of bleomycin concentration on disease progression in the classical rat bleomycin model. In a dose-response study (1.5, 2, 2.5 U/kg i.t), we characterized lung fibrosis at day 14 after bleomycin challenge using endpoints including clinical signs, inflammatory cell infiltration, collagen content, and bronchoalveolar lavage fluid-soluble profibrotic mediators. Furthermore, we investigated fibrotic disease progression after 2 U/kg i.t. bleomycin administration at days 3, 7, and 14 by quantifying the expression of clinically relevant signaling molecules and pathways, epithelial mesenchymal transition (EMT) biomarkers, ECM components, and histopathology of the lung. A single bleomycin challenge resulted in a progressive fibrotic response in rat lung tissue over 14 days based on lung collagen content, histopathological changes, and modified Ashcroft score. The early fibrogenesis phase (days 3 to 7) is associated with an increase in profibrotic mediators including TGFβ1, IL6, TNFα, IL1β, CINC1, WISP1, VEGF, and TIMP1. In the mid and late fibrotic stages, the TGFβ/Smad and PDGF/AKT signaling pathways are involved, and clinically relevant proteins targeting galectin-3, LPA1, transglutaminase-2, and lysyl oxidase 2 are upregulated on days 7 and 14. Between days 7 and 14, the expressions of vimentin and α-SMA proteins increase, which is a sign of EMT activation. We confirmed ECM formation by increased expressions of procollagen-1Aα, procollagen-3Aα, fibronectin, and CTGF in the lung on days 7 and 14. Our data provide insights on a complex network of several soluble mediators, clinically relevant signaling pathways, and target proteins that contribute to drive the progressive fibrotic phenotype from the early to late phase (active) in the rat bleomycin model. The framework of endpoints of our study highlights the translational value for pharmacological interventions and mechanistic studies using this model.
Collapse
Affiliation(s)
- Anil H Kadam
- Proteogenomics Research Institute for Systems Medicine (PRISM), 505 Coast Blvd. South, La Jolla, CA 92037, USA
| | - Jan E Schnitzer
- Proteogenomics Research Institute for Systems Medicine (PRISM), 505 Coast Blvd. South, La Jolla, CA 92037, USA
| |
Collapse
|
3
|
Yu Z, Shi M, Wei Y. Mechanistic Studies on Rhodium-Catalyzed Chemoselective Cycloaddition of Ene-Vinylidenecyclopropanes: Water-Assisted Proton Transfer. Molecules 2024; 29:1085. [PMID: 38474597 DOI: 10.3390/molecules29051085] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2024] [Revised: 02/26/2024] [Accepted: 02/27/2024] [Indexed: 03/14/2024] Open
Abstract
Rhodium-catalyzed cycloaddition reactions are a powerful tool for the construction of polycyclic compounds. Combined experimental and DFT studies were used to investigate the temperature-controlled chemoselectivity of cationic rhodium-catalyzed intramolecular cycloaddition reactions of ene-vinylidenecyclopropanes. After a series of mechanistic studies, it was found that trace amounts of water in the reaction system play an important role in generating the product with endo double bond located on a five-membered ring and revealed that trace amounts of water in the reaction system, including the rhodium catalyst, substrate and solvent, were sufficient to promote the formation of the product with endo double bond located on a five-membered ring, and additional water could not further accelerate the reaction. DFT calculation results show that the addition of water indeed significantly lowers the energy barrier of the proton transfer step, making the formation of the product with endo double bond located on a five-membered ring more likely to occur and confirming the rationality of water-assisted proton transfer occurring in the selective access to the product with endo double bond located on a five-membered ring.
Collapse
Affiliation(s)
- Ziqi Yu
- Key Laboratory for Advanced Materials, Institute of Fine Chemicals, School of Chemistry and Molecular Engineering, East China University of Science and Technology, Meilong Road No. 130, Shanghai 200237, China
| | - Min Shi
- Key Laboratory for Advanced Materials, Institute of Fine Chemicals, School of Chemistry and Molecular Engineering, East China University of Science and Technology, Meilong Road No. 130, Shanghai 200237, China
- State Key Laboratory of Organometallic Chemistry, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, University of Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, China
| | - Yin Wei
- State Key Laboratory of Organometallic Chemistry, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, University of Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, China
| |
Collapse
|
4
|
Kumar S, Sharma A, Mahala S, Gaatha K, Reddy SR, Rom T, Paul AK, Roy P, Joshi H. Macrocyclic Sulfur Ligand Stabilized Trans-Palladium Dichloride Complex: Syntheses, Structure, Chlorine Rotation, and Application in α-Olefination of Nitriles by Primary Alcohols. Chem Asian J 2024; 19:e202300935. [PMID: 38116906 DOI: 10.1002/asia.202300935] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2023] [Revised: 12/05/2023] [Accepted: 12/18/2023] [Indexed: 12/21/2023]
Abstract
Herein, we have reported the synthesis of a macrocyclic organosulfur ligand (L1) having a seventeen-membered macrocyclic ring. Subsequently, the corresponding trans-palladium complex (C1) of bulky macrocyclic organosulfur ligand (L1) was synthesized by reacting it with PdCl2 (CH3 CN)2 salt. The newly synthesized ligand and complex were characterized using various analytical and spectroscopic techniques. The complex showed a square planar geometry with trans orientation of two ligands around the palladium center. The complex possesses intramolecular SCH…Cl interactions of 2.648 Å between the macrocyclic ligand and palladium dichloride. The potential energy surface (PES) for the rotational process of C1 suggested a barrier of ~23.81 kcal/mol for chlorine rotation. Furthermore, the bulky macrocyclic organosulfur ligand stabilized palladium complex (C1) was used as a catalyst (2.5 mol %) for α-olefination of nitriles by primary alcohols. The α,β-unsaturated nitrile compounds were found to be the major product of the reaction (57-78 % yield) with broad substrate scope and large functional group tolerance. Notably, the saturated nitrile product was not observed during the reaction. The mechanistic studies suggested the formation of H2 and H2 O as only by-products of the reaction, thereby making the protocol greener and sustainable.
Collapse
Affiliation(s)
- Sunil Kumar
- ISC Laboratory, Department of Chemistry, School of Chemical Sciences and Pharmacy, Central University of Rajasthan, NH-8, Bandarsindri, Ajmer, Rajasthan, 305817, India
| | - Ashutosh Sharma
- ISC Laboratory, Department of Chemistry, School of Chemical Sciences and Pharmacy, Central University of Rajasthan, NH-8, Bandarsindri, Ajmer, Rajasthan, 305817, India
| | - Suman Mahala
- ISC Laboratory, Department of Chemistry, School of Chemical Sciences and Pharmacy, Central University of Rajasthan, NH-8, Bandarsindri, Ajmer, Rajasthan, 305817, India
| | - K Gaatha
- ISC Laboratory, Department of Chemistry, School of Chemical Sciences and Pharmacy, Central University of Rajasthan, NH-8, Bandarsindri, Ajmer, Rajasthan, 305817, India
| | - S Rajagopala Reddy
- Department of Chemistry, School of Chemical Sciences and Pharmacy, Central University of Rajasthan, NH-8, Bandarsindri, Ajmer, Rajasthan 305817, India
| | - Tanmay Rom
- Department of Chemistry, National Institute of Technology Kurukshetra, Kurukshetra, 136119, India
| | - Avijit Kumar Paul
- Department of Chemistry, National Institute of Technology Kurukshetra, Kurukshetra, 136119, India
| | - Partha Roy
- Department of Chemistry, School of Chemical Sciences and Pharmacy, Central University of Rajasthan, NH-8, Bandarsindri, Ajmer, Rajasthan 305817, India
| | - Hemant Joshi
- ISC Laboratory, Department of Chemistry, School of Chemical Sciences and Pharmacy, Central University of Rajasthan, NH-8, Bandarsindri, Ajmer, Rajasthan, 305817, India
| |
Collapse
|
5
|
Khan M, Nizamani A, Shah L, Ullah I, Waqas M, Halim SA, Ataya FS, Elgazzar AM, Batiha GES, Khan A, Al-Harrasi A. Utilizing the drug repurposing strategy on current drugs: new leads for peptic ulcers via biochemical and biomolecular dynamics studies. J Biomol Struct Dyn 2024:1-14. [PMID: 38225797 DOI: 10.1080/07391102.2024.2302926] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2023] [Accepted: 01/02/2024] [Indexed: 01/17/2024]
Abstract
The hyperactivity of urease enzymes plays a crucial role in the development of hepatic coma, hepatic encephalopathy, urolithiasis, gastric and peptic ulcers. Additionally, these enzymes adversely impact the soil's nitrogen efficiency for crop production. In the current study 100 known drugs were tested against Jack Bean urease and Proteus mirabilis urease and identified three inhibitors i.e. terbutaline (compound 1), Ketoprofen (compound 2) and norepinephrine bitartrate (compound 3). As a result, these compounds showed excellent inhibition against Jack Bean urease i.e. (IC50 = 2.1-11.3 µM), and Proteus mirabilis urease (4.8-11.9 µM). Moreover, in silico studies demonstrate maximum interactions of compounds in the enzyme's active site. Furthermore, intermolecular interactions between compounds and enzyme atoms were examined using STD-NMR spectrophotometry. In parallel, molecular dynamics simulation was carried out to study compounds dynamic behavior within the urease binding region. Urease remained stable during most of the simulation time and ligands were bound in the protein active pocket as observed from the Root mean square deviation (RMSD) and ligand RMSD analyses. Furthermore, these compounds display interactions with the crucial residues, including His492 and Asp633, in 100 ns simulations. In the binding energy analysis, norepinephrine bitartrate exhibited the highest binding energy (-76.32 kcal/mol) followed by Ketoprofen (-65.56 kcal/mol) and terbutaline (-62.15 kcal/mol), as compared to acetohydroxamic acid (-52.86 kcal/mol). The current findings highlight the potential of drug repurposing as an effective approach for identifying novel anti-urease compounds.Communicated by Ramaswamy H. Sarma.
Collapse
Affiliation(s)
- Majid Khan
- Natural and Medical Sciences Research Center, University of Nizwa, Nizwa, Sultanate of Oman
- Department of Biochemistry, University of Malakand, Totakan, Pakistan
| | - Arsalan Nizamani
- Muhammad Medical College, Ibn-e-Sina University, Mirpurkhas, Sindh, Pakistan
| | - Luqman Shah
- Department of Biochemistry, Hazara University Mansehra, Mansehra,Pakistan
| | - Imran Ullah
- Department of Biochemistry, Hazara University Mansehra, Mansehra,Pakistan
| | - Muhammad Waqas
- Natural and Medical Sciences Research Center, University of Nizwa, Nizwa, Sultanate of Oman
| | - Sobia Ahsan Halim
- Natural and Medical Sciences Research Center, University of Nizwa, Nizwa, Sultanate of Oman
| | - Farid Shokry Ataya
- Department of Biochemistry, College of Science, King Saud University, Riyadh, Saudi Arabia
| | - Ahmed M Elgazzar
- Department of Veterinary Forensic Medicine and Toxicology, Faculty of Veterinary Medicine, Alexandria University, Alexandria, Egypt
- Department of Experimental Pathology and Tumor Biology, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan
| | - Gaber El-Saber Batiha
- Department of Pharmacology and Therapeutics, Faculty of Veterinary Medicine, Damanhour University, Damanhour, Egypt
| | - Ajmal Khan
- Natural and Medical Sciences Research Center, University of Nizwa, Nizwa, Sultanate of Oman
| | - Ahmed Al-Harrasi
- Natural and Medical Sciences Research Center, University of Nizwa, Nizwa, Sultanate of Oman
| |
Collapse
|
6
|
Wilde M. The EBM+ movement. Int J Biostat 2023; 19:283-293. [PMID: 36800549 DOI: 10.1515/ijb-2022-0126] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2022] [Accepted: 12/09/2022] [Indexed: 02/19/2023]
Abstract
In this paper, I provide an introduction for biostatisticians and others to some recent work in the philosophy of medicine. Firstly, I give an overview of some philosophical arguments that are thought to create problems for a prominent approach towards establishing causal claims in medicine, namely, the Evidence-Based Medicine (EBM) approach. Secondly, I provide an overview of further recent work in the philosophy of medicine, which argues that mechanistic studies can help to address these problems. Lastly, I describe a novel approach for establishing causal claims in medicine that has been informed by this recent work in the philosophy of medicine, namely, the EBM+ approach.
Collapse
Affiliation(s)
- Michael Wilde
- Philosophy, University of Kent, CT2 7NZ, Canterbury, UK
| |
Collapse
|
7
|
Singh S, Shinde VN, Kumar S, Meena N, Bhuvanesh N, Rangan K, Kumar A, Joshi H. Mono and Dinuclear Palladium Pincer Complexes of NNSe Ligand as a Catalyst for Decarboxylative Direct C-H Heteroarylation of (Hetero)arenes. Chem Asian J 2023; 18:e202300628. [PMID: 37602812 DOI: 10.1002/asia.202300628] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2023] [Revised: 08/18/2023] [Accepted: 08/18/2023] [Indexed: 08/22/2023]
Abstract
This report describes the synthesis of a new NNSe pincer ligand and its mono- and dinuclear palladium(II) pincer complexes. In the absence of a base, a dinuclear palladium pincer complex (C1) was isolated, while in the presence of Et3 N base a mononuclear palladium pincer complex (C2) was obtained. The new ligand and complexes were characterized using techniques like 1 H, 13 C{1 H} nuclear magnetic resonance (NMR), fourier transform infrared (FTIR), high-resolution mass spectrometry (HRMS), ultraviolet-visible (UV-Visible), and cyclic voltammetry. Both the complexes showed pincer coordination mode with a distorted square planar geometry. The complex C1 has two pincer ligands attached through a Pd-Pd bond in a dinuclear pincer fashion. The air and moisture-insensitive, thermally robust palladium pincer complexes were used as the catalyst for decarboxylative direct C-H heteroarylation of (hetero)arenes. Among the complexes, dinuclear pincer complex C1 showed better catalytic activity. A variety of (hetero)arenes were successfully activated (43-87 % yield) using only 2.5 mol % of catalyst loading under mild reaction conditions. The PPh3 and Hg poisoning experiments suggested a homogeneous nature of catalysis. A plausible reaction pathway was proposed for the dinuclear palladium pincer complex catalyzed decarboxylative C-H bond activation reaction of (hetero)arenes.
Collapse
Affiliation(s)
- Sohan Singh
- ISC Laboratory, Department of Chemistry, School of Chemical Sciences and Pharmacy, Central University of Rajasthan, NH-8, Bandarsindri, Ajmer, Rajasthan, 305817, India
| | - Vikki N Shinde
- Department of Chemistry, Birla Institute of Technology and Science, Pilani, Pilani Campus, Pilani, 333031, India
| | - Sunil Kumar
- ISC Laboratory, Department of Chemistry, School of Chemical Sciences and Pharmacy, Central University of Rajasthan, NH-8, Bandarsindri, Ajmer, Rajasthan, 305817, India
| | - Neha Meena
- Department of Chemistry, Birla Institute of Technology and Science, Pilani, Pilani Campus, Pilani, 333031, India
| | - Nattamai Bhuvanesh
- Department of Chemistry, Texas A&M University, PO Box 30012, College Station, Texas, 77842-3012, USA
| | - Krishnan Rangan
- Department of Chemistry, Birla Institute of Technology and Science Pilani, Hyderabad Campus, Telangana, 500078, India
| | - Anil Kumar
- Department of Chemistry, Birla Institute of Technology and Science, Pilani, Pilani Campus, Pilani, 333031, India
| | - Hemant Joshi
- ISC Laboratory, Department of Chemistry, School of Chemical Sciences and Pharmacy, Central University of Rajasthan, NH-8, Bandarsindri, Ajmer, Rajasthan, 305817, India
| |
Collapse
|
8
|
Shen S, Butrin A, Beaupre BA, Ferreira GM, Doubleday PF, Grass DH, Zhu W, Kelleher NL, Moran GR, Liu D, Silverman RB. Structural and Mechanistic Basis for the Inactivation of Human Ornithine Aminotransferase by (3 S,4 S)-3-Amino-4-fluorocyclopentenecarboxylic Acid. Molecules 2023; 28:1133. [PMID: 36770800 PMCID: PMC9921285 DOI: 10.3390/molecules28031133] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2022] [Revised: 01/16/2023] [Accepted: 01/17/2023] [Indexed: 01/24/2023] Open
Abstract
Ornithine aminotransferase (OAT) is overexpressed in hepatocellular carcinoma (HCC), and we previously showed that inactivation of OAT inhibits the growth of HCC. Recently, we found that (3S,4S)-3-amino-4-fluorocyclopentenecarboxylic acid (5) was a potent inactivator of γ-aminobutyric acid aminotransferase (GABA-AT), proceeding by an enamine mechanism. Here we describe our investigations into the activity and mechanism of 5 as an inactivator of human OAT. We have found that 5 exhibits 10-fold less inactivation efficiency (kinact/KI) against hOAT than GABA-AT. A comprehensive mechanistic study was carried out to understand its inactivation mechanism with hOAT. pKa and electrostatic potential calculations were performed to further support the notion that the α,β-unsaturated alkene of 5 is critical for enhancing acidity and nucleophilicity of the corresponding intermediates and ultimately responsible for the improved inactivation efficiency of 5 over the corresponding saturated analogue (4). Intact protein mass spectrometry and the crystal structure complex with hOAT provide evidence to conclude that 5 mainly inactivates hOAT through noncovalent interactions, and that, unlike with GABA-AT, covalent binding with hOAT is a minor component of the total inhibition which is unique relative to other monofluoro-substituted derivatives. Furthermore, based on the results of transient-state measurements and free energy calculations, it is suggested that the α,β-unsaturated carboxylate group of PLP-bound 5 may be directly involved in the inactivation cascade by forming an enolate intermediate. Overall, compound 5 exhibits unusual structural conversions which are catalyzed by specific residues within hOAT, ultimately leading to an enamine mechanism-based inactivation of hOAT through noncovalent interactions and covalent modification.
Collapse
Affiliation(s)
- Sida Shen
- Department of Chemistry and Center for Developmental Therapeutics, Northwestern University, Evanston, IL 60208, USA
| | - Arseniy Butrin
- Department of Chemistry and Biochemistry, Loyola University Chicago, Chicago, IL 60660, USA
| | - Brett A. Beaupre
- Department of Chemistry and Biochemistry, Loyola University Chicago, Chicago, IL 60660, USA
| | - Glaucio M. Ferreira
- Department of Clinical and Toxicological Analyses, School of Pharmaceutical Sciences, University of São Paulo, São Paulo 05508-000, SP, Brazil
| | - Peter F. Doubleday
- Department of Molecular Biosciences, Northwestern University, Evanston, IL 60208, USA
- Proteomics Center of Excellence, Northwestern University, Evanston, IL 60208, USA
| | - Daniel H. Grass
- Department of Chemistry and Center for Developmental Therapeutics, Northwestern University, Evanston, IL 60208, USA
| | - Wei Zhu
- Department of Chemistry and Center for Developmental Therapeutics, Northwestern University, Evanston, IL 60208, USA
| | - Neil L. Kelleher
- Department of Chemistry and Center for Developmental Therapeutics, Northwestern University, Evanston, IL 60208, USA
- Department of Molecular Biosciences, Northwestern University, Evanston, IL 60208, USA
- Proteomics Center of Excellence, Northwestern University, Evanston, IL 60208, USA
| | - Graham R. Moran
- Department of Chemistry and Biochemistry, Loyola University Chicago, Chicago, IL 60660, USA
| | - Dali Liu
- Department of Chemistry and Biochemistry, Loyola University Chicago, Chicago, IL 60660, USA
| | - Richard B. Silverman
- Department of Chemistry and Center for Developmental Therapeutics, Northwestern University, Evanston, IL 60208, USA
- Department of Molecular Biosciences, Northwestern University, Evanston, IL 60208, USA
- Department of Pharmacology, Northwestern University, Chicago, IL 60611, USA
| |
Collapse
|
9
|
Wan Saidin WA, Jantan I, Abdul Wahab SM, Jalil J, Mohd Said M, Yusoff SD, Husain K. Pharmacological activities and mechanisms of action of hypophyllanthin: A review. Front Pharmacol 2023; 13:1070557. [PMID: 36699081 PMCID: PMC9868173 DOI: 10.3389/fphar.2022.1070557] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2022] [Accepted: 12/23/2022] [Indexed: 01/11/2023] Open
Abstract
Hypophyllanthin is a major lignan present in various Phyllanthus species and has been used as one of the bioactive chemical markers for quality control purposes as it contributes to their diverse pharmacological activities. The objective of this study is to compile up-to-date data on the pharmacological actions and mechanisms of hypophyllanthin. This review also includes the extracts of Phyllanthus species whose pharmacological actions have been partially attributed to hypophyllanthin. The scientific findings on the compound are critically analyzed and its potential as a lead molecule for the discovery of drug candidates for the development of therapeutics to treat diverse diseases is highlighted. Data collection was mainly through the exploration of Ovid-MEDLINE, Scopus, Science Direct, and Elsevier databases. Studies conducted in vitro and in vivo showed that hypophyllanthin had potent immunomodulating properties as well as a variety of other pharmacological properties, including anti-inflammatory, hepatoprotective, anti-tumor, anti-allergic, anti-hypertensive, and phytoestrogenic properties. Several mechanisms of action on the effects of hypophyllanthin on the immune system, in cancer and other disease states, were presented to provide some insights into its pharmacological effects. Before being submitted to clinical investigations, additional animal studies utilising different animal models are necessary to analyse its bioavailability, pharmacokinetics, and pharmacodynamic properties, as well as its toxicity, to determine its efficacy and safety. Understanding its potential as a lead molecule for the discovery of therapeutic candidates, particularly for the development of therapies for inflammatory and immune-related disorders, requires an understanding of its pharmacological activities and mechanisms of action. An insight into its pharmacological activities and mechanisms of action will provide an understanding of its potential as a lead compound for the discovery of drug candidates, especially for the development of therapies for inflammatory and immune related diseases.
Collapse
Affiliation(s)
- Wan Azmira Wan Saidin
- Centre for Drug and Herbal Development, Faculty of Pharmacy, Universiti Kebangsaan Malaysia, Kuala Lumpur, Malaysia
| | - Ibrahim Jantan
- Institute of Systems Biology, Universiti Kebangsaan Malaysia, Selangor, Malaysia
| | - Siti Mariam Abdul Wahab
- Centre for Drug and Herbal Development, Faculty of Pharmacy, Universiti Kebangsaan Malaysia, Kuala Lumpur, Malaysia
| | - Juriyati Jalil
- Centre for Drug and Herbal Development, Faculty of Pharmacy, Universiti Kebangsaan Malaysia, Kuala Lumpur, Malaysia
| | - Mazlina Mohd Said
- Centre for Drug and Herbal Development, Faculty of Pharmacy, Universiti Kebangsaan Malaysia, Kuala Lumpur, Malaysia
| | - Syaratul Dalina Yusoff
- Centre for Drug and Herbal Development, Faculty of Pharmacy, Universiti Kebangsaan Malaysia, Kuala Lumpur, Malaysia
| | - Khairana Husain
- Centre for Drug and Herbal Development, Faculty of Pharmacy, Universiti Kebangsaan Malaysia, Kuala Lumpur, Malaysia,*Correspondence: Khairana Husain,
| |
Collapse
|
10
|
Smajlagic I, Johnston JN, Dudding T. Secondary Orbital Effect Involving Fluorine is Responsible for Substrate-Controlled Diastereodivergence in the Catalyzed syn-aza-Henry Reaction of α-Fluoronitroalkanes. Chemistry 2023; 29:e202204066. [PMID: 36607705 DOI: 10.1002/chem.202204066] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2022] [Revised: 01/05/2023] [Accepted: 01/06/2023] [Indexed: 01/07/2023]
Abstract
The fluorine atom is a powerful, yet enigmatic influence on chemical reactions. True to form, fluorine was recently discovered to effect diastereodivergence in an enantioselective aza-Henry reaction, resulting in a very rare case of syn-β-amino nitroalkane products. More bewildering was the observation of an apparent hierarchy of substituents within this substrate-controlled behavior: Ph>F>alkyl. These cases have now been examined comprehensively by computational methods, including both non-fluorinated and α-fluoro nitronate additions to aldimines catalyzed by a chiral bis(amidine) [BAM] proton complex. This study revealed the network of non-covalent interactions that dictate anti- (α-aryl) versus syn-selectivity (α-alkyl) using α-fluoronitronate nucleophiles, and an underlying secondary orbital interaction between fluorine and the activated azomethine.
Collapse
Affiliation(s)
- Ivor Smajlagic
- Department of Chemistry, Brock University, 1812 Sir Isaac Brock Way, St., Catharines, ON L2S 3A1, Canada
| | - Jeffrey N Johnston
- Department of Chemistry and Institute of Chemical Biology, Vanderbilt University Nashville, Tennessee, 37235, USA
| | - Travis Dudding
- Department of Chemistry, Brock University, 1812 Sir Isaac Brock Way, St., Catharines, ON L2S 3A1, Canada
| |
Collapse
|
11
|
Rodríguez M, M Rodríguez A, López-Resano S, Pericàs MA, Díaz-Requejo MM, Maseras F, Pérez PJ. Non-innocent Role of the Halide Ligand in the Copper-Catalyzed Olefin Aziridination Reaction. ACS Catal 2023; 13:706-713. [PMID: 37808365 PMCID: PMC10552652 DOI: 10.1021/acscatal.2c05069] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Revised: 12/05/2022] [Indexed: 12/24/2022]
Abstract
In the context of copper-catalyzed nitrene transfer to olefins, many systems operate upon mixing a CuX salt (X = halide, OTf) and a polydentate N-based ligand, assuming that the X ligand is displaced from the coordination sphere toward a counterion position. Herein, we demonstrated that such general assumption should be in doubt since studies carried out with the well-defined copper(I) complexes (TTM)CuCl and [(TTM)Cu(NCMe)]PF6 (TTM = tris(triazolyl)methane ligand) demonstrate a dual behavior from a catalytic and mechanistic point of view that exclusively depends on the presence or absence of the chloride ligand bonded to the metal center. When coordinated, the turnover-limiting step corresponds to the formation of the carbon-nitrene bond, whereas in its absence, the highest barrier corresponds to the formation of the copper-nitrene intermediate.
Collapse
Affiliation(s)
- Manuel
R. Rodríguez
- Laboratorio
de Catálisis Homogénea, Unidad Asociada al CSIC, CIQSO-Centro
de Investigación en Química Sostenible and Departamento
de Química, Universidad de Huelva, 21007 Huelva, Spain
| | - Anabel M Rodríguez
- Laboratorio
de Catálisis Homogénea, Unidad Asociada al CSIC, CIQSO-Centro
de Investigación en Química Sostenible and Departamento
de Química, Universidad de Huelva, 21007 Huelva, Spain
| | - Sara López-Resano
- Institute
of Chemical Research of Catalonia, ICIQ, The Barcelona Institute of
Science and Technology, Av. Països Catalans, 16, 43007 Tarragona, Spain
| | - Miquel A. Pericàs
- Institute
of Chemical Research of Catalonia, ICIQ, The Barcelona Institute of
Science and Technology, Av. Països Catalans, 16, 43007 Tarragona, Spain
| | - M. Mar Díaz-Requejo
- Laboratorio
de Catálisis Homogénea, Unidad Asociada al CSIC, CIQSO-Centro
de Investigación en Química Sostenible and Departamento
de Química, Universidad de Huelva, 21007 Huelva, Spain
| | - Feliu Maseras
- Institute
of Chemical Research of Catalonia, ICIQ, The Barcelona Institute of
Science and Technology, Av. Països Catalans, 16, 43007 Tarragona, Spain
| | - Pedro J. Pérez
- Laboratorio
de Catálisis Homogénea, Unidad Asociada al CSIC, CIQSO-Centro
de Investigación en Química Sostenible and Departamento
de Química, Universidad de Huelva, 21007 Huelva, Spain
| |
Collapse
|
12
|
Kamali M, Xue Y, Khalaj M, Laats B, Teunckens R, Verbist M, Costa MEV, Capela I, Appels L, Dewil R. ZnO/γ-Fe 2O 3/Bentonite: An Efficient Solar-Light Active Magnetic Photocatalyst for the Degradation of Pharmaceutical Active Compounds. Molecules 2022; 27:3050. [PMID: 35630526 DOI: 10.3390/molecules27103050] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/16/2022] [Revised: 04/15/2022] [Accepted: 04/21/2022] [Indexed: 11/21/2022]
Abstract
For applications related to the photocatalytic degradation of environmental contaminants, engineered nanomaterials (ENMs) must demonstrate not only a high photocatalytic potential, but also a low tendency to agglomeration, along with the ability to be easily collected after use. In this manuscript, a two-step process was implemented for the synthesis of ZnO, ZnO/Bentonite and the magnetic ZnO/γ-Fe2O3/Bentonite nanocomposite. The synthesized materials were characterized using various techniques, and their performance in the degradation of pharmaceutical active compounds (PhACs), including ciprofloxacin (CIP), sulfamethoxazole (SMX), and carbamazepine (CBZ) was evaluated under various operating conditions, namely the type and dosage of the applied materials, pH, concentration of pollutants, and their appearance form in the medium (i.e., as a single pollutant or as a mixture of PhACs). Among the materials studied, ZnO/Bentonite presented the best performance and resulted in the removal of ~95% of CIP (5 mg/L) in 30 min, at room temperature, near-neutral pH (6.5), ZnO/Bentonite dosage of 0.5 g/L, and under solar light irradiation. The composite also showed a high degree of efficiency for the simultaneous removal of CIP (~98%, 5 mg/L) and SMX (~97%, 5 mg/L) within 30 min, while a low degradation of ~5% was observed for CBZ (5 mg/L) in a mixture of the three PhACs. Furthermore, mechanistic studies using different types of scavengers revealed the formation of active oxidative species responsible for the degradation of CIP in the photocatalytic system studied with the contribution of h+ (67%), OH (18%), and ·O2− (10%), and in which holes (h+) were found to be the dominant oxidative species.
Collapse
|
13
|
Docampo MJ, Lutterotti A, Sospedra M, Martin R. Mechanistic and Biomarker Studies to Demonstrate Immune Tolerance in Multiple Sclerosis. Front Immunol 2022; 12:787498. [PMID: 35069562 PMCID: PMC8766750 DOI: 10.3389/fimmu.2021.787498] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Accepted: 12/10/2021] [Indexed: 12/14/2022] Open
Abstract
The induction of specific immunological tolerance represents an important therapeutic goal for multiple sclerosis and other autoimmune diseases. Sound knowledge of the target antigens, the underlying pathomechanisms of the disease and the presumed mechanisms of action of the respective tolerance-inducing approach are essential for successful translation. Furthermore, suitable tools and assays to evaluate the induction of immune tolerance are key aspects for the development of such treatments. However, investigation of the mechanisms of action underlying tolerance induction poses several challenges. The optimization of sensitive, robust methods which allow the assessment of low frequency autoreactive T cells and the long-term reduction or change of their responses, the detection of regulatory cell populations and their immune mediators, as well as the validation of specific biomarkers indicating reduction of inflammation and damage, are needed to develop tolerance-inducing approaches successfully to patients. This short review focuses on how to demonstrate mechanistic proof-of-concept in antigen-specific tolerance-inducing therapies in MS.
Collapse
Affiliation(s)
| | | | | | - Roland Martin
- Neuroimmunology and Multiple Sclerosis Research Section, Neurology Clinic, University Hospital Zurich & University of Zurich, Zurich, Switzerland
| |
Collapse
|
14
|
Maciá M, Porcar R, Martí-Centelles V, García-Verdugo E, Burguete MI, Luis SV. Rational Design of Simple Organocatalysts for the HSiCl 3 Enantioselective Reduction of (E)- N-(1-Phenylethylidene)aniline. Molecules 2021; 26:6963. [PMID: 34834055 PMCID: PMC8625272 DOI: 10.3390/molecules26226963] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Revised: 11/16/2021] [Accepted: 11/16/2021] [Indexed: 11/17/2022] Open
Abstract
Prolinamides are well-known organocatalysts for the HSiCl3 reduction of imines; however, custom design of catalysts is based on trial-and-error experiments. In this work, we have used a combination of computational calculations and experimental work, including kinetic analyses, to properly understand this process and to design optimized catalysts for the benchmark (E)-N-(1-phenylethylidene)aniline. The best results have been obtained with the amide derived from 4-methoxyaniline and the N-pivaloyl protected proline, for which the catalyzed process is almost 600 times faster than the uncatalyzed one. Mechanistic studies reveal that the formation of the component supramolecular complex catalyst-HSiCl3-substrate, involving hydrogen bonding breaking and costly conformational changes in the prolinamide, is an important step in the overall process.
Collapse
Affiliation(s)
- María Maciá
- Department of Inorganic and Organic Chemistry, Jaume I University, Av. Vicent Sos Baynat s/n, 12071 Castellón, Spain; (M.M.); (R.P.); (V.M.-C.); (M.I.B.)
| | - Raúl Porcar
- Department of Inorganic and Organic Chemistry, Jaume I University, Av. Vicent Sos Baynat s/n, 12071 Castellón, Spain; (M.M.); (R.P.); (V.M.-C.); (M.I.B.)
- Department of Organic and Bio-Organic Chemistry, Faculty of Science, UNED—Universidad Nacional de Educación a Distancia, Avenida de Esparta s/n, 28232 Las Rozas-Madrid, Spain
| | - Vicente Martí-Centelles
- Department of Inorganic and Organic Chemistry, Jaume I University, Av. Vicent Sos Baynat s/n, 12071 Castellón, Spain; (M.M.); (R.P.); (V.M.-C.); (M.I.B.)
- Instituto Interuniversitario de Investigación de Reconocimiento Molecular y Desarrollo Tecnológico (IDM), Universitat Politècnica de València, Universitat de València, 46022 Valencia, Spain
| | - Eduardo García-Verdugo
- Department of Inorganic and Organic Chemistry, Jaume I University, Av. Vicent Sos Baynat s/n, 12071 Castellón, Spain; (M.M.); (R.P.); (V.M.-C.); (M.I.B.)
| | - Maria Isabel Burguete
- Department of Inorganic and Organic Chemistry, Jaume I University, Av. Vicent Sos Baynat s/n, 12071 Castellón, Spain; (M.M.); (R.P.); (V.M.-C.); (M.I.B.)
| | - Santiago V. Luis
- Department of Inorganic and Organic Chemistry, Jaume I University, Av. Vicent Sos Baynat s/n, 12071 Castellón, Spain; (M.M.); (R.P.); (V.M.-C.); (M.I.B.)
| |
Collapse
|
15
|
Langerman M, Hetterscheid DGH. Mechanistic Study of the Activation and the Electrocatalytic Reduction of Hydrogen Peroxide by Cu-tmpa in Neutral Aqueous Solution. ChemElectroChem 2021; 8:2783-2791. [PMID: 34589379 PMCID: PMC8453753 DOI: 10.1002/celc.202100436] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Revised: 05/04/2021] [Indexed: 11/29/2022]
Abstract
Hydrogen peroxide plays an important role as an intermediate and product in the reduction of dioxygen by copper enzymes and mononuclear copper complexes. The copper(II) tris(2-pyridylmethyl)amine complex (Cu-tmpa) has been shown to produce H2O2 as an intermediate during the electrochemical 4-electron reduction of O2. We investigated the electrochemical hydrogen peroxide reduction reaction (HPRR) by Cu-tmpa in a neutral aqueous solution. The catalytic rate constant of the reaction was shown to be one order of magnitude lower than the reduction of dioxygen. A significant solvent kinetic isotope effect (KIE) of 1.4 to 1.7 was determined for the reduction of H2O2, pointing to a Fenton-like reaction pathway as the likely catalytic mechanism, involving a single copper site that produces an intermediate copper(II) hydroxo species and a free hydroxyl radical anion in the process.
Collapse
Affiliation(s)
- Michiel Langerman
- Leiden Institute of ChemistryLeiden UniversityP.O Box 95022300 RALeidenThe Netherlands
| | | |
Collapse
|
16
|
Chandrashekar HB, Dolui P, Li B, Mandal A, Liu H, Guin S, Ge H, Maiti D. Ligand-Enabled δ-C(sp 3 )-H Borylation of Aliphatic Amines. Angew Chem Int Ed Engl 2021; 60:18194-18200. [PMID: 34117691 DOI: 10.1002/anie.202105204] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2021] [Revised: 05/18/2021] [Indexed: 02/03/2023]
Abstract
Directed C-H functionalization has been realized as a complimentary technique to achieve borylation at a distal position of aliphatic amines. Here, we demonstrated the oxidative borylation at the distal δ-position of aliphatic amines using various borylating agents, a palladium catalyst, and a rightly tuned ligand in the presence of a cheap oxidant. Moreover, an organopalladium δ-C(sp3 )-H-activated intermediate has been isolated and crystallographically characterized to get mechanistic insight.
Collapse
Affiliation(s)
| | - Pravas Dolui
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai, 400076, India
| | - Bijin Li
- Department of Chemistry and Biochemistry, Lubbock, TX, 79409-1061, USA.,Chongqing Key Laboratory of Natural Product Synthesis and Drug Research, School of Pharmaceutical Sciences, Chongqing University, Chongqing, 401331, P. R. China
| | - Astam Mandal
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai, 400076, India
| | - Hao Liu
- Department of Chemistry and Biochemistry, Lubbock, TX, 79409-1061, USA
| | - Srimanta Guin
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai, 400076, India
| | - Haibo Ge
- Department of Chemistry and Biochemistry, Lubbock, TX, 79409-1061, USA
| | - Debabrata Maiti
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai, 400076, India
| |
Collapse
|
17
|
Dutta M, Srivastava HK, Kumar A. Rational design of pincer-nickel complexes for catalytic cyanomethylation of benzaldehyde: A systematic DFT study. J Comput Chem 2021; 42:1728-1735. [PMID: 34196021 DOI: 10.1002/jcc.26708] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2021] [Revised: 06/14/2021] [Accepted: 06/17/2021] [Indexed: 11/06/2022]
Abstract
The current study dwells upon the efforts to computationally probe a phosphine-free pincer-nickel complex that would demonstrate an efficiency better than the reported phosphine-based pincer-nickel complex (iPr2 POCNEt2 )Ni(CH2 CN) for cyanomethylation reaction. For this purpose, the mechanism of cyanomethylation of benzaldehyde was studied quantum mechanically for a series of 11 pincer-nickel complexes. The energetics of various intermediates and transition states involved in the catalytic cycle for each catalyst was compared with the corresponding energetics of the Miller's catalyst (iPr2 POCNEt2 )Ni(CH2 CN) that is reported to accomplish the cyanomethylation at room temperature. While pincer complexes (iPr4 NNN)Ni(CH2 CN) and (iPr4 NCN)Ni(CH2 CN) containing strong σ-donating amines were found to fare poorly, pincer-nickel complexes (iPr2 NCN)Ni(CH2 CN) and (dm PheboxNCN)Ni(CH2 CN) based on weaker σ-donating imines had energetics more favorable than the reported efficient catalyst (iPr2 POCNEt2 )Ni(CH2 CN). While strong trans-influencing C as the pincer central atom was found to be pivotal for lowering the cyanomethylation kinetics, presence of a poor trans-influencing N proved to be detrimental on the overall energetics.
Collapse
Affiliation(s)
- Moumita Dutta
- Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati, India
| | - Hemant Kumar Srivastava
- Department of Medicinal Chemistry, National Institute of Pharmaceutical Education and Research Guwahati, Guwahati, Assam, India
| | - Akshai Kumar
- Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati, India.,Centre for Nanotechnology, Indian Institute of Technology Guwahati, Guwahati, India
| |
Collapse
|
18
|
Zhao F, Shu C, Young CM, Carpenter‐Warren C, Slawin AMZ, Smith AD. Enantioselective Synthesis of α-Aryl-β 2 -Amino-Esters by Cooperative Isothiourea and Brønsted Acid Catalysis. Angew Chem Int Ed Engl 2021; 60:11892-11900. [PMID: 33646631 PMCID: PMC8252622 DOI: 10.1002/anie.202016220] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2020] [Indexed: 01/07/2023]
Abstract
The synthesis of α-aryl-β2 -amino esters through enantioselective aminomethylation of an arylacetic acid ester in high yields and enantioselectivity via cooperative isothiourea and Brønsted acid catalysis is demonstrated. The scope and limitations of this process are explored (25 examples, up to 94 % yield and 96:4 er), with applications to the synthesis of (S)-Venlafaxine⋅HCl and (S)-Nakinadine B. Mechanistic studies are consistent with a C(1)-ammonium enolate pathway being followed rather than an alternative dynamic kinetic resolution process. Control studies indicate that (i) a linear effect between catalyst and product er is observed; (ii) an acyl ammonium ion can be used as a precatalyst; (iii) reversible isothiourea addition to an in situ generated iminium ion leads to an off-cycle intermediate that can be used as a productive precatalyst.
Collapse
Affiliation(s)
- Feng Zhao
- EaStCHEMSchool of ChemistryUniversity of St AndrewsSt AndrewsFifeKY16 9STUK
| | - Chang Shu
- EaStCHEMSchool of ChemistryUniversity of St AndrewsSt AndrewsFifeKY16 9STUK
| | - Claire M. Young
- EaStCHEMSchool of ChemistryUniversity of St AndrewsSt AndrewsFifeKY16 9STUK
| | | | | | - Andrew D. Smith
- EaStCHEMSchool of ChemistryUniversity of St AndrewsSt AndrewsFifeKY16 9STUK
| |
Collapse
|
19
|
Liu Y, Jiang H, Hou Z. Hidden Mechanism Behind the Roughness-Enhanced Selectivity of Carbon Monoxide Electrocatalytic Reduction. Angew Chem Int Ed Engl 2021; 60:11133-11137. [PMID: 33660382 DOI: 10.1002/anie.202016332] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Indexed: 02/06/2023]
Abstract
High roughness has been proved to be an effective design strategy for electrocatalyst in many systems. Especially, high selectivity of carbon monoxide reduction (CORR) in competition with the hydrogen evolution reaction has been observed on high roughness electrocatalysts. However, the two well-known mechanisms, i.e., decreasing the energy barrier of CORR and increasing local pH, failed to understand the roughness-enhanced selectivity in a recent experiment. Herein we unravel the hidden mechanism by establishing a comprehensive kinetic model for CORR on catalysts with different roughness factors. We conclude that the roughness-enhanced CORR selectivity is actually kinetic controlled by local-electric-field-directed mass transfer of adsorbed species on the electrode surface. Several ways to optimize CORR selectivity are predicted. Our work highlights the kinetics in electrocatalysis on nanocatalysts, and provides a conceptually new principle for future catalyst design.
Collapse
Affiliation(s)
- Yinghuan Liu
- Department of Chemical Physics & Hefei National Laboratory for Physical Sciences at the Microscale, iChEM, University of Science and Technology of China, Hefei, Anhui, 230026, China
| | - Huijun Jiang
- Department of Chemical Physics & Hefei National Laboratory for Physical Sciences at the Microscale, iChEM, University of Science and Technology of China, Hefei, Anhui, 230026, China
| | - Zhonghuai Hou
- Department of Chemical Physics & Hefei National Laboratory for Physical Sciences at the Microscale, iChEM, University of Science and Technology of China, Hefei, Anhui, 230026, China
| |
Collapse
|
20
|
Han Jie L, Jantan I, Yusoff SD, Jalil J, Husain K. Sinensetin: An Insight on Its Pharmacological Activities, Mechanisms of Action and Toxicity. Front Pharmacol 2021; 11:553404. [PMID: 33628166 PMCID: PMC7898666 DOI: 10.3389/fphar.2020.553404] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2020] [Accepted: 12/11/2020] [Indexed: 12/11/2022] Open
Abstract
Sinensetin, a plant-derived polymethoxylated flavonoid found in Orthosiphon aristatus var. aristatus and several citrus fruits, has been found to possess strong anticancer activities and a variety of other pharmacological benefits and promising potency in intended activities with minimal toxicity. This review aims to compile an up-to-date reports of published scientific information on sinensetin pharmacological activities, mechanisms of action and toxicity. The present findings about the compound are critically analyzed and its prospect as a lead molecule for drug discovery is highlighted. The databases employed for data collection are mainly through Google Scholar, PubMed, Scopus and Science Direct. In-vitro and in-vivo studies showed that sinensetin possessed strong anticancer activities and a wide range of pharmacological activities such as anti-inflammatory, antioxidant, antimicrobial, anti-obesity, anti-dementia and vasorelaxant activities. The studies provided some insights on its several mechanisms of action in cancer and other disease states. However, more detail mechanistic studies are needed to understand its pharmacological effects. More in vivo studies in various animal models including toxicity, pharmacokinetic, pharmacodynamic and bioavailability studies are required to assess its efficacy and safety before submission to clinical studies. In this review, an insight on sinensetin pharmacological activities and mechanisms of action serves as a useful resource for a more thorough and comprehensive understanding of sinensetin as a potential lead candidate for drug discovery.
Collapse
Affiliation(s)
- Lee Han Jie
- Drug and Herbal Research Centre, Faculty of Pharmacy, Universiti Kebangsaan Malaysia, Kuala Lumpur, Malaysia
| | - Ibrahim Jantan
- Institute of Systems Biology, Universiti Kebangsaan Malaysia, Bangi, Malaysia
| | - Syaratul Dalina Yusoff
- Drug and Herbal Research Centre, Faculty of Pharmacy, Universiti Kebangsaan Malaysia, Kuala Lumpur, Malaysia
| | - Juriyati Jalil
- Drug and Herbal Research Centre, Faculty of Pharmacy, Universiti Kebangsaan Malaysia, Kuala Lumpur, Malaysia
| | - Khairana Husain
- Drug and Herbal Research Centre, Faculty of Pharmacy, Universiti Kebangsaan Malaysia, Kuala Lumpur, Malaysia
| |
Collapse
|
21
|
de Castro AA, Polisel DA, Pereira BTL, da Cunha EFF, Kuca K, Nepovimova E, Ramalho TC. Understanding the Interaction Modes and Reactivity of Trimedoxime toward MmAChE Inhibited by Nerve Agents: Theoretical and Experimental Aspects. Int J Mol Sci 2020; 21:E6510. [PMID: 32899591 DOI: 10.3390/ijms21186510] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2020] [Revised: 08/31/2020] [Accepted: 09/02/2020] [Indexed: 11/17/2022] Open
Abstract
Organophosphorus (OP) compounds are used as both chemical weapons and pesticides. However, these agents are very dangerous and toxic to humans, animals, and the environment. Thus, investigations with reactivators have been deeply developed in order to design new antidotes with better efficiency, as well as a greater spectrum of action in the acetylcholinesterase (AChE) reactivation process. With that in mind, in this work, we investigated the behavior of trimedoxime toward the Mus musculus acetylcholinesterase (MmAChE) inhibited by a range of nerve agents, such as chemical weapons. From experimental assays, reactivation percentages were obtained for the reactivation of different AChE–OP complexes. On the other hand, theoretical calculations were performed to assess the differences in interaction modes and the reactivity of trimedoxime within the AChE active site. Comparing theoretical and experimental data, it is possible to notice that the oxime, in most cases, showed better reactivation percentages at higher concentrations, with the best result for the reactivation of the AChE–VX adduct. From this work, it was revealed that the mechanistic process contributes most to the oxime efficiency than the interaction in the site. In this way, this study is important to better understand the reactivation process through trimedoxime, contributing to the proposal of novel antidotes.
Collapse
|
22
|
Kathuria L, Din Reshi NU, Samuelson AG. N-Heterocyclic Carbene (NHC)-Stabilized Ru 0 Nanoparticles: In Situ Generation of an Efficient Transfer Hydrogenation Catalyst. Chemistry 2020; 26:7622-7630. [PMID: 32048353 DOI: 10.1002/chem.202000142] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2020] [Indexed: 11/06/2022]
Abstract
Tethered and untethered ruthenium half-sandwich complexes were synthesized and characterized spectroscopically. X-ray crystallographic analysis of three untethered and two tethered Ru N-heterocyclic carbene (NHC) complexes were also carried out. These RuNHC complexes catalyze transfer hydrogenation of aromatic ketones in 2-propanol under reflux, optimally in the presence of (25 mol %) KOH. Under these conditions, the formation of 2-3 nm-sized Ru0 nanoparticles was detected by TEM measurements. A solid-state NMR investigation of the nanoparticles suggested that the NHC ligands were bound to the surface of the Ru nanoparticles (NPs). This base-promoted route to NHC-stabilized ruthenium nanoparticles directly from arene-tethered ruthenium-NHC complexes and from untethered ruthenium-NHC complexes is more convenient than previously known routes to NHC-stabilized Ru nanocatalysts. Similar catalytically active RuNPs were also generated from the reaction of a mixture of [RuCl2 (p-cymene)]2 and the NHC precursor with KOH in isopropanol under reflux. The transfer hydrogenation catalyzed by these NHC-stabilized RuNPs possess a high turnover number. The catalytic efficiency was significantly reduced if nanoparticles were exposed to air or allowed to aggregate and precipitate by cooling the reaction mixtures during the reaction.
Collapse
Affiliation(s)
- Lakshay Kathuria
- Inorganic and Physical Chemistry Department, Indian Institute of Science, Bangalore, Karnataka, 560012, India
| | - Noor U Din Reshi
- Inorganic and Physical Chemistry Department, Indian Institute of Science, Bangalore, Karnataka, 560012, India
| | - Ashoka G Samuelson
- Inorganic and Physical Chemistry Department, Indian Institute of Science, Bangalore, Karnataka, 560012, India
| |
Collapse
|
23
|
Mu’azu ND, Zubair M, Jarrah N, Alagha O, Al-Harthi MA, Essa MH. Sewage Sludge ZnCl 2-Activated Carbon Intercalated MgFe-LDH Nanocomposites: Insight of the Sorption Mechanism of Improved Removal of Phenol from Water. Int J Mol Sci 2020; 21:E1563. [PMID: 32106562 PMCID: PMC7084656 DOI: 10.3390/ijms21051563] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2020] [Revised: 02/19/2020] [Accepted: 02/23/2020] [Indexed: 11/23/2022] Open
Abstract
Keywords: sludge-activated carbon; MgFe layered double hydroxide; nanocomposite materials; phenol aqueous uptake; mechanistic studies; reusability performance.
Collapse
Affiliation(s)
- Nuhu Dalhat Mu’azu
- Department of Environmental Engineering, College of Engineering, Imam Abdulrahman Bin Faisal University, P.O. Box 1982, Dammam 31451, Saudi Arabia; (M.Z.)
| | - Mukarram Zubair
- Department of Environmental Engineering, College of Engineering, Imam Abdulrahman Bin Faisal University, P.O. Box 1982, Dammam 31451, Saudi Arabia; (M.Z.)
| | - Nabeel Jarrah
- Department of Chemical Engineering, Mutah University, Karak 61710, Jordan
| | - Omar Alagha
- Department of Environmental Engineering, College of Engineering, Imam Abdulrahman Bin Faisal University, P.O. Box 1982, Dammam 31451, Saudi Arabia; (M.Z.)
| | - Mamdouh A. Al-Harthi
- Department of Chemical Engineering, King Fahd University of Petroleum & Minerals, Dhahran 31261, Saudi Arabia
- Center of Research Excellences in Nanotechnology, King Fahd University of Petroleum & Minerals, Dhahran 31261, Saudi Arabia
| | - Mohammed H. Essa
- Department of Civil Environmental Engineering, King Fahd University of Petroleum & Minerals, Dhahran 31261, Saudi Arabia
| |
Collapse
|
24
|
Nijamudheen A, Datta A. Gold-Catalyzed Cross-Coupling Reactions: An Overview of Design Strategies, Mechanistic Studies, and Applications. Chemistry 2019; 26:1442-1487. [PMID: 31657487 DOI: 10.1002/chem.201903377] [Citation(s) in RCA: 100] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2019] [Revised: 10/28/2019] [Indexed: 12/14/2022]
Abstract
Transition-metal-catalyzed cross-coupling reactions are central to many organic synthesis methodologies. Traditionally, Pd, Ni, Cu, and Fe catalysts are used to promote these reactions. Recently, many studies have showed that both homogeneous and heterogeneous Au catalysts can be used for activating selective cross-coupling reactions. Here, an overview of the past studies, current trends, and future directions in the field of gold-catalyzed coupling reactions is presented. Design strategies to accomplish selective homocoupling and cross-coupling reactions under both homogeneous and heterogeneous conditions, computational and experimental mechanistic studies, and their applications in diverse fields are critically reviewed. Specific topics covered are: oxidant-assisted and oxidant-free reactions; strain-assisted reactions; dual Au and photoredox catalysis; bimetallic synergistic reactions; mechanisms of reductive elimination processes; enzyme-mimicking Au chemistry; cluster and surface reactions; and plasmonic catalysis. In the relevant sections, theoretical and computational studies of AuI /AuIII chemistry are discussed and the predictions from the calculations are compared with the experimental observations to derive useful design strategies.
Collapse
Affiliation(s)
- A Nijamudheen
- School of Chemical Sciences, Indian Association for the, Cultivation of Sciences, 2A & 2B Raja S C Mullick Road, Kolkata, 700032, India.,Department of Chemical & Biomedical Engineering, Florida A&M University-Florida State University, Joint College of Engineering, 2525 Pottsdamer Street, Tallahassee, FL, 32310, USA
| | - Ayan Datta
- School of Chemical Sciences, Indian Association for the, Cultivation of Sciences, 2A & 2B Raja S C Mullick Road, Kolkata, 700032, India
| |
Collapse
|
25
|
Aguilar Troyano FJ, Ballaschk F, Jaschinski M, Özkaya Y, Gómez‐Suárez A. Light-Mediated Formal Radical Deoxyfluorination of Tertiary Alcohols through Selective Single-Electron Oxidation with TEDA 2+.. Chemistry 2019; 25:14054-14058. [PMID: 31452265 PMCID: PMC6899844 DOI: 10.1002/chem.201903702] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2019] [Indexed: 01/28/2023]
Abstract
The synthesis of tertiary alkyl fluorides through a formal radical deoxyfluorination process is described herein. This light-mediated, catalyst-free methodology is fast and broadly applicable allowing for the preparation of C-F bonds from (hetero)benzylic, propargylic, and non-activated tertiary alcohol derivatives. Preliminary mechanistic studies support that the key step of the reaction is the single-electron oxidation of cesium oxalates-which are readily available from the corresponding tertiary alcohols-with in situ generated TEDA2+. (TEDA: N-(chloromethyl)triethylenediamine), a radical cation derived from Selectfluor®.
Collapse
Affiliation(s)
| | - Frederic Ballaschk
- Organic ChemistryBergische Universität WuppertalGaußstrasse 2042119WuppertalGermany
| | - Marcel Jaschinski
- Organic ChemistryBergische Universität WuppertalGaußstrasse 2042119WuppertalGermany
| | - Yasemin Özkaya
- Organic ChemistryBergische Universität WuppertalGaußstrasse 2042119WuppertalGermany
| | - Adrián Gómez‐Suárez
- Organic ChemistryBergische Universität WuppertalGaußstrasse 2042119WuppertalGermany
| |
Collapse
|
26
|
Lanzoni A, Castoldi AF, Kass GE, Terron A, De Seze G, Bal-Price A, Bois FY, Delclos KB, Doerge DR, Fritsche E, Halldorsson T, Kolossa-Gehring M, Hougaard Bennekou S, Koning F, Lampen A, Leist M, Mantus E, Rousselle C, Siegrist M, Steinberg P, Tritscher A, Van de Water B, Vineis P, Walker N, Wallace H, Whelan M, Younes M. Advancing human health risk assessment. EFSA J 2019; 17:e170712. [PMID: 32626449 PMCID: PMC7015480 DOI: 10.2903/j.efsa.2019.e170712] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
The current/traditional human health risk assessment paradigm is challenged by recent scientific and technical advances, and ethical demands. The current approach is considered too resource intensive, is not always reliable, can raise issues of reproducibility, is mostly animal based and does not necessarily provide an understanding of the underlying mechanisms of toxicity. From an ethical and scientific viewpoint, a paradigm shift is required to deliver testing strategies that enable reliable, animal-free hazard and risk assessments, which are based on a mechanistic understanding of chemical toxicity and make use of exposure science and epidemiological data. This shift will require a new philosophy, new data, multidisciplinary expertise and more flexible regulations. Re-engineering of available data is also deemed necessary as data should be accessible, readable, interpretable and usable. Dedicated training to build the capacity in terms of expertise is necessary, together with practical resources allocated to education. The dialogue between risk assessors, risk managers, academia and stakeholders should be promoted further to understand scientific and societal needs. Genuine interest in taking risk assessment forward should drive the change and should be supported by flexible funding. This publication builds upon presentations made and discussions held during the break-out session 'Advancing risk assessment science - Human health' at EFSA's third Scientific Conference 'Science, Food and Society' (Parma, Italy, 18-21 September 2018).
Collapse
Affiliation(s)
| | | | | | | | | | | | - Frédéric Y Bois
- French National Institute for Industrial Environment and Risks FR
| | - K Barry Delclos
- National Center for Toxicological Research US Food and Drug Administration USA
| | - Daniel R Doerge
- National Center for Toxicological Research US Food and Drug Administration USA
| | - Ellen Fritsche
- Leibniz Research Institute for Environmental Medicine DE
| | | | | | | | | | | | | | - Ellen Mantus
- The National Academies of Sciences, Engineering, and Medicine USA
| | | | | | | | | | - Bob Van de Water
- Drug Discovery and Safety Leiden Academic Centre for Drug Research Leiden University NL
| | | | - Nigel Walker
- National Toxicology Program/National Institute of Environmental Health Sciences USA
| | - Heather Wallace
- Institute of Medical Sciences University of Aberdeen Scotland UK
| | | | | |
Collapse
|
27
|
Russell MS, Creskey M, Muralidharan A, Li C, Gao J, Chen W, Larocque L, Lavoie JR, Farnsworth A, Rosu-Myles M, Hashem AM, Yauk CL, Cao J, Van Domselaar G, Cyr T, Li X. Unveiling Integrated Functional Pathways Leading to Enhanced Respiratory Disease Associated With Inactivated Respiratory Syncytial Viral Vaccine. Front Immunol 2019; 10:597. [PMID: 30984178 PMCID: PMC6449435 DOI: 10.3389/fimmu.2019.00597] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2018] [Accepted: 03/06/2019] [Indexed: 02/01/2023] Open
Abstract
Respiratory syncytial virus (RSV) infection is a severe threat to young children and the elderly. Despite decades of research, no vaccine has been approved. Notably, instead of affording protection, a formalin-inactivated RSV vaccine induced severe respiratory disease including deaths in vaccinated children in a 1960s clinical trial; however, recent studies indicate that other forms of experimental vaccines can also induce pulmonary pathology in pre-clinical studies. These findings suggest that multiple factors/pathways could be involved in the development of enhanced respiratory diseases. Clearly, a better understanding of the mechanisms underlying such adverse reactions is critically important for the development of safe and efficacious vaccines against RSV infection, given the exponential growth of RSV vaccine clinical trials in recent years. By employing an integrated systems biology approach in a pre-clinical cotton rat model, we unraveled a complex network of pulmonary canonical pathways leading to disease development in vaccinated animals upon subsequent RSV infections. Cytokines including IL-1, IL-6 GRO/IL-8, and IL-17 in conjunction with mobilized pulmonary inflammatory cells could play important roles in disease development, which involved a wide range of host responses including exacerbated pulmonary inflammation, oxidative stress, hyperreactivity, and homeostatic imbalance between coagulation and fibrinolysis. Moreover, the observed elevated levels of MyD88 implicate the involvement of this critical signal transduction module as the central node of the inflammatory pathways leading to exacerbated pulmonary pathology. Finally, the immunopathological consequences of inactivated vaccine immunization and subsequent RSV exposure were further substantiated by histological analyses of these key proteins along with inflammatory cytokines, while hypercoagulation was supported by increased pulmonary fibrinogen/fibrin accompanied by reduced levels of plasma D-dimers. Enhanced respiratory disease associated with inactivated RSV vaccine involves a complex network of host responses, resulting in significant pulmonary lesions and clinical manifestations such as tachypnea and airway obstruction. The mechanistic insight into the convergence of different signal pathways and identification of biomarkers could help facilitate the development of safe and effective RSV vaccine and formulation of new targeted interventions.
Collapse
Affiliation(s)
- Marsha S Russell
- Centre for Biologics Evaluation, Biologics and Genetic Therapies Directorate, Health Products and Food Branch (HPFB), Health Canada and WHO Collaborating Center for Standardization and Evaluation of Biologicals, Ottawa, ON, Canada
| | - Marybeth Creskey
- Centre for Biologics Evaluation, Biologics and Genetic Therapies Directorate, Health Products and Food Branch (HPFB), Health Canada and WHO Collaborating Center for Standardization and Evaluation of Biologicals, Ottawa, ON, Canada
| | - Abenaya Muralidharan
- Centre for Biologics Evaluation, Biologics and Genetic Therapies Directorate, Health Products and Food Branch (HPFB), Health Canada and WHO Collaborating Center for Standardization and Evaluation of Biologicals, Ottawa, ON, Canada.,Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, ON, Canada
| | - Changgui Li
- National Institutes for Food and Drug Control, WHO Collaborating Center for Standardization and Evaluation of Biologicals, Beijing, China
| | - Jun Gao
- Centre for Biologics Evaluation, Biologics and Genetic Therapies Directorate, Health Products and Food Branch (HPFB), Health Canada and WHO Collaborating Center for Standardization and Evaluation of Biologicals, Ottawa, ON, Canada
| | - Wangxue Chen
- Human Health Therapeutics Research Centre, National Research Council Canada, Ottawa, ON, Canada
| | - Louise Larocque
- Centre for Biologics Evaluation, Biologics and Genetic Therapies Directorate, Health Products and Food Branch (HPFB), Health Canada and WHO Collaborating Center for Standardization and Evaluation of Biologicals, Ottawa, ON, Canada
| | - Jessie R Lavoie
- Centre for Biologics Evaluation, Biologics and Genetic Therapies Directorate, Health Products and Food Branch (HPFB), Health Canada and WHO Collaborating Center for Standardization and Evaluation of Biologicals, Ottawa, ON, Canada
| | - Aaron Farnsworth
- Centre for Biologics Evaluation, Biologics and Genetic Therapies Directorate, Health Products and Food Branch (HPFB), Health Canada and WHO Collaborating Center for Standardization and Evaluation of Biologicals, Ottawa, ON, Canada
| | - Michael Rosu-Myles
- Centre for Biologics Evaluation, Biologics and Genetic Therapies Directorate, Health Products and Food Branch (HPFB), Health Canada and WHO Collaborating Center for Standardization and Evaluation of Biologicals, Ottawa, ON, Canada.,Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, ON, Canada
| | - Anwar M Hashem
- Immunotherapy Unit, Department of Medical Microbiology and Parasitology, Faculty of Medicine and Vaccines, King Fahd Medical Research Center, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Carole L Yauk
- Mechanistic Studies Division, Environmental and Radiation Health Sciences Directorate, Healthy Environments and Consumer Safety Branch (HECSB), Health Canada, Ottawa, ON, Canada
| | - Jingxin Cao
- National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, MB, Canada
| | - Gary Van Domselaar
- National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, MB, Canada
| | - Terry Cyr
- Centre for Biologics Evaluation, Biologics and Genetic Therapies Directorate, Health Products and Food Branch (HPFB), Health Canada and WHO Collaborating Center for Standardization and Evaluation of Biologicals, Ottawa, ON, Canada
| | - Xuguang Li
- Centre for Biologics Evaluation, Biologics and Genetic Therapies Directorate, Health Products and Food Branch (HPFB), Health Canada and WHO Collaborating Center for Standardization and Evaluation of Biologicals, Ottawa, ON, Canada.,Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, ON, Canada
| |
Collapse
|
28
|
Yusof ENM, Latif MAM, Tahir MIM, Sakoff JA, Simone MI, Page AJ, Veerakumarasivam A, Tiekink ERT, Ravoof TBSA. o-Vanillin Derived Schiff Bases and Their Organotin(IV) Compounds: Synthesis, Structural Characterisation, In-Silico Studies and Cytotoxicity. Int J Mol Sci 2019; 20:ijms20040854. [PMID: 30781445 PMCID: PMC6413231 DOI: 10.3390/ijms20040854] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2018] [Revised: 12/28/2018] [Accepted: 12/30/2018] [Indexed: 12/23/2022] Open
Abstract
Six new organotin(IV) compounds of Schiff bases derived from S-R-dithiocarbazate [R = benzyl (B), 2- or 4-methylbenzyl (2M and 4M, respectively)] condensed with 2-hydroxy-3-methoxybenzaldehyde (oVa) were synthesised and characterised by elemental analysis, various spectroscopic techniques including infrared, UV-vis, multinuclear (1H, 13C, 119Sn) NMR and mass spectrometry, and single crystal X-ray diffraction. The organotin(IV) compounds were synthesised from the reaction of Ph2SnCl2 or Me2SnCl2 with the Schiff bases (S2MoVaH/S4MoVaH/SBoVaH) to form a total of six new organotin(IV) compounds that had a general formula of [R2Sn(L)] (where L = Schiff base; R = Ph or Me). The molecular geometries of Me2Sn(S2MoVa), Me2Sn(S4MoVa) and Me2Sn(SBoVa) were established by X-ray crystallography and verified using density functional theory calculations. Interestingly, each experimental structure contained two independent but chemically similar molecules in the crystallographic asymmetric unit. The coordination geometry for each molecule was defined by thiolate-sulphur, phenoxide-oxygen and imine-nitrogen atoms derived from a dinegative, tridentate dithiocarbazate ligand with the remaining positions occupied by the methyl-carbon atoms of the organo groups. In each case, the resulting five-coordinate C2NOS geometry was almost exactly intermediate between ideal trigonal-bipyramidal and square-pyramidal geometries. The cytotoxic activities of the Schiff bases and organotin(IV) compounds were investigated against EJ-28 and RT-112 (bladder), HT29 (colon), U87 and SJ-G2 (glioblastoma), MCF-7 (breast) A2780 (ovarian), H460 (lung), A431 (skin), DU145 (prostate), BE2-C (neuroblastoma) and MIA (pancreatic) cancer cell lines and one normal breast cell line (MCF-10A). Diphenyltin(IV) compounds exhibited greater potency than either the Schiff bases or the respective dimethyltin(IV) compounds. Mechanistic studies on the action of these compounds against bladder cancer cells revealed that they induced the production of reactive oxygen species (ROS). The bladder cancer cells were apoptotic after 24 h post-treatment with the diphenyltin(IV) compounds. The interactions of the organotin(IV) compounds with calf thymus DNA (CT-DNA) were experimentally explored using UV-vis absorption spectroscopy. This study revealed that the organotin(IV) compounds have strong DNA binding affinity, verified via molecular docking simulations, which suggests that these organotin(IV) compounds interact with DNA via groove-binding interactions.
Collapse
Affiliation(s)
- Enis Nadia Md Yusof
- Department of Chemistry, Faculty of Science, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor Darul Ehsan, Malaysia.
- Discipline of Chemistry, School of Environmental and Life Sciences, University of Newcastle, University Drive, Callaghan, NSW 2308, Australia.
| | - Muhammad A M Latif
- Department of Chemistry, Faculty of Science, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor Darul Ehsan, Malaysia.
| | - Mohamed I M Tahir
- Department of Chemistry, Faculty of Science, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor Darul Ehsan, Malaysia.
| | - Jennette A Sakoff
- Experimental Therapeutics Group, Department of Medical Oncology, Calvary Mater Newcastle Hospital, Edith Street, Waratah NSW 2298, Australia.
| | - Michela I Simone
- Discipline of Chemistry, School of Environmental and Life Sciences, University of Newcastle, University Drive, Callaghan, NSW 2308, Australia.
- Priority Research Centre for Chemical Biology & Clinical Pharmacology, University of Newcastle, University Drive, Callaghan, NSW 2308, Australia.
| | - Alister J Page
- Discipline of Chemistry, School of Environmental and Life Sciences, University of Newcastle, University Drive, Callaghan, NSW 2308, Australia.
| | - Abhi Veerakumarasivam
- Department of Biological Sciences, School of Science and Technology, Sunway University, No. 5 Jalan Universiti, 47500 Bandar Sunway, Selangor Darul Ehsan, Malaysia.
- Medical Genetics Laboratory, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor Darul Ehsan, Malaysia.
| | - Edward R T Tiekink
- Research Centre for Crystalline Materials, School of Science and Technology, Sunway University, No. 5 Jalan Universiti, 47500 Bandar Sunway, Selangor Darul Ehsan, Malaysia.
| | - Thahira B S A Ravoof
- Department of Chemistry, Faculty of Science, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor Darul Ehsan, Malaysia.
- Materials Synthesis and Characterization Laboratory, Institute of Advanced Technology, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor Darul Ehsan, Malaysia.
| |
Collapse
|
29
|
Li H, Obligacion JV, Chirik PJ, Hall MB. Cobalt Pincer Complexes in Catalytic C-H Borylation: The Pincer Ligand Flips Rather Than Dearomatizes. ACS Catal 2018; 8:10606-10618. [PMID: 30719402 DOI: 10.1021/acscatal.8b03146] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The mechanism for the borylation of an aromatic substrate by a cobalt pincer complex was investigated by density functional theory calculations. Experimental observations identified trans-(iPrPNP)CoH2(BPin) as the resting state in the borylation of five-membered heteroarenes, and 4-BPin-(iPrPNP)Co(N2)BPin as the resting state in the catalytic borylation of arene substrates. The active species, 4-R-(iPrPNP)CoBPin (R=H, BPin), were generated by reductive elimination of H2 in the former, through Berry pseudorotation to the cis isomer, and N2 loss in the latter. The catalytic mechanism of the resulting Co(I) complex was computed to involve three main steps: C-H oxidative addition of the aromatic substrate (C6H6), reductive elimination of PhBPin, and regeneration of the active complex. The oxidative addition product formed through the most favorable pathway, where the breaking C-H bond of C6H6 is parallel to a line between the two phosphine atoms, leaves the complex with a distorted PNP ligand, which rearranges to a more stable complex via dissociation and re-association of HBPin. Alternative pathways, σ-bond metathesis and the oxidative addition in which the breaking C-H bond is parallel to the Co-B bond, are predicted to be unlikely for this Co(I) complex. The thermodynamically favorable formation of the product PhBPin via reductive elimination drives the reaction forward. The active species regenerates through the oxidative addition of B2Pin2 and reductive elimination of HBPin. In the overall reaction, the flipping (refolding) of the five-membered phosphine rings, which connects the species with two phosphine rings folded in the same direction and that with them folded in different directions, is found to play an important role in the catalytic process, as it relieves steric crowding within the PNP ligand and opens Co coordination space. Metal-ligand cooperation based on the ligand's aromatization/dearomatization, a common mechanism for heavy-metal pincer complexes, and the dissociation of one phosphine ligand, do not apply in this system. This study provides guidance for understanding important features of pincer ligands with first-transition-row metals that differ from those in heavier metal complexes.
Collapse
Affiliation(s)
- Haixia Li
- Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States
| | - Jennifer V. Obligacion
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
| | - Paul J. Chirik
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
| | - Michael B. Hall
- Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States
| |
Collapse
|
30
|
Zhou B, Yan L, Tao L, Song N, Wu M, Wang T, Zhang Q. Enabling Photon Upconversion and Precise Control of Donor-Acceptor Interaction through Interfacial Energy Transfer. Adv Sci (Weinh) 2018; 5:1700667. [PMID: 29593969 PMCID: PMC5867046 DOI: 10.1002/advs.201700667] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2017] [Revised: 10/19/2017] [Indexed: 05/04/2023]
Abstract
Upconverting materials have achieved great progress in recent years, however, it remains challenging for the mechanistic research on new upconversion strategy of lanthanides. Here, a novel and efficient strategy to realize photon upconversion from more lanthanides and fine control of lanthanide donor-acceptor interactions through using the interfacial energy transfer (IET) is reported. Unlike conventional energy-transfer upconversion and recently reported energy-migration upconversion, the IET approach is capable of enabling upconversions from Er3+, Tm3+, Ho3+, Tb3+, Eu3+, Dy3+ to Sm3+ in NaYF4- and NaYbF4-based core-shell nanostructures simultaneously. Applying the IET in a Nd-Yb coupled sensitizing system can also enable the 808/980 nm dual-wavelength excited upconversion from a single particle. More importantly, the construction of IET concept allows for a fine control and manipulation of lanthanide donor-acceptor interactions and dynamics at the nanometer-length scale by establishing a physical model upon an interlayer-mediated nanostructure. These findings open a door for the fundamental understanding of the luminescence dynamics involving lanthanides at nanoscale, which would further help conceive new scientific concepts and control photon upconversion at a single lanthanide ion level.
Collapse
Affiliation(s)
- Bo Zhou
- State Key Laboratory of Luminescent Materials and Devicesand Institute of Optical Communication MaterialsSouth China University of TechnologyGuangzhou510641China
| | - Long Yan
- State Key Laboratory of Luminescent Materials and Devicesand Institute of Optical Communication MaterialsSouth China University of TechnologyGuangzhou510641China
| | - Lili Tao
- School of Materials and EnergyGuangdong University of TechnologyGuangzhou510006China
| | - Nan Song
- State Key Laboratory of Luminescent Materials and Devicesand Institute of Optical Communication MaterialsSouth China University of TechnologyGuangzhou510641China
| | - Ming Wu
- State Key Laboratory of Luminescent Materials and Devicesand Institute of Optical Communication MaterialsSouth China University of TechnologyGuangzhou510641China
| | - Ting Wang
- State Key Laboratory of Luminescent Materials and Devicesand Institute of Optical Communication MaterialsSouth China University of TechnologyGuangzhou510641China
| | - Qinyuan Zhang
- State Key Laboratory of Luminescent Materials and Devicesand Institute of Optical Communication MaterialsSouth China University of TechnologyGuangzhou510641China
| |
Collapse
|
31
|
Brazzolotto D, Cantú Reinhard FG, Smith-Jones J, Retegan M, Amidani L, Faponle AS, Ray K, Philouze C, de Visser SP, Gennari M, Duboc C. A High-Valent Non-Heme μ-Oxo Manganese(IV) Dimer Generated from a Thiolate-Bound Manganese(II) Complex and Dioxygen. Angew Chem Int Ed Engl 2017; 56:8211-8215. [PMID: 28544340 DOI: 10.1002/anie.201703215] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2017] [Revised: 05/04/2017] [Indexed: 11/12/2022]
Abstract
This study deals with the unprecedented reactivity of dinuclear non-heme MnII -thiolate complexes with O2 , which dependent on the protonation state of the initial MnII dimer selectively generates either a di-μ-oxo or μ-oxo-μ-hydroxo MnIV complex. Both dimers have been characterized by different techniques including single-crystal X-ray diffraction and mass spectrometry. Oxygenation reactions carried out with labeled 18 O2 unambiguously show that the oxygen atoms present in the MnIV dimers originate from O2 . Based on experimental observations and DFT calculations, evidence is provided that these MnIV species comproportionate with a MnII precursor to yield μ-oxo and/or μ-hydroxo MnIII dimers. Our work highlights the delicate balance of reaction conditions to control the synthesis of non-heme high-valent μ-oxo and μ-hydroxo Mn species from MnII precursors and O2 .
Collapse
Affiliation(s)
- Deborah Brazzolotto
- Univ. Grenoble Alpes, CNRS, UMR 5250, DCM, 38000, Grenoble, France.,Univ. Grenoble Alpes, CNRS, UMR 5249, LCBM, 38000, Grenoble, France
| | - Fabián G Cantú Reinhard
- Manchester Institute of Biotechnology and School of Chemical Engineering and Analytical Science, The University of Manchester, 131 Princess Street, Manchester, M1 7DN, UK
| | | | - Marius Retegan
- European Synchrotron Radiation Facility (ESRF), 71 Avenue des Martyrs, 38000, Grenoble, France
| | - Lucia Amidani
- European Synchrotron Radiation Facility (ESRF), 71 Avenue des Martyrs, 38000, Grenoble, France
| | - Abayomi S Faponle
- Manchester Institute of Biotechnology and School of Chemical Engineering and Analytical Science, The University of Manchester, 131 Princess Street, Manchester, M1 7DN, UK
| | - Kallol Ray
- Department of Chemistry, Humboldt-Universität zu Berlin, Brook-Taylor-Strasse 2, 12489, Berlin, Germany
| | | | - Sam P de Visser
- Manchester Institute of Biotechnology and School of Chemical Engineering and Analytical Science, The University of Manchester, 131 Princess Street, Manchester, M1 7DN, UK
| | - Marcello Gennari
- Univ. Grenoble Alpes, CNRS, UMR 5250, DCM, 38000, Grenoble, France
| | - Carole Duboc
- Univ. Grenoble Alpes, CNRS, UMR 5250, DCM, 38000, Grenoble, France
| |
Collapse
|
32
|
Casadevall C, Codolà Z, Costas M, Lloret-Fillol J. Spectroscopic, Electrochemical and Computational Characterisation of Ru Species Involved in Catalytic Water Oxidation: Evidence for a [Ru(V) (O)(Py2 (Me) tacn)] Intermediate. Chemistry 2016; 22:10111-26. [PMID: 27324949 DOI: 10.1002/chem.201600584] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2016] [Indexed: 01/09/2023]
Abstract
A new family of ruthenium complexes based on the N-pentadentate ligand Py2 (Me) tacn (N-methyl-N',N''-bis(2-picolyl)-1,4,7-triazacyclononane) has been synthesised and its catalytic activity has been studied in the water-oxidation (WO) reaction. We have used chemical oxidants (ceric ammonium nitrate and NaIO4 ) to generate the WO intermediates [Ru(II) (OH2 )(Py2 (Me) tacn)](2+) , [Ru(III) (OH2 )(Py2 (Me) tacn)](3+) , [Ru(III) (OH)(Py2 (Me) tacn)](2+) and [Ru(IV) (O)(Py2 (Me) tacn)](2+) , which have been characterised spectroscopically. Their relative redox and pH stability in water has been studied by using UV/Vis and NMR spectroscopies, HRMS and spectroelectrochemistry. [Ru(IV) (O)(Py2 (Me) tacn)](2+) has a long half-life (>48 h) in water. The catalytic cycle of WO has been elucidated by using kinetic, spectroscopic, (18) O-labelling and theoretical studies, and the conclusion is that the rate-determining step is a single-site water nucleophilic attack on a metal-oxo species. Moreover, [Ru(IV) (O)(Py2 (Me) tacn)](2+) is proposed to be the resting state under catalytic conditions. By monitoring Ce(IV) consumption, we found that the O2 evolution rate is redox-controlled and independent of the initial concentration of Ce(IV) . Based on these facts, we propose herein that [Ru(IV) (O)(Py2 (Me) tacn)](2+) is oxidised to [Ru(V) (O)(Py2 (Me) tacn)](2+) prior to attack by a water molecule to give [Ru(III) (OOH)(Py2 (Me) tacn)](2+) . Finally, it is shown that the difference in WO reactivity between the homologous iron and ruthenium [M(OH2 )(Py2 (Me) tacn)](2+) (M=Ru, Fe) complexes is due to the difference in the redox stability of the key M(V) (O) intermediate. These results contribute to a better understanding of the WO mechanism and the differences between iron and ruthenium complexes in WO reactions.
Collapse
Affiliation(s)
- Carla Casadevall
- Institute of Chemical Research of Catalonia (ICIQ), The Barcelona Institute of Science and Technology, Avinguda Països Catalans 16, 43007, Tarragona, Spain
| | - Zoel Codolà
- Institut de Química Computacional i Catàlisi (IQCC) and, Departament de Química, Universitat de Girona Campus Montilivi, 17071, Girona, Spain
| | - Miquel Costas
- Institut de Química Computacional i Catàlisi (IQCC) and, Departament de Química, Universitat de Girona Campus Montilivi, 17071, Girona, Spain
| | - Julio Lloret-Fillol
- Institute of Chemical Research of Catalonia (ICIQ), The Barcelona Institute of Science and Technology, Avinguda Països Catalans 16, 43007, Tarragona, Spain.
- Catalan Institution for Research and Advanced Studies (ICREA), Passeig Lluïs Companys, 23, 08010, Barcelona, Spain.
| |
Collapse
|
33
|
Baron M, Tubaro C, Basato M, Isse AA, Gennaro A, Cavallo L, Graiff C, Dolmella A, Falivene L, Caporaso L. Insights into the Halogen Oxidative Addition Reaction to Dinuclear Gold(I) Di(NHC) Complexes. Chemistry 2016; 22:10211-24. [PMID: 27297191 DOI: 10.1002/chem.201600654] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2016] [Indexed: 12/27/2022]
Abstract
Gold(I) dicarbene complexes [Au2 (MeIm-Y-ImMe)2 ](PF6 )2 (Y=CH2 (1), (CH2 )2 (2), (CH2 )4 (4), MeIm=1-methylimidazol-2-ylidene) react with iodine to give the mixed-valence complex [Au(MeIm-CH2 -ImMe)2 AuI2 ](PF6 )2 (1 a(I) ) and the gold(III) complexes [Au2 I4 (MeIm-Y-ImMe)2 ](PF6 )2 (2 c(I) and 4 c(I) ). Reaction of complexes 1 and 2 with an excess of ICl allows the isolation of the tetrachloro gold(III) complexes [Au2 Cl4 (MeIm-CH2 -ImMe)2 ](PF6 )2 (1 c(Cl) ) and [Au2 Cl4 (MeIm-(CH2 )2 -ImMe)2 ](Cl)2 (2 c(Cl) -Cl) (as main product); remarkably in the case of complex 2, the X-ray molecular structure of the crystals also shows the presence of I-Au-Cl mixed-sphere coordination. The same type of coordination has been observed in the main product of the reaction of complexes 3 or 4 with ICl. The study of the reactivity towards the oxidative addition of halogens to a large series of dinuclear bis(dicarbene) gold(I) complexes has been extended and reviewed. The complexes react with Cl2 , Br2 and I2 to give the successive formation of the mixed-valence gold(I)/gold(III) n a(X) and gold(III) n c(X) (excluding compound 1 c(I) ) complexes. However, complex 3 affords with Cl2 and Br2 the gold(II) complex 3 b(X) [Au2 X2 (MeIm-(CH2 )3 -ImMe)2 ](PF6 )2 (X=Cl, Br), which is the predominant species over compound 3 c(X) even in the presence of free halogen. The observed different relative stabilities of the oxidised complexes of compounds 1 and 3 have also been confirmed by DFT calculations.
Collapse
Affiliation(s)
- Marco Baron
- Dipartimento di Scienze Chimiche, Università degli Studi di Padova, via F. Marzolo 1, 35131, Padova, Italy
| | - Cristina Tubaro
- Dipartimento di Scienze Chimiche, Università degli Studi di Padova, via F. Marzolo 1, 35131, Padova, Italy.
| | - Marino Basato
- Dipartimento di Scienze Chimiche, Università degli Studi di Padova, via F. Marzolo 1, 35131, Padova, Italy
| | - Abdirisak Ahmed Isse
- Dipartimento di Scienze Chimiche, Università degli Studi di Padova, via F. Marzolo 1, 35131, Padova, Italy
| | - Armando Gennaro
- Dipartimento di Scienze Chimiche, Università degli Studi di Padova, via F. Marzolo 1, 35131, Padova, Italy
| | - Luigi Cavallo
- KAUST Catalyst Research Center, 4700 King Abdullah University of Science and Technology, Thuwal, 23955-6900, Kingdom of Saudi Arabia
| | - Claudia Graiff
- Dipartimento di Chimica, Università di Parma, Viale delle Scienze 17A, 43100, Parma, Italy
| | - Alessandro Dolmella
- Dipartimento di Scienze del Farmaco, Università degli Studi di Padova, via F. Marzolo 5, 35131, Padova, Italy
| | - Laura Falivene
- KAUST Catalyst Research Center, 4700 King Abdullah University of Science and Technology, Thuwal, 23955-6900, Kingdom of Saudi Arabia
| | - Lucia Caporaso
- Dipartimento di Chimica e Biologia, Università di Salerno, Via Papa Giovanni Paolo II, 84084, Fisciano, Italy
| |
Collapse
|
34
|
Gorgas N, Stöger B, Veiros LF, Kirchner K. Highly Efficient and Selective Hydrogenation of Aldehydes: A Well-Defined Fe(II) Catalyst Exhibits Noble-Metal Activity. ACS Catal 2016; 6:2664-2672. [PMID: 27660732 PMCID: PMC5023089 DOI: 10.1021/acscatal.6b00436] [Citation(s) in RCA: 106] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2016] [Revised: 03/10/2016] [Indexed: 01/01/2023]
Abstract
The synthesis and application of [Fe(PNPMe-iPr)(CO)(H)(Br)] and [Fe(PNPMe-iPr)(H)2(CO)] as catalysts for the homogeneous hydrogenation of aldehydes is described. These systems were found to be among the most efficient catalysts for this process reported to date and constitute rare examples of a catalytic process which allows selective reduction of aldehydes in the presence of ketones and other reducible functionalities. In some cases, TONs and TOFs of up to 80000 and 20000 h-1, respectively, were reached. On the basis of stoichiometric experiments and computational studies, a mechanism which proceeds via a trans-dihydride intermediate is proposed. The structure of the hydride complexes was also confirmed by X-ray crystallography.
Collapse
Affiliation(s)
- Nikolaus Gorgas
- Institute
of Applied Synthetic Chemistry and Institute of Chemical Technologies
and Analytics, Vienna University of Technology, Getreidemarkt 9, A-1060 Vienna, Austria
| | - Berthold Stöger
- Institute
of Applied Synthetic Chemistry and Institute of Chemical Technologies
and Analytics, Vienna University of Technology, Getreidemarkt 9, A-1060 Vienna, Austria
| | - Luis F. Veiros
- Centro
de Química Estrutural, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais No. 1, 1049-001 Lisboa, Portugal
| | - Karl Kirchner
- Institute
of Applied Synthetic Chemistry and Institute of Chemical Technologies
and Analytics, Vienna University of Technology, Getreidemarkt 9, A-1060 Vienna, Austria
| |
Collapse
|
35
|
Bieszczad B, Barbasiewicz M. The Key Role of the Nonchelating Conformation of the Benzylidene Ligand on the Formation and Initiation of Hoveyda-Grubbs Metathesis Catalysts. Chemistry 2015; 21:10322-5. [PMID: 26074213 DOI: 10.1002/chem.201501959] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2015] [Indexed: 11/10/2022]
Abstract
Experimental studies of Hoveyda-Grubbs metathesis catalysts reveal important consequences of substitution at the 6-position of the chelating benzylidene ligand. The structural modification varies conformational preferences of the ligand that affects its exchange due to the interaction of the coordinating site with the ruthenium center. As a consequence, when typical S-chelated systems are formed as kinetic trans-Cl2 products, for 6-substituted benzylidenes the preference is altered toward direct formation of thermodynamic cis-Cl2 isomers. Activity data and reactions with tricyclohexylphosphine (PCy3 ) support also a similar scenario for O-chelated complexes, which display fast trans-Cl2 ⇄cis-Cl2 equilibrium observed by NMR EXSY studies. The presented conformational model reveals that catalysts, which cannot adopt the optimal nonchelating conformation of benzylidene ligand, initiate through a high-energy associative mechanism.
Collapse
Affiliation(s)
- Bartosz Bieszczad
- Faculty of Chemistry, University of Warsaw, Pasteura 1, 02-093 Warsaw (Poland), Fax: (+48) 22 822 5996
| | - Michał Barbasiewicz
- Faculty of Chemistry, University of Warsaw, Pasteura 1, 02-093 Warsaw (Poland), Fax: (+48) 22 822 5996.
| |
Collapse
|
36
|
Truscott BJ, Kruger H, Webb PB, Bühl M, Nolan SP. The mechanism of CO2 insertion into iridium(I) hydroxide and alkoxide bonds: a kinetics and computational study. Chemistry 2015; 21:6930-5. [PMID: 25801203 DOI: 10.1002/chem.201406509] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2014] [Revised: 02/06/2015] [Indexed: 11/06/2022]
Abstract
The facile insertion of CO2 into iridium(I) hydroxide, alkoxide, and amide bonds was recently reported. In particular, [Ir(cod)(IiPr)(OH)] (IiPr = 1,3-bis(isopropyl)imidazol-2-ylidene) reacted with CO2 in solution and in the solid state in a matter of minutes to give the novel [{Ir(cod)(IiPr)}2(μ-κ(1)O:κ(2)O,O-CO3)] complex. In the present study, this reaction is probed using kinetics and theoretical studies, which enabled us to analyse its facile nature and to fully elucidate the reaction mechanism with excellent correlation between the two methods.
Collapse
Affiliation(s)
- Byron J Truscott
- EaStCHEM, School of Chemistry, University of St Andrews, North Haugh, St Andrews, KY16 9ST (UK) http://chemistry.st-and.ac.uk/staff/spn/group/SP_Nolan/Home.html
| | | | | | | | | |
Collapse
|
37
|
Collett CJ, Massey RS, Taylor JE, Maguire OR, O'Donoghue AC, Smith AD. Rate and equilibrium constants for the addition of N-heterocyclic carbenes into benzaldehydes: a remarkable 2-substituent effect. Angew Chem Int Ed Engl 2015; 54:6887-92. [PMID: 25908493 PMCID: PMC4510784 DOI: 10.1002/anie.201501840] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2015] [Indexed: 11/23/2022]
Abstract
Rate and equilibrium constants for the reaction between N-aryl triazolium N-heterocyclic carbene (NHC) precatalysts and substituted benzaldehyde derivatives to form 3-(hydroxybenzyl)azolium adducts under both catalytic and stoichiometric conditions have been measured. Kinetic analysis and reaction profile fitting of both the forward and reverse reactions, plus onwards reaction to the Breslow intermediate, demonstrate the remarkable effect of the benzaldehyde 2-substituent in these reactions and provide insight into the chemoselectivity of cross-benzoin reactions.
Collapse
Affiliation(s)
- Christopher J Collett
- EaStCHEM, School of Chemistry, University of St Andrews, North Haugh, St Andrews, Fife, KY16 9ST (UK) http://ch-www.st-andrews.ac.uk/staff/ads/group/
| | - Richard S Massey
- Department of Chemistry, Durham University, South Road, Durham, DH1 3LE (UK)
| | - James E Taylor
- EaStCHEM, School of Chemistry, University of St Andrews, North Haugh, St Andrews, Fife, KY16 9ST (UK) http://ch-www.st-andrews.ac.uk/staff/ads/group/
| | - Oliver R Maguire
- Department of Chemistry, Durham University, South Road, Durham, DH1 3LE (UK)
| | | | - Andrew D Smith
- EaStCHEM, School of Chemistry, University of St Andrews, North Haugh, St Andrews, Fife, KY16 9ST (UK) http://ch-www.st-andrews.ac.uk/staff/ads/group/.
| |
Collapse
|
38
|
Gordon P, Khojasteh SC. A decades-long investigation of acute metabolism-based hepatotoxicity by herbal constituents: a case study of pennyroyal oil. Drug Metab Rev 2014; 47:12-20. [PMID: 25512112 DOI: 10.3109/03602532.2014.990032] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Herbal supplements are often regarded as "natural", and are, therefore, considered by many to be safer than pharmaceuticals; however, the adverse effects of these supplements are under-reported in many cases. Many herbal supplements, such as pyrrolizidine alkaloids, kava, chaparral and germander, are known to induce liver injury, which, in general, is one of the main toxicity liabilities observed in the clinic and accounts for about half of total liver failures. One example is the hepatotoxicity of pennyroyal oil, which is ingested as an abortifacient, among other uses. For three decades, the late Professor Sidney Nelson contributed to our understanding of the mechanism of toxicity of pennyroyal and broadened our understanding of chemical toxicology. Here we present the studies and review the findings on acute hepatotoxicity of pennyroyal oil. These studies involved the isolation and characterization of pennyroyal components, determination of the appropriate animal models, identification of the structural requirement for toxicity and determination of the target enzymes and the enzymes involved in the process of bioactivation. Studies with stable isotope labeled pennyroyal metabolites, pulegone and menthofuran, furthered our understanding of the role of cytochrome P450 in the oxidation of these compounds. This review presents the investigational tools used in the study of pennyroyal oil, allowing the reader to not only appreciate these methods but also utilize them to tackle and better understand metabolism-based toxicity in their own projects.
Collapse
|
39
|
Wang L, Santos E, Schenk D, Rabago-Smith M. Kinetics and Mechanistic Studies on the Reaction between Cytochrome c and Tea Catechins. Antioxidants (Basel) 2014; 3:559-68. [PMID: 26785071 PMCID: PMC4665416 DOI: 10.3390/antiox3030559] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2014] [Revised: 05/20/2014] [Accepted: 05/22/2014] [Indexed: 12/24/2022] Open
Abstract
Green tea is characterized by the presence of an abundance of polyphenolic compounds, also known as catechins, including epicatechin (EC), epigallocatechin (EGC), epicatechin gallate (EGC) and epigallocatechin gallate (EGCG). In addition to being a popular beverage, tea consumption has been suggested as a mean of chemoprevention. However, its mode of action is unclear. It was discovered that tea catechins can react with cytochrome c. When oxidized cytochrome c was mixed with catechins commonly found in green tea under non-steady-state conditions, a reduction of cytochrome c was observed. The reaction rate of the catechins was dependent on the pH and the nature of the catechin. The pseudo-first order rate constant obtained increased in the order of EC < ECG < EGC < EGCG, which is consistent with previously reported superoxide reduction activities and Cu2+ reduction activities of tea catechins.
Collapse
Affiliation(s)
- Lihua Wang
- Department of Chemistry and Biochemistry, Kettering University, 1700 University Ave, Flint, MI 48504, USA.
| | - Elizabeth Santos
- Department of Chemistry and Biochemistry, Kettering University, 1700 University Ave, Flint, MI 48504, USA.
| | - Desiree Schenk
- Department of Chemistry and Biochemistry, Kettering University, 1700 University Ave, Flint, MI 48504, USA.
| | - Montserrat Rabago-Smith
- Department of Chemistry and Biochemistry, Kettering University, 1700 University Ave, Flint, MI 48504, USA.
| |
Collapse
|
40
|
Townsend SD, Ross AG, Liu K, Danishefsky SJ. Stereospecific cis- and trans-ring fusions arising from common intermediates. Proc Natl Acad Sci U S A 2014; 111:7931-5. [PMID: 24843125 DOI: 10.1073/pnas.1407613111] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Highly concise and stereospecific routes to cis and trans fusion, carrying various functionality at one of the bridgehead carbons, have been accomplished.
Collapse
|
41
|
Sutherland ER, Busse WW. Designing clinical trials to address the needs of childhood and adult asthma: the National Heart, Lung, and Blood Institute's AsthmaNet. J Allergy Clin Immunol 2014; 133:34-8.e1. [PMID: 24369797 DOI: 10.1016/j.jaci.2013.10.025] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2013] [Revised: 10/09/2013] [Accepted: 10/14/2013] [Indexed: 10/25/2022]
Abstract
In 2008, the National Heart, Lung, and Blood Institute announced its intent to support a new asthma network known as AsthmaNet. This clinical trials consortium, now in its fifth year, has been charged with developing and executing clinical trials to address the most important asthma management questions and identify new treatment approaches in pediatric and adult patients. This review will discuss the organization of AsthmaNet and the scientific context in which the network was developed and began its work, report the results of an internal priority-setting exercise designed to guide the network's scientific strategy, and highlight the portfolio of clinical trials, proof-of-concept studies, and mechanistic studies planned for the 7-year period of the network to update the global asthma community regarding the progress and processes of the network.
Collapse
Affiliation(s)
- E Rand Sutherland
- Department of Medicine, National Jewish Health, the University of Colorado School of Medicine, Denver, Colo.
| | - William W Busse
- Department of Medicine, University of Wisconsin, Madison, Wis
| | | |
Collapse
|
42
|
Vilhelmsen MH, Hashmi ASK. Reaction mechanism for the dual gold-catalyzed synthesis of dibenzopentalene: a DFT study. Chemistry 2014; 20:1901-8. [PMID: 24443140 DOI: 10.1002/chem.201303636] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2013] [Revised: 10/28/2013] [Indexed: 01/11/2023]
Abstract
A wide range of gold-catalyzed reactions based on a dual activation mechanism has recently been reported in the literature. Herein, we present a computational investigation of the mechanism for the formation of dibenzopentalenes from 1-ethynyl-2-(phenylethynyl)benzene. Transition states have been found, which substantiate the dual activation mechanism previously published and furthermore point towards a continuous presence of two gold moieties throughout the mechanistic cycle, an observation of high importance for all reactions in the field of dual activation. The initial activation of the diyne has been shown to proceed via an intermolecular transfer of a cationic gold catalyst from the thermodynamically preferred geminal-σ,π-acetylide complex to the active non-geminal analogue. Furthermore, the regioselectivity of a 5-endo versus a 6-endo cyclization has been addressed, and the 5-endo cyclization was found to be most favorable both thermodynamically and with regard to the activation barrier.
Collapse
Affiliation(s)
- Mie Højer Vilhelmsen
- Institute of Organic Chemistry, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 270, 69120 Heidelberg (Germany), Fax: (+49) 6221-54-4205.
| | | |
Collapse
|
43
|
Abstract
Prion protein oligomerization: Despite the crucial role of oligomers during prion protein (PrP) pathogenesis the molecular mechanism of their formation has remained largely elusive. A 2D time-resolved NMR study which made it possible to characterize the oligomerization kinetics with unprecedented site-specificity is reported.
Collapse
Affiliation(s)
- Kai Schlepckow
- Institut für Organische Chemie und Chemische Biologie, Zentrum für Biomolekulare Magnetische Resonanz (BMRZ), Johann Wolfgang Goethe-Universität Frankfurt am Main, Max-von-Laue-Strasse 7, 60438 Frankfurt am Main (Germany) http://schwalbe.org.chemie.uni-frankfurt.de
| | | |
Collapse
|
44
|
Abstract
The intermolecular hydroamination of allenes occurs readily with hydrazide nucleophiles, in the presence of 3-12% Ph(3)PAuNTf(2). Mechanistic studies have been conducted to establish the resting state of the gold catalyst, the kinetic order of the reaction, the effect of ligand electronics on the overall rate, and the reversibility of the last steps in the catalytic cycle. We have found the overall reaction to be first order in gold and allene and zero order in nucleophile. Our studies suggest that the rate-limiting transition state for the reaction does not involve the nucleophile and that the active catalyst is monomeric in gold(I). Computational studies support an "outersphere" mechanism and predict that a two-step, no intermediate mechanism may be operative. In accord with this mechanistic proposal, the reaction can be accelerated with the use of more electron-deficient phosphine ligands on the gold(I) catalyst.
Collapse
|
45
|
Abstract
Some cancer patients use therapeutic massage to reduce symptoms, improve coping, and enhance quality of life. Although a meta-analysis concludes that massage can confer short-term benefits in terms of psychological wellbeing and reduction of some symptoms, additional validated randomized controlled studies are necessary to determine specific indications for various types of therapeutic massage. In addition, mechanistic studies need to be conducted to discriminate the relative contributions of the therapist and of the reciprocal relationship between body and mind in the subject. Nuclear magnetic resonance techniques can be used to capture dynamic in vivo responses to biomechanical signals induced by massage of myofascial tissue. The relationship of myofascial communication systems (called "meridians") to activity in the subcortical central nervous system can be evaluated. Understanding this relationship has important implications for symptom control in cancer patients, because it opens up new research avenues that link self-reported pain with the subjective quality of suffering. The reciprocal body-mind relationship is an important target for manipulation therapies that can reduce suffering.
Collapse
Affiliation(s)
- S M Sagar
- Juravinski Cancer Program, Hamilton Health Sciences Corporation and McMaster University, Hamilton, Ontario.
| | | | | |
Collapse
|