Synthesis and Structural Elucidation for New Schiff Base Complexes; Conductance, Conformational, MOE-Docking and Biological Studies

Preparation, separation and identification of novel hypocholesterolemic peptides from wheat germ: An in vitro and in silico study

The aim of this study was to prepare, isolate, and identify hypocholesterolemic peptides from wheat germ protein and explore their efficacy. Wheat germ protein was hydrolyzed using four commercial enzymes. Hydrolysate, with the highest in vitro hypocholesterolemic activity was isolated using ultrafiltration and macroporous resin. The fractions with highest binding affinity to sodium taurocholate were evaluated for cholesterol-lowering activity and resistance to digestion using Caco-2 monolayers. Fraction III had the highest cholesterol-lowering activity, reducing the subcutaneous transport and absorption of cholesterol and resisted digestion. Nano-LC-MS/MS and molecular docking were used to identify cholesterol-lowering peptides from Fraction III. Three cholesterol-lowering peptides, FAAGAPP, GAGDIPGGIG, and GPVPDTGIFS, were identified. These peptides exhibited cholesterol micelle solubility, specifically by 76.2 %, 68.3 %, and 64.7 %, respectively. In summary, wheat germ peptides exhibited significant cholesterol-lowering activity in vitro, suggesting their potential for application in functional foods.

Prediction of potential drug targets and key inhibitors (ZINC67974679, ZINC67982856, and ZINC05668040) against Rickettsia felis using integrated computational approaches

Rickettsia felis, responsible for flea-borne spotted fever, is a rising zoonotic pathogen posing an increasing global threat due to its expanding geographical distribution. The rise in antibiotic-resistant strains of this pathogen underscores the urgent need for new therapeutic interventions. This study employed a comprehensive subtractive proteomics analysis of the R. felis proteome, aiming to identify essential, non-host homologous, and pathogen-specific proteins, which were subsequently evaluated as potential new drug targets. These findings offer valuable insights into the development of therapeutic strategies against rickettsiosis. The analysis revealed 343 proteins that are non-homologous to the host, including 108 essential proteins, 25 unique metabolic pathways, and 11 distinct proteins. Out of these, 10 proteins were druggable in which two associated with virulence, and one related to resistance (succinate dehydrogenase). Through a rigorous screening process and extensive literature review, succinate dehydrogenase emerged as a promising drug target. Protein interaction partners for succinate dehydrogenase were identified using the STRING database. To further assess the functionality of succinate dehydrogenase, structure-based studies were conducted. Approximately 18,000 ZINC compounds were screened, leading to the finding of six potential inhibitors: ZINC67847806, ZINC67982856, ZINC67974679, ZINC67895371, ZINC05668040, and ZINC05670149. Absorption, distribution, metabolism, excretion, and toxicity (ADMET) profiling confirmed that most compounds met the preferred pharmacokinetic properties, except for ZINC67895371 and ZINC67847806, which exhibited positive ames test results, and ZINC05670149, ZINC67895371, and ZINC67847806, showed hepatotoxicity. All compounds were found to be non-sensitizing to the skin. Based on these findings, further experimental validation of ZINC67974679, ZINC67982856, and ZINC05668040 is recommended.

Eugenol's electrochemical behavior, complexation interaction with copper chloride, antioxidant activity, and potential drug molecular docking application for Covid-19

Electrochemical studies were conducted to analyze the behavior of eugenol, CuCl2, and their complex using cyclic voltammetry. The oxidation mechanisms of eugenol and the redox behavior of copper ions were elucidated, showing differences in reversibility and charge transfer coefficients. Various kinetic and solvation parameters were determined. The redox behavior of CuCl2 was found to be more reversible compared to the copper-eugenol complex. The copper-eugenol complex exhibited enhanced antioxidant activity compared to eugenol and standard ascorbic acid. The eugenol was oxidized to form eugenol quinone methide through two postulated irreversible mechanisms. Molecular docking studies suggested higher potential bioactivity of the copper-eugenol complex towards the target protein of COVID-19 than the eugenol ligand.

Centaurea mersinensis phytochemical composition and multi-dimensional bioactivity properties supported by molecular modeling

Various studies conducted on Centaurea species indicate that the relevant plant is good source of bioactive phytochemicals. In this study, in vitro studies were used to determine bioactivity properties of methanol extract of Centaurea mersinensis - endemic species in Turkey - on extensive basis. Furthermore, the interaction of target molecules, identified for breast cancer and phytochemicals in the extract, was investigated via in silico analyses to support findings received in vitro. Scutellarin, quercimeritrin, chlorogenic acid and baicalin were primary phytochemicals in the extract. Methanol extract and scutellarin had higher cytotoxic effects against MCF-7 (IC50=22.17 µg/mL, and IC50=8.25 µM, respectively), compared to other breast cancer cell lines (MDA-MB-231, SKBR-3). The extract had strong antioxidant properties and inhibited target enzymes, especially α-amylase (371.69 mg AKE/g extract). The results of molecular docking indicate that main compounds of extract show high-strength bonding to the c-Kit tyrosine among target molecules identified in breast cancer, compared to other target molecules (MMP-2, MMP-9, VEGFR2 kinase, Aurora-A kinase, HER2). The tyrosinase kinase (1T46)-Scutellarin complex showed considerable stability in 150 ns simulation as per MD findings, and it was coherent with optimal docking findings. Docking findings and HOMO-LUMO analysis results corresponds with in vitro experiments. Medicinal properties of phytochemicals, which was determined to be suitable for oral use along with ADMET, were found to be within normal limits except for their polarity properties. In conclusion, in vitro and in silico studies indicated that the relevant plant yields promising results regarding its potential to develop novel and effective medicational products.Communicated by Ramaswamy H. Sarma.

Designing, Characterization, DFT, Biological Effectiveness, and Molecular Docking Analysis of Novel Fe(III), Co(II), and Cu(II) Complexes Based on 4-Hydroxy-2H-pyrano[3,2-c]quinoline-2,5(6H)-dione

The main target of the current framework is the designing and synthesizing of novel iron(III), cobalt(II), and cupper(II) complex compounds emanating from bioactive nucleus, 4-hydroxy-2H-pyrano[3,2-c]quinoline-2,5(6H)-dione ligand, to enhance comprehension as potential antibacterial, antifungal, and antioxidant alternatives by means of using DFT calculations and molecular docking investigation. Thus, the new complexes had been synthesized and characterized using various analytical techniques, including elemental analysis, infrared spectroscopy, mass spectrometry, UV spectroscopy, conductivity, and magnetic testing, as well as thermal analysis. The 4-hydroxy-2H-pyrano[3,2-c]quinoline-2,5(6H)-dione ligand exhibits monobasic bidentate OO donor properties toward the metal core, as shown by its infrared spectroscopic characteristics. The use of thermal analysis techniques allows for the identification and characterization of water molecules present inside the complexes, as well as the determination of their distribution patterns. The molecular structures of free ligand and its metal complex compounds have been verified through the use of density functional theory (DFT) simulations. These simulations also provide a valuable understanding of the quantum chemical characteristics associated with these structures. In vitro experiments were conducted to evaluate the antioxidant, antibacterial, as well as antifungal and the properties of the free ligand and its corresponding complex compounds. DATA revealed that synthesized metal complex compounds have heightened biological efficacy as related to the unbound ligand. Furthermore, molecular docking analysis was done to understand the interactions between the studied compounds and proteins derived from Escherichia coli (pdb ID: 2vf5), Aspergillus flavus (pdb ID: 3cku), and humans (pdb ID: 5IJT), which are considered to be significant in drug design. Lastly, a correlation between in vitro efficacies with molecular docking data was done and analyzed.

Synthesis, Characterization, and Antimicrobial Evaluation of Schiff Base-mixed Ligand Complexes with Divalent Metal Ions Derived from Amoxicillin and Vanillin/Nicotinamide

INTRODUCTION

This study focuses on the development of novel antimicrobial agents. A Schiff base ligand, 6-(2-(4-hydroxy-3-methoxybenzylideneamino)-2-(4-hydroxyphenyl)acetamido)-3,3-dimethyl-7-oxo- 4-thia-1-azabicyclo [3.2.0] heptane-2-carboxylic acid, synthesized through the condensation of amoxicillin and vanillin in methanol, served as the foundation. Polydentate mixed ligand complexes were then formed by reacting the Schiff base with metal ions (Fe(II), Co(II), Ni(II), Cu(II), and Zn(II)) and nicotinamide in specific ratios.

METHODS

Characterization involved various techniques, such as 1H-NMR, FT-IR, UV-Vis, and elemental analysis for the ligand, and Atomic Absorption, FT-IR, UV-Vis, magnetic susceptibility, and conductance measurements for the Schiff base-metal ion complexes.

RESULTS

Quantum chemical features of both ligands and metal complexes were computed, refining their electronic and molecular structures theoretically. Antimicrobial activity against Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae, Salmonella typhi, Acinetobacter baumannii, and Pseudomonas aeruginosa was assessed for the starting materials, ligands, and synthesized complexes, revealing significant effects on certain species. In-silico binding modes with Escherichia coli (PDB ID: 5iq9) were determined through molecular docking.

CONCLUSION

This study underscores the potential applications of the Schiff base ligands and their metal complexes in developing new antimicrobial agents.

Synthesis, structural characterization, and antimicrobial evaluation of new mononuclear mixed ligand complexes based on furfural-type imine ligand, and 2,2'-bipyridine

The present investigation goal was to investigate the chemistry of four new mononuclear mixed ligand Fe(III), Co(II), Cu(II), and Cd(II) complexes constructed from furfural-type imine ligand (L), and the co ligand 2,2'-bipyridine in addition to assessing their antimicrobial activity against some bacterial, and fungi strains. The structure of the complexes was interpreted by different spectroscopic techniques such as MS, IR, ¹H NMR, UV-Vis, elemental analysis, TG-DTG, conductivity, and magnetic susceptibility measurements. The correlation of all results revealed that ligand (L) acts as a neutral ONNO tetradentate whereas the co ligand acts as a neutral NN bidentate. The coordination of the ligands with the metal ions in a molar ratio of 1:1:1 leads to formation of an octahedral geometry around the metal ions. The octahedral geometry has been validated and optimized by DFT analysis. Conductivity data showed the electrolytic nature of all complexes. The thermal stability of all complexes was deduced in addition to evaluating some thermodynamic, and kinetic parameters using Coats-Redfern method. Furthermore, all complexes in comparison to their parent ligands were tested for their biological potency against some pathogenic bacterial, and fungi strains using the paper disk diffusion method. [CdL(bpy)](NO₃)₂ complex revealed the highest antimicrobial activity.

Synthesis, Physicochemical Characterization, Biological Assessment, and Molecular Docking Study of Some Metal Complexes of Alloxan and Ninhydrin as Alterdentate Ligands

A series of transition metal complexes of alloxan monohydrate (H2L1) and ninhydrin (H2L2) have been prepared where metal ions are Fe(III), Co(II), Ni(II), Cu(II), Zr(IV), and Mo(VI). Different microanalytical techniques, spectroscopic methods, and magnetic studies were applied to assign the mode of bonding and elucidate the structure of complexes. All solid complexes are of 1:1 (M:L) stoichiometry and octahedral geometry except nickel (II) complexes exist in a tetrahedral geometry. FTIR spectral interpretation reveals that HL1 coordinates to the central metal ion in a bidentate ON pattern, whereas HL2 behaves as an alterdentate ligand through hydroxyl oxygen and carbonyl oxygen either C(1) = O or C(3) = O. The thermal behavior of some complexes was followed up to 700 °C by different techniques (TGA, DTA, and DSC) where decomposition stages progress in complicated mechanisms and are ended by the formation of metal oxide residue. Besides, biological screening involving antioxidant, antibacterial, and antifungal for ligands and some of their complexes was done. Moreover, four examined metal complexes displayed anticancer activity against hepatocellular carcinoma cells (HepG-2) but to different degrees. According to the IC50 values, Cu-ninhydrin complex, [Cu(HL2)(H2O)4].Cl has a better potency impact in comparison with cisplatin which was used as a reference control. This is in harmony with the molecular docking simulation outcomes that predicted a good binding propensity of the Cu-ninhydrin complex with hepatocellular carcinoma protein (2jrs). Therefore, the Cu-ninhydrin complex should be deemed as a potential chemotherapeutic agent for hepatocellular cancer.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1007/s10904-023-02661-5.

Synthesis, characterizations of aryl-substituted dithiodibenzothioate derivatives, and investigating their anti-Alzheimer's properties

The main objective of the present study was to synthesize potential inhibitor/activators of AChE and hCA I-II enzymes, which are thought to be directly related to Alzheimer's disease. Dithiodibenzothioate compounds were synthesized by thioesterification. Six different thiolate compounds produced were characterized by ¹H-, ¹³C-NMR, FT-IR, LC-MS/MS methods. HOMO-LUMO calculations and electronic properties of all synthesized compounds were comprehensively illuminated with a semi-empirical molecular orbital (SEMO) package for organic and inorganic systems using Austin Model 1 (AM1)-Hamiltonian as implemented in the VAMP module of Materials Studio. In addition, the inhibition effects of these compounds for AChE and hCA I-II in vitro conditions were investigated. It was revealed that TE-1, TE-2, TE-3, TE-4, TE-5, and TE-6 compounds inhibited the AChE under in vitro conditions. TE-1 compound activated the enzyme hCA I while TE-2, TE-3 TE-4 compounds inhibited it. TE-5 and TE-6, on the other hand, did not exhibit a regular inhibition profile. Similarly, TE-1 activated the hCA II enzyme whereas TE-2, TE-3, TE-4, and TE-5 compounds inhibited it. TE-6 compound did not have a consistent inhibition profile for hCA II. Docking studies were performed with the compounds against AChE and hCA I-II receptors using induced-fit docking method. Molecular Dynamics (MD) simulations for best effective three protein-ligand couple were conducted to explore the binding affinity of the considered compounds in semi-real in-silico conditions. Along with the MD results, TE-1-based protein complexes were found more stable than TE-5. Based on these studies, TE-1 compound could be considered as a potential drug candidate for AD.Communicated by Ramaswamy H. Sarma.

Synthesis of a new sulfadimidine Schiff base and their nano complexes as potential anti-COVID-19 and anti-cancer activity

The primary objective of this study was to describe the cytotoxicity on HEPG-2 cells and to study the COVID‑19 activities of the novel H₂L ligand and its Cr and Cu nano-complexes. As well as exploring the chemistry of the prepared nano-complexes. In this paper novel Schiff base, N-(4, 6-dimethyl pyrimidin-2-yl)-4-(((2-hydroxyl naphthalene-1-y l) methylene) amino) benzene-sulfonamidesulfonyl) amide has been synthesized. The novel Schiff base H₂L is used to synthesize novel nano and micro-complexes with CrCl₂.6H₂O and CuCl₂.2H₂O. The prepared ligand and micro complexes were interpreted by different spectroscopic techniques. The nano-sized Cr and Cu complexes were synthesized in an environmentally friendly manner using Coriandrum sativum (CS) media extract in ethanol. The structure, morphologies and particle size of the nano-sized complexes were determined using FT-IR, TEM, and PXRD. The results showed that the nano-domain complexes are on the Sub-nano scale. Furthermore, using TGA, we studied the effect of heat on the size of newly prepared nano-complexes. Experimental data were supported by DFT calculations. The findings revealed that the metal complexes investigated are more stable than the free ligand H₂L. The antitumor activity was examined before and after heating the nano-complexes at 200 °C. The results reveal the Cr nano complex, after heating, exhibited strong antitumor activity with IC₅₀ value (3.349 μg/ml). The tested Cu nano-complex shows good DNA cleavage. The liver cancer and COVID19 proteins were examined using molecular docking to identify the potential binding energy of inhibitors.

Multidimensional in silico strategy for identification of natural polyphenols-based SARS-CoV-2 main protease (Mpro) inhibitors to unveil a hope against COVID-19

SARS-CoV-2, a rapidly spreading new strain of human coronavirus, has affected almost all the countries around the world. The lack of specific drugs against SARS-CoV-2 is a significant hurdle towards the successful treatment of COVID-19. Thus, there is an urgent need to boost up research for the development of effective therapeutics against COVID-19. In the current study, we investigated the efficacy of 81 medicinal plant-based bioactive compounds against SARS-CoV-2 M^pro by using various in silico techniques. The interaction affinities of polyphenolic compounds towards SARS-CoV-2 M^pro was assessed via intramolecular (by Quantum Mechanic), intermolecular (by Molecular Docking), and spatial (by Molecular Dynamic) simulations. Our obtained result demonstrate that Hesperidin, rutin, diosmin, and apiin are most effective compounds agents against SARS-CoV-2 Mpro as compared to Nelfinavir (positive control). This study will hopefully pave a way for advanced experimental research to evaluate the in vitro and in vivo efficacy of these compounds for the treatment of COVID-19.

Aurintricarboxylic acid and its metal ion complexes in comparative virtual screening versus Lopinavir and Hydroxychloroquine in fighting COVID-19 pandemic: Synthesis and characterization

The salt of Aurintricarboxylic acid (ATA) was utilized in this study to synthesize new alkaline earth metal ion complexes. The analytical results proposed the isolation of mononuclear (Sr+2&Ba+2) and binuclear complexes (Mg+2&Ca+2). These complexes were analyzed by available analytical and spectral techniques. The tetrahedral geometry was suggested for all complexes (SP3) through bidentate binding mode of ligand with each central atom. UV-Vis spectra reveal the influence of L → M charge transfer and the estimated optical band gap mostly appeared close to that for known semiconductors. XRD, SEM and TEM studies were executed for new complexes and reflects the nano-crystallinity and homogeneous morphology. The structural forms of ATA and its complexes were optimized by DFT/B3LYP under 6-31G and LANL2DZ basis sets. The output files (log, chk &fchk) were visualized on program screen and according to numbering scheme, many physical features were obtained. It is worthy to note that, a virtual simulation for the inhibition affinity towards COVID-19 proteins as proactive study before the actual application, was done for ATA and its complexes. This was done in addition to drugs currently applied in curing (Hydroxychloroquine & Lopinavir), for comparison and recommendation. Drug-likeness parameters were obtained to evaluate the optimal pharmacokinetics to ensure efficacy. Furthermore, simulated inhibition for COVID-19 cell-growth, was conducted by MOE-docking module. The negative allosteric binding mode represents good inhibitory behavior of ATA, Ba(II)-ATA complex and Lopinavir only. All interaction outcomes of Hydroxychloroquine drug reflect unsuitability of this drug in treating COVID-19. On the other hand, there is optimism for ATA and Lopinvir behaviors in controlling COVID-19 proliferation.