Prenylated notoamide-type alkaloids isolated from the fungus Aspergillus sclerotiorum and their inhibition of NLRP3 inflammasome activation and antibacterial activities

Notoamides are a family of prenylated indole alkaloids with unusual ring systems and possessing a range of significant pharmaceutical activities. Based on LC-MS/MS and genome orientations, ten undescribed notoamide-type alkaloids namely sclerotiamides I-R were isolated from a marine gorgonian-derived fungus Aspergillus sclerotiorum LZDX-33-4. Their structures were determined by extensive spectroscopic data, in association with ECD data and single-crystal X-ray diffraction for configurational assignments. Bioassays resulted in sclerotiamide J along with five analogs possessing inhibitory effects against LDH and IL-1β expression in BV-2 cells. Further investigation revealed that sclerotiamide J significantly inhibited NLRP3 inflammasome activation and blocked NLRP3 inflammasome-induced pyroptosis via amelioration of mitochondria damage. In addition, sclerotiamide L exhibited potent inhibition against pathogenic Staphylococcus aureus ATCC 29213 with MIC value of 4.0 μM and the growth of MRSA T144 and Enterococcus faecalis ATCC 29212. This study extends the chemical diversity of notoamide-type alkaloids, and provides potential anti-inflammasome and antibacterial lead compounds for further structure optimization.

OsBR6ox, a member in the brassinosteroid synthetic pathway facilitates degradation of pesticides in rice through a specific DNA demethylation mechanism

This manuscript described a comprehensive study on a pesticide degradation factor OsBR6ox that promoted the degradation of pesticides atrazine (ATZ) and acetochlor (ACT) in rice tissues and grains through an epigenetic mechanism. OsBR6ox was transcriptionally induced under ATZ and ACT stress. Genetic disruption of OsBR6ox increased rice sensitivity and led to more accumulation of ATZ and ACT, whereas transgenic rice overexpressing OsBR6ox lines (OEs) showed opposite effects with improved growth and lower ATZ and ACT accumulation in various tissues, including grains. OsBR6ox-mediated detoxification of ATZ and ACT was associated with the increased abundance of brassinolide (one of the brassinosteroids, BRs), a plant growth regulator for stress responses. Some Phase I-II reaction protein genes for pesticide detoxification such as genes encoding laccase, O-methyltransferase and glycosyltransferases were transcriptionally upregulated in OE lines under ATZ and ACT stress. HPLC-Q-TOF-MS/MS analysis revealed an enhanced ATZ/ATC metabolism in OE plants, which removed 1.21-1.49 fold ATZ and 1.31-1.44 fold ACT from the growth medium but accumulated only 83.1-87.1 % (shoot) and 71.7-84.1 % (root) of ATZ and 69.4-83.4 % of ACT of the wild-type. Importantly, an ATZ-responsive demethylated region in the upstream of OsBR6ox was detected. Such an epigenetic modification marker was responsible for the increased OsBR6ox expression and consequent detoxification of ATZ/ACT in rice and environment. Overall, this work uncovered a new model showing that plants utilize two mechanisms to co-regulate the detoxification and metabolism of pesticides in rice and provided a new approach for building up cleaner crops and eliminating residual pesticides in environments.

Coupling of Heteroaryl Halides with Chlorodifluoroacetamides and Chlorodifluoroacetate by Nickel Catalysis

A nickel-catalyzed cross-coupling of heteroaryl halides with chlorodifluoroacetamides and chlorodifluoroacetate has been developed. The combination of NiCl₂  ⋅ DME with 4,4'-diNon-bpy, co-ligand PPh₃ , and additive LiCl renders the catalytic system efficient for the synthesis of medicinal interest heteroaryldifluoroacetamides. The application of the method leads to short and highly efficient synthesis of biologically active molecules, providing a facile route for applications in medicinal chemistry and agrochemistry.

Sclerotiamides C-H, Notoamides from a Marine Gorgonian-Derived Fungus with Cytotoxic Activities

Bioassay-guided fractionation in association with LC-MS and NMR detection led to the isolation of six new alkaloids, sclerotiamides C-H (1-6), from the marine gorgonian-derived fungus Aspergillus sclerotiorum LZDX-33-4. Their structures were determined from extensive spectroscopic data, including ECD data and single-crystal X-ray diffraction analysis for configurational assignments. Sclerotiamides C (1) and D (2) are notoamide-type alkaloids with the incorporation of a unique 2,2-diaminopropane unit, and sclerotiamides E (3) and F (4) are unprecedented notoamide hybrids with a new coumarin unit. Sclerotiamide H (6) represents a new highly oxidized notoamide scaffold. Sclerotiamides C and F showed significant inhibition against a panel of tumor cell lines with IC₅₀ values ranging from 1.6 to 7.9 μM. Sclerotiamide C induces apoptosis in HeLa cells by arresting the cell cycle, activating ROS production, and regulating apoptosis-related proteins in the MAPK signaling pathway. The present study extends the scaffold diversity of the notoamides and provides a potential lead for the development of a cytotoxic agent.

Organocatalytic inverse-electron-demand Diels-Alder reaction between 5-alkenyl thiazolones and β,γ-unsaturated carbonyl compounds

An inverse-electron-demand oxa-Diels-Alder reaction of 5-alkenyl thiazolones with β,γ-unsaturated carbonyl compounds enabled by quinine thiourea was studied, which allows the enantioselective synthesis of a broad range of highly functionalized pyranthiazoles bearing three continuous stereocenters. This protocol is adaptable to a wide scope of substrates and has great potential for scale-up synthesis and facile transformation.

Photoredox-Catalyzed Ring-Opening Addition Reaction between Benzyl Bromides and Cyclic Ethers

A novel nucleophilic reaction between cyclic ethers and benzyl bromides is achieved under photoredox catalysis. The reaction proceeds through a single-electron-transfer (SET) pathway rather than a common SN2 mechanism. By two steps of reduction and oxidation, a benzyl bromide heterolyzes to give a carbocation and bromide ion under mild conditions, and then a cyclic ether captures both the carbo­cation and bromide ion to afford the addition product.

Characterization of Histidine Functionalization and Its Timing in the Biosynthesis of Ribosomally Synthesized and Posttranslationally Modified Thioamitides

Thioamitides are ribosomally synthesized and posttranslationally modified peptide (RiPP) natural products that hold great potential in anticancer drug development. Members in this RiPP family feature a thioamidated peptidyl chain conjugated with a macrocyclic ring system that contains two nonproteinogenic residues, 2-aminovinyl-cysteine (AviCys) and β-hydroxy-N,N-dimethyl-l-histidine (hdmHis). Focusing on the hdmHis residue that is unique to thioamitides, we report the enzymatic process for His functionalization and, more importantly, the timing of its related reactions with the other posttranslational modifications (PTMs) involved in thioamitide biosynthesis. His functionalization involves the activities of an S-adenosyl-l-methionine-dependent protein and a 2-oxoglutarate-Fe(II) monooxygenase for His bis-N-dimethylation and subsequent β-hydroxylation in a highly ordered manner. This process relies on the leader peptide sequence of the precursor peptide and on the establishment of the AviCys-containing, C-terminal macrocyclic ring system in particular. In contrast, prior peptide thioamidation is not required. Knowledge gained from the catalytic logic, specificity, and compatibility of His functionalization greatly furthers our understanding of the process through which nature develops thioamitides from a ribosomally synthesized peptide precursor.

N-acetyldopamine dimer inhibits neuroinflammation through the TLR4/NF-κB and NLRP3/Caspase-1 pathways

Neuroinflammation mediated by microglia is an important pathophysiological mechanism in neurodegenerative diseases. However, there is a lack of effective drugs to treat neuroinflammation. N-acetyldopamine dimer (NADD) is a natural compound from the traditional Chinese medicine Isaria cicada. In our previous study, we found that NADD can attenuate DSS-induced ulcerative colitis by suppressing the NF-κB and MAPK pathways. Does NADD inhibit neuroinflammation, and what is the target of NADD? To answer this question, lipopolysaccharide (LPS)-stimulated BV-2 microglia was used as a cell model to investigate the effect of NADD on neuroinflammation. Nitric oxide (NO) detection, reactive oxygen species (ROS) detection and enzyme-linked immunosorbent assay (ELISA) results show that NADD attenuates inflammatory signals and proinflammatory cytokines in LPS-stimulated BV-2 microglia, including NO, ROS, tumor necrosis factor (TNF)-α, interleukin (IL)-1β and interleukin-6 (IL-6). Western blot analysis show that NADD inhibits the protein levels of Toll-like receptor 4 (TLR4), nuclear factor kappa-B (NF-κB), NOD-like receptor thermal protein domain associated protein 3 (NLRP3), ASC and cysteinyl aspartate specific proteinase (Caspase)-1, indicating that NADD may inhibit neuroinflammation through the TLR4/NF-κB and NLRP3/Caspase-1 signaling pathways. In addition, surface plasmon resonance assays and molecular docking demonstrate that NADD binds with TLR4 directly. Our study reveals a new role of NADD in inhibiting the TLR4/NF-κB and NLRP3/Caspase-1 pathways, and shows that TLR4-MD2 is the direct target of NADD, which may provide a potential therapeutic candidate for the treatment of neuroinflammation.

Solvent directed chemically divergent synthesis of β-lactams and α-amino acid derivatives with chiral isothiourea

A protocol for the chemically divergent synthesis of β-lactams and α-amino acid derivatives with isothiourea (ITU) catalysis by switching solvents was developed. The stereospecific Mannich reaction occurring between imine and C(1)-ammonium enolate generated zwitterionic intermediates, which underwent intramolecular lactamization and afforded β-lactam derivatives when DCM and CH₃CN were used as solvents. However, when EtOH was used as the solvent, the intermediates underwent an intermolecular esterification reaction, and α-amino acid derivatives were produced. Detailed mechanistic experiments were conducted to prove that these two kinds of products came from the same intermediates. Furthermore, chemically diversified transformations of β-lactam and α-amino acid derivatives were achieved.

A protocol for the solvent directed chemically divergent synthesis of β-lactam and α-amino acid derivatives with chiral isothiourea was reported.

Naturally occurring physalins from the genus Physalis: A review

Physalins, including physalins and neophysalins, are a class of highly oxygenated ergostane-type steroids. They are commonly known by the name of 16,24-cyclo-13,14-seco steroids, in which the disconnection of C-13 and C-14 produces an eight or nine-membered ring and the carbocyclization of C-16 and C-24 generates a new six-membered ring. Meanwhile, the oxidation of C-18 methyl to carboxyl group forms a 18,20-lactone, and the oxidation of C-14 and C-17 gets a heterocyclic oxygen acrossing rings C and D. Additionly, physalins frequently form an oxygen bridge to connect C-14 to C-27. Physalins are a kind of characteristic constituents from the species of the genus Physalis (Solanaceae), which are reported with a wide array of pharmacological activities, including anticancer, anti-inflammatory, immunoregulatory, antimicrobial, trypanocidal and leishmanicidal, antinociceptive, antidiabetic and some other activities. Herein,the research progress of physalins from the genus Physalis during the decade from 1970 to 2021 on phytochemistry, pharmacology, pharmacokinetics and application in China are systematically presented and discussed for the first time.

Synthesis, Fungicidal Activity, and Mechanism of Action of Pyrazole Amide and Ester Derivatives Based on Natural Products l-Serine and Waltherione Alkaloids

The development of new green fungicides based on the structural optimization of natural products can effectively solve the problems of low safety and high pathogen resistance of traditional fungicides. In this paper, based on pyrazole amide compound h-I-9 with excellent fungicidal activity discovered in the previous work, a series of l-serine-derived pyrazole amide and waltherione alkaloid-derived pyrazole ester derivatives were synthesized. The structures were successively identified by ¹H NMR, ¹³C NMR, high-resolution mass spectrometry, and X-ray single-crystal diffraction. The in vitro and in vivo fungicidal activity screening demonstrated that compound II-5 showed a good inhibition rate against Physalospora piricola. A transmission electron microscope and fluorescence microscope observation further revealed that compound II-5 may cause damage to the cell membranes and vacuoles, and the hyphae treated with II-5 could produce obvious and easily observed blue fluorescence. The succinate dehydrogenase (SDH) enzymatic activity and molecular docking simulation indicated that compounds I-3 and I-4 may be potential SDH inhibitors against Alternaria sp.

Epigenetic Manipulation to Trigger Production of Guaiane-Type Sesquiterpenes from a Marine-Derived Spiromastix sp. Fungus with Antineuroinflammatory Effects

Epigenetic manipulation of a deep-sea sediment-derived Spiromastix sp. fungus using suberoylanilide hydroxamic acid (SAHA) induction resulted in the activation of a terpene-related biosynthetic gene cluster, and nine new guaiane-type sesquiterpenes, spiromaterpenes A-I (1-9), were isolated. Their structures were determined using various spectroscopic techniques, in association with the modified Mosher's method, computed electronic circular dichroism (ECD) spectra, and chemical conversion for configurational assignments. Compounds 4-6 exhibited significant effects against the NO production on lipopolysaccharide (LPS)-induced microglia cells BV2, and the preliminary SAR analyses demonstrated that a 2(R),11-diol unit is favorable. The most active 5 abolished LPS-induced NF-κB translocation from the cytosol to the nucleus in BV-2 microglial cells, accompanied by the marked reduction of the transcription levels of pro-inflammatory cytokines, including IL-1β, IL-6, and TNF-α dose-dependently in both LPS-induced BV-2 and BV-2 cells, as well as the protein and mRNA levels of iNOS and COX-2. This study complements the gap in knowledge regarding the anti-neuroinflammatory activity of guaiane-type sesquiterpenoids at the cellular level and suggests that 5 is promising for further optimization as a multifunctional agent for antineuroinflammation.

Concise Synthesis of 9,11-Secosteroids Pinnigorgiols B and E

Pinnigorgiols B and E are 9,11-secosteroids with a unique tricyclic γ-diketone framework. Herein, we report the first synthesis of these natural products from inexpensive, commercially available ergosterol. This synthesis features a semipinacol rearrangement and an acyl radical cyclization/hemiketalization cascade; the latter efficiently assembled the tricyclic γ-diketone skeleton, with two rings and three contiguous stereogenic centers being formed in a single step.

New protein tyrosine phosphatase inhibitors from fungus Aspergillus gorakhpurensis F07ZB1707

Twelve new compounds, aspergorakhins A-L (1-12) coupled with one known xanthone leptosphaerin D (13), were isolated from the extract of soil-derived fungus Aspergillus gorakhpurensis F07ZB1707. Their structures were elucidated by spectroscopic data analysis including UV, IR, NMR, and HRESIMS. The absolute configurations of 5 and 8-11 were identified using ECD and OR calculations. All compounds were tested by enzyme inhibitory activity assay in vitro. Aspergorakhin A (1) showed selective activities against PTP1B and SHP1 over TCPTP with IC₅₀ values 0.57, 1.19, and 22.97 μM, respectively. Compounds 1 and 2 exhibited modest cytotoxicity against tumor cell lines A549, HeLa, Bel-7402, and SMMC-7721 with IC₅₀ values in the range of 6.75-83.4 μM.

Facile synthesis of selenocarbamyl fluorides, selenoureas and their derivatives with [Me4N][SeCF3]

[Me4N][SeCF3] has proved to be an excellent precursor of Se=CF2 for amines in the preparation of selenocarbamoyl fluorides, selenoureas, and their derivatives under catalyst- and additive-free conditions, which are otherwise difficult to synthesize by other methods.

Generation of Carbocations under Photoredox Catalysis: Electrophilic Aromatic Substitution with 1-Fluoroalkylbenzyl Bromides

A novel Friedel-Crafts-type alkylation of arenes to access valuable 1-fluoroalkyl-1,1-biaryl compounds is established under mild conditions. The key to success is the efficient generation of a destabilized benzylic carbocation intermediate via two consecutive single-electron transfer processes by virtue of visible-light photoredox catalysis. This unique activation pattern avoids using strong Lewis acids and high temperatures that are required for generation of destabilized carbocations in traditional Friedel-Crafts reactions. This protocol demonstrates the first example of photoredox-catalyzed heterolysis of electronically deactivated benzylic C-Br bonds for the formation of destabilized carbocation intermediates.

Anti-inflammatory effects of cordycepin: A review

Cordycepin is the major bioactive component extracted from Cordyceps militaris. In recent years, cordycepin has received increasing attention owing to its multiple pharmacological activities. This study reviews recent researches on the anti-inflammatory effects and the related activities of cordycepin. The results from our review indicate that cordycepin exerts protective effects against inflammatory injury for many diseases including acute lung injury (ALI), asthma, rheumatoid arthritis, Parkinson's disease (PD), hepatitis, atherosclerosis, and atopic dermatitis. Cordycepin regulates the NF-κB, RIP2/Caspase-1, Akt/GSK-3β/p70S6K, TGF-β/Smads, and Nrf2/HO-1 signaling pathways among others. Several studies focusing on cordycepin derivatives were reviewed and found to down metabolic velocity of cordycepin and increase its bioavailability. Moreover, cordycepin enhanced immunity, inhibited the proliferation of viral RNA, and suppressed cytokine storms, thereby suggesting its potential to treat COVID-19 and other viral infections. From the collected and reviewed information, this article provides the theoretical basis for the clinical applications of cordycepin and discusses the path for future studies focusing on expanding the medicinal use of cordycepin. Taken together, cordycepin and its analogs show great potential as the next new class of anti-inflammatory agents.

Anti-inflammatory Withanolides from Physalis minima

Five new withanolides (1-5) along with five known ones (6-10) were isolated from the whole plants of Physalis minima Linn. The chemical structures of the new compounds were identified as (20S,22R) 15a-acetoxy-5β,6β-epoxy-4β,14a,28-trihydroxy-3β-methoxy-1-oxowitha-16,24-dienolide (1), (20S,22R) 15a-acetoxy-5β,6β-epoxy-3β,4β,14β,17β,20β-pentahydroxy-1-oxowitha-24-enolide (2), (20R,22R) 15α-acetoxy-4β,5α,6β,14α,20β-pentahydroxy-1-oxowitha-2,24-dienolide (3), (20R,22R) 15α-acetoxy-5α,6β,14α,20β-tetrahydroxy-1-oxowitha-2,24-dienolide (4), and (20S,22R) 5α,6β,14β-trihydroxy-1,15-dioxowitha-2,16,24-trienolide (5) on the basis of integration combining IR, UV, HR-ESI-MS, 1D-NMR, and 2D-NMR analyses. Biologically, compounds (1-10) were subjected to evaluate their anti-inflammatory activities via inhibiting nitric oxide production in lipopolysaccharide-stimulated murine RAW 264.7 cells in vitro. The activity screening indicated that all of the compounds showed a moderate inhibitory effect against nitric oxide production with IC₅₀ values of 23.53-66.28 μM.

Accuracy Improvement of Binocular Vision Measurement System for Slope Deformation Monitoring

This paper studies the limitations of binocular vision technology in monitoring accuracy. The factors affecting the surface displacement monitoring of the slope are analyzed mainly from system structure parameters and environment parameters. Based on the error analysis theory, the functional relationship between the structure parameters and the monitoring error is studied. The error distribution curve is obtained through laboratory testing and sensitivity analysis, and parameter selection criteria are proposed. Corresponding image optimization methods are designed according to the error distribution curve of the environment parameters, and a large number of tests proved that the methods effectively improved the measurement accuracy of slope deformation monitoring. Finally, the reliability and accuracy of the proposed system and method are verified by displacement measurement of a slope on site.