Inhibitory Effect Research Articles

Mycobacterium tuberculosis suppresses host antimicrobial peptides by dehydrogenating L-alanine

Antimicrobial peptides (AMPs), ancient scavengers of bacteria, are very poorly induced in macrophages infected by Mycobacterium tuberculosis (M. tuberculosis), but the underlying mechanism remains unknown. Here, we report that L-alanine interacts with PRSS1 and unfreezes the inhibitory effect of PRSS1 on the activation of NF-κB pathway to induce the expression of AMPs, but mycobacterial alanine dehydrogenase (Ald) Rv2780 hydrolyzes L-alanine and reduces the level of L-alanine in macrophages, thereby suppressing the expression of AMPs to facilitate survival of mycobacteria. Mechanistically, PRSS1 associates with TAK1 and disruptes the formation of TAK1/TAB1 complex to inhibit TAK1-mediated activation of NF-κB pathway, but interaction of L-alanine with PRSS1, disables PRSS1-mediated impairment on TAK1/TAB1 complex formation, thereby triggering the activation of NF-κB pathway to induce expression of AMPs. Moreover, deletion of antimicrobial peptide gene β-defensin 4 (Defb4) impairs the virulence by Rv2780 during infection in mice. Both L-alanine and the Rv2780 inhibitor, GWP-042, exhibits excellent inhibitory activity against M. tuberculosis infection in vivo. Our findings identify a previously unrecognized mechanism that M. tuberculosis uses its own alanine dehydrogenase to suppress host immunity, and provide insights relevant to the development of effective immunomodulators that target M. tuberculosis.

LP340, a novel histone deacetylase inhibitor, decreases liver injury and fibrosis in mice: role of oxidative stress and microRNA-23a

Effective therapy for liver fibrosis is lacking. Here, we examined whether LP340, the lead candidate of a new-generation of hydrazide-based HDAC1,2,3 inhibitors (HDACi), decreases liver fibrosis. Liver fibrosis was induced by CCl4 treatment and bile duct ligation (BDL) in mice. At 6 weeks after CCl4, serum alanine aminotransferase increased, and necrotic cell death and leukocyte infiltration occurred in the liver. Tumor necrosis factor-α and myeloperoxidase markedly increased, indicating inflammation. After 6 weeks, α-smooth muscle actin (αSMA) and collagen-1 expression increased by 80% and 575%, respectively, indicating hepatic stellate cell (HSC) activation and fibrogenesis. Fibrosis detected by trichrome and Sirius-red staining occurred primarily in pericentral regions with some bridging fibrosis in liver sections. 4-Hydroxynonenal adducts (indicator of oxidative stress), profibrotic cytokine transforming growth factor-β (TGFβ), and TGFβ downstream signaling molecules phospho-Smad2/3 also markedly increased. LP340 attenuated indices of liver injury, inflammation, and fibrosis markedly. Moreover, Ski-related novel protein-N (SnoN), an endogenous inhibitor of TGFβ signaling, decreased, whereas SnoN expression suppressor microRNA-23a (miR23a) increased markedly. LP340 (0.05 mg/kg, ig., daily during the last 2 weeks of CCl4 treatment) decreased 4-hydroxynonenal adducts and miR23a production, blunted SnoN decreases, and inhibited the TGFβ/Smad signaling. By contrast, LP340 had no effect on matrix metalloproteinase-9 expression. LP340 increased histone-3 acetylation but not tubulin acetylation, indicating that LP340 inhibited Class-I but not Class-II HDAC in vivo. After BDL, focal necrosis, inflammation, ductular reactions, and portal and bridging fibrosis occurred at 2 weeks, and αSMA and collagen-1 expression increased by 256% and 560%, respectively. LP340 attenuated liver injury, ductular reactions, inflammation, and liver fibrosis. LP340 also decreased 4-hydroxynonenal adducts and miR23a production, prevented SnoN decreases, and inhibited the TGFβ/Smad signaling after BDL. In vitro, LP340 inhibited immortal human hepatic stellate cells (hTERT-HSC) activation in culture (αSMA and collagen-1 expression) as well as miR23a production, demonstrating its direct inhibitory effects on HSC. In conclusions, LP340 is a promising therapy for both portal and pericentral liver fibrosis, and it works by inhibiting oxidative stress and decreasing miR23a.

Response of Anaerobic Granular Sludge Reactor to Plant Polyphenol Stress: Floc Disintegration and Microbial Inhibition

Plant polyphenols are potential inhibitors for the anaerobic treatment of wastewater from the wood processing, pharmaceutical, and leather industries. Tannic acid (TA) was selected as a model compound to assess the inhibitory effect of plant polyphenols in simulated wastewater in this study. The influences of TA on methanogenic activity, sludge morphology, and the microbial community were investigated under glucose and sodium acetate as carbon substrates, respectively. The results show that a threshold concentration of TA above 1500 mg·L−1 that triggers significant methanogenesis depression and volatile fatty acids (VFAs) accumulation. In addition, granules might be weakened by TA addition, reflected in changes in extracellular polymeric substances (EPS) within the granules and an increase in floc in the effluent. The anaerobic granular sludge (AnGS) fed with sodium acetate was more sensitive than the presence of glucose as the substrate when facing the challenge of TA. The concentration of the mcrA gene in granular sludge decreased markedly in response to TA stress, providing direct evidence that a high concentration of TA caused the inhibition of specific gene expressions. This study provides details about the adverse impacts of TA stress on methane production, the microbial community, and granule integrity, deepening our understanding of the anaerobic treatment of plant polyphenols contained in wastewater.

Diterpenoids from Acanthopanacis Cortex and their anti-inflammatory activity studies.

Acanthopanacis Cortex (A.-C) with a long history of more than1000years, has been used to treat rheumatism effectively. Nineteen diterpenoids have been isolated from A.-C, including six new compounds (1-6). Among them, compounds 7, 9-11, 13, and 17 were discovered from A.-C for the first time. The structures of 1-6 were determined by analyzing their NMR data and comparing their experimental and calculated electronic circular dichroism spectra. Moreover, the single-crystal X-ray diffraction data of 1, 2, 8, and 14 were provided. The anti-inflammatory activity of 1-5 and 7-18 on neutrophil elastase, cyclooxygenase-1 (COX-1), and cyclooxygenase-2 (COX-2) has been studied in vitro, and the results showed that 15 had almost no inhibitory effects on COX-1 at 200μM but a significant activity against COX-2 with an IC50 of 0.73±0.006 μΜ. It indicated that compound 15 can provide valuable information for the design of selective COX-2 inhibitors.

Whitening and antioxidant activities of Inonotus sanghuang Extract and development of primary whitening gel products.

Polysaccharides and flavonoids have excellent antioxidant properties and tyrosinase inhibitory effects. In this paper, the antioxidant capacity of Inonotus sanghuang extract and its inhibition kinetics on mushroom tyrosinase were investigated to determine the preparation process of Inonotus sanghuang primary whitening gel. By conducting experimental studies on the effects of water extract and alcohol extract of Inonotus sanghuang on antioxidant capacity and tyrosinase activity, their inhibitory ability and types of inhibitory effects were determined. The single factor experiment was used to determine the preparation process of Sanghuang primary whitening gel. This study has proven that the extract of Inonotus sanghuang possesses antioxidant and tyrosinase inhibitory capabilities. It also identified the preparation process for the primary whitening gel of Inonotus sanghuang, thereby providing a theoretical and experimental basis for the development of whitening products utilising Inonotus sanghuang.

Exploring traditional and modern approaches for extracting bioactive compounds from Ferulago trachycarpa

For more than two millennia, Ferulago species have been revered as therapeutic herbs, maintaining their significance in present-day folk medicine practices. Therefore, the present study was conducted to investigate the phytochemical composition, inhibitory effects on metabolic enzymes, and possible therapeutic applications of F. trachycarpa, specifically focusing on its efficacy in diabetes management, anticholinergic effects, and antioxidant capabilities. The current investigation comprised an evaluation of a range of extracts acquired via conventional and modern methodologies, such as soxhlet (SOX), maceration (MAC) accelerated solvent extraction (ASE), homogenizer-assisted extraction (HAE), supercritical fluid extraction (SFE), microwave-assisted extraction (MW), and ultrasound-assisted extraction (UAE). Various techniques were employed to assess their antioxidant capacity and enzyme inhibition. Furthermore, the research utilized ultra-high performance liquid chromatography-MS/MS (UHPLC-MS/MS) to ascertain the principal phenolic compounds that are responsible for the antioxidant capacity observed in the various F. trachycarpa extracts. Among these, extracts from HAE, ASE, and MW revealed the most promise across all methodologies tested for their antioxidant potential. Furthermore, SFE and MAC extracts inhibited the most enzymes, including cholinesterases, tyrosinase, α -amylase, and α -glycosidase, indicating their potential as efficient natural treatments for several health-related issues.

A Novel Fluorescent Probe containing dihydropyrimidinone Analogue for Highly Sensitive, Selective Detection of Al(III) Ions with its Molecular Docking, ADME/T and Anticancer Impact

AbstractIn this investigation, a novel and promising chemosensor incorporating a dihydropyrimidinone moiety, namely; (E)‐4‐(4‐(dimethylamino)phenyl)‐5‐(3‐(4‐(dimethylamino)phenyl)acryloyl)‐6‐methyl‐3,4 dihydropyrimidin‐2(1H)‐one (DPDAD), has been successfully synthesized and characterized. The DPDAD chemosensor‘s response was evaluated in diverse solvents with varying polarities, shedding light on its solvatochromic behavior. The assessment of colorimetric and optical sensing attributes toward a range of metal ions such as Al(III), Cr(III), Mn II), Fe(III), Co(II), Ni(II), and Cu(II) was undertaken. Notably, DPDAD displayed discernible color alterations upon interaction with all the examined metal ions, with a significant bathochromic shift observed in the absorption spectra in the presence of Al(III), distinguishing it from the other metal ions. Furthermore, through detailed absorption and emission spectral analyses, DPDAD exhibited remarkable selectivity, sensitivity, and an on‐off‐on switchable behavior specifically with Al(III) ions, over the other metal ions. The binding constant was determined as 0.39×105 M−1, accompanied by a limit of detection (LOD) of 1.03×10−5 M. Notably, the DPDAD′s potential extends beyond metal ion sensing; it was computationally assessed for its capability to inhibit the γ‐secretase enzyme. Moreover, DPDAD′s antioxidant attributes were probed, and its inhibitory effect against a range of cancer cell lines was verified in‐vitro.

КОФЕЙНАЯ КИСЛОТА СТИМУЛИРУЕТ СВЕЧЕНИЕ МИЦЕЛИЯ ВЫСШИХ ГРИБОВ NEONOTHOPANUS NAMBI, ARMILLARIA BOREALIS IN VIVO

In vivo experiments have shown that the addition of caffeic acid to the luminous mycelia of the higher fungi Neonothopanus nambi and Armillaria borealis stimulates a rapid and significant (by an order of magnitude or more) increase in the intensity of their light emission. It has been suggested that the observed effect of fungal luminescence activation may be mediated by the oxidation of caffeic acid by enzymes of the ligninolytic complex of basidiomycetes (in particular, by peroxidases) with the emission of visible light quanta. Comparative in vivo experiments showed that the addition of hispidin (the precursor of luciferin in the light emission reaction of higher fungi) did not affect the intensity of bioluminescence of the mycelia. At the same time, in vitro studies found that caffeic acid significantly suppressed the NADPH-hispidin-activated emission reaction of luminescent systems isolated from the mycelia of N. nambi and A. borealis. The inhibitory effect of caffeic acid is considered and discussed in the work from the standpoint of the classical biochemistry concept on enzyme inhibition by the reaction product according to the negative feedback principle. In general, the results obtained develop and supplement the understanding of the mechanisms of light emission in higher fungi and testify in favor of the fact that the generation of visible light quanta in basidiomycetes can be carried out by different biochemical pathways involving different enzymes (or enzyme systems). Clarifying the mechanism of stimulation of in vivo bioluminescence of higher fungi by caffeic acid is a priority for further research.

Revisiting the Inhibitory Effect of General Mental Ability on Counterproductive Work Behavior: The Case for GMA-Personality Interaction

Revisiting the Inhibitory Effect of General Mental Ability on Counterproductive Work Behavior: The Case for GMA-Personality Interaction

Tributelosides A-D: Four Undescribed Spirostan Glycosides Isolated from the Branches and Leaves of Tribulus terrestris with Their NO Production Inhibitory Activity in LPS Activated RAW 264.7 Cells.

Four undescribed spirostan glycosides, (25S)-5α-spirostan-12-one-2α,3β-diol-3-O-β-D-glucopyranosyl-(1→4)-β-D-galactopyranoside (1), (25S)-5α-spirostan-12-one-2α,3β-diol-3-O-β-D-galatopyranosyl-(1→2)-β-D-glucopyranosyl-(1→4)-β-D-galactopyranoside (2), (25S)-5α-spirostan-12-one-2α,3β-diol-3-O-β-D-glucopyranosyl-(1→2)-[β-D-glucopyranosyl-(1→3)]-β-D-glucopyranosyl-(1→4)-β-D-galactopyranoside (3), and hecogenin 3-O-β-D-glucopyranosyl-(1→3)-[β-D-xylopyranosyl-(1→2)]-β-D-glucopyranosyl-(1→4)-[α-L-rhamnopyranosyl-(1→2)]-β-D-galactopyranoside (4), together with eleven known compounds (5-15) were isolated from the branches and leaves of Tribulus terrestris. Their chemical structures were established through spectroscopic methods. including HR-ESI-MS, 1D-, and 2D-NMR spectra. Preliminary biological evaluation on NO production inhibitory activity in LPS activated RAW 264.7 cells showed that compounds 1-3, 5, and 6 had significant inhibitory effects with IC50 values ranging from 2.4 to 18.3 µM, compared to that of the positive control compound, dexamethazone (IC50 13.6 µM).

Crystal structure of Staphylococcus aureus lipase complex with unsaturated petroselinic acid.

Staphylococcus aureus produces large amounts of toxins and virulence factors. In patients with underlying diseases or compromised immune systems, this bacterium can lead to severe infections and potentially death. In this study, the crystal structure of the complex of S. aureus lipase (SAL), which is involved in the growth of this bacterium, with petroselinic acid (PSA), an inhibitor of unsaturated fatty acids, was determined by X-ray crystallography. Recently, PSA was shown to inhibit S. aureus biofilm formation and the enzymatic activity of SAL. To further characterize the inhibitory mechanism, we determined the half-inhibitory concentration of SAL by PSA and the crystal structure of the complex. The IC50 of the inhibitory effect of PSA on SAL was 3.4 μm. SAL and PSA inhibitors were co-crystallized, and diffraction data sets were collected to 2.19 Å resolution at SPring-8 to determine the crystal structure and elucidate the detailed structural interactions. The results show that the fatty acid moiety of PSA is tightly bound to a hydrophobic pocket extending in two directions around the catalytic residue Ser116. Ser116 was also covalently bonded to the carbon of the unsaturated fatty acid moiety, and an oxyanion hole in SAL stabilized the electrons of the double bond. The difference in inhibitory activity between PSA and ester compounds revealed a structure-activity relationship between SAL and PSA. Additional research is required to further characterize the clinical potential of PSA.

Synthesis of 1,3‐Disubtitituted Tetrahydropyrimidinium Salts and Determination of Their Biological Properties and Molecular Docking

AbstractSeveral of 3,4,5,6‐tetrahydropyrimidinium salts with 1‐methyl functionalization are produced. By using techniques for 1H‐NMR, 13C‐NMR, and IR spectroscopy, all compounds were investigated. Additionally, these compounds’ abilities to block enzymes were looked into. They had a highly effective inhibitory effect on the isoenzymes of carbonic anhydrases I and II, butyrylcholinesterase (BChE), and acetylcholinesterase (AChE). Ki values were found in the range of 57.43±7.09–170.09±50.91 nM for AChE, 7.19±0.42–69.08±2.44 nM for BChE, and 46.48±5.74–203.38±46.15 nM for hCA I, and 30.19±4.03–171.96±30.27 nM for hCA II. As a result, 1,3‐disubtitituted tetrahydroprimidinium salts exhibited potent inhibition profiles toward indicated metabolic enzymes. One of the most important methods for designing and creating novel, potent medications to treat Alzheimer's disease (AD) worldwide is the synthesis and discovery of new AChE and BChE inhibitors. The activities of synthesized 3,4,5,6‐tetrahydropyrimidinium salts were compared against various proteins that are crystal structure of AChE (PDB ID: 4 M0E), crystal structure of BChE (PDB ID: 5NN0), crystal structure of hCA I (PDB ID: 2CAB), and crystal structure of hCA II (PDB ID: 3DC3), and then the drug properties of these molecules were examined.

Inhibitory Effect of Puerarin on Lipopolysaccharide-triggered Inflammatory Responses of Bovine Kidney Cells.

Puerarin (Pue), a flavonoid compound, possesses cytoprotective effects and LPS has been reported to induce renal inflammatory injury in bovine. However, whether Pue inhibits lipopolysaccharide (LPS)-induced inflammatory damage of bovine kidney cells remains unknown. Based on an in vitro model with Madin-Darby bovine kidney (MDBK) cell line, it has found that Pue attenuated LPS-induced damage of MDBK cells, as evidenced by cell viability and lactic dehydrogenase (LDH) release rescued by Pue (P < 0.05). Additionally, the real-time quantitative PCR (qPCR) and enzyme linked immunosorbent assay (ELISA) showed that LPS elevated the levels of pro-inflammatory factors interleukin (IL)-1β, IL-8 and tumor necrosis factor (TNF)-α, which was reversed by pretreatment of Pue (P < 0.05). Besides, Pue reduced the expression of Toll like receptor 4 (TLR4) and phosphorylated nuclear factor kappa B (p-NF-κB) of LPS-exposed MDBK cells (P < 0.05). Collectively, these results showed that Pue suppresses LPS-evoked inflammatory damage of bovine kidney cells, suggesting Pue a potential compound for intervention of bovine inflammation.

Structure Identification of Ganoderma lucidum Spore Polysaccharides and Their Antitumor Activity In Vivo.

Ganoderma lucidum spore powder, valued for its nutritional and medicinal properties, contains polysaccharides crucial for its efficacy. However, the complex structural nature of these polysaccharides necessitates further investigation to fully realize their potential. This study aimed to investigate the effects of acid heat treatment on Ganoderma lucidum spore polysaccharides (GLSPs) to enhance their properties and application in antitumor activity. The GLSP was obtained via acid heat treatment, concentration, and centrifugal separation. This process led to a notable reduction in polysaccharide molecular weight, increasing water solubility and bioavailability. Analytical techniques including NMR spectroscopy and methylation analysis revealed a polysaccharide composition comprising four distinct monosaccharides, with molecular weights of 3291 Da (Mw) and 3216 Da (Mn). Six different linkage modes were identified, with a molar ratio of 1:5:2:3:4:3. In vivo experiments demonstrated the GLSP's significant inhibitory effect on the growth of four tumor models (sarcoma S180, Lewis lung cancer, liver cancer H22, and colon cancer C26) in mice, with no observed toxicity. These findings suggest the GLSP's potential as an antitumor therapeutic agent for clinical use.

Evaluation of the Clinical Drug-Drug Interaction Potential of Pritelivir on Transporters and CYP450 Enzymes Using a Cocktail Approach.

Pritelivir is a novel viral helicase-primase inhibitor active against herpes simplex virus. In vitro drug-drug interaction studies indicated that pritelivir has the potential for clinically relevant interactions on the cytochrome P450 (CYP) enzymes 2C8, 2C9, 3A4, and 2B6, and intestinal uptake transporter organic anion transporting polypeptide (OATP) 2B1 and efflux transporter breast cancer resistance protein (BCRP). This was evaluated in 2 clinical trials. In 1 trial the substrates flurbiprofen (CYP2C9), bupropion (CYP2B6), and midazolam (CYP3A4) were administered simultaneously as part of the Geneva cocktail, while the substrate celiprolol (OAPT2B1) was administered separately. In another trial, the substrates repaglinide (CYP2C8) and rosuvastatin (BCRP) were administered separately. Exposure parameters of the substrates and their metabolites (flurbiprofen and bupropion only) were compared after administration with or without pritelivir under therapeutic concentrations. The results of these trials indicated that pritelivir has no clinically relevant effect on the exposure of substrates for the intestinal uptake transporter OATP2B1 and the CYP enzymes 3A4, 2B6, 2C9, and 2C8, and has a weak inhibitory effect on the intestinal efflux transporter BCRP. In summary, the results suggest that pritelivir has a low drug-drug interaction potential.

Lauinoids A–X: Labdane-type diterpenoids with anti-inflammatory activity from Croton laui

Croton laui (Euphorbiaceae) is a traditional medicinal plant used by the Li ethnic group in China to treat headaches, stomachaches, and diphtheria. To understand the pharmacological basis of its medicinal use, an extensive investigation of the ethanolic extract of the bark of C. laui was performed. After repeated chromatography, twenty-four undescribed labdane-type diterpenoids, lauinoids A–X (1–24), and five known analogs (25–29) were isolated. Their structures and absolute configurations were established using a combination of spectroscopic analyses, electronic circular dichroism, nuclear magnetic resonance calculations, and single-crystal X-ray diffraction. Among them, compounds 1–3 exhibited an 11(12 → 13)-abeo-16-nor-labdane skeleton, which originated putatively from 9 through a plausible pathway that involves a semipinacol rearrangement process. Compounds 11 and 12 belong to the rare class of 14,15-dinor-labdane diterpenoids. Compounds 18 and 28 exhibited substantial inhibitory effects by suppressing lipopolysaccharide-induced NO production in RAW 264.7 macrophages, with IC50 values of 3.37 ± 0.23 and 5.82 ± 0.28 μM, respectively. This study has greatly expanded the chemical diversity of labdane diterpenoids from C. laui and will guide future research on this ethnomedicinal plant.

Glycoside constituents from Cayratia geniculata

Using various chromatographic separations, six glycoside derivatives (1–6), including one new ent-labdane glucoside named cayratioside (1), were isolated from the methanol extract of Cayratia geniculata stems and leaves. Their structures were elucidated by detailed analysis of the 1D, 2D NMR, and HRESIQTOF mass spectra. The inhibitory effect of 1–6 on LPS-induced NO production in RAW264.7 cells was also evaluated. Among isolated compounds, 1 exhibited moderate activity with an IC50 value of 59.65 ± 1.85 µM.

Gypenoside XVII Reduces Synaptic Glutamate Release and Protects against Excitotoxic Injury in Rats.

Excitotoxicity is a common pathological process in neurological diseases caused by excess glutamate. The purpose of this study was to evaluate the effect of gypenoside XVII (GP-17), a gypenoside monomer, on the glutamatergic system. In vitro, in rat cortical nerve terminals (synaptosomes), GP-17 dose-dependently decreased glutamate release with an IC50 value of 16 μM. The removal of extracellular Ca2+ or blockade of N-and P/Q-type Ca2+ channels and protein kinase A (PKA) abolished the inhibitory effect of GP-17 on glutamate release from cortical synaptosomes. GP-17 also significantly reduced the phosphorylation of PKA, SNAP-25, and synapsin I in cortical synaptosomes. In an in vivo rat model of glutamate excitotoxicity induced by kainic acid (KA), GP-17 pretreatment significantly prevented seizures and rescued neuronal cell injury and glutamate elevation in the cortex. GP-17 pretreatment decreased the expression levels of sodium-coupled neutral amino acid transporter 1, glutamate synthesis enzyme glutaminase and vesicular glutamate transporter 1 but increased the expression level of glutamate metabolism enzyme glutamate dehydrogenase in the cortex of KA-treated rats. In addition, the KA-induced alterations in the N-methyl-D-aspartate receptor subunits GluN2A and GluN2B in the cortex were prevented by GP-17 pretreatment. GP-17 also prevented the KA-induced decrease in cerebral blood flow and arginase II expression. These results suggest that (i) GP-17, through the suppression of N- and P/Q-type Ca2+ channels and consequent PKA-mediated SNAP-25 and synapsin I phosphorylation, reduces glutamate exocytosis from cortical synaptosomes; and (ii) GP-17 has a neuroprotective effect on KA-induced glutamate excitotoxicity in rats through regulating synaptic glutamate release and cerebral blood flow.

Myricetin Acts as an Inhibitor of Type II NADH Dehydrogenase from Staphylococcus aureus.

Staphylococcus aureus is a common pathogenic microorganism in humans and animals. Type II NADH oxidoreductase (NDH-2) is the only NADH:quinone oxidoreductase present in this organism and represents a promising target for the development of anti-staphylococcal drugs. Recently, myricetin, a natural flavonoid from vegetables and fruits, was found to be a potential inhibitor of NDH-2 of S. aureus. The objective of this study was to evaluate the inhibitory properties of myricetin against NDH-2 and its impact on the growth and expression of virulence factors in S. aureus. A screening method was established to identify effective inhibitors of NDH-2, based on heterologously expressed S. aureus NDH-2. Myricetin was found to be an effective inhibitor of NDH-2 with a half maximal inhibitory concentration (IC50) of 2 μM. In silico predictions and enzyme inhibition kinetics further characterized myricetin as a competitive inhibitor of NDH-2 with respect to the substrate menadione (MK). The minimum inhibitory concentrations (MICs) of myricetin against S. aureus strains ranged from 64 to 128 μg/mL. Time-kill assays showed that myricetin was a bactericidal agent against S. aureus. In line with being a competitive inhibitor of the NDH-2 substrate MK, the anti-staphylococcal activity of myricetin was antagonized by MK-4. In addition, myricetin was found to inhibit the gene expression of enterotoxin SeA and reduce the hemolytic activity induced by S. aureus culture on rabbit erythrocytes in a dose-dependent manner. Myricetin was newly discovered to be a competitive inhibitor of S. aureus NDH-2 in relation to the substrate MK. This discovery offers a fresh perspective on the anti-staphylococcal activity of myricetin.

CEO’s Financial Background and Corporate Green Innovation

Innovation is the primary driving force for development, and enterprises, as the main drivers of innovation, are an important part of implementing the national innovation strategy. This paper, combining the perspective of the enterprise lifecycle, thoroughly examines the differential impact of the CEO’s financial background on green innovation in enterprises at different stages of the lifecycle. This study finds that the CEO’s financial background has a significant inhibitory effect on green innovation in enterprises, and this conclusion holds true after multiple robustness tests. From the perspective of the lifecycle, it is found that when enterprises are in the mature stage, the CEO’s financial background has a strong inhibitory effect on innovation output. The impact of the CEO’s financial background on green innovation output in the growth stage is relatively weak, while there is no significant impact on green innovation in the declining period. Furthermore, based on the enterprise lifecycle, it is found that the CEO’s financial background has a stronger inhibitory effect on green innovation in non-state-owned enterprises and high-tech industries. The research findings of this paper have important theoretical value and practical significance for promoting green innovation in enterprises and implementing the national innovation strategy.