Enoyl-acyl Carrier Protein Reductase Research Articles

In vitro and in vivo enhancement effect of glabridin on the antibacterial activity of colistin, against multidrug resistant Escherichia coli strains

Background: The increase in antimicrobial resistance leads to complications in treatments, prolonged hospitalization, and increased mortality. Glabridin (GLA) is a hydroxyisoflavan from Glycyrrhiza glabra L. that exhibits multiple pharmacological activities. Colistin (COL), a last-resort antibiotic, is increasingly being used in clinic against Gram-negative bacteria. Previous reports have shown that GLA is able to sensitize first line antibiotics such as norfloxacin and vancomycin on Staphylococcus aureus, implying that the use of GLA as an antibiotic adjuvant is a promising strategy for addressing the issue of drug resistance. However, the adjuvant effect on other antibiotics, especially COL, on Gram-negative bacteria such as Escherichia coli has not been studied. Purpose: The objective of our study was to investigate the targets of GLA and the synergistic effect of GLA and COL in E. coli, and to provide further evidence for the use of GLA as an antibiotic adjuvant to alleviate the problem of drug resistance. Methods: We first investigated the interaction between GLA and enoyl-acyl carrier protein reductase, also called "FabI", through enzyme inhibition assay, differential scanning fluorimetry, isothermal titration calorimetry and molecular docking assay. We tested the transmembrane capacity of GLA on its own and combined it with several antibiotics. The antimicrobial activities of GLA and COL were evaluated against six different susceptible and resistant E. coli in vitro. Their interactions were analyzed using checkerboard assay, time-kill curve and CompuSyn software. A series of sensitivity tests was conducted in E. coli overexpressing the fabI gene. The development of COL resistance in the presence of GLA was tested. The antimicrobial efficacy of GLA and COL in a mouse model of urinary tract infection was assessed. The anti-biofilm effects of GLA and COL were investigated. Results: In this study, enzyme kinetic analysis and thermal analysis provided evidence for the interaction between GLA and FabI in E. coli. GLA enhanced the antimicrobial effect of COL and synergistically suppressed six different susceptible and resistant E. coli with COL. Overexpression experiments showed that targeted inhibition of FabI was a key mechanism by which GLA synergistically enhanced COL activity. The combination of GLA and COL slowed the development of COL resistance in E. coli. Combined GLA and COL treatment significantly reduced bacterial load and mitigated urinary tract injury in a mouse model of E. coli urinary tract infection. Additionally, GLA + COL inhibited the formation and eradication of biofilms and the synthesis of curli. Conclusion: Our findings indicate that GLA synergistically enhances antimicrobial activities of COL by targeting inhibition of FabI in E. coli. GLA is expected to continue to be developed as an antibiotic adjuvant to address drug resistance issues.

Evaluation of novel pyridoxal isonicotinoyl hydrazone (PIH) derivatives as potential anti‐tuberculosis agents: An in silico investigation

AbstractThis investigation employed computational methodologies to assess the therapeutic potential of derivatives (1–16) of pyridoxal isonicotinoyl hydrazone (PIH) as potential treatments for tuberculosis. Various computational techniques, including molecular dynamics simulation, molecular docking, density functional theory, and global chemical descriptors, were employed to analyze the interactions between the ligands and target proteins. Docking results indicated that ligands 6, 7, 8, and rifampin exhibited binding affinities of −8.4, −7.4, −9.2, and − 7.2 kcal mol−1, respectively, against mycobacterium tuberculosis enoyl acyl carrier protein reductase (INHA), with ligand 8 demonstrating superior inhibition. Molecular dynamics (MD) simulations were utilized to assess the stability of protein‐ligand interactions. Remarkably, the Root Mean Square Deviation (RMSD) of the INHA‐ligand 8 complex remained minimal, with peak values at .40, .56, .37, and .50 nm at temperatures of 300, 305, 310, and 320 K, respectively. This suggests superior stability compared to the reference drug rifampin and INHA complex, which exhibited an RMSD range of .2 to .8 nm at 300 K. Furthermore, analysis using Frontier Molecular Orbital (FMO) revealed that the Egap value of ligand 8 (4.407 eV) is lower than all the reference drugs except rifampin. This comprehensive theoretical analysis positions ligand 8 as a promising candidate for anti‐tuberculosis drug development, underscoring the need for further exploration through in vitro and in vivo studies.

FabV, the Unique Enoyl-Acyl Carrier Protein Reductase in Xanthomonas arboricola pv. juglandis Associated with Walnut Bacterial Blight, Is Essential for the Growth and Confers Triclosan Resistance to the Strain.

Walnut bacterial blight caused by Xanthomonas arboricola pv. juglandis (Xaj) is one of the most prevalent diseases of walnut (Juglans spp.), causing significant reductions in nut yield and important losses in economy. Enoyl-acyl carrier protein (ACP) reductase (ENR) is one of the key enzymes involved in the biosynthesis of bacterial fatty acids. In this study, we identified a single ENR-encoding gene, RS10040, in the genome of the XajDW3F3 strain. Sequence alignment analysis suggested RS10040 as a candidate fabV gene in Xaj. Expression of XajfabV restored the growth of the Escherichia coli fabI temperature-sensitive mutant under a nonpermissive growth condition. In vitro assays demonstrated that XajFabV catalyzed enoyl-ACPs of various chain lengths to acyl-ACPs, demonstrating its role in de novo fatty acid biosynthesis. Furthermore, we confirmed that XajfabV is an essential gene for growth, as no XajfabV deletion mutant could be obtained, although XajfabV in the chromosome could be deleted after compensating with a functional ENR-encoding gene via an exogenous plasmid. The fabV replacement mutants showed similar growth characteristic and fatty acid compositions. Our data further identified that fabV conferred Xaj with tolerance to various environmental stresses. Although XajFabV conferred Xaj with triclosan resistance, the resistance of Xaj was weaker than that found for Pseudomonas aeruginosa. Moreover, triclosan exhibited a control effect against infection of the ΔfabV/EcfabI to its host walnut. This study revealed the function of XajFabV and laid a theoretical foundation for the fatty acid synthesis mechanism of Xaj.

Design, Synthesis, Characterization and Antitubercular Activity of Novel Benzimidazole Mannich Base Derivatives

In present work, the newly synthesized benzimidazole Mannich base derivatives were design, synthesized and evaluated the in silico and in vitro antitubercular activity. These compounds were synthesized by condensation reaction between 1-(1H-benzo[d]imidazol-1-yl)ethanone and aliphatic/aromatic amines. The synthesized compound structures were identified by FTIR, 13C NMR, 1H NMR and mass spectroscopies. The results indicated that these derivatives have significant antitubercular activity against Mycobacterium tuberculosis (M.tb) cell wall enzyme enoyl acyl carrier protein reductase (InhA), EthR regulatory protein in H73Rv strain. The results found in the in vitro study are firmly similar to the in silico study. Among the synthesized compounds, 3d and 3e exhibited the highest activity due to the connection of the electron-donating group to the Mannich base. Therefore, these compounds deserve the development of new antitubercular agents.

Navigating the Chemical Space of ENR Inhibitors: A Comprehensive Analysis.

Antimicrobial resistance is a global health threat that requires innovative strategies against drug-resistant bacteria. Our study focuses on enoyl-acyl carrier protein reductases (ENRs), in particular FabI, FabK, FabV, and InhA, as potential antimicrobial agents. Despite their promising potential, the lack of clinical approvals for inhibitors such as triclosan and isoniazid underscores the challenges in achieving preclinical success. In our study, we curated and analyzed a dataset of 1412 small molecules recognized as ENR inhibitors, investigating different structural variants. Using advanced cheminformatic tools, we mapped the physicochemical landscape and identified specific structural features as key determinants of bioactivity. Furthermore, we investigated whether the compounds conform to Lipinski rules, PAINS, and Brenk filters, which are crucial for the advancement of compounds in development pipelines. Furthermore, we investigated structural diversity using four different representations: Chemotype diversity, molecular similarity, t-SNE visualization, molecular complexity, and cluster analysis. By using advanced bioinformatics tools such as matched molecular pairs (MMP) analysis, machine learning, and SHAP analysis, we were able to improve our understanding of the activity cliques and the precise effects of the functional groups. In summary, this chemoinformatic investigation has unraveled the FAB inhibitors and provided insights into rational antimicrobial design, seamlessly integrating computation into the discovery of new antimicrobial agents.

Quinazolin-4-one Derivatives: Enoyl-acyl Carrier Protein (ACP) Reductase (InhA) Antagonists Using in silico Drug Design Approach

Quinazolin-4-one Derivatives: Enoyl-acyl Carrier Protein (ACP) Reductase (InhA) Antagonists Using in silico Drug Design Approach

Abstract 1150 Determination of Potential Novel Inhibitors for Francisella tularensis enoyl-acyl carrier protein reductase I (FabI) via High-Throughput Virtual Screening Methods

Abstract 1150 Determination of Potential Novel Inhibitors for Francisella tularensis enoyl-acyl carrier protein reductase I (FabI) via High-Throughput Virtual Screening Methods

Machine learning assisted methods for the identification of low toxicity inhibitors of Enoyl-Acyl Carrier Protein Reductase (InhA)

Tuberculosis (TB) is one of the life-threatening infectious diseases with prehistoric origins and occurs in almost all habitable parts of the world. TB mainly affects the lungs, and its etiological agent is Mycobacterium tuberculosis (Mtb). In 2022, more than 10 million people were infected worldwide, and 1.3 million were children. The current study considered the in-silico and machine learning (ML) approaches to explore the potential anti-TB molecules from the SelleckChem database against Enoyl-Acyl Carrier Protein Reductase (InhA). Initially, the entire database of ∼ 119000 molecules was sorted out through drug-likeness. Further, the molecular docking study was conducted to reduce the chemical space. The standard TB drug molecule's binding energy was considered a threshold, and molecules found with lower affinity were removed for further analyses. Finally, the molecules were checked for the pharmacokinetic and toxicity studies, and compounds found to have acceptable pharmacokinetic parameters and were non-toxic were considered as final promising molecules for InhA. The above approach further evaluated five molecules for ML-based toxicity and synthetic accessibility assessment. Not a single molecule was found toxic and each of them was revealed as easy to synthesise. The complex between InhA and proposed and standard molecules was considered for molecular dynamics simulation. Several statistical parameters showed the stability between InhA and the proposed molecule. The high binding affinity was also found for each of the molecules towards InhA using the MM-GBSA approach. Hence, the above approaches and findings exposed the potentiality of the proposed molecules against InhA.

In silico design, synthesis and antitubercular activity of novel 2-acylhydrazono-5-arylmethylene-4-thiazolidinones as enoyl-acyl carrier protein reductase inhibitors

Mycobacteria regulate the synthesis of mycolic acid through the fatty acid synthase system type 1 (FAS I) and the fatty acid synthase system type-2 (FAS-II). Because mammalian cells exclusively utilize the FAS-I enzyme system for fatty acid production, targeting the FAS-II enzyme system could serve as a specific approach for developing selective antimycobacterial drugs. Enoyl-acyl carrier protein reductase enzyme (MtInhA), part of the FAS-II enzyme system, contains the NADH cofactor in its active site and reduces the intermediate. Molecular docking studies were performed on an in-house database (∼2200 compounds). For this study, five different crystal structures of MtInhA (PDB Code: 4TZK, 4BQP, 4D0S, 4BGE, 4BII) were used due to rotamer difference, mutation and the presence of cofactors. Molecular dynamics simulations (250 ns) were performed for the novel 2-acylhydrazono-5-arylmethylene-4-thiazolidinones derivatives selected by molecular docking studies. Twenty-three compounds selected by in silico methods were synthesized. Antitubercular activity and MtInhA enzyme inhibition studies were performed for compounds whose structures were elucidated by IR,1H-NMR,13C-NMR, HSQC, HMBC, MS and elemental analysis. Communicated by Ramaswamy H. Sarma

Identification of new anti-mycobacterial agents based on quinoline-isatin hybrids targeting enoyl acyl carrier protein reductase (InhA)

Tuberculosis (TB) is a global issue that poses a significant economic burden as a result of the ongoing emergence of drug-resistant strains. The urgent requirement for the development of novel antitubercular drugs can be addressed by targeting specific enzymes. One such enzyme, Mycobacterium tuberculosis (MTB) enoyl-acyl carrier protein (enoyl-ACP) reductase (InhA), plays a crucial role in the survival of the MTB bacterium. In this research study, a series of hybrid compounds combining quinolone and isatin were synthesized and assessed for their effectiveness against MTB, as well as their ability to inhibit the activity of the InhA enzyme in this bacterium. Among the compounds tested, 7a and 5g exhibited the most potent inhibitory activity against MTB, with minimum inhibitory concentration (MIC) values of 55 and 62.5 µg/mL, respectively. These compounds were further evaluated for their inhibitory effects on InhA and demonstrated significant activity compared to the reference drug Isoniazid (INH), with IC50 values of 0.35 ± 0.01 and 1.56 ± 0.06 µM, respectively. Molecular docking studies investigated the interactions between compounds 7a and 5g and the target enzyme, revealing hydrophobic contacts with important amino acid residues in the active site. To further confirm the stability of the complexes formed by 5g and 7a with the target enzyme, molecular dynamic simulations were employed, which demonstrated that both compounds 7a and 5g undergo minor structural changes and remain nearly stable throughout the simulated process, as assessed through RMSD, RMSF, and Rg values.

Structural and Biochemical Studies on Klebsiella Pneumoniae Enoyl-ACP Reductase (FabI) Suggest Flexible Substrate Binding Site.

Klebsiella pneumoniae, a bacterial pathogen infamous for antibiotic resistance, is included in the priority list of pathogens by various public health organizations due to its extraordinary ability to develop multidrug resistance. Bacterial fatty acid biosynthesis pathway-II (FAS-II) has been considered a therapeutic drug target for antibacterial drug discovery. Inhibition of FAS-II enzyme, enoyl-acyl carrier protein reductase, FabI, not only inhibits bacterial infections but also reverses antibiotic resistance. Here, we characterized Klebsiella pneumoniae FabI (KpFabI) using complementary experimental approaches including, biochemical, x-ray crystallography, and molecular dynamics simulation studies. Biophysical studies shows that KpFabI organizes as a tetramer molecular assembly in solution as well as in the crystal structure. Enzyme kinetics studies reveal a distinct catalytic property towards crotonyl CoA and reducing cofactor NADH. Michaelis-Menten constant (Km) values of substrates show that KpFabI has higher preference towards NADH as compared to crotonyl CoA. The crystal structure of tetrameric apo KpFabI folds into a classic Rossman fold in which β-strands are sandwiched between α-helices. A highly flexible substrate binding region is located toward the interior of the tetrameric assembly. Thermal stability assay on KpFabI with its substrate shows that the flexibility is primarily stabilized by cofactor NADH. Moreover, the molecular dynamics further supports that KpFabI has highly flexible regions at the substrate binding site. Together, these findings provide evidence for highly dynamic substrate binding sites in KpFabI, therefore, this information will be vital for specific inhibitors discovery targeting Klebsiella pneumoniae.

Structure-based identification of novel inhibitors targeting the enoyl-ACP reductase enzyme of Acinetobacter baumannii

Acinetobacter baumannii is a Gram-negative multidrug-resistant bacterial pathogen primarily associated with nosocomial infections resulting in increased morbidity and mortality in adults and infants, especially in sub-Saharan Africa where the clinical burden is high. New therapeutics are needed to treat multidrug-resistant Acinetobacter baumannii infections and reduce transmission. The study used computer-integrated drug discovery approaches including pharmacophore modelling, molecular docking, and molecular dynamics simulation to screen potential inhibitors against the enoyl-acyl carrier protein reductase—FabI protein of Acinetobacter baumannii. The top three potential inhibitors: 21272541 > 89795992 > 89792657 showed favourable binding free energies including coulombic energy, van der Waals energy, and polar and non-polar energies. Furthermore, all three complexes were extremely stable and compact with reduced fluctuations during the simulations period. Inhibitor 21272541 exhibited the highest binding affinity against the Acinetobacter baumannii FabI protein. This is similar to our recent report, which also identified 21272541 as the lead inhibitor against Klebsiella pneumoniae infections. Future clinical studies evaluating drug effectiveness should prioritise inhibitor 21272541 which could be effective in treating infections caused by Gram-negative organisms.

Design and In-silico Screening of Short Antimicrobial Peptides (AMPs) as Anti-Tubercular Agents Targeting INHA

Introduction: Tuberculosis has been studied as a potentially serious bacterial infection affecting the lung caused by Mycobacterium tuberculosis. In addition to its severe impact on health, resistance to existing drugs has also been seen as a rising concern in the space of medicinal solutions. Therapeutic peptides have the potential to complement existing drug designs to provide effective outcomes against Mycobacterium tuberculosis-resistant strains. Methods: This study illustrated a computational approach to design and test peptides against NADHdependent enoyl-acyl carrier protein reductase of Mycobacterium tuberculosis. A human antimicrobial peptide LL-37 was used as a template, and a further 6 peptides were designed, and their binding and interactions against NADH-dependent enoyl-acyl carrier protein reductase were examined. Further, toxicity, immunogenicity, and a broad spectrum of physicochemical properties were calculated to evaluate the therapeutic and safety profile of these peptides. Results: These peptides were structurally modelled and docked with the protein to determine their binding poses and affinity. The molecular interaction of LL-37 with protein was treated as a reference to evaluate the effectiveness of designed peptides. Solvent accessible surface area (SASA) and ΔG binding free energy of docked complexes assisted in the ranking of these peptides. Eventually, peptides P1: LLGDFFRKSKEK, P3: LLFGDRFLLKEK and P7: LLGDFFRLLKEK were selected for 100 ns molecular dynamic simulation as they showed predicted dissociation constants of 8.7×10-4 M, 3.3×10-4 M and 1.2×10-4 M, respectively. These peptides showed direct hydrogen bond formation with ILE21 and LYS165, which are critical active site residues of the protein. The structural variation pattern collected from the MD simulation suggested a strong and stable binding of P3 and P1 with the protein with RMSD 4-5 Å with the starting conformation under the non-fluctuating state. These two peptides showed relatively similar binding results compared with the control peptide LL-37. Comprehensive structural analysis was performed for the middle structures of the most populated cluster generated from 100 ns MD simulation trajectory. Conclusion: Later, MMPBSA binding energies of these structures were computed, where the average binding free energies of P1, P3, and P7 peptides were -146.93 kcal/mole, -161.16 kcal/mole, and - 151.44 kcal/mole, respectively. These energies suggested that P3 is strongly bound to the active site of NADH-dependent enoyl-acyl carrier protein reductase. Overall, this study proposed the application of these peptides as a possible therapeutic solution to inhibit the growth of Mycobacterium tuberculosis.

Design, Synthesis, Evaluation of Antitubercular and Antioxidant Activity of Isoxazoline Derivatives Derived from Novel Chalcone Intermediates

Tuberculosis (TB), a bacterial infection caused by Mycobacterium tuberculosis (M-TB) is a fatal disease associated with a high degree of mortality. Present work involved synthesis of a series of novel isoxazoline derivatives (ISOA1-ISOA8) the new antitubercular agents using newly synthesized chalcones (CHL1-CHL8). This was done by subjecting the chalcones to a reaction with hydroxylamine hydrochloride in presence of acetic acid and sodium acetate. The structure of the synthesized compounds was elucidated by IR, 1H NMR and mass spectra. In silico studies of isoxazoline were performed for antitubercular activity by using an enoyl acyl carrier protein (EACP) reductase enzyme. Compound ISOA4 exhibited the best interaction among all these compounds having a docking score of -5.94 compared to standard drug pyrazinamide -6.1. Using in vitro models, purified compounds were tested for their antioxidant and antitubercular properties. Compound ISOA5 showed a significant antioxidant activity compared to ascorbic acid as a standard drug. This study claims new isooxazolines to possess high antioxidant and antitubercular potential, however they must be evaluated for preclinical and clinical significance.

Molecular Modeling of Enoyl Acyl Carrier Protein Reductase Inhibitors for Mycobacterium tuberculosis and their Pharmacokinetic Predictions

Tuberculosis (TB) is a deep public health concern worldwide worsened by reported multi drugresistant (MDR) and extensively drug- resistant (XDR) stralins of Mycobacterium tuberculosis, the causative agent of the disease. A new class of thiadiazole inhibitors were reported to inhibit the enoyl-acyl transporter protein reductase (InhA) of Mycobacterium tuberculosis (MTb). We performed here the computer-aided molecular design of novel thiadiazole (TDZ) inhibitors of InhA by in situ modifying the reference crystal structure of (S)-1-(5-((1-(2,6-difluorobenzyl)-1 H-pyrazol-3yl)amino)-1,3,4-thiadiazol-2-yl)-1-(4-methylthiazol-2-yl)ethanol-InhA (PDB code: 4BQP). Thus a training set of 15 hybrids with known inhibition potency \(\left(\mathrm{IC}_{50}^{\exp }\right)\) was selected to establish a onedescriptor quantitative structure-activity relationship (QSAR) model resulting in a linear correlation between the Gibbs free energy (GFE) during the formation of the InhA-TDZ complex and \(\mathrm{IC}_{50}^{\mathrm{exp}}\left(\mathrm{plC} \mathrm{C}_{50} \exp ==-0.29 \mathrm{x} \Delta \Delta \mathrm{G}_{\mathrm{com}}+8.13 ; \mathrm{n}=15 ; \mathrm{R}^2=0.92, \mathrm{R}^2{ }_{\mathrm{xv}}=0.91 ;\right.\) F-test of \(142.6 ; \sigma=0.21 ; \alpha>\) \(\left.95 \% ; R^2-R_{x v}^2=0.01\right)\). The 3D pharmacophore model \((\mathrm{PH} 4)\) generated from the active conformations of TDZs ( \(\mathrm{pIC}_{50}^{\mathrm{exp}}=0.93 \times \mathrm{pIC}_{50}^{\text {pred }}+0.47 ; \mathrm{n}=15 ; \mathrm{R}^2=0.97 ; \mathrm{R}_{\mathrm{xv}}=0.94 ;\) F-test of \(215.45 ; \sigma=0.17 ; \alpha>98 \% ; R^2-R_{x v}^2=0.03\) ) served as a virtual screening tool for new analogs from a virtual library (VL). The combination of molecular modeling and \(\mathrm{PH} 4\) in silico screening of (\(\mathrm{VL}\)) resulted in the identification of novel potent antitubercular agent candidates with favorable pharmacokinetic profiles of which the six best hits predicted inhibitory potencies \(\mathrm{IC}_{50}^{\text {pre }}\) in the sub nanomolar range \((0.1-0.2 \mathrm{nM})\).

Chemoinformatics approach to the screening and development of quassinoids from Brucea javanica as antituberculosis drugs

Background: The morbidity and mortality of tuberculosis (TB) remain high in various countries as a result of pharmacological intervention failures, such as incomplete treatment regimens and inadequate doses, triggering resistance of Mycobacterium tuberculosis strains to anti-TB drugs used. This phenomenon requires innovation to explore and develop novel anti-TB drugs so that the problem of resistance is overcome and treatment of TB is more optimal. Objective: In this study, chemoinformatics investigations were carried out on quassinoids derived from Brucea javanica to be developed as anti-TB drugs. Method: Evaluation of drug-likeness with the SwissADME online tool, prediction of toxicity with the pkCSM online tool, and molecular docking studies with AutoDock Vina software were performed on 18 quassinoids from Brucea javanica. Result: The findings showed that Bruceine A, Bruceine, and Bruceine D, met the drug-likeness criteria, showed a good toxicity profile, and had better binding energy (-7.5; -7.5; and -7 kcal/mol, respectively) than isoniazid (-5.8 kcal/mol) which is a first-line anti-TB drug on enoyl acyl carrier protein reductase (InhA; PDB ID: 2NSD). Conclusion: This study found several quassinoids from Brucea javanica with the potential to be developed as anti-TB drugs.

Design, synthesis, in vitro and in silico evaluation of novel substituted 1,2,4-triazole analogues as dual human VEGFR-2 and TB-InhA inhibitors

Cancer is a leading cause of death globally and has been associated with Mycobacterium tuberculosis (Mtb). The angiogenesis-related VEGFR-2 is a common target between cancer and Mtb. Here, we aimed to synthesize and validate potent dual human VEGFR-2 inhibitors as anticancer and anti-mycobacterial agents. Two series of 1,2,4-triazole-based compounds (6a-l and 11a-e) were designed and synthesized through a molecular hybridization approach. Activities of all synthesized compounds were evaluated against human VEGFR-2 in addition to drug-sensitive, multidrug-resistant and extensive-drug resistant Mtb. Compounds 6a, 6c, 6e, 6f, 6h, 6l, 11a, 11d and 11e showed promising inhibitory effect on VEGFR-2 (IC50 = 0.15 – 0.39 µM), anti-proliferative activities against cancerous cells and low cytotoxicity against normal cells. The most potent compounds (6e and 11a) increased apoptosis percentage. Additionally, compounds 6h, 6i, 6l and 11c showed the highest activities against all Mtb strains, and thus were evaluated against enoyl-acyl carrier protein reductase (InhA) which is essential for Mtb cell wall synthesis. Interestingly, the compounds showed excellent InhA inhibition activities with IC50 range of 1.3 – 4.7 µM. Docking study revealed high binding affinities toward targeted enzymes; human VEGFR-2 and Mtb InhA. In conclusion, 1,2,4-triazole analogues are suggested as potent anticancer and antimycobacterial agents via inhibition of human VEGFR-2 and Mtb InhA.

Discovery of novel and potent InhA direct inhibitors by ensemble docking-based virtual screening and biological assays.

Multidrug-resistant tuberculosis (MDR-TB) continues to spread worldwide and remains one of the leading causes of death among infectious diseases. The enoyl-acyl carrier protein reductase (InhA) belongs to FAS-II family and is essential for the formation of the Mycobacterium tuberculosis cell wall. Recent years, InhA direct inhibitors have been extensively studied to overcome MDR-TB. However, there are still no inhibitors that have entered clinical research. Here, the ensemble docking-based virtual screening along with biological assay were used to identify potent InhA direct inhibitors from Chembridge, Chemdiv, and Specs. Ultimately, 34 compounds were purchased and first assayed for the binding affinity, of which four compounds can bind InhA well with KD values ranging from 48.4 to 56.2 µM. Among them, compound 9,222,034 has the best inhibitory activity against InhA enzyme with an IC50 value of 18.05 µM. In addition, the molecular dynamic simulation and binding free energy calculation indicate that the identified compounds bind to InhA with "extended" conformation. Residue energy decomposition shows that residues such as Tyr158, Met161, and Met191 have higher energy contributions in the binding of compounds. By analyzing the binding modes, we found that these compounds can bind to a hydrophobic sub-pocket formed by residues Tyr158, Phe149, Ile215, Leu218, etc., resulting in extensive van der Waals interactions. In summary, this study proposed an efficient strategy for discovering InhA direct inhibitors through ensemble docking-based virtual screening, and finally identified four active compounds with new skeletons, which can provide valuable information for the discovery and optimization of InhA direct inhibitors.

Chitosan grafted polyacrylic acid doped MnO2 nanocomposite an efficient dye degrader and antimicrobial agent

Manganese dioxide (MnO2) nanorods and (3, 6, and 9 mL) chitosan grafted polyacrylic acid (CS-g-PAA) doped MnO2 were prepared hydrothermally. The study objective is to decrease the recombination rate of MnO2 upon doping to enhance the dye degradation efficiency and antimicrobial activity. The doping-dependent properties of CS-g-PAA on phase identification, functional groups, optical characteristics, elemental compositions, and morphological analyses of MnO2 nanorods were conducted using systematic characterization techniques. XRD pattern shows that MnO2 has a tetragonal structure, with increased crystallite size (15.87 to 29.36 nm) upon doping. The TEM analysis showed that MnO2 has nanorods and that CS-g-PAA doped MnO2 displayed nanoflakes-like structures. The decrease in electron-hole pair recombination rate on doping was verified by PL spectroscopy, demonstrating the enhanced catalytic activity. Moreover, adding grafted binary polymers to MnO2 inhibits bacterial cell growth by binding with the negatively charged cell wall and preventing biofilm formation. The 9 mL doped sample displayed a maximum degradation (99.27 %) in a neutral medium and 85.84 % antimicrobial efficiency against E. coli. The enoyl-acyl carrier protein reductase (FabIE. coli) and DNA gyrase(E. coli) were inhibited by these CS-g-PAA doped MnO2 nanostructures (NSs), as shown by in silico molecular docking studies.

Identification of potential inhibitors of Mtb InhA: a pharmacoinformatics approach

The emergence of superbugs of multi-drug resistant (MDR/RR) and extensively drug-resistant (XDR) Mycobacterium tuberculosis (Mtb) strains at a faster rate is posing a serious threat to Tuberculosis (TB) control worldwide. Mtb enoyl-acyl carrier protein reductase (InhA) is a well-established target of the front-line anti-TB prodrug Isoniazid (INH), which requires activation by Catalase-peroxidase enzyme (KatG) in order to inhibit InhA enzyme, that is crucial for the biosynthesis of the mycobacterial cell wall. Currently, due to widespread resistance to this drug, it is necessary to identify new clinical candidates that directly inhibit InhA enzyme and do not require activation by KatG, thereby circumventing most of the resistance mechanisms. In the present study, high-throughput virtual screening of ASINEX database was carried out to identify potential direct inhibitors of Mtb InhA. Best twenty compounds with good binding energies ranging between −12.36 and −9.27 kcal/mol were selected as promising virtual screening hits. These molecules were subjected to ADME study followed by toxicity prediction. Finally, four top-ranked molecules which are structurally diverse and possess best binding affinity than the co-crystalized ligand have been chosen for MD simulation studies followed by MM-GBSA analysis to validate and ensure the stability of hits in the active site of the enzyme. Based on the 100 ns MD simulation studies and binding free energy estimates, three hit molecules B244, B369, and B310 could be considered as potential inhibitors for Mtb InhA, which are likely to be potent against INH-resistant Mtb strains after successful experimental validation. Communicated by Ramaswamy H. Sarma