Acyl Carrier Protein Reductase Research Articles

In-silico and in-vitro analysis of novel substituted benzimidazolyl derivatives for antimycobacterial potentials targeting enoyl acyl carrier protein reductase (InhA)

BackgroundThe emergence of mutated drug-resistant strains of Mycobacterium tuberculosis has reinvigorated the development of effective chemotherapy for MDR-TB (multidrug-resistant resistance tuberculosis). Enoyl acyl carrier protein reductase (InhA) involved in the mycobacterial fatty acid elongation system has been chosen as a potential target.ResultAll of the lead compounds had a definite Rf value and a sharp melting point, confirming that no tautomeric forms exist and that the keto (CO) group is apparent in the IR and 13C NMR spectrum data. Structure-based drug design revealed the presence of amino acid residues like TYR 158, ILE 194, and PHE 149 which are crucial for InhA inhibitory activity and were considered favorable interactions. Among all, compounds 4, 5a, and 5c showed better docking and binding free energy owing to favorable interactions. Interestingly, there was a strong correlation between the binding free energy and the antimycobacterial susceptibility assay, where compounds 4, 5a, and 5c had greater activity. All the lead compounds also had good oral absorption and gut permeability. The presence of a carboxylic linker (–COOH–) between benzimidazole and the rest of the structure of the lead compounds was found to be crucial for activity as the oxygen atom and hydroxyl group of the linker formed most of the favorable interactions. The presence of chlorophenyl showed a favorable effect on InhA inhibition which might be owing to its hydrophobic interaction with PHE 149.ConclusionThree of the seven lead compounds synthesized had an IC value of approximately 0.5 μg/ml in the in-vitro Alamar blue assay against the Mycobacterium tuberculosis H37Rv strain, which is roughly comparable to the standard marketed drug, Isoniazid (INH). This manifestation of promising activity that resulted from combining in-silico and wet lab experimentation could be a great starting point for developing potent antimycobacterial agents to combat multidrug-resistant tuberculosis.Graphical abstract

Isoniazid Linked to Sulfonate Esters via Hydrazone Functionality: Design, Synthesis, and Evaluation of Antitubercular Activity.

Isoniazid (INH) is one of the key molecules employed in the treatment of tuberculosis (TB), the most deadly infectious disease worldwide. However, the efficacy of this cornerstone drug has seriously decreased due to emerging INH-resistant strains of Mycobacterium tuberculosis (Mtb). In the present study, we aimed to chemically tailor INH to overcome this resistance. We obtained thirteen novel compounds by linking INH to in-house synthesized sulfonate esters via a hydrazone bridge (SIH1–SIH13). Following structural characterization by FTIR, 1H NMR, 13C NMR, and HRMS, all compounds were screened for their antitubercular activity against Mtb H37Rv strain and INH-resistant clinical isolates carrying katG and inhA mutations. Additionally, the cytotoxic effects of SIH1–SIH13 were assessed on three different healthy host cell lines; HEK293, IMR-90, and BEAS-2B. Based on the obtained data, the synthesized compounds appeared as attractive antimycobacterial drug candidates with low cytotoxicity. Moreover, the stability of the hydrazone moiety in the chemical structure of the final compounds was confirmed by using UV/Vis spectroscopy in both aqueous medium and DMSO. Subsequently, the compounds were tested for their inhibitory activities against enoyl acyl carrier protein reductase (InhA), the primary target enzyme of INH. Although most of the synthesized compounds are hosted by the InhA binding pocket, SIH1–SIH13 do not primarily show their antitubercular activities by direct InhA inhibition. Finally, in silico determination of important physicochemical parameters of the molecules showed that SIH1–SIH13 adhered to Lipinski’s rule of five. Overall, our study revealed a new strategy for modifying INH to cope with the emerging drug-resistant strains of Mtb.

Novel diaryl ether derivatives as InhA inhibitors: Design, synthesis and antimycobacterial activity

A new series of triclosan (TCL)-mimicking diaryl ether derivatives 7–25 were synthesized and evaluated as inhibitors of enoyl acyl carrier protein reductase InhA enzyme. In addition, these derivatives were screened as inhibitors of drug-susceptible (DS), multidrug-resistant (MDR), and extensive drug-resistant (XDR) Mycobacterium tuberculosis (MTB) strains. Most compounds exihibted superior anti-TB activities and improved ClogP compared to TCL as a standard drug. The present work has led to the identification of compounds 14, 19 and 24 which possess remarkable activities against DS, MDR and XDR MTB strains with MIC values of 1.95, 3.9 and 15.63 µg/ml, respectively for compound 14, 1.95, 3.9 and 7.81 µg/ml, respectively for compound 19 and 0.98, 1.95 and 3.9 µg/ml, respectively for compound 24. Most compounds did not exhibit toxicity to HePG2 normal cell line. Compounds 14, 19 and 24, presenting the best MIC values, were further evaluated as inhibitors of InhA enzyme. They showed high binding affinities in the micromolar range with IC50 values of 1.33, 0.6, and 0.29 µM for compounds 14, 19, and 24, respectively. Furthermore, molecular docking approach was utilized to understand the difference in bioactivities between the new compounds. In particular, the results revealed strong binding interactions and high docking scores of compounds 14, 19 and 24, which could correlate with their high activities. Mainly, the molecular modelling study of compound 24 provides an excellent platform for understanding the molecular mechanism regarding InhA inhibition. Thus, compound 24 could be a lead compound for future development of new antitubercular drugs.

Design and Synthesis of Quinazolinone-Triazole Hybrids as Potent Anti-Tubercular Agents.

A straightforward and convenient methodology has been developed for the reaction of 2-aminobenzamide and carbonyls affording 2,3-dihydroquinazolin-4(1H)-ones using aqueous solution of [C12Py][FeCl3Br]. The developed methodology was applied for the synthesis of 25 quinazolinone-triazole hybrids followed by evaluation of their in vitro anti-tubercular (TB) activity. The results revealed that 8 quinazolinone-triazole hybrids displayed promising activity having MIC values of 0.78-12.5 μg/mL. The compound 3if with MIC 0.78 μg/mL was found to be the lead nominee among the series, better than Ethambutol, a first line anti-TB drug and comparable with Rifampicin. The active compounds with MIC values ≤ 6.25 μg/mL were subjected to in vitro cytotoxicity and found nontoxic. In drug-drug interaction, compounds 3ia and 3ii interacted synergistically with all the three anti-TB drugs, INH, RFM, and EMB. Other 3 compounds interacted either in synergistic or additive manners. Important information on the binding interaction of the target compounds with the active sites of 1DQY Antigen 85C from Mycobacterium tuberculosis and Enoyl acyl carrier protein reductase (InhA) enzymes was obtained from molecular docking studies. Screening of the drug-likeness properties and bioactivity score indicates that synthesized molecules could be projected as potential drug candidates. Based on the current study, quinazolinone-triazole hybrids framework can be useful in drug development for TB.

Discovery of newer pyrazole derivatives with potential anti-tubercular activity via 3D-QSAR based pharmacophore modelling, virtual screening, molecular docking and molecular dynamics simulation studies.

Tuberculosis is one of the leading causes of death of at least one million people annually. The deadliest infectious disease has caused more than 120 million deaths in humans since 1882. The cell wall structure of Mycobacterium tuberculosis is important for survival in the host environment. InhA is the foremost target for the development of novel anti-tubercular agents. Therefore, we report pharmacophore-based virtual screening (ZINC and ASINEX databases) and molecular docking study (PDB Code: 4TZK) to identify and design potent inhibitors targeting to InhA. A five-point pharmacophore model AADHR_1 (with R2 = 0.97 and Q2 = 0.77) was developed by using 47 compounds with its reported MIC values. Further, to identify and design potent hit molecules based on lead identification and modification, generated hypothesis employed for virtual screening using ZINC and ASINEX databases. Predicted pyrazole derivatives further gauged for drug likeliness and docked against enoyl acyl carrier protein reductase to categorize the essential amino acid interactions to the active site of the enzyme. Structure elucidation of these synthesized compounds was carried out using IR, MS, 1H-NMR and 13C-NMR spectroscopy. Amongst all the synthesized compounds, some of the compounds 5a, 5c, 5d and 5e were found to be potent with their MIC ranging from 2.23 to 4.61µM. Based on preliminary anti-tubercular activity synthesized potent molecules were further assessed for MDR-TB, XDR-TB and cytotoxic study.

In silico evaluation of natural bioactive compounds as Mycobacterium leprae enoyl acyl carrier protein reductase inhibitors

Background and Objectives:
 The present study was designed to assess the antileprotic effectiveness of some bioactive natural compounds towards enoyl acyl carrier protein reductase inhibition. Leprosy still constitutes a global pandemic in spite of long years of discovery. The current therapy option is multi-drug treatment using a combination of Dapsone, Rifampicin and Clofazimine. However, mycobacterium leprae counteracted by mutating the drug targets which necessitates the search for novel targets. One such target is enoyl acyl carrier protein reductase that mediates the fatty acid biosynthesis.
 Materials and Methods:
 Multiple (14) ligands of natural origin were drawn from PubChem database and their ADMET parameters were preicted using ADMETLab 2.0 webserver. After, the ligands were docked against the enzyme (PDB ID: 2NTV) at its active site using iGEMDOCK software.
 Results:
 ADMET parameters of the tested ligands proven to be accepted by Lipinski's rule of five except for two ligands. Furthermore, molecular docking results revealed that all of the tested compounds showed better binding energy than the reference drug Dapsone. The best of which was silymarin.
 Conclusion:
 The tested natural ligands have the capability to control M.leprae.

Urea derivatives carrying a thiophenylthiazole moiety: Design, synthesis, and evaluation of antitubercular and InhA inhibitory activities.

The recent emergence of drug-resistant strains of Mycobacterium tuberculosis (Mtb) has complicated and significantly slowed efforts to eradicate and/or reduce the worldwide incidence of life-threatening acute and chronic cases of tuberculosis. To overcome this setback, researchers have increased the intensity of their workto identify new small-molecule compounds that are expected to remain efficacious antimicrobials against Mtb. Here, we describe our effort to apply the principles of molecular hybridization to synthesize 16 compounds carrying thiophene and thiazole rings beside the core urea functionality (TTU1-TTU16). Following extensive structural characterization, the obtained compounds were initially evaluated for their antimycobacterial activity against Mtb H37Rv. Subsequently, three derivatives standing out with their anti-Mtb activity profiles and low cytotoxicity (TTU5, TTU6, and TTU12) were tested on isoniazid-resistant clinical isolates carrying katG and inhA mutations. Additionally, due to their pharmacophore similarities to the well-known InhA inhibitors, the molecules were screened for their enoyl acyl carrier protein reductase (InhA) inhibitory potentials. Molecular docking studies were performed to support the experimental enzyme inhibition data. Finally, drug-likeness of the selected compounds was established by theoretical calculations of physicochemical descriptors.

A chromosome-level genome assembly and intestinal transcriptome of Trypoxylus dichotomus (Coleoptera: Scarabaeidae) to understand its lignocellulose digestion ability.

Lignocellulose, as the key structural component of plant biomass, is a recalcitrant structure, difficult to degrade. The traditional management of plant waste, including landfill and incineration, usually causes serious environmental pollution and health problems. Interestingly, the xylophagous beetle, Trypoxylus dichotomus, can decompose lignocellulosic biomass. However, the genomics around the digestion mechanism of this beetle remain to be elucidated. Here, we assembled the genome of T. dichotomus, showing that the draft genome size of T. dichotomus is 636.27 Mb, with 95.37% scaffolds anchored onto 10 chromosomes. Phylogenetic results indicated that a divergent evolution between the ancestors of T. dichotomus and the closely related scarabaeid species Onthophagus taurus occurred in the early Cretaceous (120 million years ago). Through gene family evolution analysis, we found 67 rapidly evolving gene families, within which there were 2 digestive gene families (encoding Trypsin and Enoyl-(Acyl carrier protein) reductase) that have experienced significant expansion, indicating that they may contribute to the high degradation efficiency of lignocellulose in T. dichotomus. Additionally, events of chromosome breakage and rearrangement were observed by synteny analysis during the evolution of T. dichotomus due to chromosomes 6 and 8 of T. dichotomus being intersected with chromosomes 2 and 10 of Tribolium castaneum, respectively. Furthermore, the comparative transcriptome analyses of larval guts showed that the digestion-related genes were more commonly expressed in the midgut or mushroom residue group than the hindgut or sawdust group. This study reports the well-assembled and annotated genome of T. dichotomus, providing genomic and transcriptomic bases for further understanding the functional and evolutionary mechanisms of lignocellulose digestion in T. dichotomus.

3-Oxoacyl acyl carrier protein reductase overexpression reveals its unprecedented roles in biofuel production and high-temperature tolerance in diatom

Due to its high lipid accumulation capability, Phaeodactylum tricornutum has attracted considerable attention as a promising candidate for biofuel production. However, the derived lipid cannot satisfy the industrial biofuel manufacturing requirements given its poor fatty acid characteristics. Genetic engineering, as a prospective approach, has been employed to overcome this bottleneck. Relevant research indicates that the fabG gene plays a crucial role in fatty acid biosynthesis in bacteria, but its significance in microalgae remains unclear. In this study, FabG was successfully introduced, transcribed, and overexpressed in P. tricornutum. FabG overexpression significantly enhanced lipid (1.49-fold) and fatty acid (1.31-fold) biosynthesis without altering growth and photosynthesis, and this method thus exhibits great potential in high-quality biodiesel production. Moreover, increased saturation of fatty acids (e.g., C16:0) and improved antioxidative activities enhanced the tolerance of transgenic P. tricornutum to high temperature stress. To conclude, this study reports a feasible approach for high-quality algae-based biofuel production via the unprecedented roles of FabG retrieved from diatom.

Novel Hybrid 1,2,4- and 1,2,3-Triazoles Targeting Mycobacterium Tuberculosis Enoyl Acyl Carrier Protein Reductase (InhA): Design, Synthesis, and Molecular Docking.

Tuberculosis (TB) caused by Mycobacterium tuberculosis is still a serious public health concern around the world. More treatment strategies or more specific molecular targets have been sought by researchers. One of the most important targets is M. tuberculosis’ enoyl-acyl carrier protein reductase InhA which is considered a promising, well-studied target for anti-tuberculosis medication development. Our team has made it a goal to find new lead structures that could be useful in the creation of new antitubercular drugs. In this study, a new class of 1,2,3- and 1,2,4-triazole hybrid compounds was prepared. Click synthesis was used to afford 1,2,3-triazoles scaffold linked to 1,2,4-triazole by fixable mercaptomethylene linker. The new prepared compounds have been characterized by different spectroscopic tools. The designed compounds were tested in vitro against the InhA enzyme. At 10 nM, the inhibitors 5b, 5c, 7c, 7d, 7e, and 7f successfully and totally (100%) inhibited the InhA enzyme. The IC50 values were calculated using different concentrations. With IC50 values of 0.074 and 0.13 nM, 7c and 7e were the most promising InhA inhibitors. Furthermore, a molecular docking investigation was carried out to support antitubercular activity as well as to analyze the binding manner of the screened compounds with the target InhA enzyme’s binding site.

Characterization of Pyridomycin B Reveals the Formation of Functional Groups in Antimycobacterial Pyridomycin.

Pyridomycin, a cyclodepsipeptide with potent antimycobacterial activity, specifically inhibits the InhA enoyl reductase of Mycobacterium tuberculosis. Structure-activity relationship studies indicated that the enolic acid moiety in the pyridomycin core system is an important pharmacophoric group, and the natural configuration of the C-10 hydroxyl contributes to the bioactivity of pyridomycin. The ring structure of pyridomycin was generated by the nonribosomal peptide synthetase (NRPS) and polyketide synthase (PKS) hybrid system (PyrE-PyrF-PyrG). Bioinformatics analysis reveals that short-chain dehydrogenase/reductase (SDR) family protein Pyr2 functions as a 3-oxoacyl acyl carrier protein (ACP) reductase in the pyridomycin pathway. Inactivation of pyr2 resulted in accumulation of pyridomycin B, a new pyridomycin analogue featured with enol moiety in pyridyl alanine moiety and a saturated 3-methylvaleric acid group. The elucidated structure of pyridomycin B suggests that rather than functioning as a post-tailoring enzyme, Pyr2 catalyzes ketoreduction to form the C-10 hydroxyl group in pyridyl alanine moiety and the double bond formation of the enolic acid moiety derived from isoleucine when the intermediate assembled by PKS-NRPS machinery is still tethered to the last NRPS module in a special energy-saving manner. Ser-His-Lys residues constitute the active site of Pyr2, which is different from the typically conserved Tyr-based catalytic triad in the majority of SDRs. Site-directed mutation identified that His154 in the active site is a critical residue for pyridomycin B production. These findings will improve our understanding of pyridomycin biosynthetic logic, identify the missing link for the double bound formation of enol ester in pyridomycin, and enable the creation of chemical diversity of pyridomycin derivatives. IMPORTANCE Tuberculosis (TB) is one of the world's leading causes of death by infection. Recently, pyridomycin, the antituberculous natural product from Streptomyces has garnered considerable attention for being determined as a target inhibitor of InhA enoyl reductase of Mycobacterium tuberculosis. In this study, we report a new pyridomycin analogue from mutant HTT12, demonstrate the essential role of a previously ignored gene pyr2 in pyridomycin biosynthetic pathway, and imply that Pyr2 functions as a trans ketoreductase (KR) contributing to the formation of functional groups of pyridomycin utilizing a distinct catalytic mechanism. As enol moiety are important for pharmaceutical activities of pyridomycin, our work would expand our understanding of the mechanism of SDR family proteins and set the stage for future bioengineering of new pyridomycin derivatives.

Identification of natural products against enoyl-acyl-carrier-protein reductase in malaria via combined pharmacophore modeling, molecular docking and simulations studies

Plasmodium falciparum is counted as one of the deadly species causing malaria. In that respect, enoyl acyl carrier protein reductase is recognized as one of the attractive druggable targets for the identification of antimalarials. Thus, from the structural proteome of ENR, common feature pharmacophores were constructed. To identify the representative models, all the hypotheses were subjected to validation methods, like, test set, enrichment factor, and Güner-Henry method, and the selected representative hypotheses were used to screen out the drug-like natural products. Further, the screened candidates were advanced to molecular docking calculations. Based on the docking score criteria and presence of essential interaction with Tyr277, seven candidates were shortlisted to conduct the HYDE and QSAR assessment. Further, the stability of these complexes was evaluated by employing molecular dynamics simulations, molecular mechanics‐generalized born surface area approach‐based free binding energy calculations with the residue-wise contribution of PfENR to the total binding free energy of the complex. On comparing the root mean square deviation, and fluctuation plots of the docked candidates with the reference, all the candidates displayed stable behavior, and the same outcome was depicted from the secondary structure element. However, from the free energy calculations, and residue-wise contribution conducted after dynamics, it was observed that out of seven, only five candidates sustain the binding with Tyr277 and cofactor of PfENR. Therefore, in the current work, the hybrid study of screening and stability lead to the identification of five structurally diverse candidates that can be employed for the design of novel antimalarials. Communicated by Ramaswamy H. Sarma

Isoniazid: An Exploratory Review

Isoniazid (INH) is one of the most successful tuberculosis medications in the market today. In particular, isoniazid is used as a prophylaxis medication to avoid resurgence of illness in those who have underlying Mycobacterium tuberculosis (MTB) infection. The mode of action of isoniazid is complicated and incorporates a number of distinct aspects in which various biomolecular routes are impacted, including mycolic acid production. Catalase-peroxidase (KatG) activates the prodrug isoniazid and enzymes such as β-ketoacyl ACP synthase (KasA) and enoyl acyl carrier protein (ACP) reductase target the active isoniazid products. Various genes in diverse biochemical networks and pathways are involved in the physiological mechanisms of isoniazid resistance. Isoniazid resistance is the most common of all clinical drug-resistant isolates, with incidence in some areas of up to 20 to 30%. In this review article, several existing components that may influence to the complexities of isoniazid function including mechanism of action, resistance mechanisms in MTB, along with their history, different synthetic procedures, uses, dosage forms, side effects, adverse drug reactions, physico-chemical characteristics, ADME properties, contraindications as well as future perspectives are discussed. Studies of pharmacokinetics have found that the cause of the drug mediated hepatotoxicity is possible by metabolism of isoniazid. Because of inter-individual heterogeneity of polymorphism that affect isoniazid metabolism rates, customized medicines may be required in various populations to prevent hepatotoxicity. The isoniazid multidrug combination treatment which would proved to be effective tuberculosis treatment in future. Further exploration is needed for better comprehension of pathogenesis mechanism of Mycobacterium tuberculosis (MTB) and drug resistance studies are required for building up better therapeutics and diagnostic against tuberculosis.

Design and synthesis of novel imidazolidine-2,4-dione derivatives as InhA inhibitors: Spectral characterization, computational, and biological studies

Tuberculosis is a global disease caused by bacteria called Mycobacterium tuberculosis (M.tb) and is one of the top 10 causes of death from a single infectious agent. InhA (enoyl acylcarrier proteinreductase) from M.tb is the target that is involved in cell wall biosynthesis. The most effective drug to treat TB (tuberculosis) is INH (isoniazide) which is a prodrug, activated by KatG (catalase-peroxidaseenzyme) to generate isonicotinoyl radical that reacts with NAD (nicotinamide adenine dinucleotide) to form an INH-NADH complex, acting as a real InhA inhibitor. A series of novel imidazolidine-2,4-dione were designed by site identification and molecular docking using GLIDE. After synthesis, the compounds were characterized by 1H NMR, LC-MS, FT-IR, and elemental analysis. The compounds were found to be moderately active against M.tb. MTT (3-[4,5-dimethylthiazole-2-yl]-2,5-diphenyltetrazolium bromide) assay was used to test the compounds for anticancer activity against human breast cancer cell line MCF-7.

In-silico Studies of Thiopyridine Compounds as Anti-Bacterial agents Targeting Enoyl - Acyl Carrier Protein Reductase

In the Fatty Acid Synthase II system, Enoyl-(acyl-carrier-protein) reductase (ENR) encoded by FabI genes is a limiting step enzyme and there is no homologue ENR found in invertebrates which makes it selective target for drug discovery. From Molecular dynamics simulations it was concluded that the solvated protein stabilized at 2.5 ns with larger mobility in the substrate - binding loop and the conformational flexibility of the molecule was revealed. To study the inhibitory effects of novel small molecules in the thiopyridine series, a 2D QSAR model was developed and evaluated for its efficiency. The R2 > 0.96 and Q2 = 0.978 depicted the predictive ability of the models which was determined using a test set of 3 compounds. The receptor-ligand interactions were studied and highest affinity was reported for GCT ID, 343129 (-9.09 Kcal/mol), 341772 (-8.90 Kcal/mol) and 268776 (-8.85 Kcal/mol). These compounds were analysed for their drug like properties and toxicity which projected acceptable blood brain barrier permeation and human intestinal absorption and reduced lipotoxicity. Thus the results suggest further synthesis of new thipyridine series of compounds and experimental testing against drug resistant Staphylococcal infections

Antituberculosis and Antiproliferative Activities of the Extracts and Tetrahydrobisbenzylisoquinoline Alkaloids from Phaeanthus ophthalmicus: In Vitro and In Silico Investigations

Tuberculosis (TB) and cancer are among the maladies with high morbidity and mortality rates to date. This prompted the utilization of natural products in the discovery and development of new anti-TB and anticancer derivatives. In this study, we explored the antitubercular and antiproliferative activities of extracts and tetrahydrobisbenzylisoquinoline alkaloids tetrandrine (1) and limacusine (2) from the Philippine medicinal plant Phaeanthus ophthalmicus. Antitubercular evaluation using colorimetric MABA (microplate Alamar blue assay) assays revealed antitubercular activities of the extracts and fractions [minimum inhibitory concentration (MIC) = 15.6 to < 64 μg/mL]. Among the two isolated alkaloids, limacusine (2) exhibited inhibitory activity against Mycobacterium tuberculosis (MIC = 42.6 μg/ml). In addition, CellTiter-Blue cell viability assay showed antiproliferative activity for limacusine (2) against K-562. Both tetrahydrobisbenzylisoquinoline alkaloids exhibited cytotoxicity on HeLa cells. To probe the binding mechanisms of 1 and 2 against putative protein targets, molecular docking simulations were carried out. Limacusine (2) showed high binding propensities to mycobacterial enzymes ATP-dependent murE ligase and enoyl acyl carrier protein reductase, thus illustrating possibilities of cell wall and mycolic biosynthesis inhibitory mechanisms, respectively. High binding affinity was also observed in 2 vs. FLT3, a protein target implicated in myeloid leukemia cell proliferation. Additionally, the limacusine-InhA and limacusine-FLT3 complexes were found to be dynamically stable as per molecular dynamics (MD) simulations. The results of in vitro experiments and molecular docking studies suggest tetrahydrobisbenzylisoquinoline alkaloids from P. ophthalmicus, especially limacusine (2), as promising natural products against TB and myeloid leukemia.

DESIGN, SYNTHESIS AND BUILDING A QSAR MODEL FOR THE INHIBITION OF MYCOBACTERIUM TUBERCULOSIS BY PYRAZOLINE DERIVATIVES

A series of chalcone annulated pyrazoline conjugates have recently been synthesized from our laboratory and identified as possible “LEAD”s against Mycobacterium tuberculosis (MTB) through an in-silico study. The MTB enoyl acyl carrier protein reductase (InhA) plays a vital role in the MTB fatty acid synthesis pathway as essential in the mycolic acid biosynthesis. Therefore, inhibition of InhA could block the biosynthesis of mycolic acids, resulting in mycobacteria death. To further explore the potency of the compounds, a quantitative structure-activity relationship (QSAR) study is carried out. To develop a new pharmacophoric model for this inhibition, a QSAR approach of reported pyrazoline derivatives against tuberculosis has been studied. Multiple linear regression analysis was performed to derive the QSAR models, which were further evaluated internally as well as externally for the prediction of activity. The accurate MIC values (μg/ml) were collected for 23 pyrazoline analogs, and other descriptor parameters, such as log p (o/w), MR, DM, EELE, LUMO, HOMO, and TPSA were compared with these analogs. A training set of 23 analogs, all having a common pyrazoline moiety, provided a cross-validated correlation coefficient (r2) value of 0. 45112 and root mean square error (RMSE) value of 0. 0.27760. Moreover, based on this QSAR study, we have hypothetically estimated the predicted pMIC50 by using trainpred.fit file from Molecular Operating Environment 2009.10 software for the newly synthesized test set i.e., six chalcone based pyrazoline compounds. The resulting QSAR model generated from the present study may be useful in the design of a similar group of pyrazoline analogs as anti-tubercular agents.

Design, Synthesis and Biological Investigation of Some Novel Quinazolin-4(3H)-One Tethered 1, 3, 4-Thiadiazole-Thiol Motifs as Direct Enoyl Acyl Carrier Protein Reductase Inhibitors

Aims: In this study was two noteworthy pharmacophores quinazolin-4(3H)-one and 1,3,4-thiadiazole through methylene bridge were utilized to design, synthesize and characterize some novel 2-methyl quinazolin-4(3H)-one and 6-chloro-2-methyl quinazolin-4(3H)-one tethered S-substituted-1,3,4-thiadiazole-thiol structural analogs respectively as direct Mycobacterium Tuberculosis (MTB) enoyl acyl carrier protein reductase (InhA) inhibitors.
 Study Design: Design of structural analogs of quinazolin-4(3H)-one tethered 1,3,4-thiadiazole-thiol through methylene bridge by functional group modifications in core scaffold followed by computational studies to select promising compounds. Synthesis of some novel compounds, structural characterization and screening of biological activity of the same.
 Methodology: The molecular docking of designed compunds was carried out using schrodinger Glide XP into the active site of MTB InhA with protein data bank code (PDB ID: 2H7M). The interactions were evaluated based on the glide G score compared with reference standard isoniazid. Ten new compounds 7(A1-A10) were synthesized, characterized and screened for their in-vitro antitubercular activity by Microplate Almar Blue Assay (MABA) method followed by cytotoxicity evaluation of compounds 7A4 and 7A10 using Vero cell line.
 Results: All the designed compounds of series 7(A1-A10) had drug-like characteristics and were non-toxic to normal cells. In the molecular docking studies, compounds 7A4, 7A5, and 7A10 demonstrated strong binding affinity in the active region of MTB InhA protein and retained necessary amino acid interaction, similar to co-crystal 2H7M. Synthesized compounds 7(A1-A10) were found to have good antitubercular activity. Out of the series the compounds 7A4 and 7A10 were found to possess excellent antitubercular activity equipotent to reference standard streptomycin with minimum inhibitory concentration (MIC) value of 6.25µg/ml. The cytotoxic potential of compounds 7A4 and 7A10 showed remarkable selectivity index against Vero cell line.
 Conclusion: The findings of this study highlights the importance of tethering two pharmacophoric motifs in one compound to develop novel antitubercular agents that can be exploited as promising leads as direct InhA inhibitors.

The Effect of Thespesia populnea Against Plasmodium falciparum Enoyl Acyl Carrier Protein Reductase Receptor by Study In Silico

Indonesia is a country that has abundant natural resources; one of them is the Baru laut plant which is the latest breakthrough because it has an active substance that can be used as an anti-malaria medicine. It is very beneficial because there has been a case of resistance of artemisinin derivatives in Indonesia. The purpose of this study was to determine the potential of active compounds in Baru laut plants (Thespesia populnea (L.) Soland ex. Correa) against the Plasmodium falciparum enoyl acyl carrier protein reductase receptor in P. falciparum through in silico studies. This research is purely experimental using the One-Shot Experimental Study research design method. Observations were only made once between the variables studied through three analyzes, namely prediction analysis of active compound content, prediction analysis of the mechanism of action of active compound content, and prediction analysis of ADME active compound. The study results show that there are three active compounds in Baru laut plants that have antimalarial potential. The three compounds include gossypol, linoleic acid, and beta-sitosterol, have their respective potential in becoming a malaria drug. This study concludes that Baru laut plants have potential as anti-malaria drugs.

Anti-TB evaluation of novel 2,3-dihydroquinazolin-4(1H)-ones and in silico studies of the active compounds

In vitro anti-tubercular activity of a series of 15 novel 2,3-dihydroquinazolin-4(1H)-one analogues were evaluated against Mycobacterium tuberculosis H37Ra (ATCC 25177 strain). Among the series, seven compounds showed moderate to good anti-TB activity with minimum inhibitory concentration (MIC) values ranging from 25.0–12.5 μg/mL. Further, in silico experiments were carried out to identify the probable ligand-protein interaction. Molecular docking of the target compounds into the active site of enzymes 1DQY Antigen 85C from Mycobacterium Tuberculosis and 2NSD Enoyl Acyl Carrier Protein Reductase reveals notable information on the possible binding interactions.