Amit Trivedi

Synthesis, antimicrobial and cytotoxic activities of some novel thiazole clubbed 1,3,4-oxadiazoles

Abstract A series of thiazole clubbed 1,3,4-oxadiazole derivatives (5a–l) have been synthesized and characterized by IR, 1H NMR, 13C NMR and mass spectral analysis. Synthesized compounds were evaluated for their antimicrobial and cytotoxic activities. The results indicated that, compounds 5c and 5i exhibited the most potent antibacterial activity. Compound 5f was found to be the most potent antifungal agent. The structure activity relationship revealed that the presence of electron withdrawing groups at para position of phenyl ring remarkably enhanced the antibacterial activity of synthesized compounds. Further, the results of preliminary MTT cytotoxicity studies on HeLa cells suggested that potent antimicrobial activity of 5b, 5c, 5f, 5h and 5i is accompanied by low cytotoxicity.

Studies on molecular properties prediction, antitubercular and antimicrobial activities of novel quinoline based pyrimidine motifs

In the present study, a series of 3-((6-(2,6-dichloroquinolin-3-yl)-4-aryl-1,6-dihydro-pyrimidin-2-yl)thio)propanenitriles 5a-o were synthesized and subjected to molecular properties prediction and drug-likeness model score by Molinspiration property calculation toolkit and MolSoft software, respectively. Compound 5m (4-OCH3) was found to be maximum drug-likeness model score (0.42). Among the screened compounds, 5m showed the most promising antitubercular activity with MIC of 0.20 μg/mL, while compounds 5g, 5k and 5m displayed broad spectrum antibacterial activity against all the bacterial strains. Moreover, compound 5k was found to be the most potent antifungal agent. Further, the results of preliminary MTT cytotoxicity studies on HeLa cells suggested that potent antimicrobial activity of 5g, 5k and 5m was escorted by low cytotoxicity.

4,5-Dihydro-1H-pyrazolo[3,4-d]pyrimidine containing phenothiazines as antitubercular agents

A series of novel dihydropyrazolo[3,4-d]pyrimidine derivatives bearing a phenothiazine nucleus were synthesized in excellent yields via a modified Biginelli multicomponent reaction. The newly synthesized compounds were characterized by IR, (1)H NMR, (13)C NMR, Mass spectra and elemental analysis followed by antimycobacterial screening. Among all the screened compounds, compound 4g showed most pronounced activity against Mycobacterium tuberculosis (Mtb) with minimum inhibitory concentration (MIC) of 0.02μg/mL, making it more potent than first line antitubercular drug isoniazid.

Synthesis, biological evaluation and molecular docking study of some novel indole and pyridine based 1,3,4-oxadiazole derivatives as potential antitubercular agents

A series of indole and pyridine based 1,3,4-oxadiazole derivatives 5a-t were synthesized and evaluated for their in vitro antitubercular activity against Mycobacterium tuberculosis H37Ra (MTB) and Mycobacterium bovis BCG both in active and dormant state. Compounds 5b, 5e, 5g and 5q exhibited very good antitubercular activity. All the newly synthesized compounds 5a-t were further evaluated for anti-proliferative activity against HeLa, A549 and PANC-1 cell lines using modified MTT assay and found to be noncytotoxic. On the basis of cytotoxicity and MIC values against Mycobacterium bovis BCG, selectivity index (SI) of most active compounds 5b, 5e, 5g and 5q was calculated (SI=GI50/MIC) in active and dormant state. Compounds 5b, 5e and 5g demonstrated SI values ⩾10 against all three cell lines and were found to safe for advance screening. Compounds 5a-t were further screened for their antibacterial activity against four bacteria strains to assess their selectivity towards MTB. In addition, the molecular docking studies revealed the binding modes of these compounds in active site of enoyl reductase (InhA), which in turn helped to establish a structural basis of inhibition of mycobacteria. The potency, low cytotoxicity and selectivity of these compounds make them valid lead compounds for further optimization.

Design, Synthesis, and Biological Evaluation of 1,4-dihydropyridine Derivatives as Potent Antitubercular Agents.

A series of novel 1,4‐dihydropyridine‐3,5‐dicarbamoyl derivatives bearing an imidazole nucleus at C‐4 position were synthesized in excellent yields via multicomponent Hantzsch reaction. The newly synthesized compounds were characterized by IR, 1H NMR, 13C NMR, and mass spectroscopy. The synthesized compounds 3a‐p were screened for antitubercular activity. Among all the screened compounds, compounds 3j and 3m showed most prominent activity against Mycobacterium tuberculosis with minimum inhibitory concentration of 0.02 μg/mL and SI > 500, making it more potent than first‐line antitubercular drug isoniazid. In addition, these compounds displayed relatively low cytotoxicity.

Preparation, biological evaluation and molecular docking study of imidazolyl dihydropyrimidines as potential Mycobacterium tuberculosis dihydrofolate reductase inhibitors.

A series of novel dihydropyrimidine derivatives bearing an imidazole nucleus at C-4 position were synthesized in excellent yields via Biginelli multi-component reaction. The newly synthesized compounds were characterized by IR, (1)H NMR, (13)C NMR and Mass spectroscopy. In vitro antitubercular evaluation of all the newly synthesized compounds 4a-p against Mycobacterium tuberculosis (Mtb) H37Rv showed, 4j (MIC: 0.39μg/mL; SI: >25.64), 4m (MIC: 0.78μg/mL; SI: >12.82) and 4p (MIC: 0.39μg/mL; SI: 24.10) as the most promising lead analogues. Compounds 4j, 4m and 4p displayed effective reduction in residual Mtb growth within the tuberculosis-infected macrophage model. Further, molecular docking study of active molecules 4j, 4m and 4p against Mycobacterium tuberculosis dihydrofolate reductase (Mtb DHFR) proved their potency as Mtb DHFR inhibitors acting as potential leads for further development. Pharmacokinetic properties leading to drug-likeness were also predicted for most active molecules 4j, 4m and 4p.

Synthesis, biological valuation, and QSAR studies of novel pyrazole bearing pyridyl oxadiazole analogues as potential antimicrobial agents

A new series of 1-(2-(3-(4-nitrophenyl)-1-phenyl-1H-pyrazol-4-yl)-5-(pyridin-4-yl)-1,3,4-oxadiazol-3(2H)-yl)-3-(aryl)prop-2-en-1-ones (5a–l) were synthesized by a simple and efficient synthetic protocol. The newly synthesized compounds were characterized by IR, 1H NMR, 13C NMR and Mass spectroscopy. The resulting structural diversity was screened for its antimicrobial activity the following bacterial and fungal strains: two Gram-positive bacteria [Staphylococcus aureus (MTCC-96), Streptococcus pyogenes (MTCC-442)], two Gram-negative bacteria [Escherichia coli (MTCC-443), Pseudomonas aeruginosa (MTCC-1688)] and three fungal species (C. albicans, A. niger and A. clavatus). Following this, in vitro cytotoxicity activity against HeLa cell lines was measured by MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazoliumbromide] assay. The observations derived from the diverse assays were utilized for building classification models based on a binary QSAR approach termed recursive partitioning (RP) analysis to probe the physic-chemical properties influencing the SAR for molecules. The decision tree derived from RP analysis could highlight structural characteristics that discriminate the actives from inactives which can serve as guide to design molecules with improved potency. In silico ADME predictions were performed to gauge their pharmacokinetic, safety and drug likeness profile.

Hybrid Bioactive Heterocycles as Potential Antimicrobial Agents- A Review

The ever increasing cases of microbial resistance pose a major threat to the scientific community and therefore the need for discovery and development of newer antimicrobial agents with novel mode of action is becoming critical. One of the ways to tackle this herculean problem is to generate hybrid molecules by combining two or more bioactive heterocyclic moieties in a single molecular platform. The review here describes published results of our research groups endeavors towards development of potential new and safe antimicrobial agents with better effectiveness by using the hybrid approach. In the present review article the landscaping of heterocycles like 4-thiazolidinones, benzimidazole and quinoline are described. Compounds displaying two of more fold antimicrobial activity are included in the review.

Design, synthesis, and biological evaluation of novel fluorinated pyrazole encompassing pyridyl 1,3,4-oxadiazole motifs

A rational approach was adopted for the synthesis of 1-(2-(3-(4-fluorophenyl)-1-phenyl-1H-pyrazol-4-yl)-5-(pyridin-4-yl)-1,3,4-oxadiazol-3(2H)-yl)-3-(aryl)prop-2-en-1-ones (5a–n) using conventional heating as well as microwave irradiation techniques. Compounds 5a–n were tested for their in vitro antimicrobial activity and cytotoxicity. Compounds 5g showed most potent antibacterial activity, while compound 5k emerged as the most effective antifungal agent. The most active compounds 5f, 5g, 5l, and 5m were also screened against methicillin-resistant Staphylococcus aureus. Among these compounds, 5g and 5m inhibited the growth against MRSA at low level of cytotoxicity. A binary quantitative structure–activity relationship based recursive partitioning model was developed to probe the physico-chemical properties influencing the structure-activity relationship for this class of molecules, which was used to correctly classify active and inactive compounds.

Synthesis, biological evaluation, and molecular docking study of pyridine clubbed 1,3,4-oxadiazoles as potential antituberculars

ABSTRACT A series of pyridine clubbed 1,3,4-oxadiazole derivatives were efficiently synthesized, characterized by standard spectral techniques and evaluated for their in vitro antitubercular activity against Mycobacterium tuberculosis (MTB) H37Ra and Mycobacterium bovis BCG in active and dormant state using an established methods. Compounds 5a, 5m, and 5t were identified as the most active compounds against MTB. Molecular docking was performed against MTB enoyl-ACP (CoA) reductase (FabI/ENR/InhA) enzyme to predict the binding modes and affinity. The theoretical predictions from molecular docking could establish a link between the observed biological activity and the binding affinity shedding light into specific bonded and non-bonded interactions influencing the activity. The active compounds were studied for cytotoxicity against three cell lines and were found to be non-cytotoxic. Specificity of these compounds was checked by screening them for their antibacterial activity against four bacterial strains. GRAPHICAL ABSTRACT