Pradeep Kumar

Synthesis, antimicrobial and antiviral evaluation of substituted imidazole derivatives

In the present study, we have synthesized 2-(substituted phenyl)-1H-imidazole (1-12) and (substituted phenyl)-[2-(substituted phenyl)-imidazol-1-yl]-methanone (13-26) analogues and screened them for their antimicrobial activity against gram positive, gram negative and fungal species. The results of antibacterial study indicated that compounds 15, 17 and 24 showed appreciable antibacterial activity and compound 26 emerged as the most potential antifungal agent. The results of SAR studies indicated that the presence of electron withdrawing groups is necessary for the antimicrobial activity of the synthesized compounds. The results of the present study indicated that compounds 15, 17 and 24 might be of interest for the identification of new antimicrobial molecules as their antibacterial activity is equivalent to the standard drug norfloxacin. Further, the antiviral screening of (substituted phenyl)-[2-(substituted phenyl)-imidazol-1-yl]-methanones (13-26) against a panel of viral strains indicated that compounds 16 and 19 can be selected as lead compounds for the development of novel antiviral agents.

Benzimidazole: a medicinally important heterocyclic moiety

Benzimidazole nucleus is a constituent of many bioactive heterocyclic compounds that are of wide interest because of their diverse biological and clinical applications. Moreover, benzimidazole derivatives are structural isosters of naturally occurring nucleotides, which allows them to interact easily with the biopolymers of the living system. This created interest in researchers who have synthesized variety of benzimidazole derivatives and screened them for their various biological activities, viz., anticancer, hormone antagonist, antiviral, anti-HIV, anthelmintic, antiprotozoal, antimycobacterial, antihypertensive, anti-inflammatory, analgesic, anxiolytic, antiallergic, coagulant, anticoagulant, antioxidant as well antidiabetic activities.

Biological importance of imidazole nucleus in the new millennium

Imidazole nucleus is a constituent of many bioactive heterocyclic compounds that are of wide interest because of their diverse biological and clinical applications. This created interest in researchers to synthesize variety of imidazole derivatives and to screen them for their various biological activities viz. anti-cancer, anti-viral, antiHIV, anti-protozoal, anti-mycobacterial, anti-inflammatory, analgesic, anxiolytic, as well anti-diabetic activities.

Synthesis and QSAR evaluation of 2-(substituted phenyl)-1H-benzimidazoles and [2-(substituted phenyl)-benzimidazol-1-yl]-pyridin-3-yl-methanones

A series of 2-(substituted phenyl)-1H-benzimidazole (1-10) and [2-(substituted phenyl)-benzimidazol-1-yl]-pyridin-3-yl-methanone (11-19) derivatives were synthesized and tested in vitro for their antimicrobial activity. The results of QSAR investigation indicated the importance of molecular descriptors, dipole moment (mu), log of octanol water partition coefficient (logP) and second order molecular connectivity index ((2)chi) in describing the antimicrobial activity of the synthesized compounds.

Hansch analysis of substituted benzoic acid benzylidene/furan-2-yl-methylene hydrazides as antimicrobial agents.

A series of substituted hydrazide derivatives have been synthesized and screened for their in vitro antimicrobial activities against five representative microorganisms. The results of antimicrobial study indicated that the presence of electron withdrawing groups on the benzoic acid moiety improved antimicrobial activity. Further, the presence of heterocyclic ring furan does not improve the antimicrobial activity of substituted hydrazides. To understand the relationship between physicochemical parameters and antimicrobial activity of substituted hydrazide derivatives, QSAR investigation was performed by the development of one-target and multi-target models. The multi-target model was found to be effective in describing the antimicrobial activity of substituted hydrazides in comparison to the one-target models. Further, it indicated the importance of the topological parameter, valence third order molecular connectivity index ((3)chi(v)) and the electronic parameter, energy of highest occupied molecular orbital (HOMO) in describing the antimicrobial activity of substituted hydrazides.

Synthesis, antimicrobial, anticancer evaluation and QSAR studies of 6-methyl-4-[1-(2-substituted-phenylamino-acetyl)-1H-indol-3-yl]-2-oxo/thioxo-1,2,3,4-tetrahydropyrimidine-5-carboxylic acid ethyl esters.

A series of 6-methyl-4-[1-(2-substituted-phenylamino-acetyl)-1H-indol-3-yl]-2-oxo/thioxo-1,2,3,4-tetrahydropyrimidine-5-carboxylic acid ethyl esters (1-16) were synthesized and evaluated inxa0vitro for their antimicrobial and anticancer potential. 6-Methyl-4-{1-[2-(4-nitro-phenylamino)-acetyl]-1H-indol-3-yl}-2-thioxo-1,2,3,4-tetrahydropyrimidine-5-carboxylic acid ethyl ester (15, pMIC(ec)xa0=xa02.50xa0μM/mL) was found to be almost equipotent to the standard drug, norfloxacin (pMIC(ec)xa0=xa02.61xa0μM/mL) against Escherichia coli and emerged as most potent antimicrobial agent (pMIC(am)xa0=xa01.84xa0μM/mL). 4-{1-[2-(2-Chloro-4-nitro-phenylamino)-acetyl]-1H-indol-3-yl}-6-methyl-2-oxo-1,2,3,4-tetrahydropyrimidine-5-carboxylic acid ethyl ester (4, IC(50)xa0=xa05xa0μg/mL) was more potent than the standard drug 5-fluorouracil (IC(50)xa0=xa06xa0μg/mL) against HCT-116 a colon cancer cell line, and emerged as the most potent anticancer agent. The QSAR studies demonstrated the importance of topological parameter, Balaban index (J) followed by lipophillic parameter, log P in describing the antimicrobial activity of the synthesized compounds.

Synthesis and antitubercular activities of substituted benzoic acid N'-(substituted benzylidene/furan-2-ylmethylene)-N-(pyridine-3-carbonyl)-hydrazides.

A series of benzoic acid hydrazones and its nicotinyl derivatives (1-10) were prepared and evaluated for their antitubercular activity towards a strain of Mycobacterium tuberculosis (MTB). The structures of newly synthesized compounds were confirmed by infrared (IR) and 1H-nuclear magnetic resonance (NMR) spectral data and elemental analysis. The in vitro antitubercular activity of synthesized compounds against MTB was carried out in Middlebrook 7H11agar medium supplemented with OADC by agar dilution method. The antitubercular activity results indicated that nicotinic acid N-(3,5-dinitro-benzoyl)-N-(4-methoxy-benzylidene)-hydrazide (1) is the most potent among the synthesized compounds with MIC of 3.5×10(-3) μM.

Design, synthesis, antimicrobial, anticancer evaluation, and QSAR studies of 4-(substituted benzylidene-amino)-1,5-dimethyl-2-phenyl-1,2-dihydropyrazol-3-ones

A series of 4-(substituted benzylidene-amino)-1,5-dimethyl-2-phenyl-1,2-dihydropyrazol-3-ones (1–17) was synthesized and tested in vitro for its antimicrobial and anticancer potentials. The biological screening results indicated that compounds having m-chloro substituent on benzaldehyde portion showed antimicrobial potential, whereas compounds having chloro, methoxy, and hydroxyl groups showed anticancer potential. The quantitative structure activity relationship (QSAR) studies indicated the importance of topological parameter, valence first order molecular connectivity index in describing antifungal activity. The developed QSAR models, however, were statistically insignificant with reference to anticancer activity of the synthesized compounds.

Synthesis, antimicrobial and antiviral activity of substituted benzimidazoles

In the present study we have synthesized (4-nitrophenyl)-[2-(substituted phenyl)-benzoimidazol-1-yl]-methanones, (2-bromophenyl)-[2-(substituted phenyl)-benzoimidazol-1-yl]-methanone analogues (1–14) and evaluated them for their antimicrobial and antiviral potential. The results of antimicrobial screening indicated that none of the synthesized compounds were effective against the tested bacterial strains. Compounds 3, 11, 13 and compounds 5, 11, 12 were found to be active against Aspergillus niger and Candida albicans respectively, and may be further developed as antifungal agents. Furthermore, evaluation against a panel of different viruses pointed out the selective activity of compounds 5 and 6 against vaccinia virus and Coxsackie virus B4.

Synthesis, antimicrobial evaluation, ot-QSAR and mt-QSAR studies of 2-amino benzoic acid derivatives

A series of 2-amino benzoic acid derivatives (1–28) were synthesized and evaluated for their in vitro antimicrobial activity against the panel of Gram positive, Gram negative bacterial and fungal strains. The results of antimicrobial studies indicated that, in general, the synthesized compounds were found to be bacteriostatic and fungistatic in action. QSAR studies performed by the development of one target and multi target models indicated that multi-target model was effective in describing the antimicrobial activity as well demonstrated the effect of structural parameters viz. LUMO, 3χv and W on antimicrobial activity of 2-amino benzoic acid derivatives.