V. V. Joshi

Synthesis of pyrazole encompassing 2-pyridone derivatives as antibacterial agents

A series of novel compounds 6-amino-1-((1,3-diphenyl-1H-pyrazole-4-yl)methyleneamino)-4-(aryl)-2-oxo-1,2-dihydropyridine-3,5-dicarbonitriles (4a-t) were synthesized and characterized by IR, (1)H NMR, (13)C NMR and mass spectral data. These compounds were screened for their in vitro antibacterial activity against Staphylococcus aureus, Streptococcus pyogenes (Gram positive), Escherichia coli, Pseudomonas aeruginosa (Gram negative) by serial broth dilution and cytotoxic activity (NIH 3T3 & HeLa) by MTT assay. The results indicated that compounds 4g, 4i, 4m, 4o, 4r and 4t exhibit potent antibacterial activity against bacterial strains at non-cytotoxic concentrations.

Synthesis and characterization of some new quinoline based derivatives endowed with broad spectrum antimicrobial potency.

The synthesis of a novel series of 2-(5-(2-chloro-6-fluoroquinolin-3-yl)-3-(aryl)-4,5-dihydro-1H-pyrazol-1-yl)thiazol-4(5H)-ones (4a-l) and N-(4-(2-chloro-6-fluoroquinolin-3-yl)-6-(aryl)pyrimidin-2-yl)-2-morpholinoacetamides (7a-l) are described in the present paper. The chemical structures of compounds have been elucidated by IR, (1)H NMR, (13)C NMR and mass spectral data. Antimicrobial activity was measured against Escherichia coli (MTCC 443), Pseudomonas aeruginosa (MTCC 1688), Staphylococcus aureus (MTCC 96), Streptococcus pyogenes (MTCC 442), Candida albicans (MTCC 227), Aspergillus niger (MTCC 282) and Aspergillus clavatus (MTCC 1323) by serial broth dilution. Evaluation of antimicrobial activity showed that several compounds exhibited greater activity than reference drugs and thus could be promising new lead molecules.

Synthesis of promising antimicrobial agents: a novel series of N-(4-(2,6-dichloroquinolin-3-yl)-6-(aryl)pyrimidin-2-yl)-2-morpholinoacetamides

A series of novel compounds N-(4-(2,6-dichloroquinolin-3-yl)-6-(aryl)pyrimidin-2-yl)-2-morpholinoacetamides (5a–l) were synthesized by a series of multistep reactions. Newly synthesized compounds have been characterized by IR, 1H NMR, 13C NMR, and mass spectral data. Antimicrobial screening of title compounds 5a–l was examined against Gram-positive bacteria (Staphylococcus aureus and Streptococcus pyogenes), Gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa), and three fungi (Candida albicans, Aspergillus niger, and Aspergillus clavatus) by serial broth dilution method. Synthesized compounds showed potent inhibitory action against test organisms. Screened compounds 5e–g and 5i–l were associated with considerably higher antibacterial and antifungal activities than commercially used antibiotics.

Microwave-assisted synthesis and antimicrobial screening of new imidazole derivatives bearing 4-thiazolidinone nucleus

A new series of compounds 2-((1-(4-(4-arylidene-2-methyl-5-oxo-4,5-dihydro-1H-imidazol-1-yl)phenyl)ethylidene)hydrazono)thiazolidin-4-ones (4a–o) have been synthesized under conventional and microwave irradiation method. All compounds were characterized by IR, 1H NMR, 13C NMR and mass spectra. Newly synthesized compounds were screened for their antibacterial and antifungal activities on Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Staphylococcus pyogenes, Candida albicans, Aspergillus niger and Aspergillus clavatus by bioassays, namely serial broth dilution. The synthesized compounds showed potent antimicrobial activity against tested microorganisms. Compounds 4h, 4j, 4m and 4n were the most potent amongst tested compounds.

Synthesis, characterization, and antimicrobial evaluation of novel naphthalene-based 1,2,4-triazoles

In order to search for new bioactive molecules with significant antimicrobial action, a series of 1,2,4-triazole and naphthalene analogs bearing structurally diverse substituents, N-(3-mercapto-5-(naphthalen-1-yl)-4H-1,2,4-triazol-4-yl)(aryl)amides 3a–l were synthesized in good yield by a multi-step synthetic procedure. Their antimicrobial activity was screened against various Gram-positive and Gram-negative bacteria and fungi. Compounds 3a, 3f, 3g, 3j, and 3k exerted strong inhibition of the investigated bacterial and fungal strains compared to control antibiotic ampicillin and antifungal griseofulvin. On the basis of statistical analysis, it is observed that the compounds give significant co-relation. All the synthesized compounds have been characterized by IR, 1H NMR, 13C NMR, and mass spectral data.

Synthesis and antimicrobial screening of novel series of imidazo-[1,2-a]pyridine derivatives

In an attempt to find new bio-active molecules, a series of mannich bases N,N-dimethyl-1-(7-methyl-2-(aryl)imidazo[1,2-a]pyridin-3-yl)methanamines 4a–l were synthesized by mannich reaction of 7-methyl-2-(aryl)imidazo-[1,2-a]pyridines 3a–l with paraformaldehyde and N,N-dimethyl amine. Compounds 3a–l were prepared from reaction between different substituted 2-bromo-1-(aryl)ethanones 2a–l and 4-methylpyridin-2-amine 1. Structures of these compounds were confirmed by IR, 1H NMR, 13C NMR, and mass spectral data. Antimicrobial screening of title compounds 3a–l was examined against Gram-positive bacteria (Staphylococcus aureus, Streptococcus pyogenes), Gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa), and fungi (Candida albicans, Aspergillus niger, Aspergillus clavatus) using serial broth dilution method. Some derivatives bearing halogen group was found to be equipotent or more potent than commercial drugs, against most of the employed strains, as evident from the screening data.

Synthesis of new quinoline-2-pyrazoline-based thiazolinone derivatives as potential antimicrobial agents

A series of 2-(5-(2-chloro-6-methylquinolin-3-yl)-3-(aryl)-4,5-dihydro-1H-pyrazol-1-yl)thiazol-4(5H)ones (4a–l) were synthesized and characterized by IR, 1H NMR, 13C NMR, and mass spectra. All the synthesized compounds were tested for their in vitro antimicrobial activity against Escherichia coli (MTCC 443), Pseudomonas aeruginosa (MTCC 1688), Staphylococcus aureus (MTCC 96), Streptococcus pyogenes (MTCC 442), Candida albicans (MTCC 227), Aspergillus niger (MTCC 282), and Aspergillus clavatus (MTCC 1323) by serial broth dilution. Compounds 4e, 4f, 4g, 4i, 4j, and 4l were the most distinctive derivatives identified in present study because of their remarkable in vitro antimicrobial potency.

Synthesis, characterization and antimicrobial screening of hybrid molecules containing quinoline, pyrimidine and morpholine analogues

AbstractIn an attempt to find new bio-active molecules, a series of compounds N-(4-(2-chloroquinolin-3-yl)-6-(aryl)pyrimidin-2-yl)-2-morpholinoacetamides (5a–l) were synthesized by multistep reactions. Compounds were characterized by IR, NMR and mass spectra. Antimicrobial screening of title compounds (5a–l) was carried out against Gram-positive bacteria (Staphylococcus aureus, Streptococcus pyogenes), Gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa) and fungi (Candida albicans, Aspergillus niger, Aspergillus clavatus) using serial broth dilution method. On the basis of statistical analysis, it is observed that these compounds gave significant co-relation. Newly synthesized compounds 5e, 5f, 5g, 5i and 5l showed significant potency against different microbial strains. Graphical AbstractA novel series of compounds N-(4-(2-chloroquinolin-3-yl)-6-(aryl)pyrimidin-2-yl)-2-morpholinoacetamides (5a–l) were synthesized by multi-step reactions. Newly synthesized compounds were characterized by various spectroscopic techniques and screened for in vitro antimicrobial activity.

Synthesis and antimicrobial screening of 5-(benzylidene)-3-phenylthiazolidin-4-one derivatives incorporating thiazole ring

The present article deals with the synthesis and antimicrobial screening of a series of N-(5-(2-(5-(arylidene)-4-oxo-3-phenylthiazolidin-2-ylidene)hydrazinecarbonyl)-4-methylthiazol-2-yl)-4-methoxybenzamides (6a–o). The structures of these compounds have been elucidated by spectra (IR, 1H NMR, 13C NMR, mass spectra). All the synthesized compounds were screened for in vitro antibacterial activity against Gram-positive (Staphylococcus aureus, Streptococcus pyogenes) and Gram-negative (Escherichia coli, Pseudomonas aeruginosa) bacteria. These compounds were also tested for their inhibitory action against three strains of fungi (Candida albicans, Aspergillus niger, Aspergillus clavatus). The thiazole derivatives discovered in this study may provide valuable therapeutic intervention for the treatment of microbial diseases, especially against bacterial and fungal infections.

Synthesis of some novel C-5 and N-3 substituted 2-(2-hydroxyphenylimino)thiazolidin-4-one derivatives with broad-spectrum antimicrobial activity

In the present article, compounds 5-((substituted-2-chloroquinolin-3-yl)methylene)-2-(2-hydroxyphenylimino)thiazolidin-4-ones (3a–k), 1-(2-(2-(2-hydroxyphenylimino)-4-oxothiazolidin-3-yl)-2-oxoethyl)pyrimidine-2,4,6(1H,3H,5H)-trione (6) and 1-(2-(5-((substituted-2-chloroquinolin-3-yl)methylene)-2-(2-hydroxyphenylimino)-4-oxothiazolidin-3-yl)-2-oxoethyl)pyrimidine-2,4,6(1H,3H,5H)-triones (8a–k) have been synthesized by substituting C-5 and N-3 position of parent compound 2-(2-hydroxyphenylimino)thiazolidin-4-one (1). Structures of the newly synthesized compounds were assigned on the basis of elemental analyses, IR, 1H NMR, 13C NMR, and mass spectra. In vitro antimicrobial activity of target compounds (3a–k, 6 and 8a–k) was investigated against two Gram-positive, two Gram-negative bacteria and three fungal strains. Among the tested compounds (3e), (3f), and (3h) showed very good antifungal activity, while compound (6) showed very good antibacterial activity. Compounds (8e), (8f), and (8h) showed excellent antifungal and antibacterial activities.