S. K. Peethambar

Hantzsch reaction: Synthesis and characterization of some new 1,4-dihydropyridine derivatives as potent antimicrobial and antioxidant agents

In the present study two new series of Hantzsch 1,4-dihydropyridine derivatives (1,4-DHPs) containing substituted pyrazole moiety (4a-f and 5a-f) were synthesized by the reaction of 3-aryl-1H-pyrazole-4-carbaldehydes with 1,3-dicarbonylcompounds (ethylacetoacetate and methylacetoacetate) and ammonium acetate. The newly synthesized compounds were characterized by IR, NMR, mass spectral study and also by C, H, N analyses. New compounds were screened for their antimicrobial activity by well plate method (zone of inhibition). Antioxidant studies of the synthesized compounds were also performed by measuring the DPPH radical scavenging assay. Compounds 4c, 4e and 4f were found to be potent antibacterial and antioxidant agents. The acute oral toxicity study for the compounds 4c, 4e and 4f were carried out and the experimental studies revealed that compounds 4c and 4e is safe up to 3000 mg/kg and no death of animals were recorded. However in compound 4f, we found mortality above 2000 mg and also significant behavioral changes in experimental animals.

Synthesis and antimicrobial activity of 2-substituted [4-(1,3,4-oxadiazol-2-yl methyl)] phthalazin-1(2H)-one derivatives.

A series of new 2-substituted [4-(1,3,4-oxadiazol-2-yl)methyl]phthalazin-1(2H)-one derivatives 7a-h to 9a-h were designed and synthesized from methyl (4-oxo-3,4-dihydrophthalazin-1-yl)acetate (4), which in was turn prepared from phthalic anhydride. The structure of synthesized new compounds were characterized by spectral data and screened for their antimicrobial activities against various bacteria and fungi strains. Several of these compounds showed antimicrobial activity.

Synthesis, characterization and molecular docking studies of some new 1,3,4-oxadiazolines bearing 6-methylpyridine moiety for antimicrobial property.

A new series of 3-acetyl-2-aryl-2H/methyl-5-[3-(6-methylpyridinyl)]-2,3-dihydro-[1,3,4]-oxadiazole derivatives were synthesized from 6-methyl nicotinate through a multistep reaction sequence. The structures of newly synthesized compounds were established on the basis of elemental analysis, IR, 1H NMR, 13C NMR and mass spectral data. Three dimensional structure of the compound 5f was further confirmed by single crystal X-ray analysis. All the synthesized compounds were screened for their antimicrobial activity and antioxidant activity. The final compounds were subjected to molecular docking studies for the inhibition of enzyme L-glutamine: D-fructose-6-phosphate amidotransferase [GlcN-6-P] (EC 2.6.1.16). The in silico molecular docking results are matching with the in vitro studies and they may be considered as good inhibitor of GlcN-6-P synthase.6-methylpyridine.

Synthesis, antimicrobial and cytotoxicity studies of some novel modified Strobilurin derivatives

A series of some new 3-isoxazoline substituted methyl-3-methoxy-2-(4-oxo-3,4-dihydrophthalazin-1-yl)prop-2-enoate derivatives were designed and synthesized from methyl-(4-oxo-3,4-dihydrophthalazin-1-yl)acetate, which in turn was prepared from phthalic anhydride. The structures of synthesized new compounds were characterized by spectral data and studied for their antimicrobial activities and cytotoxicity. Several of these compounds showed good antimicrobial activity

Type II diabetes-related enzyme inhibition and molecular modeling study of a novel series of pyrazolone derivatives

AbstractInhibitors of alpha-amylase are targets for the development of novel drugs for the treatment of diabetes and obesity. Alpha amylase is an enzyme which increases the bio availability of glucose in the blood. Hence, the inhibition effects of alpha amylase of 2-[1-(4-isobutylphenyl)ethyl]-5-methyl-4-[2-(aryl-substituted)hydrazinylidene]-2,4-dihydro-3H-pyrazol-3-one (4a–l) were investigated, among them compounds 4d, 4f, 4a, and 4g have displayed good inhibitory activity. The compounds with significant results were further evaluated for their molecular modeling study using in silico method. The new series of compounds were synthesized by solvent-free microwave irradiation method and were characterized by spectral and analytical data.

Synthesis and Antimicrobial Studies of Some New 3-Isoxazoline Substituted Phthalazine Methylsulfonyl Oxadiazoles

A series of new 3-isoxazoline substituted phthalazine methylsulfonyl-oxadiazoles were prepared from methyl 2-(4-oxo-3,4-dihydrophthalazin-1-yl) acetate. The structure of synthesized compounds were characterized by spectral data and screened for their antimicrobial activities against various bacteria and fungi strains. Several of these compounds showed antimicrobial activity.

Synthesis of new 3-aryl-4-(3-aryl-4,5-dihydro-1H-pyrazol-5-yl)-1-phenyl-1H-pyrazole derivatives as potential antimicrobial agents

New (E)-1-aryl-3-(3-aryl-1-phenyl-1H-pyrazol-4-yl)prop-2-en-1-ones 6 (pyrazolic chalcones) were synthesized from Claisen–Schmidt reaction of 3-aryl-1-phenylpyrazol-4-carboxaldehydes 4 with several acetophenone derivatives 5. Subsequently, the cyclocondensation reaction of chalcones 6 with phenylhydrazine in acetic acid medium afforded the new 3-aryl-4-(3-aryl-4,5-dihydro-1H-pyrazol-5-yl)-1-phenyl-1H-pyrazoles 7. The synthesized compounds were characterized by spectral studies and evaluated for their in vitro antibacterial activity against three pathogenic bacterial strains, Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa, and in vitro antifungal activity against three pathogenic fungal strains Aspergillus flavus, Chrysosporium keratinophilum, and Candida albicans.

Regioselective one pot synthesis of 1,2,3-triazole derivatives bearing phthalazine moiety and their pharmacological activity

A new series of phthalazine-based 1,2,3-triazole derivatives (5a–h, 6a–f and 7a–d) were synthesized from the corresponding 2-(4-methyl/chloro benzyloxy) benzoic acid by multi-step reactions. Synthesized compounds were characterized by spectral studies and C, H, N analysis. The final compounds were screened for their antimicrobial, antifungal and antioxidant activity. Among them compounds 5c, 5g, 5h, 6b and 6e showed good antibacterial activity as compared to the standard drug streptomycin,whereas compounds 5g and 6d showed good antifungal activity comparable to the standard drug Fluconazole. Compounds 5a, 5f and 7c showed significant antioxidant property when compared with the standard butylated hydroxytoluene.