Synthesis and biological evaluation of 1,2,4-triazoles and 1,3,4-oxadiazoles derivatives linked to 1,4-dihydropyridines scaffold

Abstract

A series of diethyl-2,6-dimethyl-4-phenyl-1,4-dihydropyridine-3,5-dicarboxylate derivative coupled to 1,3,4-oxadiazole-5-thiones and 1,2,4-triazole-5-thiones moieties at C2,C6 positions of 1,4-dihydropyridine ring system was prepared. This linkage was carried out by the reaction of 1,3,4-oxadiazole-5-thiones and 1,2,4-triazole-5-thiones with 2,6-dibromomethyl-3,5-diethoxycarbonyl-4-phenyl-1,4-dihydropyridine in the presence of potassium carbonate as a weak base and dry acetone as the solvent. The newly synthesized compounds were characterized by FT-IR, ¹H NMR, ¹³C NMR spectral data, elemental analysis and FAB-MS. The synthesized compounds were tested for their antimicrobial and antifungal activity against Escherichia coli and Aspergillus fumigatus in vitro in comparison with Enrofloxacin and Amphotericin as the reference drugs which are normally used for treating such infections. The synthetic compounds showed different inhibition zones against tested bacteria and fungi. Compound 8d showed more antagonistic activity against E. coli and A. fumigatus.