Synthesis, and docking studies of novel tetrazole-S-alkyl derivatives as antimicrobial agents

A series of novel tetrazole-S-alkyl-piperazine derivatives were synthesized and evaluated for their antifungal activity against C. albicans (ATCC 24433), C. krusei (ATCC 6258) and C. parapsilosis (ATCC 22019) and antibacterial activity against E. coli (ATCC 25922), S. marcescens (ATCC 8100), K. pneumoniae (ATCC 13883), P. aeruginosa (ATCC 27853), E. faecalis (ATCC 2942), B. subtilis (ATCC), S. aureus (ATCC 29213), S. epidermidis (ATCC 12228). Among the synthesized compounds, 1-(4-cycylohexylpiperazin-1-yl)-2-((1-methyl-1H-tetrazol-5-yl)thio)ethan-1-one (2b) (MIC = 7.81 µg/mL) and 1-(4-(4-chlorobenzyl)piperazin-1-yl)-2-((1-methyl-1H-tetrazol-5-yl)thio)ethan-1-one (2f) (MIC = 3.90 µg/mL) displayed significant antifungal activity and compared to reference drugs voriconazole and fluconazole. Besides, compound 2b has showed also higher antibacterial activity against E. faecalis (ATCC 2942) as a reference drug azithromycin, with a MIC value of 3.90 µg/mL, and compound 2d was found to be effective against S. epidermidis (ATCC 12228) as the same reference drug, with a MIC value of 7.81 µg/mL. All the derivatives were efficiently synthesized by a two-step process. The structure of the newly synthesized compounds was elucidated by their 1H NMR, 13C NMR, LC-MS/MS, and elemental analysis. In this study, the detailed synthesis, spectroscopic and biological evaluation data are reported. Molecular docking studies of all compounds were performed with the sterol 14-alpha demethylase enzyme of C. albicans, the target enzyme of azole antifungal drugs.