Evaluation of antimicrobial activity of synthesized 9H-alkylcarbazole and 10H-alkylphenothiazine derivatives on the cells of Salmonella enterica ser. Typhimurium, Saccharomyces cerevisiae, and Candida albicans

2 Department of Biochemistry, Faculty of Medicine, Lithuanian University of Health Sciences, Tilžės str. 18, 47181 Kaunas, Lithuania 10H-substituted phenothiazine and 9H-substituted carbazole derivatives are important because of a very wide range of applications and especially in medical chemistry due to their pharmacological activities. In this study, we synthesized 9H-alkylcarbazole and 10H-alkylphenothiazine derivatives with various lengths of alkyl chains and evaluated their antimicrobial and efflux inhibiting activities on the cells of Salmonella enterica ser. Typhimurium, Saccharomyces cerevisiae, and Candida albicans. Results of our study revealed that an increased length of alkyl chains of the carbazoles increased the accumulation of efflux indicator tetraphenylphosphonium (TPP+) ions. Cells of S. enterica efflux mutant ΔTolC had a considerable susceptibility to the synthesized compounds. The compounds exerted synergy with fluconazole against S. cerevisiae yeast. Efflux pump mutant ΔPdr5 was hypersensitive to the investigated carbazole and phenothiazine derivatives. The inhibitory effect of the compounds with a shorter alkyl chain (10-methyl-10H-phenothiazine and 9-methyl-9H-carbazole) was the highest for Candida albicans cells.