Chain-length-specific anti-Candida activity of cationic lipo-oxazoles: a new class of quaternary ammonium compounds.

Abstract

Candida species have become resistant to commonly used anti-fungal drugs like fluconazole and echinocandins. In our screen, a series of quaternary ammonium compounds (QACs) emerged as an alternative treatment choice for drug-resistant Candida infections. Medium alkyl chain cationic lipo-oxazoles comprising six to thirteen twin carbon chains and a quaternary ammonium unit were synthesized and evaluated for their in vitro anti-Candida and biofilm inhibition activity. SEM was performed to visualize membrane distortion.Results/Key findings. Heptyl and octyl chain analogues (5c, 6b and 6c) showed promising anti-fungal activity. Compound 5c was active against both fluconazole-sensitive and resistant clinical isolates of Candida albicans as well as non-albicans Candida strains. 5c also inhibited the adhesion of C. albicans cells to a polystyrene surface and restricted biofilm formation. SEM further confirmed Candida cell membrane distortion by 5c. A novel class of QACs, called cationic lipo-oxazoles, was tested and found to exhibit anti-fungal activity against planktonic cells as well as biofilms of Candida.