Antifungal and Drug Efflux Inhibitory Activity of Selected Flavonoids Against Candida albicans and Candida krusei

Abstract

Flavonoids have been shown to have potential healthy properties in humans. The aims of this study was investigate antifungal activities of selected flavonoids against C. albicans and C. krusei in vitro. The antifungal effects of the flavonoids epicatechin, ferulic acid, resveratrol, quercetin and catechin were determined using the agar-disc diffusion. The broth dilution method was then used to determine the MIC and MFC of the flavonoids. Inhibition of ATP-dependent drug efflux activity was determined using Rhodamine 6G. Epicatechin, ferulic acid and resveratrol showed antifungal effects against C. albicans with zones of inhibition of 26, 19 and 13 mm respectively whilst for C. krusei the zone of inhibition of epicatechin was 18 mm. Epicatechin had the highest antifungal activity with MIC values of 88 and 213 μg/ml for C. krusei and C. albicans respectively. There was increase in accumulation of R6G in the presence of ferulic acid and reserpine for C. krusei but efflux in the presence of epicatechin was observed for C. albicans. Epicatechin and ferulic acid might serve as chemical templates for development of novel antifungal agents. Ferulic acid may restore drug sensitivity to C. krusei where resistance to azoles has been implicated to be through antifungal drug efflux.

Key words:

• Flavonoids
• drug efflux
• growth inhibition
• plant polyphenols
• candidiasis