Antifungal Activity of the Ethanol Extract fromFlos Rosae Chinensiswith Activity against Fluconazole-Resistant ClinicalCandida

Abstract

This study was designed to investigate the antifungal activity of a hydroalcoholic extract fromFlos Rosae Chinensis(FRC) combined with fluconazole (FCZ) against clinical isolates ofCandida albicansresistant to FCZ. The minimum inhibitory concentration (MIC) of FRC was determined using a checkerboard microdilution assay. The synergistic effects of the combination of FRC and FCZ against clinical isolates ofC. albicansresistant to FCZ were further confirmed by constructing time-growth curves and performing an agar diffusion test. FRC alone exerted efficient antifungal activities againstC. albicanswithin a MIC80ranging from 20 μg/ml to 40 μg/ml. FRC failed to enhance the effects of FCZ against sensitiveC. albicansstrains, although it rendered FCZ-resistantC. albicansmore sensitive. These results were further confirmed by the result of in vivo study. Our study is the first to discover that FRC can inhibit the growth ofC. albicansto a certain degree. An FRC antifungal mechanism study showed that FRC strengthens FCZ to inhibit the action of ergosterol biosynthesis by promoting the transformation of lanosterol to eburicol, suggesting that the antifungal mechanism of FRC involves the inhibition of ergosterol biosynthesis.