Potent Antifungal Activity of Pure Compounds from Traditional Chinese Medicine Extracts against Six OralCandidaSpecies and the Synergy with Fluconazole against Azole-ResistantCandida albicans

Abstract

This study was designed to evaluate thein vitroantifungal activities of four traditional Chinese medicine (TCM) extracts. The inhibitory effects of pseudolaric acid B, gentiopicrin, rhein, and alion were assessed using standard disk diffusion and broth microdilution assays. They were tested against six oralCandidaspecies,Candida albicans, Candida glabrata, Candida tropicalis, Candida krusei, Candida dubliniensis,andCandida guilliermondii, including clinical isolates from HIV-negative, HIV-positive, and Sjögren's syndrome patients. It was found that pseudolaric acid B had the most potent antifungal effect and showed similar antifungal activity to all sixCandidaspp, and to isolates from HIV-negative, HIV-positive, and Sjögren's syndrome patients. The MIC values ranged from 16 to 128 μg/mL. More interestingly, a synergistic effect of pseudolaric acid B in combination with fluconazole was observed. We suggest that pseudolaric acid B might be a potential therapeutic fungicidal agent in treating oral candidiasis.