A promising anti-Candida activity of Buchenavia tomentosa extracts was recently described. In the present work, experiments were carried out to determine the fraction with higher antifungal activity from a B. tomentosa extract. Acetone fraction (AF) was obtained from the aqueous extract from dried leaves (5 min/100°C) and it was the most effective one. Gallic acid (GA) was identified by electrospray ionization mass spectrometry (ESI-MS) and also chosen to perform antifungal tests due to its promising activity on Candida albicans. Minimal inhibitory and fungicidal concentrations (MIC and MFC) were determined by broth microdilution technique. The effect on virulence factors of C. albicans was evaluated, and the cytotoxicity was determined. MIC50 and MIC90 values were both equal to 0.625 mg ml-1 for AF and 2.5 and 5 mg ml-1, respectively, for GA. AF and GA showed ability to inhibit C. albicans adherence and to disrupt 48 h-biofilm. AF and GA were effective in reducing the formation of hyphae of C. albicans SC5314. AF and GA decreased adherence of C. albicans to oral epithelial cells. AF and GA showed slight to moderate toxicity to Vero cells. This result suggests further studies for topic use of these compounds. AF, which contains a combination of several molecules, presented greater potential of antimicrobial activity than GA, with lower values of MIC and lower cytoxicity.
Keywords: Buchenavia tomentosa; Candida albicans; antifungal; gallic acid; phytotherapy; virulence factors.