Antifungal activity of 4-hydroxy-3-(3-methyl-2-butenyl)acetophenone against Candida albicans: evidence for the antifungal mode of action.

The main secondary metabolite of Senecio nutans is 4-hydroxy-3-(3-methyl-2-butenyl)acetophenone (4HMBA). The antifungal activity of this compound and three derivatives was assessed using Candida albicans. 4HMBA exhibited the highest antifungal activity among the assayed compounds. The Fractional Inhibitory Concentration (FIC = 0.133) indicated a synergistic fungicidal effect of 4HMBA (5 mg L(-1)) and fluconazole (FLU) (0.5 mg L(-1)) against the C. albicans reference strain (ATCC 10231). Microscopy showed that 4HMBA inhibits filamentation and reduces cell wall thickness. Our findings suggest that 4HMBA is an interesting compound to diminish resistance to commercial fungistatic drugs such as fluconazole.