Antimicrobial triterpenes from Ilex integra and the mechanism of antifungal action.

Antimicrobial triterpenes were isolated from the fruits of Ilex integra. Their structures were elucidated by spectral data and identified as rotundic acid (1), ulsolic acid (2) and peduncloside (3). Triterpene 1 showed significantly broad antimicrobial activity against bacteria, yeast and filamentous fungi. The antifungal activity of 1 was reversed by fatty acids. Cellular constituents leaked from Candida albicans cells incubated with triterpene 1. These results suggest that the antimicrobial activity of triterpenes in I. integra is due to a change of membrane permeability arising from membrane lipid alteration.