Antifungal activity from Alpinia galanga and the competition for incorporation of unsaturated fatty acids in cell growth.

An antimicrobial diterpene was isolated from Alpinia galanga in the screening for potentiators of phytochemical antibiotic action. The structure was elucidated by spectral data and identified as (E)-8 beta, 17-epoxylabd-12-ene-15, 16-dial (1). Diterpene 1 synergistically enhanced the antifungal activity of quercetin and chalcone against Candida albicans. Antifungal activity of 1 was reversed by unsaturated fatty acids. Protoplasts of C. albicans were lysed by 1. These results suggest that antifungal activity of 1 is due to a change of membrane permeability arising from membrane lipid alternation.