The biotransformation of antcin K, a major ergostane triterpenoid from the fruiting bodies of Antrodia cinnamomea, by Bacillus subtilis (B. subtilis) ATCC 6633 was studied. Four metabolites from the biotransformation were isolated with preparative high-performance liquid chromatography and identified as 25S-antcin K 26-O-beta-glucoside, 25R-antcin K 26-O-beta-glucoside, 25S-antcin K 26-O-beta-(6'-O-succinyl)-glucoside, and 25R-antcin K 26-O-beta-(6'-O-succinyl)-glucoside with mass and nuclear magnetic resonance spectral analysis. By using either 25S-antcin K 26-O-beta-glucoside or 25R-antcin K 26-O-beta-glucoside as the biotransformation precursor, it was proven that 25S-antcin K 26-O-beta-(6'-O-succinyl)-glucoside and 25R-antcin K 26-O-beta-(6'-O-succinyl)-glucoside were biotransformed from 25S-antcin K 26-O-beta-glucoside and 25R-antcin K 26-O-beta-glucoside, respectively. To the best of our knowledge, this is the first study on the glycosylation of triterpenoids from A. cinnamomea, and the first time the succinylation of triterpenoid glycosides by microorganisms has been found. In addition, all four antcin K glucoside derivatives are new compounds.
