Composition of Triterpenoids in Inonotus obliquus and Their Anti-Proliferative Activity on Cancer Cell Lines

The objective of this study was to determine the composition of triterpenoids in the extracts from the inner and outer parts of Inonotus obliquus and to evaluate their anti-proliferative activity against cancer cell lines (HT-29, AGS, MCF-7, and PC3). Inner and outer parts of I. obliquus were extracted with 80% methanol for 24 h. The extract was fractionated by Diaion HP-20 resin to obtain the triterpenoid fraction. Composition of triterpenoids in the fraction was analyzed by HPLC and LC-ESI-MS. Anti-proliferative activity was evaluated by MTT assay against cancer cell lines. Inotodiol and trametenolic acid were major triterpenoids in both of the inner and outer parts of I. obliquus. Inotodiol in triterpenoid fractions from the inner and outer parts of I. obliquus was 153.9 +/- 15.4 mg/g (dry basis (db)) and 194.1 +/- 11.5 mg/g, respectively. Trametenolic acid in triterpenoid fractions from the inner and outer parts of I. obliquus was 94.5 +/- 9.15 mg/g (db) and 106.3 +/- 8.23 mg/g, respectively. Triterpenoids in the outer part were significantly higher than those in the inner part. Anti-proliferative activity of the triterpenoid fraction from the outer part against AGS, MCF-7, and PC3 was also significantly higher than that of the inner part.