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

Abstract

Inonotus obliquus has been known to have biological activities such as anti-cancer, anti-inflammatory, and anti-oxidant activities. Although triterpenoids in I. obliquus have been reported to have anti-proliferative activity, triterpenoids in outer part of I. obliquus have been little studied. The aim of the study was to determine composition of triterpenoids in the extract from inner and outer parts of I. obliquus and to evaluate their anti-proliferative activity against HT-29, AGS, MCF-7, and PC-3 cancer cells. Dried I. obliquus powder was extracted using 80% methanol. Triterpenoid fraction was obtained from the methanol extract using a Diaion HP-20 column. Betulin, betulinic acid, inotodiol, and trametenolic acid were identified in the triterpenoid fractions. Inotodiol and trametenolic acid were major triterpenoids in both of the inner and outer parts of I. obliquus. The amount of triterpenoids in the outer part of I. obliquus (369.9 ± 10.7 mg/g fraction, dry basis) was significantly higher than that of the inner part (324.3 ± 22.3 mg/g). The triterpenoid fractions had dose-dependent anti-proliferative activity against AGS, MCF-7, and PC-3 cells. Anti-proliferative activity of the triterpenoid fraction from the outer part against the cancer cells was also significantly higher than that of the inner part. The outer part of I. obliquus, a by-product of the mushroom from extraction process, may be used as a functional material for foods or drugs.