作者:Takashi Kikuchi、Emiko Uchiyama、Motohiko Ukiya、Keiichi Tabata、Yumiko Kimura、Takashi Suzuki、Toshihiro Akihisa
DOI:10.1021/np100402b
日期:2011.2.25
Six lanostane-type triterpene acids (1a-6a), isolated from Poria cocos, and their methyl ester (1b-6b) and hydroxy derivatives (1c-6c) were prepared. Upon evaluation a of the cytotoxic activity of these compounds against leukemia (HL60), lung (A549), melanoma (CRL1579), ovary (NIH:OVCAR-3), breast (SK-BR-3), prostate (DU145), stomach (AZ521), and pancreas (PANC-1) cancer cell lines, 11 compounds (5a, 6a, 2b-5b, 1c, and 3c-6c) exhibited activity with single digit micromolar IC50 values against one or more cell lines. Poricotriol A (1c), a hydroxy derivative of poricoic acid A (la), exhibited potent cytotoxicities against six cell lines with IC50 values of 1.2-5.5 mu M. Poricotriol A induced typical apoptotic cell death in HL60 and A549 cells on evaluation of the apoptosis-inducing activity by flow cytometric analysis. Western blot analysis in HL60 cells showed that poricotriol A activated caspases-3, -8, and -9, while increasing the ratio of Bax/Bcl-2. This suggested that poricotriol A induced apoptosis via both mitochondrial and death receptor pathways in HL60, On the other hand, poricotriol A did not activate caspases-3, -8, and -9, but induced translocation of apoptosis-inducing factor (AIF) from mitochondria and increased the ratio of Bax/Bcl-2 in A549. This suggested that poricotriol A induced apoptosis via the mitochondrial pathway mostly by translocation of AIF, independent from the caspase pathway in A549. Furthermore, poricotriol A was shown to possess high selective toxicity in lung cancer cells since it exhibited only weak cytotoxicity against a normal lung cell line (WI-38).