Tetranorlanostane and Lanostane Triterpenoids with Cytotoxic Activity from the Epidermis of Poria cocos (Schw.) Wolf.

Two unprecedented tetranorlanostane triterpenoids, poricolides A ( 1 ) and B ( 2 ), and two new lanostane triterpenoids, 3 β -acetoxy-24-methyllanosta-8,16,24(31)-trien-21-oic acid ( 3 ) and 3 β -acetoxylanosta-7,9(11),16,23-tetraen-21-oic acid ( 4 ), were isolated from the epidermis of Poria cocos . The structures of 1 - 4 were determined via analysis of 1 H-, 13 C-, and 2D-NMR, and HR-ESI-MS data, and the absolute configurations of 1 and 3 were established by single-crystal X-ray diffraction analysis. Compounds 1 and 2 were the first report of tetranorlanostane triterpenoid having a δ- lactone ring at C(17). Compounds 3 and 4 were rare lanostane triterpenoids having a double bond between C(16) and C(17). Compounds 1 - 4 exhibited potent antiproliferative effects against A549, SMMC-7721, MCF-7, and SW480 cancer cell lines with IC 50 values between 16.19 ± 0.38 to 27.74 ±1.12 μ M.