Chemical constituents from Inonotus obliquus and their antitumor activities

Four new lanostane-type triterpenes (inonotusanes D–G, 1 – 4 ), including a 24,25,26,27-tetranorlanostane, together with 11 known compounds ( 5 – 15 ), including 7 lanostane derivatives, 2 steroids and 2 aromatic compounds, were isolated from the sclerotia of Inonotus obliquus . Their structures were elucidated by 1D and 2D NMR spectroscopy and HRMS. To our knowledge, 1 is the first 24,25,26,27-tetranorlanostane-type triterpenoid from fungus, and this is the first time that 31-member lanostane-type triterpenes, 5 and 6 , have been isolated from the sclerotia of I. obliquus instead of from its submerged culture. 7 and 8 are also new isolates of this genus. Compounds 1 , 8 , 12 and 13 exhibited strong cytotoxicity against the 4T1 (mouse breast cancer) cell line, with IC 50 9.40, 7.79, 9.06 and 9.31 μM, respectively. 8 , 12 and 13 also exhibited strong cytotoxicity against the the MCF-7 (human breast cancer) cell line, with IC 50 8.35–9.01 μM.