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Three new lanostane-type triterpenoids, inonotsulides A, B, and C (1–3, resp.) were isolated from the sclerotia of Inonotus obliquus (Pers.: Fr.) (Japanese name: Kabanoanatake; Russian name: Chaga). Their structures were determined to be (20R,24S)-3β,25-dihydroxylanost-8-en-20,24-olide (1), (20R,24R)-3β,25-dihydroxylanost-8-en-20,24-olide (2), and (20R,24S)-3β,25-dihydroxylanosta-7,9(11)-dien-20,24-olide (3) on the basis of chemical transformation, NMR spectroscopy including 1D and 2D (1H,1H-COSY, NOESY, HMQC, HMBC), EI-MS, and single-crystal X-ray analysis.

Two new lanostane-type triterpenoids, inonotsuoxides A (1) and B (2) along with three known lanostane-type triterpenoids, inotodiol (3), trametenolic acid (4), and lanosterol (5), were isolated from the sclerotia of Inonotus obliquus (Pers.: Fr.) (Japanese name: Kabanoanakake) (Russian name: Chaga). Their structures were determined to be 22R,25-epoxylanost-8-ene-3beta,24S-diol (1) and 22S,25-epoxylanost-8-ene-3beta,24S-diol (2) on the basis of spectral data including single crystal X-ray analysis. These compounds except for 2 were tested for their inhibitory effects on Epstein-Barr virus early antigen (EBV-EA) activation induced by 12-O-tetradecanoylphorbol-13-acetate (TPA), as a test for potential cancer chemopreventive agents. The most abundant triterpene, inotodiol (3), was investigated for the inhibitory effect in a two-stage carcinogenesis test on mouse skin using 7,12-dimethylbenz[a]anthracene (DMBA) as an initiator and TPA as a promoter. Compound 3 was found to exhibit the potent anti-tumor promoting activity in the in vivo carcinogenesis test.

Three new lanostane-type triterpenoids, inonotsulides A, B, and C (1–3, resp.) were isolated from the sclerotia of Inonotus obliquus (Pers.: Fr.) (Japanese name: Kabanoanatake; Russian name: Chaga). Their structures were determined to be (20R,24S)-3β,25-dihydroxylanost-8-en-20,24-olide (1), (20R,24R)-3β,25-dihydroxylanost-8-en-20,24-olide (2), and (20R,24S)-3β,25-dihydroxylanosta-7,9(11)-dien-20,24-olide (3) on the basis of chemical transformation, NMR spectroscopy including 1D and 2D (1H,1H-COSY, NOESY, HMQC, HMBC), EI-MS, and single-crystal X-ray analysis.

Two new lanostane-type triterpenoids, 1 and 2 besides two known lanostane-type triterpenoids, 3 and 4 were isolated from the sclerotia of Inonotus obliquus. Their structures were determined to be lanosta-8,23E-diene-3beta,22R,25-triol (1) and lanosta-7:9(11),23E-triene-3beta,22R,25-triol (2) by spectral data. These compounds were tested for their anti-tumor-promoting activity using a short-term in vitro assay for EBV-EA activation induced by TPA. Compounds 1, 2 and 4 were stronger than the positive control, oleanolic acid. The most abundant compound 4 was investigated for the inhibitory effect in a two-stage carcinogenesis test on mouse skin using DMBA as an initiator and TPA as a promoter. Compound 4 was found to exhibit the potent anti-tumor promoting activity in the in vivo carcinogenesis test.