Piptolinic acids F–J, five new lanostane-type triterpenoids from Piptoporus betulinus
Five new lanostane-type triterpenoids, named piptolinic acids F − J (1–5), as well as seven known analogues (6–12), were isolated from methanolic extract of the fruiting bodies of Piptoporus betulinus. Compounds 1–4 were 24-methyl-lanostane triterpenoids, while compound 5 was a 3,4-seco-lanostane derivative. Their structures were established on the basis of extensive spectroscopic analysis (1D, 2D NMR, and HRESIMS). Cytotoxicity evaluation indicated that compound 6 exhibited moderate cytotoxic activity against human melanoma cell line A-375 (IC50 = 42.8 μM) and human renal carcinoma cell line 786-O (IC50 = 56.5 μM).