Cytotoxic lanostane triterpenoids from the fruiting bodies of Piptoporus betulinus.

Chemical investigation of a bioactive methanolic extract of the fruiting bodies of Piptoporus betulinus led to the isolation of five previously undescribed lanostane triterpenoids named piptolinic acids A-E, as well as five known lanostane triterpenoids. Their structures were elucidated on the basis of 1D and 2D NMR spectroscopic and HRESIMS analysis. Piptolinic acid A with an unusual moiety (3-hydroxy-4-methoxycarbonyl-3-methylbutyryloxy) at C-3 exhibited comparable cytotoxic activity against human promyelocytic leukemia cell line HL-60 (IC50 = 1.77 μM) and human acute monocytic leukemia cell line THP-1 (IC50 = 8.21 μM) to those of positive control, fluorouracil (IC50 = 6.38 and 4.41 μM, respectively).