Lanostane triterpenoids from the inedible mushroom Fomitopsis spraguei

Investigation of the methanolic extract of the inedible mushroom Fomitopsis spraguei (Polyporaceae) led to the isolation of five lanostane-type triterpenoids (1-5): three new compounds named fomitopsins A-C (2-4), and two known compounds, quercinic acid C (1) and 3alpha-carboxyacetyl-12beta-hydroxyquercinic acid (5). Their structures were determined by 2D NMR, MS, IR, UV spectra, and X-ray crystallographic analyses. An X-ray crystal structure analysis of quercinic acid C (1) established its stereochemistry as 3R,12R-dihydroxy-24R-methyl-23-oxo-25S-lanost-8-en-26-oic acid.