Tyromycic acids B-E, new lanostane triterpenoids from the mushroom Tyromyces fissilis.

Four new triterpenoids, tyromycic acids B-E (1-4), were isolated from a methanol-soluble extract of the fruit bodies of the Japanese inedible mushroom Tyromyces fissilis. Tyromycic acids B-D possess a lanostane skeleton, while tyromycic acid E is based on a rare 14(13-->12)abeo-lanostane skeleton. Their structures were determined by spectral data analysis and by single-crystal X-ray crystallography.