Conosilane A, an unprecedented sesquiterpene from the cultures of basidiomycete Conocybe siliginea.

Conosilane A (1), a novel sesquiterpene with an unprecedented carbon skeleton, was isolated from the cultures of the basidiomycete Conocybe siliginea. Its structure was elucidated by extensive spectroscopic methods, and the absolute configuration was determined by single crystal X-ray diffraction analysis. Conosilane A was found to inhibit 11β-hydroxysteroid dehydrogenase significantly.