Two novel ravenelones from the edible mushroom Pulveroboletus ravenelii.

Two novel butenolides, isoravenelone (1) and ravenelone (2), and a large amount of a known compound, vulpinic acid (3), were isolated from the methanolic extract of the Japanese fungus Pulveroboletus ravenelii (Boletales). These structures were elucidated by two dimensional (2D) NMR, MS, IR and UV spectra, and X-ray crystallographic analysis.