Conosiligins A-D, Ring-Rearranged Tremulane Sesquiterpenoids from .

Conosiligins A-D (-), four ring-rearranged sesquiterpenoids, were isolated from cultures of the basidiomycete . Their structures and absolute configurations were determined by detailed spectroscopic analyses and equivalent circulating density (ECD) calculations. Compounds and possess a 5/8-fused ring system, while has a 5/6-fused backbone conjugated with a γ-lactone. Compound is a 5,6-seco tremulane derivative with the loss of a skeletal carbon, featuring a tetracyclic system involving a pyranone moiety. Compounds and inhibited Con A-induced T cell proliferation with IC values of 12.3 and 6.6 μM, respectively.