Irlactane and Tremulane Sesquiterpenes from the Cultures of the Medicinal Fungus Irpex lacteus HFG1102.

A new irlactane-type, namely irlactin K (1), and 22 tremulane-type sesquiterpenes including fourteen previously undescribed ones, namely irpexolactins A-N (2-15), and a known irlactane-type sesquiterpenoid, were isolated from the fermentation broth of the medicinal fungus Irpex lacteus HFG1102. The structures of all the isolates were characterized by extensive spectroscopic methods, including 1D and 2D NMR and MS spectroscopic analysis. The absolute configurations of irlactin K and the known compound conocenol B (20) were established by single-crystal X-ray diffraction analysis. The vasorelaxant effects of irlactin K (1), irpexolactins A (2), C (4), K (12), and irlactam (22) were evaluated.