Purpurolide A, 5/5/5 Spirocyclic Sesquiterpene Lactone in Nature from the Endophytic Fungus Penicillium purpurogenum

Purpurolide A (1), an unprecedent sesquiterpene lactone with a rarely encountered 5/5/5 spirocyclic skeleton, along with two new 6/4/5/5 tetracyclic sesquiterpene lactones (2 and 3), were isolated from the cultures of the endophytic fungus Penicillium purpurogenum IMM003. The structures and absolute configurations of 1–3 were established by spectroscopic analysis, single-crystal X-ray diffraction, and calculations of the 13C NMR and ECD data. Compounds 1–3 showed significant inhibitory activity against pancreatic lipase.