New Squalene Triterpenes From the Fungus Irpex laceratus

ABSTRACT Six undescribed squalene triterpenes, named irpelacerins A–F ( 1–6 ), together with three known lanostane triterpenoids ( 7–9 ) were isolated from the solid fermentation of the endophytic fungus Irpex laceratus , which was collected from the medicinal plant Casuarina equisetifolia L. Compounds 1–6 were a group of uncommon chain triterpenoids, which existed in the form of acyclic or monocyclic structures. Their chemical structures were determined by extensive analyses of NMR spectroscopic data, high‐resolution electrospray ionization mass spectrometry, and comparison with literature analogs. Moreover, all these compounds were evaluated for their biological activities, and the results clarified that compounds 3 , 6 , 8 , and 9 showed notable inhibitory activity against LPS‐induced NO production with IC 50 values of 32.5, 48.0, 76.8, and 58.8 µM, respectively.