Three new thiodiketopiperazines (1⁻3), along with two known analogues (4 and 5), were isolated from the fermentation broth of Penicillium crustosum. Their structures were elucidated through extensive spectroscopic analysis and the absolute configurations of new compounds were determined by Mosher ester analysis and calculated ECD spectra. Compound 4 and 5 have the activity to promote the gastrointestinal motility of zebrafish via acting on the cholinergic nervous system.
Keywords: ECD calculation; Isaria cicadae; Mosher analysis; Penicillium crustosum; gastrointestinal motility; thiodiketopiperazines.