New azaphilone, isocoumarin and α-pyrone derivatives from the marine-derived gut fungus Paraphaeosphaeria sp. XZD2-1

Abstract

Six new compounds including two azaphilones, lunatoic acids D–E (1, 2), three isocoumarins, lunatinins B–D (3-5), and one α-pyrone derivative, lunatinin E (6), as well as four known ones, lunatoic acid A (7), lunatinin (8), penicipyran D (9) and chaetoquadrin F (10) were isolated from the rice medium of the gut fungus Paraphaeosphaeria sp. XZD2-1. Their planar structures were elucidated by analysis of 1D and 2D NMR as well as HRESIMS spectroscopic data. The absolute configurations of compounds 1-3 were assigned by experimental and calculated ECD data and an ester hydrolysis reaction. Compounds 4 and 5 were a pair of enantiomeric excess mixture. Structure of compound 6 was further confirmed by comparing optical rotation with known compounds according to literature. The antimicrobial activity and cytotoxicity of compounds 1-10 were examined.