Sclerotiorin-Type Azaphilones Isolated from a Marine-Derived Fungus Microsphaeropsis arundinis P1B.

Abstract

Seven pairs of new epimers, microsphazaphilones A-G (1, 3, 5, 7, 9, 11, and 13) and epimicrosphazaphilones A-G (2, 4, 6, 8, 10, 12, and 14), were isolated and identified from the fermentation of a marine-derived fungus Microsphaeropsis arundinis P1B. Their structures, including the absolute configurations, were determined by NMR and MS data analysis, comparison of experimental and calculated electronic circular dichroism (ECD) curves, and dimolybdenum tetraacetate induced ECD. Microsphazaphilones A-G and epimicrosphazaphilones A-G represent the sclerotiorin-type azaphilones with a rare γ-lactone or a tetrahydrofuran fragment at the end of the branched C₇ side chain at the C-3 position of the pyranoquinone core skeleton. Among them, compound 2 demonstrated the strongest anti-inflammatory activity that inhibited the expression of multiple inflammatory factors in LPS-induced Raw264.7 cells, possibly through the inhibition of the Erk1/2 MAPK signaling pathway.