Asperfloketals A and B, the First Two Ergostanes with Rearranged A and D Rings: From the Sponge-Associated 16D-1.

Asperfloketals A () and B (), two 1(10 → 6)--14,15-secosteroids featuring a novel trioxahexaheterocyclic ring system, were isolated from the sponge-associated fungus 16D-1. Their structures were elucidated by extensive spectroscopic analysis and NMR chemical shifts calculations, supported by DP4+ probability analysis, and their absolute configurations were determined by ECD calculations and the modified Mosher's method. Asperfloketals A and B showed strong anti-inflammatory activity in the CuSO-induced transgenic fluorescent zebrafish but displayed no cytotoxicity against HeLa, HepG2, and SW480 cell lines.