17,20-Epoxysteroids from octocoral Isis hippuris (Linnaeus, 1758)

Abstract

Three 17,20-epoxysteroids, including a new metabolite, hippuristeroketal B (1), as well as two known compounds, hippuristerones A (2) and I (3), have been isolated from octocoral Isis hippuris collected off the waters of Taiwan. The structure of steroid 1 was deduced by extensive 1D and 2D NMR studies. The absolute stereochemistry of steroids 1–3 was determined by single-crystal X-ray diffraction analysis. Steroid 2 exhibited cytotoxic effect against HT-29 and DLD-1 cancer cells with IC50 values of 11.39 and 12.86 μM, respectively.