Two new steroids with cytotoxicity from the marine sponge Dactylospongia elegans collected from the South China Sea

A new steroid, (3S,5R,9R,10S,13R,17R,20R,24S,22E)-ergosta-6,8,22-triene-3,25-diol (1), and its sulfonated analogue (2) together with a known one, 5α,8α-epidioxy-cholest-6-en-3β-ol (3) were isolated from the marine sponge Dactylospongia elegans collected from the South China Sea. The new structures including absolute configurations were established by the HRESIMS and 1D and 2D NMR analysis coupled with the X-ray crystal analysis. Both of 1 and 2 exhibited cytotoxicity against cancer cell line MCF-7 with IC₅₀ values of 9.7 and 8.5 μM, respectively.