J. Nat. Prod., 2018, 81 (7), pp 1645–1650
Swinhoeisterols C–F (1–4), four new steroids having a rearranged 6/6/5/7 ring system, were isolated from the Xisha sponge Theonella swinhoei, together with the known analogue swinhoeisterol A (5). Their structures were determined based on spectroscopic analysis, TDDFT-ECD and optical rotation calculations, and biogenetic correlations. In an in vitro assay, compound 1 showed an inhibitory effect on (h)p300 with an IC50 value of 8.8 μM, whereas compounds 2–4were not active.