New bioactive steroids from the soft coral Klyxum flaccidum

Six new steroids, klyflaccisteroids A-E (1-5) and a new 9,11-secogorgosteroid klyflaccisteroid F (6), along with two known steroids 9,11-secosteroid 3 beta, 11-dihydroxy-9,11-secogorgost-5-en-9-one (7) and gorgost-5-ene-3 beta, 9 alpha, 11 alpha-triol (8), and a known eunicellin-based diterpenoid cladiellisin (9), were discovered from the soft coral K. flaccidum. Compound 6 is the first 9,11-secogorgosteroid 11-carboxylic acid isolated from natural sources. Cytotoxicity of these compounds and anti-inflammatory activities of 1-4 and 6-9 were also evaluated. Some compounds were shown to exhibit attractive bioactivities.