Ximaoornatins A-C, Polyoxygenated Diterpenoids from the Hainan Soft Coral Sinularia ornata .

Three complex polyoxygenated diterpenoids possessing uncommon tetradecahydro-2,13:6,9-diepoxybenzo[10]annulene scaffold, namely ximaoornatins A-C ( 1 - 3 ), one new eunicellin-type diterpene, litophynin K ( 4 ), and a related known compound, litophynol B ( 5 ) were isolated from the South China Sea soft coral Sinularia ornata . The structures and absolute configurations of 1 - 4 were established by extensive spectroscopic analysis, X-ray diffraction analysis, and/or modified Mosher's method. A plausible biosynthetic relationship of 1 and its potential precursor 4 was proposed. In a bioassay, none of the isolated compounds showed obvious anti-inflammatory activity on LPS-induced TNF-α release in RAW264.7 macrophages and PTP1B inhibitory effects.