A new sterol from the Formosan soft coral Lobophytum durum

Chromatographic investigation on the ethyl acetate extract of the soft coral Lobophytum durum collected from the waters of Guishan Island in northeast Taiwan resulted in the isolation of three sterols 1–3, including one new sterol, 3β-hydroxy-25-methylene-5-cholesten-7-one (1), and two previously reported sterols, 7-oxogorgosterol (2), and (24R)-ergostane-3β,5α,6β,25-tetraol 25-monoacetate (3). The structures of sterols 1–3 were determined by extensive spectroscopic data analysis and by comparison with literatures. Additionally, the 24R-configuration of sterol 3 was identified by a single-crystal X-ray diffraction analysis and ¹³C chemical shifts for first time. The anti-inflammatory activities of sterols 1–3 were evaluated by examining their inhibitory effects on the generation of superoxide anions and the release of elastase against activated human neutrophils.