Revision of the Absolute Configuration at C(23) of Lanostanoids and Isolation of Secondary Metabolites from Formosan Soft Coral Nephthea erecta

Three new oxygenated ergostanoids, 1-3, one known ergostanoid, 4, one new trinoreudesmadienone, 5, one new calamenene type sesquiterpene, 6, and one known aristolane-type sesquiterpene, (-)aristolone (7), have been isolated from the AcOEt extract of the soft coral Nephthea erecta. The structures of these compounds were determined by extensive spectroscopic and X-ray crystallographic analysis, as well as Mosher's method. We revised the absolute configuration at C(23) in the side chain of some lanostanoids as a result of the Mosher's products of 1 (i.e., 1a and 1b). The cytotoxicities against selected cancer cells and the anti-inflammatory effects of these tested metabolites 1-7 were determined hi vitro.