A New Cembranoid Diterpene and Other Related Metabolites from the South-China-Sea Soft Coral Lobophytum crassum

A new hydroperoxy-substituted cembranoid diterpene, 2-hydroperoxysarcophine (=(1aR*,4E,11-E,14aR*)-2,3,6,7,10a,13,14,14a-octahydro-10a-hydroperoxy-1a,5,8,12-tetramethyloxireno[9,10]cyclotetradeca[1,2-b]furan-9(1aH)-one; 1), was isolated from the marine soft coral Lobophytum crassum. Also isolated were two other cembranoid diterpenes, obtained for the first time from a natural source, i.e., 7b,8b-epoxy-4a-hydroxycembra-1(15),2,11-trien-16,2-olide (2) and 7b,8b-epoxy-4b-hydroxycembra-1(15),2,11-trien-16,2-olide (3), along with three further cembranoid derivatives, five sterols, and two open-chain metabolites. Their structures and relative configurations were elucidated on the basis of extensive spectroscopic analyses including 1D- and 2D-NMR, and HR-ESI-MS experiments.