Isoprenoids of the soft coral Sarcophyton glaucum: Nyalolide, a new biscembranoid, and other terpenoids.

The chemical content of Sarcophyton glaucum, one of the more abundant soft corals on many coral reefs, collected from many seas, was thoroughly explored, resulting in the discovery of a large number of cembranoids, biscembranoids, sterols, and other secondary metabolites. The presently investigated Kenyan specimens of S. glaucum yielded three new metabolites, i.e., nyalolide (15), a biscembranoid, 16-oxosarcoglaucol acetate (16), a cembranoid, and the sesquiterpene guaiacophine (17). Nyalolide was also isolated from the Kenyan soft coral Sarcophyton elegans. The structures of the new compounds were elucidated by interpretation of their MS and 1D and 2D NMR experiments and, in the case of nyalolide, possessing 11 chiral centers, secured by X-ray diffraction analysis.