Bioactive substances isolated from marine sponge, a miniature conglomerate of various organisms

Due to their unusual living environment as compared with terrestrial organisms, marine organisms, such as sponge, octocoral, tunicate and bryozoan, metabolite and produce a variety of substances which often have various unprecedented chemical structures and exhibit significant biological activities. These bioactive constituents may offer interesting subjects of studies in view of bioorganic chemistry. In search of new pharmaceutically valuable substances from marine organisms, we have been engaged recently in chemical studies on the constituents of octocorals and marine sponges mostly inhabiting the Okinawan coral reefs.') We have found various types of marine natural products, among which some possess rather uncommon moieties in their structures, such as a hydroperoxy group [found in octocorals, e.g. nephtheoxydiol (1)2), clavukerin C (2)3)] or a cyclic peroxide moiety (found in marine sponge, vide infra). other findings of interest are that some soft corals metabolite several sesquiterpenes having carbon frameworks antipodal to those isolated from terrestrial plants [e.g. valerenenol (3)4), ent-oplopanone (4)2)] and that the Okinawan stolonifer Clavu lar ia vir idis produces ent-prostanoid compounds [e.g. claviridenone A ( 5 ) 5 ) ] . that a soft coral of Xen ia sp. contains a pair of diastereomeric diterpenes [e.g. xeniolone The