Development of Biochemical Reagents to Study Signal Transduction from Awuatic Organisms

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We have collected marine invertebrates along the coast of Japan and carried out screening for biological activities. Based on the results of the screening we have isolated and characterized the active principles and studied their modes of action, which may lead to the development of biochemical reagents.1. Isolation and structure elucidation of novel bioactive metabolitesFrom the marine sponge Theonella swinhoei collected off Hachijo-jima Island, we have isolated novel serine protease inhibitors, pseudotheonamides, which were related to the known cyclotheonamides with different modes of cyclization. From the sponge Stelletta globostellatta were isolated three novel isomalabaricane triterpenes which induce morphological changes in rat 3Y1 fibroblasts. We also examined the structure-activity relationships among these triterpenes. Seven 3-alkylpyridine alkaloid were isolated from sponges of genera Xestospongia and Amphimedon. Novel calyculin derivatives were isolated from Discodermia calyx. Chemically modified derivatives and novel natural calyculins were examined for their effects against protein phosphatases and some structure-activity relationships were established.2. Studies on the modes of action of bioactive marine natural productsBy using a sponge-derived alkaloid xestospongin C which inhibits the binding of IP3 to its receptor, the involvement of Ca ions in the contraction of guinea-pig papillary muscle.