Structural and Biogenic Analysis of Bioactive Marine Natural Products

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I divided the theme into five next items and studied it.1. From the red alga genus Laurencia nidifica, two new halogenated sesqiterpenes, chamigrane derivatives were obtained together with ten known compounds and two artifacts. Also, three halogenated monoterpenes, octodene derivatives were isolated from the red alga, Scinecia okamurae. The structures of these compounds were elucidated by NMR and mass spectroscopy, and plausible reaction pathways were proposed.2. Nine novel oxylipin metabolites together with several known ones were isolated from the brown alga, Eisenia bicyclis. Though bioactive investigation against B. subtilis and S. aureus, was done, unfortunately these compounds have poorer inhibition against their bacteria than a standard sample of vancomycin.3. Two new cyclic depsipeptides (kulokekahilide-1, -2) which showed cytotoxity against P388 murine lymphocytic leukemia cells with IC_<50> values of 2.1 μg/mL and 3.5 ng/mL were isolated from a marine mollusk Pilinopsis speciosa in Hawaii. The absolute stereochemistry of amino acids and hydroxy acids composed with depsipeptides were determined by Marfey analysis and chiral HPLC analysis. In order to examine the relationship between activity and structure, the total synthesis of kulokekahilide-2 was attempted.4. The analysis of components contained in deep-sea organisms, Calytogena soyoae, Ifremeria nautilei, and Rimicaris kairei was studied. No novel compounds were obtained but many known compounds were isolated from their materials. It was clear that fatty acids composition in deep-sea organisms was different from that in shallow-sea organisms.5. Data-mining method applied for the active compounds against E.coli, B.subtilis, and S.aureus. Thus, it was found that the classification rules of the activity were extracted from flavonoid and terpene derivatives