[Search for Structurally Unique Bioactive Natural Products].

In our continuing search for structurally and biologically interesting metabolites from marine organisms and plants, we investigated the constituents of Okinawan marine sponges and Hypericum plants, resulting in the isolation of several new and unique natural products. Their structures were elucidated on the basis of spectroscopic analyses and chemical conversions. Novel bromopyrrole alkaloids, nagelamides X-Z, were isolated from a sponge Agelas sp. Heteroaromatic alkaloids, hyrtimomines A and B, were isolated from a sponge Hyrtios sp. together with bisindole alkaloids, hyrtimomines C-E. An oxylipin with a trimeric structure, manzamenone O, was obtained from a sponge Plakortis sp. Dimeric eudesmane sesquiterpenes connected through various linker moieties, halichonadins K-L, were isolated from a sponge Halichondria sp., and isomalabaricane triterpenes, stelliferins J-N, were obtained from a sponge Rhabdastrella sp. The investigation for the extracts of Hypericum plants gave new meroterpenes, acylphloroglucinols, and xanthones. Biyoulactones A-E are meroterpenoids from the roots of Hypericum chinense. Acylphloroglucinols, chipericumines A-D, and highly prenylated xanthones, biyouxanthones A-D, were also isolated from the same origin. Tricyclic meroterpenes, yezo'otogirins A-C, and liner meroterpenos, yojironins A and B, were isolated from Hypericum yezoense and Hypericum yojiroanum, respectively.