| Research Abstract |
(1) A new species, Laurencia omaezakiana Masuda that is distributed in the warm temperate region of the Pacific coast of Japan was established on the basis of morphological and chemical features. It produces a characteristic triterpenoid, enshuol.
(2) Laurencia japonensis Masuda et Abe widely distributed along the coasts of Japan except for Hokkaido and Okinawa was described as a new species on the basis of morphological and chemical features as well as the presence of complete reproductive isolation between related species. Three novel secondary metabolites were reported from this species : anhydroaplysiadiol (diterpenoid) and japonenyne-A and japonenyne-B (C_<15> acetogenin).
(3) Genetic variation in the synthesis of halogenated secondary metabolites and affinity between chemical races in Laurencia nipponica Yamada were investigated in laboratory crossing experiments and chemical analyses.
(4) Three sesquiterpenoids were detected from Laurencia majuscula (Harvey) Lucas growing in Okinaw
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a and Kagoshima for the first time, which indicates that this worldwide distributed species includes 4 chemical races. The occurrence of a novel sesquiterpenoid, 10-bromo-9-hydroxy-chamigra-2,7(14)-diene in the Nago population in Okinawa indicates that diversification in the synthesis of halogenated secondary metabolites still continues within a single race that is distributed in the western Pacific ranging from Queensland (Australia) to Okinoshima, Kochi (Japan).
(5) An unidentified species of Laurencia that was collected from Okinawa and is considered to be a new species produces two novel C_<15> acetogenins, bisezakyne-A and bisezakyne-B.
(6) A novel C_<15>, acetogenin, mariannenyne, was isolated from Laurencia mariannensis Yamada which was collected from Okinawa.
(7) Two novel C_<15> acetogenins, lembyne-A and lembyne-B, were isolated from an unidentified species of Laurencia that was collected from Kedah, Malaysia, and two novel sesquiterpenoids, pannosane and pannosanol, were isolated from Laurencia pannosa Zanardini that was collected from an island close to its type locality, Tanjung Datu, Sarawak (Malaysia). Less
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