Chemical Constituents And Bioactivities Of Laurencia Okamurai

The marine red algal species of the genus Laurencia(family Rhodomalaceae,order Ceramiales, class Rhodophyceae, and phylum Rhodophyta) are consisted of 135 species in the world and over 37 of them distributed in China. They mainly spread along tropical, subtropical, and temperate coasts. The genus Laurencia is rich source of secondary metabolites, The secondary metabolites of the genus Laurencia are mainly composed of sesquiterpenes, diterpenes, triterpenes, and C15-acetogenins,which are usually halogenated and possess antibacterial, cytotoxic and antifeedant activities. In recent years, some new secondary metabolites with biological activity and structural elucidation were reported from the marine red algae of genus Laurencia,and these were reviewed in this dissertation. The isolation, structural elucidation,bioactivity assay, and chemotaxonomic significance of the secondary metabolites of L. Okamurai collected from the East China Sea near Nanji Island.Dried and powdered algal material was extracted with organic solvents. Each extract isolated and purified upon repeated silica gel and Sephadex LH-20 column chromatography, by preparative thin layer chromatography(PTLC), and by high performance liquid chromatography(HPLC) to yield pure compounds, while their structures were identified on the basis of spectroscopic data analysis including 1H NMR、13C NMR、EIMS and so on. As results, one new compound and nineteen known compounds were isolated from the Me OH extract of L. okamurai. The new compound were diphenyl ether(1). The structures of these nineteen known compounds were identified as aplysin(2), debromolaurinterol(3), aplysinol(4),debromoisolaurinterol(5), 3β-hydroperoxyaplysin(6), laurinterol acetate(7),Laurokomurenene A(8), debromoaplysinol(9), isoaplysin(10), cuparene-type ether(11), laurinterol(12), isolaurinterol(13), 3a-hydroperoxy-3-epiaplysin(14),cholesterol(15), 9-hexadecenoic acid(16), octadec-3(E)-en-2-one(17),(2E)-2-tridecyl-2-heptadecenal(18), Diisobutyl phthalate(DIBP)(19) andDi-n-octylo-phthalate(DOP)(20).The isolation of new and unusual structures was a new addition to the molecular diversity of the genus Laurencia, and the possibility of new compounds synthesis pathway gave new reference to the biogenetical synthesis. Compounds 6, 7, 8, 14 only isolated from L. okamurai, which for L.okamurai from the chemical identification provides a reference basis.Bioactivity assay including antibacterial against S.agalactiae, V. anguillarum,A.hydrophila, V. Tubiashii, S.iniae, Edwardsiella ictaluri, and HN016 showed that some secondary metabolites for aplysin(2), debromolaurinterol(3), aplysinol(4),debromoisolaurinterol(5), 3β-hydroperoxyaplysin(6) and debromoaplysinol(9) from L. okamurai. The result showed that compound 3 showed significant specific antibacterial activity against S.agalactiae and V. Anguillarum. The rest of the compounds showed no obvious antibacterial activity. The bioactivities provided new evidence for the research of new drug.