Studies On Two Red Algae Of The Genus Laurencia:Chemistry And Bioactivities

Marine bioactive substances have great potential for application.The genus Laurencia have high research value because they are rich in marine active substances with novel structure and unique biological activity.In order to provide basic data for the search of drugs from the ocean and enrich the research of marine bioactive substances.During the course of our search for bioactive secondary metabolites,two species of the genus Laurencia,including L.okamurai and L.intermedia Yamada collected from the Nanji Island,Zhejiang Province,China,have chemically been investigated.The two Fresh algae were shaded and dried and extracted with 95% ethanol and acetone,respectively.The extracts were separated and purified by repeated column chromatography and semi-preparative high performance liquid chromatography.The structures of the monomer compounds were identified by one-dimensional and two-dimensional spectroscopy.As results,a total of twenty two compounds were isolated and identified from the two species of Laurencia.Twelve compounds,including nine sesquiterpenoids,one diterpen-oid,one pa-lmitoleic acid and one isobutyl phthalate,were isolated and identified from th e L.okamurai.The structures of these twelve compounds were identified as La u-rinterol(1-1),Laurokomurenene A(1-2),laurinterol acetate(1-3),Debromol au-rinterol(1-4),Debromoaplysin(1-5),Aplysin(1-6),Aplysinol(1-7),(E)-3,7,11,15-Tetramethyl-hexadec-2-en-l-ol(1-8),Cuparene-type ether(1-9),NanJi A(1-10),9-hexadecenoic acid(1-11)and Diisobutyl phthalate(DIBP)(1-12).Ten co-mpounds were isolated from the acetone extract of L.intermedia Yamada.The st-ructures of these ten compounds were identified as Dibromopherol(2-1),(6S)-2,10-dibromo-3-chloro-7,9-chamigradiene(2-2),(6R)-2,10-dibromo-3-chloro-7,9-ch-amigradiene(2-3),2,10-dibromo-3-chloro-7-chamigradiene(2-4),Pacifenol(2-5),Dimer of laurinterol(2-6),Laurinterol(2-7),Debromoisolaurinterol(2-8),9-he-xadecenoic acid(2-9),(2E)-2-tridecyl-2-heptadecenal(2-10).The known biological activities of the isolated compounds were summarized by consulting the literature.Antifungal(Saprolegnia)and antibacterial(V.parahe molyticus,V.alginolyticus,A.sobria,A.hydrophila)activities of some monomer c-ompounds were screened.The selected compounds include Laurinterol(1-1),De bromolaurinterol(1-4),Debromoaplysin(1-5),Aplysin(1-6),Dibromopherol(2-1),(6S)-2,10-dibromo-3-chloro-7,9-chamigradiene(2-2),2,10-dibromo-3-chloro-7-cham igradiene(2-4),Pacifenol(2-5),Dimer of laurinterol(2-6),Debromoisolaurinte rol(2-8)from L.okamurai and L.intermedia Yamada.The results showed that only compounds 1-6 had significant antimicrobial activity against V.parahemolytic us and V.alginolyticus,and the other compounds had no obvious antimicrobial ac-tivity.The preliminary biological screening in this paper provides a valuable lead structure for the research and development of innovative drugs for the seconda-ry metabolites of algae of genus Laurencia,and provides more possibilities fo r the search for drugs in the ocean.