Laurencia chemistry : Structural diversity chemotaxonomy and bioactive properties of halogenated metabolites
Red algae genus Laurencia is known to be prolific producer of halogenated metabolites such as brominated indoles, terpenes and C15 acetogenins. Malaysian waters are rich with many species of Laurencia, but very few are documented and published. In this investigation, we have analyzed the chemical co...
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| Format: | Thesis |
| Language: | English English |
| Published: |
2013
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| Subjects: | |
| Online Access: | https://eprints.ums.edu.my/id/eprint/41888/1/24%20PAGES.pdf https://eprints.ums.edu.my/id/eprint/41888/2/FULLTEXT.pdf https://eprints.ums.edu.my/id/eprint/41888/ |
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| Summary: | Red algae genus Laurencia is known to be prolific producer of halogenated metabolites such as brominated indoles, terpenes and C15 acetogenins. Malaysian waters are rich with many species of Laurencia, but very few are documented and published. In this investigation, we have analyzed the chemical composition of L. similis, L. snackeyi, L. majuscula and L. nangii. A total of 72 secondary metabolites including 17 new compounds were isolated. Laurencia similis contained 1 new and 6 known metabolites that belongs to brominated indoles and non-halogenated aristolan type. Laurencia snackeyi contained 2 new and 15 known metabolites of snyderane, monocyclofarnesol, cuparane, cyclolaurane and chamigrene types. Laurencia majuscula produced 12 new and 14 known metabolites of chamigrene, rhodolaurane and omphalane types. Laurencia nangii contained 2 new and 20 known metabolites of acetogenins, sesquiterpenes, diterpenes and triterpenes chemical types. It also revealed the possible presence of "chemical race" in L. snackeyi with the isolation of chamigrene, cuparane and cyclolaurane type compounds. First record of Laurencia derived omphalane type halogenated secondary metabolites were isolated from populations of L. majuscula. It was also clear that L. majuscula is present in two chemical types; 1) population that produces elatol, laurencenone B and 2-chloro-3-hydroxy-α-chamigren-9-one, 2) population that produces (E)-10,15-dibromo-9-hydroxy-chamigra-1,3(15),7(14)-triene and (Z)-10,15-dibromo-9-hydroxy-chamigra-1,3(15),7(14)-triene. Laurencia nangii consist of two chemical races; 1) race that produces C15 acetylenes and terpenes, 2) race that produces C15 bromoallenes and terpenes. All the isolated compounds were subjected to biological activity evaluations such as antibacterial, cytotoxic and antiinflammatory activities. Potent antibacterial activities were observed in α-chamigrenes and brominated indole. Cytotoxic activities, particularly against Adult T-Cell Leukemia were seen in α-chamigrene, β-chamigrene, rhodolaurane and snyderane type compounds. While, strong anti-inflammatory activity was exhibited by aplysistatin, 5β- hydroxypalisadin B and nangiol. Hence, secondary metabolites from Laurencia have potential to be developed into a lead pharmaceutical metabolites. |
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