Laurencia okamurai

A study of Laurencia tristicha from the South China Sea has discovered the hydroxylated aplysins, 10-hydroxyepiaplysin (406) and 10-hydroxyaplysin (407) (602), and 4-bromo-l,l-epoxylaur-ll-ene (408), which was previously synthesized but not found naturally (603). Laurencia microcladia from the North Aegean Sea has yielded the new 409 and 410, which exhibit significant cytotoxicity against two lung cancer cell lines (604). This red alga also contains the dimeric cyclolaurane 411 (595). An East China Sea collection of Laurencia okamurai has led to the isolation of the novel laureperoxide (412) and 10-bromoisoaplysin (413)... 

Mao S-C, Guo Y-W (2005) Cuparene-Derived Sesquiterpenes from the Chinese Red Alga Laurencia okamurai Yamada. Helv Chim Acta 88 1034... 

Based on the structural diversity of the many congeners originating from Laurencia, the elucidation of a bios5mthetic mechanism for the likely development of these metabolites is of much interest. The isolation and characterization of monoepoxide 30 (Scheme 1) from Laurencia okamurai [15] has allowed investigators to postulate that this compound (30) may be a common precursor for the biosynthesis of all other secondary metabolites derived from squalene [3]. Its absolute stereochemistry was verified via asymmetric synthesis utilizing a Sharpless asymmetric epoxidation [16] of trans, trara-famesol,... 

Squalene occurs in cod-liver oil and in several vegetable oils, for example those from rape and cotton seed. Red algae Laurencia okamurai produce (+)-l,10-epoxy-squalene. Botryococcane is the parent hydrocarbon of some branched and alkylated triterpenoid polyenes found in the algae Botryococcus braunii and referred to as C3o-C37-botryococcenes, depending on the number of their carbon atoms. 

The preceding tetraepoxide is not yet a natural product, but (+)-10(R),ll(R)-epoxysqualene was isolated from Laurencia okamurai (Kigoshi et al., 1986). The presence of this epoxide is surprising to the extent that it is the enantiomer of 10(S)ll(S)-epoxysqualene identified in the Chlorophyceae Caulerpa prolijera (Chapter 12). 

Laurencia okamurai Suzuki M. Kurosawa, 1981 Suzuki etal., 1989... 

Ji, N.-Y, Li, X.-M., Zhang, Y., and Wang, B.-G. (2007a) Two new halogenated chamigrane-type sesquiterpenes and other secondary metabolites from the marine red alga Laurencia okamurai and their chemotaxonomic significance. Biochem. Syst. Ecol., 35, 627-630. 

Kigoshi, H., Ojika, M., Shizuri, Y., Niwa, H., and Yamada, K. (1986) Isolation of (10R,llR)-(+)-squalene-10,ll-epoxide from the red alga Laurencia okamurai and its enantioselective synthesis. Tetrahedron, 42, 3789-3792. 

Mao, S.-C. and Guo, Y.-W. (2005) Cuparene-derived sesquiterpenes from the Chinese red alga Laurencia okamurai Yamada. Hdv. Chim. Ada, 88, 1034-1039. 

Suzuki, M. and Kurosawa, E. (1978) New aromatic sesquiterpenoids from the red alga Laurencia okamurai Yamada. Tetrahedron Lett., 19, 2503-2506,... 

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