Halogenated eudesmane derivatives and other terpenes from the marine red alga Laurencia pinnata and their chemotaxonomic significance

• Four new and five known halogenated terpenes have been obtained from Laurencia pinnata.
• The isolates support the taxonomic position of this alga under the genus Laurencia.
• Eudesmane derivatives may be taken as the chemotaxonomic markers for L. pinnata.

Chemical investigation of the marine red alga Laurencia pinnata collected from Nanji Island of China resulted in the isolation and identification of three new eudesmane (selinane) sesquiterpenes, 1β-bromoselin-11-en-4α-ol (1), 1β-bromo-4α,5α-epoxyselinane (2), and 1β-bromoselin-3,11-diene (3), and one new 6,8-cycloeudesmane sesquiterpene, 1β-bromo-6,8-cycloselin-4(15)-ene (4), together with one known eudesmane sesquiterpene, 1β-bromoselin-4(15),11-diene (5), two known chamigrane sesquiterpenes, 2,10-dibromo-3-chlorochamigr-7-ene (6) and 2,10-dibromo-3-chlorochamigr-7-en-9-ol (7), one kahukuane diterpene, kahukuene B (8), and one parguerane diterpene, 15-bromoparguer-9(11)-en-16-ol (9). These halogenated isolates were found in L. pinnata for the first time, and they support the taxonomic position of this species under the genus Laurencia. Eudesmane derivatives (1–5) are predominant and rarely reported from this genus, and they may be taken as chemotaxonomic markers for L. pinnata in the future.

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