(S)-12-hydroxygeranylgeraniol-derived diterpenes from the brown alga Bifurcaria bifurcata

Four novel diterpenes were isolated from the brown alga Bifurcaria bifurcata collected off the Atlantic coast from Morocco, and their structures established by spectral and chemical methods. These compounds are acyclic diterpenes derived from (S)-12-hydroxygeranylgeraniol. One of them is its dehydration product at C-12, while the others are its oxidation derivatives: the methyl ester of the acid at C-1 and two stereoisomers (Z and E) of the aldehyde at C-1. These results are discussed from a chemotaxonomic point of view.