Diterpenes content of the brown alga Dictyota ciliolata (Dictyotales, Phaeophyceae) and recognition of a Brazilian haplotype based on psbA sequences

Abstract

Macroalgae of the genus Dictyota produce large amount of diterpenes, which have many ecological and biological functions. We analysed the crude extracts of three Brazilian populations of the brown alga Dictyota ciliolata by hydrogen nuclear magnetic resonance (1H-NMR) spectroscopy and high-resolution gas chromatography coupled to mass spectrometry (HRGC/MS). All of the HRGC/MS profiles showed that D. ciliolata contained prenylated guaiane (Group I), xeniane, and crenulidane diterpenes (Group III) as major constituents. Eleven diterpenes were detected, dictyol B acetate, dictyol B, dictyol C, dictyoxide, isopachydictyol A, pachydictyol A, 4β-acetoxydictyodial A, and four crenulidane diterpenes. Dictyol B acetate was the major product in all of algal populations in Brazil. The diterpene profiles of the Brazilian populations were compared to other ones obtained in populations from the Atlantic and Pacific Oceans. The genomic DNA of a separate Brazilian population was extracted and amplified for psbA, the sequences of which were used to build a haplotype network with other sequences available in Genbank. Ten psbA haplotypes were found, five in the Indian Ocean, four in the Western Pacific Ocean and three in the Atlantic Ocean. The eastern (Western Pacific Ocean) and the western (Indian Ocean) coasts of Australia were the most diverse areas and they contained most of known haplotypes. One haplotype identified via the molecular network was found to be common in all of the oceans and thus is proposed as the ancestral form. The chemical and molecular data are consistent at the recent proposal in which D. ciliolata was classified as an essentially pantropical species, which may prove to be highly beneficial to bioprospection studies as this species is a source of potential bioactive products.