Dolabellane Diterpenes from the Marine Brown Alga Dictyota dolabellana and their Potential Antiviral Activity.

Abstract

Introduction: The brown alga Dictyota dolabellana is a rare species that was described based on morphological and natural product analyses from a population found in 2004 at Itaparica Island in Bahia, Brazil. However, it has not been found anywhere since then.

Methods: The original crude acetonic extract was analyzed by 1H and 13C NMR and showed as the major secondary metabolite, the dolabellane diterpene (1S*, 2E, 4S*, 7S*, 8R*, 11S*, 12R*)-4- hydroxy-7,8-epoxy-2-dolabellene, which is the chemotaxonomic marker of this species. Two additional new diterpenes for this species were obtained: (1S*, 2E, 4S*,7R*, 8E, 11S*, 12R*)-4,7- hydroxy-2,8-dolabelladiene and (1R*, 4S*, 7R*, 8E, 11S*,12R*)-4,7-hydroxy-8-dolabellene. All three structures were assigned by 1D and 2D NMR spectral data.

Results: Biological tests carried out with those three diterpenes revealed that diterpenes 1 and 2 inhibited the replication of herpes simplex virus type 1 (HSV-1) in a dose-dependent manner. Supplementary data showed that diterpene 1 has no inhibitory activity against the reverse transcriptase enzyme of human immunodeficiency virus type 1 (HIV-1 RT).

Discussion: Finally, the antiviral and cytotoxic activities of dolabellanes of Dictyota spp depend on both the functionality of the molecule and the position of the hydroxyl groups and double bonds.

Conclusion: This study may enhance the interest in D. dolabellana for its biotechnological applications, such as antiviral products and assist in its chemotaxonomy.