Free accessResearch articleFirst published online 2006-4
Hydroperoxysterols from the Brazilian Brown Seaweeds Dictyopteris justii and Spatoglossum schroederi (Dictyotales): A Defensive Strategy against Herbivory
Extracts of the Brazilian brown seaweeds Dictyopteris justii and Spatoglossum schroederi showed the presence of a cytotoxic mixture of 24R- and 24S-epimers of 24-hydroperoxy-24-vinylcholesterol (1). The derivation of 1 from fucosterol is proposed. Laboratory experiments assessed the anti-herbivory properties against the crab, Pachygrapsus transversus, of the crude extract and the epimers of 1 found in D. justii. The crude extract did not inhibit feeding, but the mixture of 1 epimers had a significant inhibitory effect. We propose that these unusual sterol compounds cannot be easily converted to assimilable compounds by this crustacean, thus acting as a defensive strategy for the seaweed against herbivory.
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