4α-Acetoxyamijidictyol - A New Antifeeding Dolastane Diterpene from the Brazilian Brown Alga Canistrocarpus cervicornis.

Chemical investigation of the CH2 Cl2 crude extract from the brown alga Canistrocarpus cervicornis (Dictyotaceae) led to isolation of one new (1) and four previously reported dolastane diterpenes (2-5). Their structures were characterized by 1D- and 2D-NMR spectroscopic techniques, including a full single crystal X-ray diffraction analysis for 1, 2, and 4. In addition, the new structure 1 was assayed as chemical defense inhibiting the feeding by the sea urchin Lytechinus variegatus. This study constitutes an additional report broadening the known spectrum of action and defensive roles of secondary metabolites of the C. cervicornis and Dictyotales species.