RESUMEN
The chemical study of the Brazilian brittle star Ophionereis reticulata led to the isolation of three chamigrene sesquiterpenes, including the partially characterized isoobtusadiene (1), its unreported acetyl derivative (2), and the known (+)-elatol (3). The complete elucidation of the structures 1 and 2 was accomplished by 1D and 2D NMR spectroscopy. The first assignment of the absolute configuration of the isoobtusadiene skeleton is suggested as 6S,9R,10S on the basis of the NMR analysis of the Mosher's ester derivatives of 1 and the ECD study of the acetyl derivative 2. Chamigrenes are typical constituents of Laurencia red algae. O. reticulata is a predator with a preference for algae. Thus, the origin of these metabolites can be likely ascribed to diet.
Asunto(s)
Equinodermos/química , Laurencia/química , Sesquiterpenos/aislamiento & purificación , Animales , Brasil , Estructura Molecular , Sesquiterpenos/química , Compuestos de Espiro/química , Compuestos de Espiro/aislamiento & purificaciónRESUMEN
A new Late Cretaceous species of Petalobrissus, Petalobrissus lehugueurae sp. nov., is described from the Jandaíra Formation, Potiguar Basin, state of Rio Grande do Norte. To date, this genus comprises a total of 20 species, only two of which, Petalobrissus setifensis and Petalobrissus cubensis have so far been recorded from the Jandaíra Formation. Petalobrissus lehugeurae sp. nov. is distinguished from its congeners in that gonopores occupy only a small portion of the genital plates, in having a slit-like periproct and a unique abrupt depression of the test that forms a pronounced keel below the periproct. In addition, an identification key to species of Petalobrissus is presented.