POLYPHENOLS, TERPENES AND STEROLS IN BRAZILIAN DICTYOTALES AND FUCALES (PHAEOPHYTA)

In this work concentrations of polyphenols (phlorotannins), terpenes and sterols of brown algae were estimated in species of Fucales and Dictyotales and were tested as chemical defence against the amphipod Parhyale hawaiensis. While Fucales show high quantities of sterols, the Dictyotales are rich in terpenes. Both orders were found to be very poor in polyphenols, in contrast with general results reported from temperate regions. A dolastane diterpene from Dictyota cervicornis, Dictyol H from Dictyota mertensii and the steroidal fraction from Sargassum furcatum were not active against the amphipod. In fact these metabolites seemed to some extent to stimulate grazing by the herbivore.