THE CHEMISTRY OF THE DEMOSPONGE DYSIDEA-FRAGILIS FROM THE LAGOON-OF-VENICE

In a study of the filtering organisms of the lagoon of Venice a series of specimens of the cosmopolitan keratose sponge Dysidea fragilis has been examined. This study led to the isolation of two new sesquiterpe nes, 4 and 5, in addition to three known sesquiterpenoids (1-3) isolat ed previously from different sources. The remarkable differences exist ing. between the secondary metabolites of Venice sponges and those rep orted in the literature, for specimens from other geographic localitie s, still remain unexplained. They may be related either to real specif ic differences or less probably to a geographic influence on the metab olites production.