POLYPROPIONATES FROM THE MEDITERRANEAN MOLLUSK ELYSIA-TIMIDA

The Mediterranean sacoglossan Elysia timida contains, along with the already known photodeoxytridachione [2] and 9,10-deoxytridachione [3], two new related polypropionates, 15-norphotodeoxytridachione [5] and iso-9,10-deoxytridachione [6]. The presence of all these propionates in the mucous secretion of the mollusc suggests a potential defensive role of these metabolites toward attacks oi predators, which is supported by their ichthyotoxicity in a mosquito fish bioassay.