New Propionate-derived Metabolites From Aglaja-depicta and From Its Prey Bulla-striata (opisthobranch, Mollusks)

Two new polypropionate metabolites aglajne-2 (14) and -3 (2) and the previously known aglajne-1 (1) have been isolated from the opisthobranch mollusc Bulla striata, a prey of the opistobranch Aglaja depicta in which these compounds were first detected. This finding establishes the dietary origin of these metabolites in A. depicta. The structures were determined by extensive use of 'H and 13C NMR techniques on the compounds and on their derivatives and by chemical proofs. Two additional compounds (12 and 13), isolated as racemic diastereoisomers, are artifacts originating from aglajne-2 (14) during the extraction and purification procedures. The relative and absolute stereochemistry at C-3 and C-6 of aglajne-1 (1) and -3 (2) has been also determined