Biosynthesis and cellular localization of functional polyketides in the gastropod mollusc Scaphander lignarius.

Opisthobranchs belong to a subclass of highly evolved and specialised marine gastropods that rely on the use of secondary metabolites for their survival. Here we report the full elucidation of the biosynthesis of aromatic metabolites, lignarenones, in one of these gastropods, the cephalaspidean Scaphander lignarius. Feeding experiments with ²H- and ¹³C-labelled precursors revealed a mixed acetate/propionate polyketide pathway primed by benzoic acid.

First biosynthetic evidence on the phenyl-containing polyketides of the marine mollusc Scaphander lignarius.

The biosynthesis of lignarenones 1 and 2, the major polyketides of the Mediterranean mollusc Scaphander lignarius is described. The process is primed by benzoic acid and requires acetate and propionate as extender units. The labeling pattern suggests PKS-like synthesis of an unusual E,Z,E-triene chain and origin of the benzoate unit from phenylalanine.

Lipase-mediated production of defensive toxins in the marine mollusc Oxynoe olivacea.

Metabolites related to caulerpenyne (1), a toxic sesquiterpene featured by two enol-acetate residues, play a major role in the chemical defence of both algae of the genus Caulerpa and a few molluscs of the order Sacoglossa. Here we report the direct evidence that cell-free preparations of Oxynoe olivacea, a Mediterranean sacoglossan, transform efficiently the algal metabolite 1 to oxytoxin-2 (3), the main defensive metabolite of the mollusc. The process implies two distinct hydrolytic activities, here named LIP-1 and LIP-2, able to operate either hydrolysis of the acetyl residue at C-1 or concerted elimination of the acetyl groups at C-4 and C-13.