INVESTIGATIONS OF TERPENOID BIOSYNTHESIS BY THE DORID NUDIBRANCH CADLINA-LUTEOMARGINATA

Stable isotope incorporation studies with [1,2-C-13(2)]acetate, [1,2-C -13(2),O-18(1)]acetate, [1,2-C-13],mevalonolactone, and [2-C-13]mevalo nolactone have been used to investigate the biosynthesis of the terpen oids albicanyl acetate (1), cadlinaldehyde (2), and luteone (3) by the dorid nudibranch Cadlina luteomarginata. The results have shown that all three terpenoids are synthesized de novo by C, luteomarginata and the incorporation patterns are consistent with the biogenetic proposal that the new cadlinalane and luteane carbon skeletons are formed by d egradation of a sesterterpenoid precursor. This represents the first d emonstration of sesterterpenoid biosynthesis by a marine mollusc. Quan titative analysis has shown that only a small turnover of metabolites takes place during the feeding experiments but that the newly formed m olecules have extremely high levels of incorporation of labeled precur sors.