| Summary: | Precursor incorporation experiments with several widespread species of Northeastern
Pacific Ocean dorid nudibranchs have led to the conclusion that each species studied is capable
of de novo biosynthesis. Incorporation studies with [1,2- 1 3C2] acetate, [l,2-13C2,18Oi] acetate, and
[2-13C] mevalonate were used to demonstrate the biosynthesis of the sesquiterpenoid albicanyl
acetate (18), and the sesterterpenoids cadlinaldehyde (19) and luteone (20) by Cadlina
luteomarginata. Quantitative analysis of C NMR data showed that only a small turnover of
metabolite took place but that the newly formed molecules had extremely high levels of label
incorporation. As a by-product of the examination of biosynthesized metabolites of C.
luteomarginata, a novel diterpenoid metabolite, seco-spongian 22, was isolated and identified. [Chemical models not reproduced] A study of Californian specimens of C. luteomarginata indicated that the three
biosynthesized metabolites are present across its geographic range. Examination of individual C.
luteomarginata specimens from one B.C. population revealed significant variation in metabolite
concentration between individuals and between tissues of each individual.
Incorporation experiments with [1,2- 1 3C2] acetate were also used to demonstrate the de
novo biosynthesis of acanthodoral (28) by Acanthodoris hudsoni, a metabolite previously known
only from the related nudibranch A. nanaimoensis. Attempts to incorporate 180 labels into the
aldehyde oxygen atoms of nanaimoal (24), isoacanthodoral (27), and 28 in these two species
revealed that the aldehyde oxygens are not retained in the biosynthesis. [Chemical models not reproduced] De novo biosynthesis of the 3-hydroxybutyrate side chain of diaulusterol A (34) in
Diaulula sandiegensis was proven by incorporation of [1,2- C2]acetate. None of [1,2-
13C2] acetate, [2-14C] mevalonate, and [4-14C]cholesterol was successfully incorporated in the
steroid portion of 34. Synthesis of [2,l'-13C2]disodium 2-ethylmalonate and [2,3-13C2] sodium
butyrate followed by injection into the nudibranch Triopha catalinae demonstrated that T.
catalinae utilizes butyrate in the processive polyketide biosynthesis of triophamine (43). This
represented the first proven use of butyrate in polyketide biosynthesis by a marine invertebrate. [Chemical model not reproduced]
Investigation of the extracts of the North Sea flatworm Prostheceraeus vUlatus and its
prey, the ascidian Clavelina lepadiformis, revealed the presence of one known and four novel
secondary metabolites: the decahydroquinoline alkaloid lepadins A, B, and C and pyrrolidine
alkaloid villatamines A and B.P. villatus concentrates the alkaloids from its diet, analogous to
the relationship between many shell-less molluscs and their algal or sponge dietary organisms. === Science, Faculty of === Chemistry, Department of === Graduate
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