Skin extracts from a number of British Columbia nudibranchs have proven to be a rich source of novel metabolites. This thesis describes the structural investigation of several of these compounds and includes some preliminary studies of their biosynthetic origin and physiological role. The unique diacylguanidine triophamine (75) has been isolated from Triopha catalinae and Polycera tricolor. Its structure was deduced by classical chemical methods and confirmed by an unambiguous synthesis.

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... ris nobilis provided the odoriferous degraded sesquiterpene dihydroapof arnesal (15). The structure of aldehyde jL5 was assigned by interpretation of spectral data. Extracts of Archidoris mohtereyensis contain the diterpenoic acid glyceride 17, its two monoacetates 18 and 19, the drimane sesquiterpenoic acid glyceride 20 and its monoacetate 21, the monocyclof arnesic acid glyceride 22 and the glyceryl ether 23. These compounds were established by a combination of spectral analysis, chemical interconversion and/or single crystal X-ray diffraction analysis. The structure of a free diterpenoic acid found in only one collection of A. montereyensis, was also tentatively identified. The isomeric farnesic acid glyceride 27 in addition to glycerides 17, 18, 20, 22 and ether 23 have also been isolated from Archidoris odhneri. The drimenoic acid glyceride 20 and the glyceryl ether 23 exhibit antifeedant activity against fish. Biosynthetic studies showed that ¹⁴C labeled mevalonic acid is incorporated into the terpenoid portion of glycerides 17 and 20 by A. montereyensis and into the farnesic acid portion of glyceride 24 by Archidoris odhneri. Preliminary results suggest that triophamine (75) is synthesized in situ by T. catalinae and the drimane skeleton of albicanyl acetate (36) is biosynthesized by Cadlina luteomarginata.