Biosynthesis of (Z,Z)-6,9-heptacosadiene in the American cockroach

Abstract

The biosynthesis of (Z,Z)-6,9-heptacosadiene, the major cuticular hydrocarbon component of the American cockroach, was examined by radiotracer and¹³C-nuclear magnetic resonance (NMR) techniques. Sodium [1-¹⁴C] acetate was incorporated about equally into the saturated and diunsaturated hydrocarbons, whereas [1-¹⁴C] linoleate preferentially labeled the C₂₇ alkadiene and [9,10-³H] oleate labeled the C₂₇ alkadiene almost exclusively.¹³C-NMR demonstrated that [2-¹³C] acetate labeled carbons 25 and 27 but not carbon 3 of the C₂₇ alkadiene. In addition, ozonolysis of the diene labeled from [1-¹⁴C] acetate followed by radio-gas liquid chromatography showed that carbons 1–6 were not labeled, whereas the fragment containing carbons 10–27 was labeled. The data presented in this paper indicate that linoleate from the diet or synthesized de novo is elongated by the addition of acetate units and is then decarboxylated.