Einbauversuche mit Geraniol und Farnesol in Cantharidin. 4. Mitteilung zur Biosynthese des Cantharidins

On the incorporation of geraniol and farnesol into cantharidin Earlier investigations [1] have shown that cantharidin (1) is biosynthesized by the male Lytta vesicatoria L. (Meloidae, Coleoptera) from the common terpenoid precursors mevalonate and farnesol (3). To prove if geraniol (2) is incorporated via farnesol (3) into cantharidin (1) the following geraniols have been synthesized and injected into either larvae or male adult Lytta vesicatoria, partly in a mixture with synthetic 11′, 12‐[3H]‐farnesol as an internal standard: 2‐[14C]‐, 7‐[14C]‐, 7′, 8‐[14C]‐, 7′, 8‐[3H]‐geraniol. Unexpectedly, geraniol (2) was not specifically incorporated into cantharidin (1) perhaps due to its higher toxicity or its faster degradation relative to the other precursors before incorporation. The incorporation of U‐[14C]‐leucine, U‐[14C]‐isoleucine and 1‐[14C]‐glucose into cantharidin (1) via their metabolites is evident by degradation studies, whereas 1‐[14C]‐ and 2‐[14C]‐glycine do not serve as precursors for cantharidin (1).