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‐[ 3 H]‐farnesol as an internal standard: 2‐[ 14 C]‐, 7‐[ 14 C]‐, 7′, 8‐[ 14 C]‐, 7′, 8‐[ 3 H]‐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‐[ 14 C]‐leucine, U‐[ 14 C]‐isoleucine and 1‐[ 14 C]‐glucose into cantharidin (1) via their metabolites is evident by degradation studies, whereas 1‐[ 14 C]‐ and 2‐[ 14 C]‐glycine do not serve as precursors for cantharidin (1) .