THE METABOLISM OF TROPINONE IN INTACT DATURA-INNOXIA PLANTS

[methyl-14C]Tropinone was synthesized by reaction of nortropinone with [14C]methyl iodide. This labelled ketone was administered to intact Datura innoxia plants (3-4-month-old) by addition to the nutrient solution in which the roots were growing. The resultant alkaloids isolated from the plants after two days were radioactive with high specific incorporations: hyoscyamine (2.5 %), scopolamine (7.3 %). Degradations of these alkaloids indicated that essentially all of the activity was present in their basic moieties and located on their N-methyl groups. These results are, thus, consistent with the hypothesis that tropinone is an intermediate in the biosynthesis of tropine from ornithine. The higher level of activity in the scopolamine indicates that the hyoscyamine is rapidly oxidized to this alkaloid. © 1990.