Metabolism of the alpha-Pyridone Ring of Ricinine in Ricinus communis L.

Chemically synthesized ricinine-3,5-(14)C was used to study the metabolism of this alkaloid in the plant which produces it, Ricinus communis L. In a time course study, ricinine-3,5-(14)C was administered to a series of castor plants (Ricinus communis L.) and the radioactivity recovered in the ricinine samples showed a decrease with increase in time. It was also observed that the alkaloid was translocated to the seed. The in vivo conversion of ricinine-3,5-(14)C to respiratory (14)CO(2) occurred in both light and dark and indicated that the alpha-pyridone ring of ricinine could be degraded.In a comparison of the ricinine content of the various tissues it was observed that in the yellow leaf only a trace amount of the alkaloid was present. Preliminary results indicated that the yellow leaf can also metabolize ricinine-3,5-(14)C to (14)CO(2).