Role of Betaine in Transmethylation Reactions in the Barley Plant Origin of the Methylenedioxy Groups of the Alkaloid Protopine

Abstract

The role of the labile methyl groups of betaine in the transmethylation reactions in the barley plants was investigated using carbon-14 methyl labelled betaine. The N-methyl groups of N-methyl tyramine, hordenine and choline were found to arise from betaine. Betaine was also administered to castor bean seedlings and the alka­loid ricinine isolated. It was found that its N- and 0-mthyl groups did not arise from betaine methyl. The origin of the methylenedioxy and N-methyl groups of the alkaloid protopine was also investigated by the tracer technique. Carbon-14 methyl labelled L-methionine, carbon-14 labelled choline and carbon-14 labelled sodium formate were fed to Dicentra species and the extent and position of labelling of the protopine molecule determined by degradation