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Interconversion of Ricinine and N-Demethylricinine in Senescent and Green Castor Plant Leaves

1969; Elsevier BV; Volume: 244; Issue: 12 Linguagem: Inglês

10.1016/s0021-9258(18)93119-4

1083-351X

Ladislav Skurský, D. Burleson, George R. Waller,

Calcium signaling and nucleotide metabolism

Senescent yellow leaves of Ricinus communis L. rapidly metabolize exogenous ricinine (N-methyl-3-cyano-4-methoxy-2-pyridone) which is present in all R. communis tissues except the one mentioned. Identity of the metabolic product was examined by mass spectrometry, ultraviolet, infrared, and nuclear magnetic resonance spectra; it proved to be N-demethylricinine (3-cyano-4-methoxy-2-pyridone). N-Demethylricinine is not present in green leaves but when supplied as an exogenous source it is rapidly methylated yielding ricinine. Thus, it also appears to be the immediate precursor of the alkaloid in green leaves. These N-methylation and N-demethylation reactions may have a role in ricinine translocation during senescence. This is the first report describing: (a) a specific alkaloid catabolic reaction occurring in the plant that produced it; (b) the fact that the catabolic product formed in yellow leaves can also serve as a precursor in green leaves; and (c) the fact that alkaloid catabolism may be related to the aging process.