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Plant Physiology 73:961-964 (1983)
© 1983 American Society of Plant Biologists

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Articles

Metabolic Relations between Methylxanthines and Methyluric Acids in Coffea L. 1

Joseph B. Petermann and Thomas W. Baumann2

Institut für Pflanzenbiologie, Universität Zürich, CH-8008 Zürich, Switzerland

Metabolism of purine alkaloids in the leaves of Coffea dewevrei De Wild et Durand var excelsa Chev, Coffea liberica Bull ex Hiern and Coffea abeokutae Cramer was studied by analyzing leaf discs collected during vegetative development and by feeding the following radioactive tracers: [14C]theobromine, [14C]caffeine, and [14C]theacrine (1,3,7,9-tetramethyluric acid). Their principal metabolites were quantitatively and qualitatively determined. All three species convert the precursors to the same radioactive products, and proceed through the same four maturity stages characterized by the alkaloid accumulation pattern and by a particular transformation potency: (stage 1) young plant accumulating caffeine, transforms theobromine to caffeine; (stage 2) caffeine is gradually replaced by theacrine, theobromine and caffeine are converted to theacrine; (stage 3) theacrine disappears whereas liberine (O(2), 1,9-thrimethyluric acid) accumulates, theacrine is metabolized to liberine; (stage 4) branched-out plant containing liberine but no theacrine, caffeine is converted rapidly to liberine via theacrine. Methylliberine (O(2),1,7,9-tetramethyluric acid), presumably the direct precursor of liberine, is occasionally found in low concentrations at stage 3 and 4.

The collective term `liberio-excelsoid' introduced by geneticists for the numerous races or species of Pachycoffea is in accordance with the phytochemical equality found in this work.


2 Address reprint requests to this author.

1 Supported by the Swiss National Science Foundation and by Stiftung für wissenschaftliche Forschung an der Universität Zürich







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Copyright © 1983 by the American Society of Plant Biologists