Metabolism of Caffeine and Related Purine Alkaloids in Leaves of Tea (Camellia sinensis L.) |
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| Authors: | Ashihara, Hiroshi Gillies, Fiona M. Crozier, Alan |
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| Affiliation: | 1 Department of Biology, Faculty of Science, Ochanomizu University Otsuka, Bunkyo-ku, Tokyo, 112 Japan
2 Bower Building, Division of Biochemistry and Molecular Biology, Institute of Biomedical and Life Sciences, University of Glasgow Glasgow G12 8QQ, U.K. |
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| Abstract: | Purine alkaloid catabolism pathways in young, mature and agedleaves of tea (Camellia sinensis L.) were investigated by incubatingleaf sections with 14C-labelled theobromine, caffeine, theophyllineand xanthine. Incorporation of label into CO2 was determinedand methanol-soluble metabolites were analysed by high-performanceliquid chromatography-radiocounting and thin layer chro-matography.The data obtained demonstrate that theobromine is the immediateprecursor of caffeine, which accumulates in tea leaves becauseits conversion to theophylline is the rate limiting step inthe purine alkaloid catabolism pathway. The main fate of [8-14C]theophyllineincubated with mature and aged leaves, and to a lesser extentyoung leaves, is conversion to 3-methylxanthine and onto xanthinewhich is degraded to 14CO2 via the purine catabolism pathway.However, with young leaves, sizable amounts of [8-14C]-theophyllinewere salvaged for the synthesis of caffeine via a 3-methylxanthine |
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