Caffeine metabolism in Coffea arabica and other species of coffee

High performance liquid chromatography has been used to measure the quantities of caffeine, theobromine, and theophylline in aqueous extracts of endosperm from immature and mature fruits of Coffea arabica and six other species of Coffea. Caffeine was the alkaloid present in largest amounts and, with one exception, in concentrations that were broadly similar in immature and mature fruit. The highest concentrations of caffeine were found in C. canephora at 35.1 and 24.5 mg g⁻¹, respectively, in immature and mature endosperm. The lowest concentrations were in C. bengalensis, where caffeine was not detected in extracts from mature fruit. [8-³H]Caffeine was metabolised relatively slowly by immature endosperm of C. arabica and C. canephora. In contrast, C. dewevrei, C. eugenioides, C. stenophylla, C. salvatrix and C. bengalensis all appeared to metabolise [8-³H]caffeine much more rapidly, as the percentage recovery of the applied label was much lower and there was more extensive incorporation of radioactivity into theobromine, theophylline, 3-methylxanthine and two unidentified polar metabolites. The endogenous caffeine concentrations and the metabolism data indicate that there may be marked differences in the rate of turnover of caffeine in the various species of Coffea. Potential sources of material for the production of naturally decaffeinated coffee are discussed.