Caffeine has been found in tissues of several plants. Because of its stimulating effect on the central nervous system, a great number of reports have been published on its content in beverages and foodstuffs. However, a much more restricted number of reports have dealt specifically with caffeine metabolism in plants. This review presents, in chronological manner, the contribution of these reports to the vast knowledge accumulated on caffeine catabolism in plants and microorganisms over the last 40 years. In plants, the accumulated data indicate the operation of a main catabolic pathway: caffeine --> theophylline --> 3-methylxantine --> xanthine --> uric acid --> allantoin --> allantoic acid --> glyoxylic acid + urea --> NH3 + CO2. Some studies have shown that, depending on the plant species, other minor routes may operate with the formation of theobromine and 7-methylxantine, which are salvaged for caffeine formation since they also appear in the biosynthetic pathway. A specific group of coffee known as liberio-excelsioides has the ability to convert caffeine to the corresponding methyluric acid, which is methylated to other uric acid derivatives. In bacteria caffeine is either degraded to theobromine or paraxanthine. Both dimethylxanthines are demethylated to 7-methylxantine which in turn is demethylated to xanthine and then enters the catabolic pathway of purines. In bacteria, theobromine, paraxanthine and 7-methylxantine may also be oxidized to their corresponding methyluric acids.

Catabolism of caffeine in plants and microorganisms.

Analytical Raman spectroscopic study of cacao seeds and their chemical extracts

Purine alkaloid distribution with Herrania and Theorbroma

Tocopherol, fatty acids and sterol distributions in wild Ecuadorian Theobroma subincanum (Sterculiaceae) seeds

A reverse-phase liquid chromatography analysis is used to access the quantity of theobromine, (+)-catechin, caffeine, and (-)-epicatechin in Standard Reference Material 2384 Baking Chocolate, cocoa, cocoa beans, and cocoa butter using water or a portion of the mobile phase as the extract. The procedure requires minimal sample preparation. Theobromine, (+)-catechin, caffeine, and (-)-epicatechin are detected by UV absorption at 273 nm after separation using a 0.3% acetic acid-methanol gradient (volume fractions) and quantified using external standards. The limit of detection for theobromine, (+)-catechin, caffeine, and (-)-epicatechin averages 0.08, 0.06, 0.06, and 0.06 microg/mL, respectively. The method when applied to Standard Reference Material 2384 Baking Chocolate; baking chocolate reference material yields results that compare to two different, separate procedures. Theobromine ranges from 26000 mg/kg in cocoa to 140 mg/kg in cocoa butter; (+)-catechin from 1800 mg/kg in cocoa to below detection limits of < 32 mg/kg in cocoa butter; caffeine from 2400 mg/kg in cocoa to 400 mg/kg in cocoa butter, and (-)-epicatechin from 3200 mg/kg in cocoa to BDL, < 27 mg/kg, in cocoa butter. The mean recoveries from cocoa are 102.4 +/- 0.6% for theobromine, 100.0 +/- 0.6 for (+)-catechin, 96.2 +/- 2.1 for caffeine, and 106.2 +/- 1.7 for (-)-epicatechin.

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Simultaneous Determination of Theobromine, (+)-Catechin, Caffeine, and (−)-Epicatechin in Standard Reference Material Baking Chocolate 2384, Cocoa, Cocoa Beans, and Cocoa Butter

The content of purine alkaloids in seeds of fourTheobroma species from the Amazon basin was analized by a reversed phase high-performance liquid chromatographic method.Theobroma grandiflorum was found to contain 0.38% of 1,3,7,9-tetramethyluric acidT. subincanum 0.07% 1,3,7,9-tetramethyluric acid,T. speciosum 0.01% theobromine and 0.04% 1,3,7,9-tetramethyluric acid and finallyT. mariae 2.35% theobromine and 0.12% caffeine. Theophylline could not be detected in any of these species. The results were confirmed qualitatively by thin-layer chromatography.

José G. S. Maia

Papers

Purine alkaloids in seeds of Theobroma species from the Amazon