ABSTRACT
The methylxanthines of interest are caffeine, theophylline, and theobromine and they occur in coffee, tea, mate, cocoa products, and cola beverages. Purine is the parent heterocyclic compound of the methylxanthines, which are often referred to as the purine alkaloids. Caffeine dissolves well in boiling water, but at room temperature chloroform is one of the best solvents. Theobromine is generally much less soluble than caffeine but it will dissolve readily in aqueous acids and alkalis. Theophylline is intermediate between caffeine and theobromine in its ability to form solutions. Schulthess and Baumann examined caffeine biosynthesis in suspension cultured coffee cells. Several studies have investigated the biosynthesis of caffeine in tea. The conversion of purine nucleosides and nucleotides to caffeine in tea plants was investigated by Negishi et al. While caffeine biosynthesis in coffee and tea has been reasonably well investigated, little information is available about the biosynthetic pathways of methylxanthines in cacao.
