Theobromine, also known as xantheose, is the principal alkaloid of Theobroma cacao (cacao plant). Theobromine is slightly water-soluble (330 mg/L) with a bitter taste. In industry, theobromine is used as an additive and precursor to some cosmetics. It is found in chocolate, as well as in a number of other foods, including the leaves of the tea plant, and the kola nut. It is a white or colourless solid, but commercial samples can appear yellowish. Structure Theobromine is a flat molecule, a derivative of purine. It is also classified as a dimethyl xanthine. Related compounds include theophylline, caffeine, paraxanthine, and 7-methylxanthine, each of which differ in the number or placement of the methyl groups. History Theobromine was first discovered in 1841 in cacao beans by Russian chemist A. Woskresensky. Synthesis of theobromine from xanthine was first reported in 1882 by Hermann Emil Fischer. Etymology Theobromine is derived from Theobroma, the name of the genus of the cacao tree, with the suffix -ine given to alkaloids and other basic nitrogen-containing compounds. That name in turn is made up of the Greek roots theo ("god") and broma ("food"), meaning "food of the gods". Despite its name, the compound contains no bromine, which is based on Greek bromos ("stench"). Sources Theobromine is the primary alkaloid found in cocoa and chocolate. Cocoa butter only contains trace amounts of theobromine. There are usually higher concentrations in dark than in milk chocolate. There are approximately of theobromine in of milk chocolate, while the same amount of dark chocolate contains about . Cocoa beans naturally contain approximately 1% theobromine. Plant species and components with substantial amounts of theobromine are: Theobroma cacao – seed and seed coat Theobroma bicolor – seed coat Ilex paraguariensis – leaf Camellia sinensis – leaf Theobromine can also be found in trace amounts in the kola nut, the guarana berry, yerba mate (Ilex paraguariensis), Ilex vomitoria, Ilex guayusa, and the tea plant. The mean theobromine concentrations in cocoa and carob products are: Biosynthesis Theobromine is a purine alkaloid derived from xanthosine, a nucleoside. Cleavage of the ribose and N-methylation yields 7-methylxanthosine. 7-Methylxanthosine in turn is the precursor to theobromine, which in turn is the precursor to caffeine. Pharmacology Even without dietary intake, theobromine may occur in the body as it is a product of the human metabolism of caffeine, which is metabolised in the liver into 12% theobromine, 4% theophylline, and 84% paraxanthine.