Coffea arabica, caffeine

Xanthines such as caffeine (1)> theophylline (aminophylline) (2), and theobromine (3) are a class of alkaloids that occur in numerous plants. The CNS stimulant activity of aqueous infusions containing these compounds has been recognized since antiquity. This has, of course, led to widespread consumption of such well-known beverages as coffee (Coffea arabica), tea (Thea sinesis), mate, and cola beverages (in part Cola acuminata). The annual consumption of caffeine in the United States alone has been estimated to be in excess of a billion kilos. The pure compounds have found some use in the clinic as CNS stimulants. In addition, caffeine is widely used in conjunction with aspirin in various headache remedies. 

Roberts, M.F. and Waller, G.R., N-methyltransferases and 7-methyl-N9-nucleo-side hydrolase activity in Coffea arabica and the biosynthesis of caffeine, Phytochemistry, 18,451,1979. 

The two major species of coffee grown commercially are Coffea arabica and Coffe a canephora var. robusta. For ease of reference in the following pages they are described as Arabica and Robusta, respectively. They are mentioned separately because they do show differences in their chemical composition. For example, Robusta contains approximately twice as much caffeine as Arabica. 

The world s coffee supply comes primarily from two major types of coffee beans, Arabica (Coffea arabica) and Robusta (Coffea canephora), which differ in several characteristics as well as caffeine content. Arabica is favored for its finer aroma, flavor, and body, and contains 1% caffeine. Robusta is neutral and contains twice as much caffeine.1 The ratio of... 

As these examples show, different defenses among plant parts and seasonal differences have to be considered together. Coffee Coffea arabica) is a well-investigated example of increased chemical defenses when the plant is most vulnerable to herb ivory. The concentration of the alkaloid caffeine (Fig. 11.18) varies between plant parts and with the growth cycle. In the germinating seed, the... 

In contrast with the seed caffeine of Coffea species, relatively little attention has been paid to that of tea. This is in part because the fruit of tea, including the seeds, is of minor economic importance compared with that of coffee moreover earlier studies revealed little caffeine in the tea seed (13.141. Recently we (H) found that the pericarp contains the greatest concentrations of alkaloids in the dry fruit of tea, and that appreciable amounts occur in the seeds, especially in the coats. Thus, from physiological and ecological viewpoints, our concerns are the roles of purine alkaloids and seed coats of tea during fruit development (seed formation) and seed germination. Caffeine in Coffea arabica seed is synthesized in the pericarp, transported to the seed, and accumulated there during fruit... 

Purine alkaloids Caffeine synthase Camellia sinensis, Coffea arabica... 

Frischknecht, P. M., T. W. Baumann, and H. Wanner. Tissue culture of Coffea arabica-growthand caffeine formation. Planta Med 1977 31 344. 

Waller, G. R. and M. F. Roberts. N-methyltransferases and 7-methyl-N-nucleoside hydrolase activity in vitro of Coffea arabica fruits, and the biosynthesis of caffeine , and the in vivo metabolism of caffeine. Proc lUPAC 11th International Symp Chem Nat Prod 1978 4(2) 55-71. 

Waller, G. R. and C. F. Cumberland. High production of caffeine by sterile tissue cultures of Coffea arabica. Colloq Sci Int Cafe [C.R.] 1980 9 611-618. Koenig, W. A., W. Rahn, and R. Vetter. Identify and quantify emetic active constituents in roast coffee. Colloq Sci Int Cafe [C.R.] 1980 9 145-149. 

Caffeine Caffeine [l,3,7-trimethyl-l//-purine-2,6(3/7,7//)-dione], molecular formula C8H10N4O2, is a xanthine (purine) alkaloid, found mainly in tea leaves Camellia sinensis) and coffee beans (Coffea arabica). Caffeine is sometimes called guaranine when found in guarana (Paullinia cupana), mateine when found in mate (Ilex paraguariensis) and theine when found in tea. Caffeine is found in a number of other plants, where it acts as a natural pesticide. It is odourless white needles or powder. Apart from its presence in the tea and coffee that we drink regularly, caffeine is also an ingredient of a number of soft drinks. 

Coffee beans are the primary source of caffeine. These beans are obtained from a variety of plants but can be broadly grouped into two classes arabica and robusta. Arabica is obtained from the species Coffea arabica and robusta from the species Cojfea canephora. Robusta, as the... 

Caffeine (1.10), found in coffee (Coffea arabica), was introduced to Europe through Constantinople (modem Istanbul) in the 1500s (Figure 1.5). The stimulant effects of coffee were widely acknowledged, but coffee was recognized as a useful diuretic. Caffeine was first synthesized by Emil Fischer in 1882. Two related compounds, theobromine (1.11) and theophylline (1.12), found in cacao seeds (Theobroma cacao) and tea (Camellia sinensi), respectively, are more potent diuretics than caffeine.1 All three compounds are based on the purine ring system (1.13). 

The PA caffeine is produced from xanthosine via three distinct N-methylations (Fig.7.5).87 89 Partially purified enzyme extracts from tea (Camellia senensis) and coffee (Coffea arabica) were shown to exhibit all three activities, suggesting either that the A-methyltransferase steps in caffeine biosynthesis are catalyzed by a single enzyme, or by multiple enzymes with similar properties.90 However, a specific A-methyltransferase purified from coffee was active only toward 7-methylxanthine and theobromine91 An A-methyltransferase catalyzing the methylation of methylxanthines and designated caffeine synthase (CS) was purified from tea.92 CS catalyzes two consecutive methylations involved in the conversion of 7-methylxanthine to caffeine, but is inactive toward xanthosine, indicating that the first methylation proceeds via a different enzyme. Heterologous expression of the CS cDNA showed that the enzyme was active toward 7-methylxanthine, paraxanthine,... 

WALDHAUSER, S. S. M KRETSCHMAR, J. A., BAUMANN, T. W N-methyltransferase activities in caffeine biosynthesis Biochemical characterization and time course during leaf development of Coffea arabica., Phytochemistry., 1997, 44, 853-859. 

Figure 2.17 Biosynthesis of theobromine and caffeine in Coffea arabica. SAM, 5-adenosyl-L-methionine SAH, 5-adenosyl-L-homocysteine.

Caffeine and related purines are uncharged under physiological conditions and, due to their dual hydrophilic and lipophilic character, easily penetrate cell-, tissue- and organ-related barriers. In Coffea arabica, compartmentation of purine alkaloids, e.g. caffeine, depends exclusively on the physical chemistry of their vacuolar complexation with chlorogenic acid (Waldhauser and Baumann, 1996). 

Pathways of caffeine metabolism are described and discussed by Waller and Suzuki (1990). One methyl source is 5-adenosylmethionine synthesized from methionine. In Coffea arabica, caffeine is synthesized in the pericarp and transported to the seeds where it accumulates. 

Waller G.R. and Suzuki T. (1990) Caffeine metabolism by Coffea arabica L. fruit. 13th Int. Colloq. Chem. Coffee (Paipa, 21-25.8.1989) (ASIC, 1990), 351-61. 

The methyixanthines naturally occur in coffee Coffea arabica), cacao Theobroma cacao), and tea Camellia sinensis) (29). The major methyixanthines are caffeine, theophylline, and theobromine, and they differ by the... 

Caffeine, theobromine Coffea arabica Suspension 0.47 g/liter 750... 

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