Topic
Theobromine
About: Theobromine is a research topic. Over the lifetime, 1137 publications have been published within this topic receiving 29723 citations. The topic is also known as: 3,7-Dimethylxanthine & Theobromin.
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TL;DR: Analysis for theophylline in plasma and saliva samples obtained from patients showed a saliva-plasma ratio of approximately 0.5, which is sufficiently sensitive to detect 1 μg theophyLLine/ml plasma or saliva.
68 citations
TL;DR: This review focuses on the enzymes and genes involved in the methylation of purine ring of caffeine biosynthetic pathway, which contains three S-adenosyl-L-methionine (SAM) dependent methylation steps, and N-methyltransferases play important roles.
Abstract: Caffeine (1,3,7-trimethylxanthine) is a purine alkaloid present in high concentrations in tea and coffee and it is also found in a number of beverages such as coca cola. It is necessary to elucidate the caffeine biosynthetic pathway and to clone the genes related to the production of caffeine not only to determine the metabolism of the purine alkaloid but also to control the content of caffeine in tea and coffee. The available data support the operation of a xanthosine-->7-methylxanthosine-->7-methylxanthine-->theobromine-->caffeine pathway as the major route to caffeine. Since the caffeine biosynthetic pathway contains three S-adenosyl-L-methionine (SAM) dependent methylation steps, N-methyltransferases play important roles. This review focuses on the enzymes and genes involved in the methylation of purine ring. Caffeine synthase, the SAM-dependent methyltransferase involved in the last two steps of caffeine biosynthesis, was originally purified from young tea leaves (Camellia sinensis). The isolated cDNA, termed TCS1, consists of 1,483 base pairs and encodes a protein of 369 amino acids. Subsequently, the homologous genes that encode caffeine biosynthetic enzymes from coffee (Coffea arabica) were isolated. The recombinant proteins are classified into the three types on the basis of their substrate specificity i.e. 7-methylxanthosine synthase, theobromine synthase and caffeine synthase. The predicted amino acid sequences of caffeine biosynthetic enzymes derived from C. arabica exhibit more than 80% homology with those of the clones and but show only 40% homology with TCS1 derived from C. sinensis. In addition, they share 40% homology with the amino acid sequences of salicylic carboxyl methyltransferase, benzoic acid carboxyl methyltransferase and jasmonic acid carboxyl methyltransferase which belong to a family of motif B' methyltransferases which are novel plant methyltransferases with motif B' instead of motif B as the conserved region.
68 citations
TL;DR: The xanthine content of seven Ilex spp. was studied by HPLC using UV and a photodiode-array detector as discussed by the authors, and the results showed that I. paraguariensis has the highest amounts of caffeine and theobromine.
Abstract: The xanthine (caffeine, theobromine and theophylline) content of decoctions of seven Ilex spp. was studied by HPLC using UV and a photodiode-array detector. Ilex paraguariensis (‘Mate’ or ‘Yerba Mate’) is widely used in South America as a tealike beverage and the other six species are used as substitutes or adulterants of it. The results showed that I. paraguariensis has the highest amounts of caffeine and theobromine. Traces of caffeine were detected in I. theezans, I. dumosa, I. microdonta and I. pseudobuxus. Traces of theobromine were detected in I. argentina and I. microdonta. From the seven Ilex species investigated, theophylline was detected in I. theezans, I. dumosa and I. pseudobuxus, but only I. pseudobuxus has quantifiable amounts: 0.6 mg% (6 ppm). © 1998 John Wiley & Sons, Ltd.
68 citations
TL;DR: Observations suggest that hydrophobic substances, in general, can alter dye fluorescence in a dye-specific manner and can seriously distort fluorescence measurements of intracellular ion concentrations with metal indicator dyes.
67 citations
TL;DR: The effects of both coffee components and coffee extract on the electrical responses of GABA(A) receptors expressed in Xenopus oocytes were studied by injecting cRNAs of the alpha(1) and beta(1%) subunits of the bovine receptors.
Abstract: To study the effects of tea components on ionotropic gamma-aminobutyric acid (GABA) receptor response, ionotropic GABA receptors (GABA(A) receptors) were expressed in Xenopus oocytes by injecting cRNAs synthesized from cloned cDNAs of the alpha(1) and beta(1) subunits of the bovine receptors, and their electrical responses were measured by a voltage clamping method. Extracts of green tea, black tea, and oolong tea in an aqueous solution induced the GABA-elicited response, which showed that these teas contain GABA, whereas coffee does not. Caffeine weakly inhibited the response in a competitive manner (K(i) = 15 mM), and (+)-catechin inhibited it in a noncompetitive one (K(i) = 1.7 mM). Especially, two catechin derivatives, (-)-epicatechin gallate and (-)-epigallocatechin gallate, inhibited the response strongly. Alcohols such as leaf alcohol or linalool potentiated the response, possibly because their binding to the potentiation site enhances the GABA-binding affinity to GABA(A) receptors when they bind. Extracts of green tea made with ethyl ether, which must contain lipophilic components of green tea, inhibited the response elicited by GABA, possibly because the amounts of caffeine and catechin derivatives were much larger than fragrant alcohols in such extracts of tea.
67 citations