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: The observed competitive isotope effects for the metabolites, which do not result from deuterium abstraction (theobromine, theophylline), demonstrate that the nondissociative mechanism applies to caffeine metabolism by cytochrome P4501A2.
Abstract: Caffeine (1,3,7-trimethylxanthine) has previously been shown to undergo metabolic switching in vivo when the N-1 or the N-7 methyl groups were trideuteromethylated [Horning et al. (1976) Proceedings of the Second International Conference on Stable Isotopes, pp 41–54]. We have examined the effect of replacing the N-3 methyl group with a trideuteromethyl group. The corresponding isotope effects can then be used to distinguish the kinetic mechanism by which four primary metabolites can be formed from one substrate by one cytochrome P450 (P450). We have synthesized 3-CD3-caffeine and 3-CD3-7-CD3-caffeine as well as trideuteromethylated analogs of each of the in vitro metabolites formed by cytochrome P4501A2. The observed competitive isotope effects for the metabolites, which do not result from deuterium abstraction (theobromine, theophylline), demonstrate that the nondissociative mechanism applies to caffeine metabolism by cytochrome P4501A2. Thus, there must be equilibration of the kinetically distinguishable activated P450-substrate complexes at rates competitive with hydrogen abstraction. The true isotope effects for the N-3 demethylation of caffeine were derived from the ratios of the amount of paraxanthine relative to the amount of theobromine or theophylline. The resultant ratios indicate that these isotope effects are essentially intrinsic. Observation of the isotope effects on N-3 demethylation was facilitated by branching to the minor in vitro metabolites as well as water formation. Product release is not rate-limiting for this system.
15 citations
TL;DR: Evidence is presented that 3-methylxanthine and 7-methyl Xanthine are metabolites from theophylline and theobromine, occurring in stimulants such as tea and chocolate; 1-methylXanthine probably originates from coffee.
14 citations
TL;DR: Two components of cocoa powder, caffeine and theobromine, were evaluated for their effect on growth of L. monocytogenes strain V7; both compounds allowed some growth of the pathogen; however, longer lag phases occurred in samples with (6 to 9 h) rather than without (<3 h) caffeine.
14 citations
TL;DR: In this article, the thermal behavior of alladium compounds has been studied using TG, DTG and DSC techniques, and enthalpies have been calculated for dehalogenation and dehydration.
14 citations
TL;DR: By means of a simple cluster analysis using “group average” as the clustering algorithm, the samples were divided into eight different groups according to the contents of both purine alkaloids so that appropriate genotypes for breeding ideotypes which meet more precisely the different specific consumer expectations can be picked.
Abstract: Marked differences regarding both caffeine and theobromine contents of mate leaves (Ilex paraguariensis) were found among 230 mass selected candidate trees distributed across 5 plantations in the region of Misiones, Argentina. In the vast majority of the analyzed samples, the caffeine concentrations ranged within the established limits for mate leaves, however theobromine contents (average content 0.96%) generally surpassed literature figures so far published [4,10]. By means of a simple cluster analysis using “group average” as the clustering algorithm, the samples were divided into eight different groups according to the contents of both purine alkaloids. Based upon this division it will be possible to pick appropriate genotypes for breeding ideotypes which meet more precisely the different specific consumer expectations.
14 citations