Caffeine interactions

Pina, R, Caffeine interaction with synthetic flavylium salts. A flash photolysis study for the adduct involving 4,7-dihydroxyflavylium, J. Photochem. Photobiol. A Chem., 117, 51, 1998. 

The determination of theophylline in plasma can also be accomplished by various immunoassay techniques.66-67 Theophylline was also determined by a polarization fluoroimmunoassays but found to have a caffeine interference.88. In a more research oriented application, the interaction of caffeine with L-tryptophan was studied using h NMR with the results indicating that caffeine interacted with tryptophan in a 1 1 molar ratio through parallel stacking.69... 

The known changes in polyphenolic material have already been noted. Fermentation also results in slight loss of extractable caffeine. Decreases of 5 to 7% have been observed.31 Higher-than-normal fermentation times and temperatures accelerate this effect. The fate of caffeine made unavailable during fermentation is not definitely known. It has been demonstrated that caffeine interacts with polyphenols,80-81 so it is likely that the alkaloid becomes complexed with the most insoluble thearubigen fractions that do not become part of the beverage.31... 

Azcona, O., Barbanoj, M. J., Torrent, J., and Jane, F., Evaluation of the effects of alcohol-caffeine interaction on the central nervous system. Journal of Psychopharmacology 6, 136, 1992. 

Jeppesen U, Loft S, Poulsen HE, Brsen K. A fluvoxamine-caffeine interaction study. Pharmacogenetics 1996 6(3) 213-222. 

Azcona O, Barbanoj MJ, Torrent J, Jane F. Evaluation of the centtal effects of alcohol and caffeine interaction. BrJ Clin Pharmacol 995) 40, 393-400. 

Bums, M. and H. Moskowitz (1990). Two experiments on alcohol-caffeine interaction. Alcohol Drugs Driving, 6(1), 303-315. 

Muschol, M. Dasgupta, B. R. Salzberg, B. M. Caffeine interaction with fluorescent calcium indicator dyes. Biophys. J. 1999, 77, 577-586. 

In addition, adenosine is implicated in sleep regulation. During periods of extended wakefulness, extracellular adenosine levels rise as a result of metabolic activity in the brain, and this increase promotes sleepiness. During sleep, adenosine levels fall. Caffeine promotes wakefulness by blocking the interaction of extracellular adenosine with its neuronal receptors. ... 

Several selective interactions by MIP membrane systems have been reported. For example, an L-phenylalanine imprinted membrane prepared by in-situ crosslinking polymerization showed different fluxes for various amino acids [44]. Yoshikawa et al. [51] have prepared molecular imprinted membranes from a membrane material which bears a tetrapeptide residue (DIDE resin (7)), using the dry phase inversion procedure. It was found that a membrane which contains an oligopeptide residue from an L-amino acid and is imprinted with an L-amino acid derivative, recognizes the L-isomer in preference to the corresponding D-isomer, and vice versa. Exceptional difference in sorption selectivity between theophylline and caffeine was observed for poly(acrylonitrile-co-acrylic acid) blend membranes prepared by the wet phase inversion technique [53]. 

Interactions with caffeine and aspirin can increase the effects of ephedrine. Norepinephrine works in part by increasing the levels of cyclic aminomethyl propanol (AMP) in cells. Caffeine inhibits the enzyme that breaks down cyclic AMP. Together, ephedrine makes more cyclic AMP, and caffeine prevents it from breaking down. Aspirin inhibits the receptors that turn off release of norepinephrine. 

As the solvent mixture also contained 225 mg of tetramethyl ammonium hydroxide pentahydrate per liter at a high water content (75%), the surface of the reverse phase would have been largely covered with the tetramethyl ammonium hydroxide pentahydrate. This would have acted as an adsorbed ion exchange stationary phase. It is clear that the free acids, salicylic acid, acetylsalicylic acid (aspirin) and benzoic acid were retained largely by ionic interactions with adsorbed basic ion exchanger and partly by dispersive interactions with the exposed reversed phase. The acetaminophen and the caffeine, on the other hand, being unionized substances, were retained only by dispersive interactions with the exposed reversed phase. 

Nishio, J., Yonetani, I., Iwamoto, E., Tokura, S.,Tagahara, K., and Sugiura, M., Interaction of caffeine with 1-tryptophan study of 1H nuclear magnetic resonance spectroscopy, J. Pharm. Sci., 79,14,1990. 

Tea is second only to water in worldwide consumption. Annual production of about 1.8 million T of dry leaf provides world per capita consumption of 40 L of beverage (Table l).1 The scientific interest in tea is due in part to the unusual chemical composition of its leaf and the complex series of reactions that occur when these components are converted to those found in commercial dry tea. Many of the reaction products interact with caffeine, modifying flavor and contributing to the technical problems of tea processing, as will be shown later. 

The organoleptic properties of black tea depend to a considerable extent on the astringency resulting from the interaction of caffeine with the oxidized galloyl ester of the flavanols. The aroma components of black tea also constitute a unique flavor profile that blends well with the taste of the nonvolatile materials. The caffeine provides a moderate level of stimulation, which adds further to the appeal of the beverage, although tea has been shown to provide relaxation as well as revival of character.119... 

Human functioning the dual-interaction model. (From Smith, B.D., Effects of acute and habitual caffeine ingestion in physiology and behavior Tests of a biobehavioral arousal theory. Special issue Caffeine Research, Pharmacopsychoecologia, 7(2), 151-167, 1994. With permission.)... 

The inconsistent effects of caffeine in cognitively mediated performance tasks may result from differences in age groups, dosage levels, and environmental factors.124-125 The latter have been shown to substantially affect arousal126-127 in both adults128-129 and children.130-131 Office noise is effective in increasing self-reported arousal,132 as are white noise in the laboratory,94 exercise,133 and stress.134 Such environmental factors are sources of arousal and can interact with stimulants like caffeine.135... 

Eysenck hypothesizes that extraversion reflects an underlying continuum of activation or arousal.243 245 Many studies have been conducted to test this assumption, and caffeine is sometimes employed in order to determine how its effects vary as a function of the individual differences in arousability reflected by the Eysenck dimension. Interactions involving EEG,246-247 EDA,248 249 mood,148 and task performance148-247 have been examined. 

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