I Caffeine

Table I. Caffeine (Cf) and Theobromine (Tb) Contents of Coffee and Tea Seeds...

Fig. 3.6. Electrochromatogram of benzylamine (I), caffeine (II) and benzoic acid (III). Efficiency values of 4642, 76331, and 6399 plates per column were obtained respectively for I, II, and III. Electrochromatography was performed at 15°C with an applied voltage of 25 kV on a 25 cm, 100 pm i.d., 3 pm Hypersil Phenyl packed capillary. Mobile phase ACN-50 mM triethanolamine phosphate, pH 2.5-H20 (6 2 2 v/v/v). Sample concentration was 100 pg ml 1 of each component, 5 kV/5s injection. Detection at 214 nm. From [63]. Reproduced with permission of The Royal Society of Chemistry...

There are four broad classes of alkaloids whose general economic aspects are important ( /) the opiates such as morphine and codeine (2, R = H and R = CH3, respectively) (2) cocaine (11) (both licit and illicit) (i) caffeine (16) and related bases in coffee and tea, and (4) the tobacco alkaloids such as nicotine (21). 

In a systematic review of comparisons of Saridon (propyphenazone 150 mg + paracetamol 250 mg -I- caffeine 50 mg), paracetamol 500 mg + aspirin 500 mg -I-ibuprofen 200 mg, and placebo in 500 healthy adults, of whom 329 (66%) had moderate and 171 (34%) severe acute dentoalveolar pain, more of the patients who received Saridon reported pain gone/partly gone and fewer reported pain unchanged or worse at 30 and 60 minutes (1). There were adverse events in 20 patients (4.0%), with no significant differences between the groups. The most common adverse events were gastrointestinal disorders, followed by nervous system, skin, subcutaneous tissue, respiratory, cardiac, and general disorders. 

FIGURE 16.10 Structures of compounds normally found in cocaine samples (a) cocaine, (b) benzoylecgonine, (c) cinnamoylcocaine, (d) benzoic acid, (e) ketamine, (f) lidocaine, (g) procaine, (h) benzocaine, and (i) caffeine. (FromSabino, B.D. et al. 2011. Am. J.Anal. Chem., 2 658-664. With permission.)... 

Fig. 79. Detection with iodine, of a mixed pharmaceutical preparation after thin-layer chromatographic separation [215]. I caffeine II aminopyrine III phena-cetin /F benzyl mandelate. 15 cm run using cyclohexane-acetone (40 -h 50) on silica gel G...

I Caffeine, the stimulant in coffee and tea, is a weak base that ionizes in water according to the equation... 

Haddad and associates report the following capacity factors for the reverse-phase separation of salicylamide (k i) and caffeine... 

The pyrido[2,3-[Pg.227]

Procedure. Inject 1 fiL of the sample solution and obtain a chromatogram. Under the above conditions the compounds are separated in about 3 minutes, the elution sequence being (1) aspirin (2) phenacetin (3) caffeine. Measure peak areas with an integrator and normalise the peak area for each compound (i.e. express each peak area as a percentage of the total peak area). Compare these results with the known composition of the mixture discrepancies arise because of different detector response to the same amount of each substance. 

Nassar-Gentina, V., Passonneau, J.V., Rapoport, S.I. (1981). Fatigue and metabolism of frog muscle fibers during stimulation and in response to caffeine. Am. J. Physiol. 241, CI60-C166. 

Jalal and Collin19 used paper chromatography and TLC to determine caffeine in both coffee and tea, and theobromine in tea. Their TLC method used cellulose plates that were developed with butanokhydrochloric acid water (I 00 1 1 28) for 4 h. The spots were eluted from the plates with ammonium hydroxide and measured spectrophotometrically against a blank at 272 nm for caffeine and 274 nm for theobromine. 

GC has seen wide use in food analysis but has not seen a large following in the determination of the nonvolatile alkaloids in foods when compared to HPLC. The 13th edition of the AO AC Methods of Analysis22 lists a GC method for the determination of caffeine in coffee or tea using a thermionic KCI detector with a glass column 6 ft x 4 mm i.d. packed with 10% DC-200 on 80 to 100-mesh Gas Chrom Q. 

Midha, K.K., Sved, S., Hossie, R.D., and McGilveray, I.J., High performance liquid chromatographic and mass spectrometric identification of dimethylxanthine metabolites of caffeine in human plasma, Biomed. Mass. Spectrom., 4,172,1977. 

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. 

Farr, D. R. and Horman, I., Treatment of an aqueous extract of plant material for reducing the content of caffeine and/or chlorogenic acid, Ger. Offen. 2,826,466, 1979. (CA90 166789x)... 

Sakanaka, S. and Nakamura, I., Removal of caffeine from solutions with clay, Jpn. Kokai Tokkyo Koho JP 06,142,405, 1994. (CA121 156270r)... 

Caffeine is also effective in the antagonism of peripheral adenosine (type I) receptors, which are known to inhibit lipolysis by subduing adenylate cyclase activity.28 The appeal of this mechanism of action is that the majority of the pharmacological effects of adenosine on the central nervous system can be inhibited by doses of caffeine that are well within physiologically non-toxic levels comparable to only a couple of cups of coffee.5... 

Some researchers reject the explanation that caffeine inhibits glycogen depletion during short term exercise54 but there is an increasing abundance of research supporting the notion of variable sensitivity to caffeine by muscle type. Muscles with higher ratios of type I fibers appear more sensitive than type II fibers, both in animal55-56 and human models.57... 

Wendt, I. and Stephenson, D., Effects of caffeine on calcium-activated force production in skinned cardiac and skeletal muscle fibers of the rat, European Journal of Physiology, 398, 210, 1983. 

Falk, B., Burstein, R., Ashkenazi, I., Spillberg, O., Alter, J., Zylber-Katz, E., Rubinstein, A., Bashan, N., and Shapiro, Y., The effect of caffeine on physical performance after prolonged exercise, European Journal of Applied Physiology, 59, 168, 1989. 

Sasaki, H., Takaoka, I, and Ishiko, T., Effects of sucrose or caffeine ingestion on running performance and biochemical responses to endurance running, International Journal of Sports Medicine, 8, 203, 1987. 

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