Of xanthine derivatives

Fig. 1 A) Chromatogram of xanthine derivatives Track 1 theophylline, Track 2 proxiphylline, Track 3 mixture, Track 4 etophylline, IVack 5 caffeine.

Varagic, V. M. and Zugic, M., Interactions of xanthine derivatives, catecholamines, and glucose-6-phosphate on the isolated phrenic nerve diaphragm preparation of the rat, Pharmacology, 5, 275, 1971. 

Thevis M, Opfermann G, Krug O, Schanzer W. 2004. Electrospray ionization mass spectrometric characteri zation and quantitation of xanthine derivatives using isotopically labeled analogues an application for equine doping control analysis. Rapid Commun Mass Spectrom 18 1553. 

Korman, M., Vindevogel, J., and Sandra, P. (1994). Application of micellar electrokinetic chromatography to the quality-control of pharmaceutical formulations — the analysis of xanthine derivatives. Electrophoresis 15, 1304—1309. 

Natural antagonists for ARs, such as caffeine and theophylline show in general low affinity for the A3 AR subtype (Baraldi et al. 2003). In a recent work, the approach based on the annelation of xanthine derivatives for the development of adenosine receptors antagonists has been extensively considered (Drabczy ska et al. 2003). 

Clarke H, Cushley MJ, Persson CG, Holgate ST (1989) The protective effects of intravenous theophylline and enprofylline against histamine- and adenosine 50-monophosphate-provoked bronchoconstriction implications for the mechanisms of action of xanthine derivatives in asthma. Pulm Pharmacol 2(3) 147-154... 

CAPACITY FACTOR OF XANTHINE DERIVATIVES ON A THEOPHYLLINE-IMPRINTED POLYMER ROD COLUMN... 

Sample preparation is an important step in HPLC. It influences not only the sensitivity and the selectivity of the analysis, but also the column life and the analysis time. The general problems in alkaloid sample preparation have been dealt with in Volume 23A of this series. Some special problems connected with the analysis of alkaloids in body fluids have also been discussed there (Chapter 12), while other special problems have been dealt with in connection with the analysis of xanthine derivatives in biological fluids (Chapter 11 of this volume). 

The already mentioned influence of the pH of the buffer on the retention of 8-chlorotheophylline was investigated by Hill64, who found that an optimum separation of xanthine derivatives was obtained at a pH of 5.0 for a mobile phase consisting of 1% propionic acid - methanol (8 2) on an octadecyl column. For a simultaneous analysis of theophylline, proxyphylline and... 

For the analysis of xanthine derivatives in food and beverages, octadecyl type of columns have been used in combination with the mobile phase methanol - water - acetic acid (20 79 1) (ref. 86,141,148), or similar ratios142,205,207. 

Fig. 11.3. Separation of a standard mixture of xanthine derivatives in serum ...

Fig. 11.9. Straight-phase separation of xanthine derivatives Column Lichrosorb Si60 5 urn (300x3 mm ID), mobile phase dichloro-water (936 47 17), flow rate 70 ml/h, detection...

HPLC ANALYSIS OF XANTHINE DERIVATIVES IN BIOLOGICAL FLUIDS... 

Mayer MC and Guttman DE, Interactions of xanthine derivatives with bovine serum albumin III. Inhibition of binding, /. Pharm. Sci., 57, 245-249 (1968). NB The pK value was quoted without experimental details. Refs. Eichman ML, Guttman DE, van Winkle Q and Guth EP, Interactions of xanthine... 

Another example of marked B-adrenoreceptor potency enhancement by N-substltution is illustrated by fenoterol (60a). which is strikingly more potent than its N-tert-butyl counterpart, ter-butallne (6. Fenoterol is a clinically effective bronchodilator by either oral or aerosol administration however, some cardiac stimulation and tremors are noted (136, 137). Cat soleus muscle, bronchial and heart rate experiments indicate selective B2 adrenoreceptor potency for 60b (138). Another resorcinol, one of a series of xanthine derivatives, is reproterol (60c). Repro-terol is clinically effective in bronchial asthma it causes minimum CNS and cardiovascular side effects upon administration orally or by inhalation, and tachyphylaxis is not observed (139). 

Methods for the synthesis of xanthine-derived polycyclic fused systems 13HC297. 

Physiological Activity of Xanthine Derivatives Pyrazine Alkaloids Securinega Alkaloids Sesbania Alkaloids Betalains Biosynthesis Chemosystematic Value Betalains in Foods and Beverages Miscellaneous Alkaloids Trigonelline and an Unusual Pyrrole Histronionicotoxins Huperzine A References... 

Papadoyannis, I. Samanidou, V. Georga, K. Solid-phase extraction study and photodiode array RP-HPLC analysis of xanthine derivatives in human biological fluids. J. Liq. Chromatogr 1996,19 (16), 2559. 

Matissek, R. 1997. Evaluation of xanthine derivatives in chocolate— Nutritional and chemical aspects. Eur. Food Res. Techn. 205 175-184. 

Other calorimetric studies [22] on human blood platelets were performed in order to clarify the mechanism of action of xanthine derivatives in relation to adenosine receptor. In addition, there were investigations on the effect of adenosine and adenosine agonists on platelet metabolism. The results showed that the two xanthine derivatives tested, enprofylline and theophylline, at therapeutic concentrations, did not modify the heat production induced by adenosine. Both adenosine and one adenosine agonist, NECA (5-N-ethyl carboxamide adenosine) increased platelet metabolism. The other adenosine agonist tested, PIA (L-N -phenylisopropyl-adenosine) induced a reduction of heat production. The adenosine uptake inhibitor, dipyridamol, was without effect. Thus, by microcalorimetry, useful information could be obtained concerning the complex mechanisms behind the effects on human cell metabolism of adenosine and adenosine agonists. The same applies to substances used in the treatment of asthma, xanthine derivatives they are thought to act by inhibition of adenosine receptors. 

A series of xanthine derivatives including theophylline, cafleine, theobromine and pentoxifylline (Fig. 12.15) that have bronchcxUlator properties have been shown to be non-selective phosphodiesterase inhibitors. 

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