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The Info List - Paraxanthine


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PARAXANTHINE, or 1,7-dimethylxanthine, is a dimethyl derivative of xanthine , structurally related to caffeine . Like caffeine, paraxanthine is a psychoactive central nervous system (CNS) stimulant . It possesses a potency roughly equal to that of caffeine and is likely involved in the mediation of the effects of caffeine itself.

CONTENTS

* 1 Production and metabolism * 2 Physiological effects * 3 Toxicity
Toxicity
* 4 References * 5 External links

PRODUCTION AND METABOLISM

Paraxanthine
Paraxanthine
is not produced by plants and is only observed in nature as a metabolite of caffeine and theobromine in animals. After intake, roughly 84% of caffeine is demethylated at the 3-position to yield paraxanthine, making it the chief metabolite of caffeine in the body.

Certain proposed synthetic pathways of caffeine make use of paraxanthine as a bypass intermediate. However, its absence in plant alkaloid assays implies that these are infrequently, if ever, directly produced by plants.

PHYSIOLOGICAL EFFECTS

Paraxanthine
Paraxanthine
has a number of physiological effects on animals:

* Paraxanthine
Paraxanthine
is a competitive nonselective phosphodiesterase inhibitor which raises intracellular cAMP , activates PKA , inhibits TNF-alpha and leukotriene synthesis, and reduces inflammation and innate immunity . * Paraxanthine
Paraxanthine
is a nonselective adenosine receptor antagonist which raises plasma epinephrine and diastolic blood pressure. * Paraxanthine
Paraxanthine
may be responsible for the lipolytic properties of caffeine , and its presence in the blood causes an increase in serum free fatty acid concentration. * Paraxanthine, unlike caffeine , acts as an enzymatic effector of Na+/K+ ATPase . As a result, it is responsible for increased transport of potassium ions into skeletal muscle tissue. Similarly, the compound also stimulates increases in calcium ion concentration in muscle.

TOXICITY

Paraxanthine
Paraxanthine
is believed to exhibit a lower toxicity than caffeine. While blood levels commensurate with average intake appear to be fairly innocuous, high blood concentrations of paraxanthine have been linked to miscarriage in pregnant mothers.

REFERENCES

* ^ Guerreiro S, Toulorge D, Hirsch E, Marien M, Sokoloff P, Michel PP (October 2008). "Paraxanthine, the primary metabolite of caffeine, provides protection against dopaminergic cell death via stimulation of ryanodine receptor channels". Mol. Pharmacol. 74 (4): 980–9. PMID 18621927 . doi :10.1124/mol.108.048207 . * ^ Essayan DM. (2001). "Cyclic nucleotide phosphodiesterases.". J Allergy Clin Immunol. 108 (5): 671–80. PMID 11692087 . doi :10.1067/mai.2001.119555 . * ^ Deree J, Martins JO, Melbostad H, Loomis WH, Coimbra R (2008). "Insights into the Regulation of TNF-α Production in Human Mononuclear Cells: The Effects of Non-Specific Phosphodiesterase Inhibition" . Clinics (Sao Paulo). 63 (3): 321–8. PMC 2664230  . PMID 18568240 . doi :10.1590/S1807-59322008000300006 . * ^ Marques LJ, Zheng L, Poulakis N, Guzman J, Costabel U (February 1999). " Pentoxifylline inhibits TNF-alpha production from human alveolar macrophages". Am. J. Respir. Crit. Care Med. 159 (2): 508–11. PMID 9927365 . doi :10.1164/ajrccm.159.2.9804085 . * ^ A B Peters-Golden M, Canetti C, Mancuso P, Coffey MJ (2005). "Leukotrienes: underappreciated mediators of innate immune responses". J Immunol. 174 (2): 589–94. PMID 15634873 . doi :10.4049/jimmunol.174.2.589 . * ^ Daly JW, Jacobson KA, Ukena D (1987). " Adenosine
Adenosine
receptors: development of selective agonists and antagonists". Prog Clin Biol Res. 230 (1): 41–63. PMID 3588607 . * ^ Hetzler RK, Knowlton RG, Somani SM, Brown