Paraxanthin

Structural formula
General
Surname	Paraxanthin
other names	1,7-dimethylxanthine; 1,7-dimethyl-3 H -purine-2,6-dione ( IUPAC );
Molecular formula	C 7 H 8 N 4 O 2
Brief description	colorless solid
External identifiers / databases
EC number	210-271-9
ECHA InfoCard	100.009.339
PubChem	4687
Wikidata	Q419223
properties
Molar mass	180.16 g mol −1
Physical state	firmly
density	1.36 g cm −3 (25 ° C)
Melting point	294-296 ° C
solubility	slightly soluble in water and ethanol: 1 or 0.6 g l −1 (20 ° C)
safety instructions
GHS labeling of hazardous substances Caution
H and P phrases	H: 302
	P: no P-phrases
	As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Paraxanthin is a chemical compound from the group of xanthines . It is the dimethyl derivative of xanthine and structurally related to caffeine . It is isomeric to theobromine and theophylline .

Occurrence

7-methylxanthine

Paraxanthin occurs only in traces in plants; there it is formed by the slow methylation of 7-methylxanthine by S-adenosylmethionine . It is then almost immediately further methylated to caffeine in plants.

Biological importance and metabolism

Paraxanthin is an adenosine receptor ligand and a major metabolite of caffeine in animals. In humans, around 80% of the caffeine ingested is demethylated to paraxanthin by the enzyme cytochrome P450 1A2, which means that it can also be detected in human urine. The main metabolite of paraxanthine ingested directly in humans and mice is 1-methylxanthine; demethylation takes place in the microsomes of the liver by the enzyme cytochrome 2A6 ( CYP2A6 ). CYP1A2 cytochromes can also convert paraxanthine into 7-methylxanthine. About 60% is excreted unchanged in the urine.

literature

Klaus Unna, Friedrich Winiwarter: To the pharmacology of Paraxanthin. In: Naunyn-Schmiedebergs Archive for Experimental Pathology and Pharmacology. 187, 1937, p. 163, doi : 10.1007 / BF01972015 .

Web links

Synthesis of Paraxanthine and Isoparaxanthine Analogs

Individual evidence

↑ ^a ^b ^c ^d ^e ^f data sheet 1,7-Dimethylxanthine from Sigma-Aldrich , accessed on April 18, 2011 ( PDF ).
^ Carl L. Yaws: Thermophysical properties of chemicals and hydrocarbons. William Andrew, Norwich 2008, ISBN 978-0-8155-1596-8 , p. 231.
^ Bertil B. Fredholm: Methylxanthines. Handbook of Experimental Pharmacology, Volume 200, Springer, Stockholm 2010, ISBN 978-3-642-13442-5 , p. 18.
↑ Rudolf Hänsel, Otto Sticher, Ernst Steinegger: Pharmakognosie - Phytopharmazie (Springer textbook) (German edition) . Springer DE, 2010, ISBN 978-3-642-00963-1 , p. 288 ( limited preview in Google Book search).
^ Bertil B. Fredholm: Methylxanthines. Handbook of Experimental Pharmacology, Volume 200, Springer, Stockholm 2010, ISBN 978-3-642-13442-5 , p. 75.

[Sigma-1] ↑ ^a ^b ^c ^d ^e ^f data sheet 1,7-Dimethylxanthine from Sigma-Aldrich , accessed on April 18, 2011 ( PDF ).

[2] Carl L. Yaws: Thermophysical properties of chemicals and hydrocarbons. William Andrew, Norwich 2008, ISBN 978-0-8155-1596-8 , p. 231.

[3] Bertil B. Fredholm: Methylxanthines. Handbook of Experimental Pharmacology, Volume 200, Springer, Stockholm 2010, ISBN 978-3-642-13442-5 , p. 18.

[HSS-4] Rudolf Hänsel, Otto Sticher, Ernst Steinegger: Pharmakognosie - Phytopharmazie (Springer textbook) (German edition) . Springer DE, 2010, ISBN 978-3-642-00963-1 , p. 288 ( limited preview in Google Book search).

[5] Bertil B. Fredholm: Methylxanthines. Handbook of Experimental Pharmacology, Volume 200, Springer, Stockholm 2010, ISBN 978-3-642-13442-5 , p. 75.