Xanthine /methylxanthines diuretic

The principal xanthines of medical interest include caffeine, theophylline and aminophylline. Caffeine is synthesized by several plants and was originally isolated from tea in 1838. It is a methylxanthine (Figure 1.12) which stimulates the central nervous system, increasing mental alertness. It also acts as a diuretic and stimulates gastric acid secretion. It is absorbed upon oral administration and is frequently included in drugs containing an analgesic, such as aspirin or paracetamol. 

Methylxanthine is the major purine constituent of human urine (3.1 g in 10001) (1898ZPC(24)364). 3- and 7-Methylpurines are also minor constituents of urine, especially following large doses of caffeine or other methylated xanthines. 1,3-Dimethylxanthine (theophylline) occurs with caffeine in tea leaves and is a powerful diuretic and has been used clinically for this purpose (generally as an adduct with salts of organic acids) and also in the treatment of asthma. 1,7-Dimethylxanthine (paraxanthine) is also an efficient diuretic and, in addition, possesses antithyroid properties (45JCS751). The main purine constituent... 

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