Purine Alkaloids : Sources, Properties and Chemical Nature

Distribution and Uses of Purine Alkaloids:

Purine alkaloids occur in various parts of the world and are used in stimulant beverages as it consists of caffeine, a CNS stimulant principle.

Sources of Purine Alkaloids:

Various plants like tea, coffee, cola, cocoa, guavana and mate contains the derivatives of xanthine, they are called purine alkaloids.

Purine alkaloids mainly includes caffeine, theobromine and theophylline. These alkaloids contain purine base, which is a fusion of an imidazole and pyrimidine rings.

Chemical Nature of Purine Alkaloids:

Purine base is derived into xanthine and this to caffeine (1,3,7 trimethyl xanthine), theobromine (3,7 dimethyl xanthine), theophylline (1,3 dimethyl xanthine).

Properties of Purine Alkaloids:

• Xanthine does not occur free in nature.
• Although they are known as alkaloids, they do not respond to common alkaloidal reagents.
• Purine Alkaloids gives a positive murexide colour reaction.
• They are sublimatory in nature.
• All these 3 alkaloids have stimulant and diuretic properties.
• Caffeine has mainly stimulating effect and theobromine has diuretic effects.
• Theophylline has both the above activities and mainly smooth muscle relaxant properties.