376 



NITROGEN BASES 



the dried leaves of Ilex paragiiensis, contains about 0-2-I-6 

 per cent of caffeine. 



Caffeine is a powerful cerebral stimulant, but also acts 

 somewhat on the heart ; it is furthermore a powerful diuretic. 



Three further purine bases deserve mention, namely, 

 Adenine, Hypoxanthine, and Guanine, the formulae of which 

 are as follows :— 



N. 



rCNH, 



CH C— 



N^ 



NH 



/ 



-N 



NH— CO 



C— NH 



NH^C 



NH— CO 



NH 



CH 



N 



/" 



CH 



CH 



-N 



6 Aminopurine or 

 Adenine 



6 Oxypurine or 

 Hypoxanthine 



N C N 



2 Amino 6 oxypurine or 

 Guanine 



All three substances have been obtained by the hydrolysis 

 of nucleo-proteins from plants (see p. 428) and of nucleic acids 

 from yeast * and from Triticum sativum.^ 



Guanine and Hypoxanthine are usually found together ; 

 they occur in sprouting seeds of a number of plants, notably 

 Cucurhita Pepo, Acer pseudoplatanus, Vicia sativa, Trifolium 

 pratense, Lupinus luteiis, Hordeum sativum, and in the juice of 

 the beet, etc. 



Adenine, which is less widely distributed, likewise occurs 

 in the juice of the beet and in tea leaves, and has also been 

 found in leaves of Trifolium repens, Chrysanthemum sinense 

 Artemisia, etc.J 



Uric acid, which is systematically named 2:6:8 trioxy- 

 purine, has the formula — 



NH— CO 



CO C— NH 



>CO 

 NH— C— NH 



It does not occur in plants, but is a well-known waste 

 product in the animal. In view of the close relationship be- 



* Schittenhelm and Schroter : " Zeit. physiol. Chem.," 1904, 41, 290. 

 t Osborne and Harris : id., 1902, 36, 85. Osborne : " Amer. Joum. 

 Pharm.," 1903, 9, 69. 



Yoshimara : " Zeit. Physiol. Chem.," 1913, 334. 



