182 HYPOXANTHIN. ADENIN. 



Although the xanthin-bases undoubtedly result in the body from 

 the metabolism of nitrogenous (proteid) tissues there is as yet no 

 evidence as to the manner in which they can be formed from true 

 proteids 1 . The genetic relationship of hypoxanthin to nuclein probably 

 accounts for the marked occurrence of the former in leukhaemic blood. 

 Bearing in mind the close chemical relationship of uric acid, 

 xanthin and hypoxanthin, and regarding the xanthin bases as distinctly 

 and typically products of the downward metabolism of nitrogenous 

 tissues, the question at once suggests itself whether in the body there 

 is any antecedental relationship between these substances and uric 

 acid (or urea). As with kreatin (above, p. 162), so with the xanthin 

 bodies, the disproportion between the amount presumably arising in 

 the tissues and that which is actually excreted makes it probable that 

 they are converted into something else, uric acid (or urea), before 

 leaving the body. And in support of this belief there is a certain 

 amount of experimental evidence which was wanting in the case of 

 kreatin. It is found that hypoxanthin administered to a dog does not 

 reappear as such externally in the urine 2 , and that when given to fowls 

 it leads to an increased excretion of uric acid amounting to some 60 p.c. 

 of the hypoxanthin employed 3 . Since the latter result is obtained in 

 fowls with extirpated livers, it appears that the conversion is not 

 effected in this organ, although it is known that normally no incon- 

 siderable portion of the uric acid is formed in their liver. 



6. Adenin. C 5 H 5 N 5 . 



This base was obtained by Kossel 4 during the treatment of 

 pancreatic tissue for the preparation of hypoxanthin. It bears the 

 same relationship to the latter that guanin does to xanthin, and can 

 similarly be converted into hypoxanthin by the action of nitrous acid. 

 It is stated to have been found in urine 5 . 



When pure it crystallises in needles from aqueous solutions. Is 

 soluble in 1086 parts of cold water, readily in hot water, insoluble in 

 ether, slightly soluble in hot alcohol. Yields crystalline compounds 

 with acids, also with some salts. The compound with nitrate of silver 

 is soluble in hot nitric acid (sp. gr. 1*1), and is thus separable, together 



1 Cf. Drechsel, Ber d. d. chem. Gesell 1880, S. 240. But see also Salomon, Ibid. 

 S. 1160. 



2 Baginsky. Zt. f. physiol Chem. Bd. vin. (1884), S. 397. 



3 Von Mach, Arch. f. exp. Path. u. Pharm. Bde. xxin. (1887), S. 148, xxiv. 

 (1888), S. 389. See also Stadthagen, loc. cit. below. 



4 Ber. d. d. chem. Gesell. 1885, Sn. 79, 1928, Zt. f. physiol. Chem. Bde. x. (1886), 

 S. 250, xn. (1888), S. 241, xvi. (1892), S. 1. See also Schindler, Ibid. xm. (1889), 

 S. 432. Gives directions for separation of xanthin, hypoxanthin, guanin and 

 adenin. Thoiss, Ibid. Bd. xm. S. 395. Bruhns, Ibid. Bd. xiv. (1890), S. 533. 

 Kriiger, Ibid. Bd. xvi. (1892), S. 160. 



5 Stadthagen, Virchow's Arch. Bd. cix. (1887), S. 390. 



