394 CHEMISTRY OF THE LEUCOMAINS. 



As to the physiological relation of xanthin very little need be 

 said (page 369). It bears the same relation to guanin that hypo- 

 xanthin does to adenin, and, like the latter, is to be looked upon as 

 an intermediate compound, a step lower than guanin, and nearer the 

 limit of oxidation — uric acid. It is quite probable that in the body 

 it is oxidized about as rapidly as it is formed. Like hypoxanthin, 

 it is to be regarded as a true muscle stimulant, especially of the heart 

 (Baginsky). According to Filehne, it produces in frogs a decided 

 muscular rigor and paralysis of the spinal cord. The heart muscle 

 is also affected, which is not the case with caffein or theobromin. 

 The fatal dose is less than one-half pro mille. In its action it is 

 stronger than theobromin, while caffein is weaker than either of the 

 two. Paschkis and Pal hold that the reverse is true. 



As pointed out on p. 339 xanthin may form three mono-methyl de- 

 rivatives — 1-, 3-, and 7-methyl xan thins ; likewise three di-methyl 

 compounds, namely, theobromin, theophyllin and paraxanthin ; and 

 one tri-methyl derivative, which is caffein. With the probable ex- 

 ception of caffein, all of these methyl xanthin derivatives appear in 

 the urine, where they are to be looked upon not as cleavage products 

 of tissue nuclein, but rather as hydrolytic bodies derived from the 

 caffein and other higher methyl derivatives present in the food. 

 For the existence of other methyl derivatives see page 340. 



1-Methyl xanthin, CgH^Np^ . were isolated from urine in 1897 

 by Kriiger and Salomon.' As shown on page 389, it is by far the 

 most abundant of the purin bases in urine. Okerblom has also ob- 

 tained this base from adrenals (p. 390), which fact demonstrates that 

 1-methyl xanthin may be derived from higher homologues of xanthin 

 contained within the tissue nuclein, as well as from those contained 

 in the food. As shown below it appears in rabbits' urine after feed- 

 ing with paraxanthin. The constitution of this base cannot be said 

 to be definitely established. The conclusion as to its structure was 

 reached by comparison with the 3- and 7-methyl xanthins, with 

 neither of which it was identical. Hence it was given the structure 

 assigned. The base has not been synthesized. 



On treatment with methyl iodid it is easily changed into caffein 

 and into theophyllin (1-3-di-methyl xanthin) which can be identi- 

 fied by the sodium salt which is rather difficultly soluble in ten per 

 cent, sodium hydrate (Kriiger '). 



The free base crystallizes best from acetic acid forming very thin, 

 superposed, six-sided, rarely four-sided rhombic plates. It separates 

 from water as dull, colorless crystalline powder which shows rosette- 

 like groups. 



It is difficultly soluble in cold water, but more easily than xanthin. 



' Zeiix. physid. Chem., 24, 380 ; 26, 367. 

 'BeriehU, 33, 3666 (1900). 



