334 CEEMISTRy OF THE LEUGOMAINS. 



mann, that alkapton is produced from tyrosin by similar changes in 

 the intestines. The production of intestinal products, their absorp- 

 tion and excretion by the kidneys, is likewise seen in such well 

 known compounds as phenol, indol, skatol, etc. The origin of the 

 true leucomains cannot, however, be accounted for in this manner, 

 for they are indissolubly connected with the metabolism of the cell 

 itself, and are, therefore, formed in the tissues and organs proper. As 

 such they are endogenous whereas the intestinal products are chiefly 

 the result of bacterial action and are therefore of exogenous origin. 



The leucomains have been credited by many as playing the chiet 

 r6le in auto-intoxications. It should be noted, however, that most 

 of the basic bodies which have been studied up to the present are 

 far from being poisonous. The antecedents of these bases, how- 

 ever, such as the nucleinic acids and more especially the histons and 

 protamins exert a pronounced toxic action and hence may play a 

 most important part in auto-intoxications. Of course, it must be 

 admitted that there may be generated Avithin the body toxic leuco- 

 mains which, as yet unknown, normally undergo prompt destruction. 

 The fact that amino derivatives of purin and pyrimidin are highly 

 toxic is deserving of attention. 



The known sources of leucomains are the nucleins of the nuclei and 

 the proteids of the protoplasm of the cells. The former gives rise 

 to the purin and pyrimidin bases whereas the latter generate the hexon 

 bases. In addition to these there is a fairly large number of substances, 

 as yet but poorly studied, which remain to be accounted for. Cholin 

 and allied bodies may be looked upon as leucomains derived from 

 lecithin. They have been described in the preceding chapter. 



The leucomains may be divided into the following groups : (1) 

 the purin or uric acid group ; (2) the pyrimidin group ; (3) the hexon 

 bases ; (4) the creatinin group. 



The first of these divisions contains a number of well known bases 

 which are derivatives of purin and for that reason are closely allied 

 to uric acid. 



PUBIN, CsHiNj. 



AdENIN, C5H5N5. 



Hypoxanthin, CjHjNjO. 



GuANDf, CjHjNjO. 



Methyl OTjANur, CjH,N50 (Epiguanin). 



Xanthin, CjHiNtOj. 



(Ubicacid, CsH^NA)- 



1-METHYL XANTHIN, CjHjNjOj. 



3-METHYL XANTHIN, C.HjNjO,. 



7-METHYL XANTHIN, CeHgN^Oj ( Heteroianthin ) . 



1-7 Di-MBTHYi/ XANTHIN, CfHjNjOj (Paraxanthin). 



1-3 Di-MBTHYL XANTHIN, CtHjNiOj (Theophyllin). 



3-7 Dl-METHYi XANTHIN, CiHgN^Oj (Theobromin). 

 1-3-7 TBi-METHYii XANTHIN, CgHijNiOj (Caffein). 



Cabnin, C,HjN403. . 



Cabnosin, CgHnNjOj. 



Cytosin, CjiHaoNieOi. 



