162 CHEMICAL MEANS OF DEFENSE AGAINST POISONS 



C(OH) C-0-SO.OK 



CjH/ > CH + HO - S0 2 OK = C 6 H, < JCS + H 2 O. 



X NH/ M 



(indoxyl) (indican) 



A host of other aromatic organic substances are similarly com- 

 bined with sulphuric acid/ with or without preliminary oxida- 

 tion, including all substances resembling phenol or which through 

 oxidation are changed into phenols, such as cresol, thymol, 

 anilin, naphthalin, pyrogallol, and tannin. By this means a 

 poisonous substance is converted into a relatively harmless one, 

 which is readily soluble and rapidly eliminated. 



2. Glycuronic acid occupies the same position as sulphuric 

 acid, combining particularly with naphthol, thymol, camphor, 

 chloral hydrate, and butyl chloral. Sometimes a substance may 

 appear in the urine combined in part with sulphuric, in part 

 with glycuronic acid, showing the similarity of their function. 

 Apparently when there is not sufficient sulphuric acid in the 

 body to combine with all the poison, the excess unites with gly- 

 curonic acid, 2 although combination between glycuronic acid and 

 the aromatic substance begins to occur before all the sulphuric 

 acid is exhausted. 3 Glycuronic acid represents merely a first 

 step in the oxidation of glucose, as follows : 



OHC - (CHOH) 4 - CH 2 OH + O 2 = OHC - (CHOH) 4 - COOH + H 2 O. 



(glucose) (glycuronic acid) 



This oxidation occurs after the aldehyde group of the glucose 

 has been combined by some other substance ; hence the aldehyde 

 group escapes oxidation, although ordinarily more easily oxidized 

 than the alcohol group. 



Just as with the addition of sulphuric acid, oxidation may be 

 a preliminary step to the addition of glycuronic acid ; e. g., 

 naphthalin is oxidized into a-naphthol, before uniting to gly- 

 curonic acid, as follows : 



H H 



/C C x H H H 



HC< V Ck , C N OH 



\C C( >CH + 0=HC/ NCCv 



H X C-C/ XJ-CC >CH 



H H H \C <y 



H H 



(naphthalin) (a-naphthol) 



1 See Hammarsten's Text-book (fourth American ed.), p. 542. 



2 See Austin and Barron, Boston Med. and Surg. Jour., 1905 (152), 269. 

 Wohlgemuth has observed a case in which all the sulphuric acid of the urine 

 was in organic combination (Berl. klin. Woch., 1906 (43), 508). 



3 See Salkowski, Zeit. physiol. Chem., 1904 (42), 230. 



