ORIGIN OF GLYCURONIC ACID 319 



In determining the amount of aromatic substances ex- 

 creted in the urine it is necessary besides the conjugated 

 sulphuric acids to also keep in mind the conjugated gly- 

 curonic acids, with possible complex interrelations. Thus 

 Neuberg isolated 50 from the urine of dogs to which cresol 

 had been fed, the barium salt of a double combination of 

 cresol-glycuronic acid and cresol-sulphuric acid: 



Ba O SOz O C6H 4 .CH 3 . 



Properly considered the conjugation of foreign substances 

 with glycuronic acid is really a detoxifying process. Ap- 

 parently the economy sometimes provides a larger amount 

 of glycuronic acid than is absolutely needed. At least 

 F. Blumenthal noticed in a case of lysol poisoning the form- 

 ation of considerably more glycuronic acid than required 

 for fixing the amount of cresol introduced. 



Origin of Glycuronic Acid from Oxidation of Sugar. 

 The origin of glycuronic acid from sugar by oxidation 

 (which can be performed artificially in vitro by careful oxi- 

 dation of dextrose by means of peroxide of hydrogen) 51 

 directly explains a positive dependence of the physiological 

 formation of this substance upon the body supply of carbo- 

 hydrates. One can readily appreciate that an animal, with 

 its glycogen reduced from long continued starvation, would 

 react to dosage with camphor with only a slight excretion 

 of glycuronic acid, and that this would increase progressively 

 with exhibition of sugar. And when it is recalled that sugar 

 may be formed from protein, there is just as little occasion 



60 C. Neuberg and E. Kretschmer, Biochem. Zeitschr., 86, 15, 1911; cf. also 

 F. Stern (Kiel), Zeitschr. f. physiol. Chem., 68, 52, 1910. 

 51 A. Jolles, Biochem. Zeitschr., 34, 242, 1911. 



