GLUCURONIC ACID. 215 



and reduces after boiling with acids. As hydrolytic cleavage product it yields 

 c?-glucosamine. 



Galactosamine is claimed to have been found by SCHULZ and DITTHORN in 

 a glycoprotein of the spawn of the frog. This claim is not generally accepted. 

 v. EKENSTEIN and BLANKSMA l obtained galactose on the hydrolysis of the slimy 

 envelope of frog eggs. 



b. Glucuronic Acids. 



The glucuronic acids occurring in the animal body either physiolog- 

 ically or pathologically, are conjugated acids which will be described in 

 detail in a subsequent chapter (XV). We here will only describe the 

 d-glucuronic acid in connection with the carbohydrates. 



CHO 



d-Glucuronic acid (glycuronic acid) , C 6 H 10 O 7 = (CH.OH) 4 , is a derivative 



COOH 



of dextrose, and has been synthetically prepared by E. FISCHER and PILOTY 2 

 by the reduction of the lactone of saccharic acid. On oxidation with 

 bromine it forms saccharic acid, and on reduction it yields gulonic-acid 

 lactone. SALKOWSKI and NEUBERG 3 have obtained Z-xylose from glu- 

 curonic acid by splitting off CO 2 by means of putrefaction bacteria. 



Glucuronic acid has not been found in the free state in the animal 

 body. It occurs to a slight extent in normal urine as a conjugated acid, 

 phenol and probably also indoxyl- and skatoxylglucuronic acid (MAYER 

 and NEUBERG). It occurs to a much greater extent in urine as con- 

 jugated acid after the ingestion of certain aromatic and also aliphatic 

 substances, especially camphor and chloral hydrate. It was obtained 

 first by SCHMIEDEBERG and MEYER from camphoglucuronic acid, and 

 then by v. MERING 4 from urochloralic acid by cleavage with dilute acids. 

 According to P. MAYER, 5 on the oxidation of dextrose a partial formation 

 of glucuronic acid and oxalic acid takes place, and therefore, according 

 to him, an increased elimination of conjugated glucuronic acids shows 

 in certain cases an incomplete oxidation of dextrose. Conjugated glucu- 

 ronic acids may also occur in the blood (P. MAYER, LEPINE and BOULUD 6 ), 

 in the feces, and in the bile. 7 NEUBERG and NEIMANN 8 have prepared 



1 Schulz and Ditthorn, Zeitschr. f. physiol. Chem., 29; v. Ekenstein and Blanksma, 

 Chem. Centralbl., 1907, 2, p. 1001. 



2 Ber. d. d. chem. Gesellsch., 24. 



3 Zeitschr. f. physiol. Chem., 36. 



4 Mayer and Neuberg, Zeitschr. f. physiol. Chem., 29; Schmiedeberg u. Meyer, ibid., 

 3; v. Mering, ibid., 6. 



5 Zeitschr. f. klin. Med., 47. See Chapter XV. 



6 Zeitschr. f. physiol. Chem., 32; Lupine and Boulud, Compt. rend., 133, 134, 138. 



7 See Bial, Hofmeister's Beitrage, 2, and v. Leersum, ibid., 3. 



8 Zeitschr. f. physiol. Chem., 44. 



