CONJUGATED GLUCORONIC ACIDS. 713 



starvation is going on, the elimination of glucuronic acid rises again to 

 the same height as it was before the starvation period. This shows that 

 the sugar had conjugated itself with the camphor as glucuronic acid. 

 HILDEBRANDT 1 has also made experiments showing that glucuronic acid 

 can very likely be formed from sugar. The observations of MAYER are 

 not substantiated by the recent investigations of FENYVESSY^ and the 

 observers do not agree on this question. 



The conjugated glucuronic acids are formed, based upon the investi- 

 gations -of SUNDWIK, FISCHER and PILOTY, S by a combination taking 

 place first between the conjugator and the dextrose by means of the alde- 

 hyde group, and then the end alcohol group, CH 2 OH, is oxidized to COOH. 

 The conjugated glucuronic acids, at least in most cases, seem to be con- 

 structed after the glucoside type, a view which has received further 

 support by the synthesis of phenolglucuronic acid and euxanthonglu- 

 curonic acids by NEUBERG and NEIMANN:* Based upon their cleavage 

 (as far as they have been investigated) by kephir lactase and emulsin, 

 but not by yeast lactase (NEUBERG and WOHLGEMUTH S ), the conjugated 

 glucuronic acids must belong to the /3-series of glucosides. We also 

 know of certain conjugated glucuronates that are constructed upon the 

 ester type, namely, the dimethylaminobenzoicglucuronate, discovered by 

 JAFFE and also the benzoicglucuronic acid, after feeding benzoic acid 

 (MAGNUS-LEVY) . 6 



According to the body with which they are conjugated the glucuronates 

 vary in behavior. On taking up water they split into glucuronic acid 

 and the conjugated group and this is brought about by boiling with 

 a dilute mineral acid. They are precipitated by basic lead acetate or 

 by basic lead acetate and ammonia. Most of the conjugated glucuronic 

 acids do not have a direct reducing action but are reducing after hydrolysis. 

 Certain of them, and to this group belong especially those acids of the 

 ester type, reduce copper oxide and certain othei metallic oxides in alkaline 

 solution directly, and hence cause errors in the investigations of the urine 

 for sugar. The conjugated acids of the glucoside type rotate the plane 

 of polarized light to the left, while the glucuronic acid itself is dextro- 

 rotatory. The conjugated acids of the ester type, which as a rule are 

 less stable, rotate the ray of polarized light to the right. As the detection 

 of conjugated glucuronic acids is connected with the tests for sugar in 

 the urine, we will treat of this in connection with these tests. 



1 Arch. f. exp. Path. u. Pharm., 44. 



2 See Maly's Jahresber., 34. 



3 E. Sundwik, Akademische Abhandlung Helsingfors, 1886; see also Maly's 

 Jahresber., 16, 76; Fischer and Piloty, Ber. d. d. chem. Gesellsch., 24. 



4 Zeitschr. f. physiol. Chem., 44. 



5 See Neuberg, Ergebnisse der Physiologic, Bd. 3, Abt. 1, 444. 



6 Jaffe, Zeitschr. f. physiol. Chem., 43; Magnus-Lavy, Bioch., Zeitschr., 6. 



