72 PHYSIOLOGICAL CHEMISTRY 



COOH 

 H C OH 



H C OH 



I 

 HO C H 



H C OH 



I 

 CHO 



Glucuronic acid 



It is interesting chiefly because it combines with various pro- 

 ducts formed by putrefaction in the intestine such as phenol, 

 indol, skatol, etc. These substances are absorbed into the blood 

 stream, and would exert a toxic influence upon the cells if it 

 were not for the fact that the body promptly unites them to 

 glucuronic acid, (or some other compounds) forming the con- 

 jugated glucuronates which are relatively harmless, and are 

 excreted in the urine. This is one of nature's protective de- 

 vices for shielding the cells against the influence of injurious 

 substances. Solutions of glucuronic acid give the same reduc- 

 tion tests as glucose, are dextrorotatory, but do not ferment. 

 The conjugated glucuronates are strongly levorotatory. 



Disaccharides. 



The disaccharides are formed by the union of two molecules 

 of monosaccharide with loss of water. 



C 6 H 12 6 + C 6 H 12 6 -* C 12 H 2 Ai + H 2 0. 



By the action of dilute acids, enzymes, etc., they may be 

 split into their constituent monosaccharides. The three disac- 

 charides of importance are saccharose, lactose and maltose. 

 These sugars are of great importance as food substances. 



Saccharose. (Sucrose, Cane Sugar.) Cane sugar is found 

 in many plants, notably in the juice of the sugar cane, which 

 contains about 20%, and in carrots. It is found in many sweet 

 fruits, such as the banana, strawberry, pineapple, etc., and in 



