632 METABOLISM 



Ethereal Sulphates and Glycuronates. The other substances used for 

 detoxication purposes are sulphuric and glycuronic acids. Phenol, and 

 its derivative cresol, after being absorbed from the intestine, in the 

 contents of which they are produced by the bacterial decomposition. of 

 protein (see page 501) become combined in the body, probably in the 

 liver, with sulphuric acid or with glycuronic acid to form the sulphate 

 or glycuronate. The aromatic sulphate further combines with potassium 

 to form the so-called ethereal sulphates, ias which the substance is excreted 

 in the urine. A small amount of phenol may however appear in the 

 urine unchanged. As we have already seen, the sources of the phenol 

 in the intestine are tyrosine and phenylalanine (see page 530), and 

 since these amino acids are also present in the tissues, it might be sup- 

 posed that some of the phenol sulphate of potassium present in the 

 urine could come from the tissues. It is usually assumed that, however, 

 derivation from the tissues does not occur. 



Another ethereal sulphate is indoxyl sulphate of potassium, which re- 

 sults from the absorption into the blood of the indole and skatole pro- 

 duced by intestinal putrefaction from tryptophane (see page 502). 

 Immediately after absorption indole is- oxidized to indoxyl, which then 

 combines with sulphuric acid and with potassium to form indoxyl sul- 

 phate of potassium, which is the well-known indican of the urine. As 

 in the case of phenol sulphate of potassium, none of the urinary indican 

 seems to come from the normal metabolism (of the tryptophane) of the 

 tissue proteins. It is a much more reliable indicator than phenol sul- 

 phate of potassium of the extent of intestinal putrefaction, but it also 

 becomes increased in amount during putrefaction in the body itself, 

 as for example in abscess formation. 



The amount of indican in the urine may be roughly gauged by oxi- 

 dizing the urine by means of hypochlorite and then shaking out with 

 chloroform. If the resulting extract is more than light blue in color, 

 it indicates excessive putrefaction. A negative test does not neces- 

 sarily mean that intestinal putrefaction is absent, but a marked positive 

 test always indicates that it is occurring. Skatole, the methyl deriva- 

 tive of indole, may undergo similar processes and appear in the urine 

 during excessive intestinal putrefaction. Its presence in the blood some- 

 times confers on the breath a distinct fecal odor, for this body, as its 

 name indicates, is that to which the odor of the feces is due. 



Glycuronic acid, the other substance used for detoxication processes, 

 is of the nature of a dextrose molecule with the one end-group oxidized 

 to carboxyl (CHO - (CHOH) 4 - COOH). It is probably produced under 

 normal processes of metabolism in the animal body, but is destroyed 

 unless when such poisonous substances as camphor, chloral hydrate or 



