Plant Qroivth'Suhstances 



with the further one that it is not intended as an introduction 

 to urine chemistry in the wider sense. 



Normally, benzene compounds possessing short side- 

 chains are excreted as phenols. Free phenols sometimes exist 

 in traces in urine, but phenol and cresols are usually found in 

 urine as compounds of sulphuric acid and glucuronic acid. 

 Such compounds are said by biochemists to be "conjugated". 

 The combination (conjugation) prevents the phenols from 

 attacking the walls of the urinary passage. It will be seen 

 later that othier irritant substances also have their caustic 

 group "protected" or "detoxicated" by the formation of 

 nearly neutral organic compounds. 



V 



A 



V 



OK,HS0. 



phenol 



potassium 



sulphate 



phenol- 



glucuronic 



acid 



/\°-7 



CH 



V 



OH-C-H 



O H-C-OH 



OH-C- H 



C-H 



I 

 COOH 



72 



