282 MISCELLANEOUS NITROGEN AND SULFUR COMPOUNDS 



The general structure of all the parent glucosides is: 



R S-^-(yLUCOSYL 



C 



II 

 N 

 I 

 



I 



o=s=o 

 I 



0" 



R may be a simple alkyl group or may be rather complex. As shown, the glucosides are 

 anions which normally are found as potassium salts but may also occur as salts of organic 

 nitrogen bases. The salts are colorless, water-soluble compounds which can be crystal- 

 lized with difficulty. The glucosides are split by the action of an enzyme or enzyme com- 

 plex known as myrosinase (24) which is present in all plants containing these glucosides. 

 Simple hydrolysis would be expected to yield a hydroxamic acid, glucose, and inorganic 

 sulfate. In fact, the hydromamic acid usually undergoes an immediate Lossen rearrange- 

 ment to form an eso -thiocyanate: 



R S-(rLUCOSYL 



N 

 I 







I 



o=s 

 I 

 0- 



II 



N 

 I 

 OH 





->RN=:C=S + 



H2O 



There are other alternate enzymatic processes which frequently occur to some extent. 

 In some plants the R group migrates to sulfur rather than to nitrogen so that thiocyanates 

 rather than iso -thiocyanates are formed (25). In Lepidium sativum both types of reaction 

 go on simultaneously. In still other plants nitriles are formed by an entirely obscure 

 reaction: 



RC 



^NOSOg 



S-&LUCOSYL 



RSCN THIOCYANATE 



RCN 



NITRiLE 



If an Jso-thiocyanate is produced, it may undergo further non-enzymatic reaction with 

 sufficiently active hydroxyl groups which may be present. This is a well-known reaction 

 of all is ti -thiocyanates and results in an N-substituted thiourethane: 



