88 CHEMISTRY OF PLANT LIFE 



its hydrolysis. It is found in the leaves and stems of several 

 species of millets and sorghums. Frequent cases of poisoning of 

 cattle from eating of these plants as forage have been reported. 

 On hydrolysis, dhurrin first yields glucose and paraoxy-mandelo 

 nitrile; the latter then breaks down into paraoxy-benzaldehyde 

 and HCN. 



Vicianin, CioIbsOioN, is a cyanophoric glucoside, found in 

 the seeds of wild vetch, etc. On hydrolysis, it yields glucose, 

 arabinose, and d-mandelo nitrile. It is, therefore, similar to 

 amygdalin, except that one glucose molecule is replaced by ara- 

 binose. 



THE MUSTARD OIL GLUCOSIDES 



The seeds of several species of plants of the Cruciferse or mus- 

 tard family contain glucosides in which the other characteristic 

 group is a sulfur-containing compound. These glucosides yield 

 " mustard oils " when they are hydrolyzed by the enzyme myrosin, 

 which ^accompanies them in the plant. The following glucosides, 

 found in the seeds of white and black mustard, are the best-known 

 representatives of this class. 



Sinigrin, CioHi6OgNS2K, found in black mustard seeds, when 

 hydrolyzed yields glucose, acid potassium sulfate, and allyl iso- 

 sulfocyanide (mustard oil), as indicated by the equation. 



CioHi 6 9 NS2K-{-H 2 O = C 6 Hi2O6+C 3 H5=N=C=S+KHSO4. 



The acid potassium sulfate group separates first and most 

 readily, leaving a compound known as merosinigrin, for which the 

 following formula has been suggested : 



O 



CH 2 OH . CHOH CH CHOH CH CH 



i 



i 



This compound usually breaks down into glucose and mustard 

 oil; but by special treatment it is possible to obtain from it thio- 

 glucose, CeHiiOs-SH. This indicates that in the original glu- 

 coside the glucose is linked with the mustard oil through the sulfur 

 atom. 



