86 CHEMISTRY OF PLANT LIFE 



Natural indigo dye is prepared by fermentation of indigo leaves, 

 the decay of the cell-walls liberating the enzymes in the tissues, 

 which bring about the chemical changes illustrated in the above 

 equations. 



THE CYANOPHORE GLUCOSIDES 



Several glucosides which yield hydrocyanic acid as one of the 

 products of their hydrolysis are of common occurrence in plants. 

 These are generally spoken of as the " cyanogenetic " glucosides; 

 but as they do not actually produce cyanogen compounds, but only 

 liberate them when hydrolyzed, the recently suggested term "cy- 

 anophore" undoubtedly more correctly indicates their properties. 



The best known and most widely distributed of these is 

 amygdalin. Amygdalin was first discovered in 1830, and was one 

 of the first substances to be recognized as a glucoside. It is found 

 in large quantities in bitter almonds and in the kernels of apricots, 

 peaches, and plums; also in the seeds of apples, etc., in fact in 

 practically all the seeds of plants of the Rose family. It is the 

 mother substance for " oil of bitter almonds," which is widely 

 used as a flavoring extract. 



Amygdalin has been the object of very extensive studies, and 

 even yet the exact nature of the linkage between its constituent 

 groups is not certainly known. When completely hydrolyzed, it 

 yields two molecules of glucose and one each of benzaldehyde and 

 hydrocyanic acid. Recent studies indicate that the two sugar 

 molecules are separately united to the other constituents, rather 

 than united with each other in the disaccharide relationship. In 

 other words, amygdalin is a true glucoside rather than a maltoside. 

 This is indicated by the fact that when submitted to the action of 

 all known hydrolyzing agents which affect it, it has never been 

 found to yield maltose as one of the products of hydrolysis. 

 Furthermore, the rate of hydrolysis of amygdalin is not affected 

 by the presence of maltose; and the segregation of the two glu- 

 cose molecules is accomplished by enzymes other than maltase, 

 which is the only enzyme which is known to break up a maltose 

 molecule. Since the exact nature of the linkage is not known, it is 

 customary and convenient to indicate the unit groups as linked 

 together in the following order: 



C 6 Hn0 5 O C 6 Hi 4 O C 6 H 5 CH C=N 



(1) (2) (3) (4) 



