GLUCOSIDES 257 



AMYGDALIN. 



Amygdalin, C20H27NO11, is a laevo-rotatory bitter substance 

 which is fairly soluble in water, and gives with concentrated 

 sulphuric acid a pale reddish-violet coloration ; this, however, 

 is not a distinctive test, since the same coloration is given by 

 some other glucosides. 



Amygdalin occurs in the seeds of the bitter almond, Pyrus 

 Amygdalus ; it is, however, generally stated not to occur in 

 the seeds of the cultivated almond, the sweet variety, although 

 emulsin, its appropriate enzyme, is present. Dunstan and 

 Henry have shown that traces of hydrocyanic acid occur in 

 the seeds, and more than traces in the seedlings, of the sweet 

 almond ; it is probable, therefore, that a small quantity of 

 amygdalin does occur in the sweet variety. This relative 

 absence of glucoside in the cultivated plant is important, and 

 the same phenomenon occurs in Phaseolus lunatus. The seeds 

 of the wild plant yield large quantities of hydrocyanic acid, 

 whereas those of the cultivated plants give very Uttle or 

 none. 



Amygdalin has also been described as occurring in Pyrus 

 Malus, Pyrus Aucuparia, Pyrus cydonia and other plants. 



This glucoside may be obtained by crushing the seeds of 

 the bitter almond and subjecting the mass to considerable 

 pressure between hot iron plates in order to remove the oil. 

 The solid cake is then digested with hot alcohol which dis- 

 solves out the amygdalin. The alcoholic extract is evaporated 

 down when the amygdalin separates out in scale-like crystals 

 belonging to the monoclinic system. 



It has already been mentioned that the appropriate enzyme 

 generally occurs in the same tissues as the glucoside ; this 

 being so, the bitter almonds have only to be crushed in water 

 in order to bring the ferment emulsin into contact with the 

 amygdalin to bring about the hydrolysis. 



The study of the enzymic hydrolysis of amygdalin has 

 revealed the fact that emulsin is not a single enzyme, as was 

 once thought, but a preparation consisting of a number of 

 different constituents comparable to an extract of yeast or 



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