90 CHEMISTRY OF PLANT LIFE 



Cymarin, the active principle of Indian hemp (Apocynum can- 

 nabinum), is similar in type to the digitalis glucosides. When 

 hydrolyzed, it yields a sugar known as "cymarose," CyHuOy, 

 which seems to be a monomethyl derivative of digitoxose, and 

 cymarigenin, C23H3oOs, a compound which is either identical or 

 isomeric with the organic residue obtained from other members of 

 this group. 



THE SAPONINS 



The saponins constitute a group of glucosides which are widely 

 distributed in plants, whose properties have been known since 

 early Grecian times. They have been found in over four hundred 

 different species of plants, belonging to more than forty different 

 orders. 



The most characteristic property of saponins is that they 

 form colloidal solutions in water which produce a soapy foam when 

 agitated, and are peculiarly toxic, especially to frogs and fishes. 

 In dry form, they have a very bitter, acrid taste, and their dust is 

 very irritating to the mucous membranes of the eye, nose, and 

 throat. 



On hydrolysis, the saponins yield a variety of sugars, glu- 

 cose, galactose, arabinose, and sometimes fructose, and even other 

 pentoses and a group of physiologically active substances, known 

 as " sapogenins." 



The more toxic forms of these glucosides are known as " sapo- 

 toxins." 



The chemical composition of the saponins varies so widely 

 that it is scarcely possible to cite typical individuals. Sarsaparilla, 

 .the dried root of smilax plants, contains a mixture of non-poi- 

 sonous saponins, from which at least four individual glucosides 

 have been isolated and studied. Corn cockle contains a highly 

 poisonous sapotoxin which, on hydrolysis, yields four molecules of 

 a sugar and one of sapogenin, CioHieC^. Other sapotoxins are 

 obtained from the roots of soapwort and from several species of 

 Gypsophila. Digitonin and digito-saponin are glucosides of this 

 type which are found in the extracts from various species of 

 Digitalis. 



