SAPONINS 261 



LOTUSIN. 



Lotusin, CggHgiNOie, occurs in Lotus arahicus. It is a 

 bitter, yellow-coloured substance, which when fresh does not 

 reduce Fehling's solution. 



On hydrolysis it yields glucose, hydrocyanic acid, and 

 lotoflavin, a bright yellow crystalline precipitate — 



C^gHsiNOie + 2H2O = 2CeHi20e + HCN -f C^,n^,0^ 



Lotoflavin 



Lotusin, like dhurrin, does not occur in old plants with 

 ripe seeds ; it is present only in the younger stages of develop- 

 ment. 



It is hardly necessary to point out the economic importance 

 of this occurrence of cyanogenetic glucosides in the younger 

 stages of plants like Lotus arabicus and Sorghum ; much loss 

 of stock has been sustained by their consumption by cattle. 



SAPONINS. 



According to the researches of Greshoff,* the saponins are 

 very widely distributed in the higher plants ; he has identified 

 them in various plants belonging to the natural orders : Pipe- 

 raceae, Saururacege, Primulaceae, Loganiaceae, Oleaceae, Pole- 

 moniaceae, Proteacese, Caprifoliaceae, Compositae, Cucurbitaceae, 

 the majority of the natural orders of the cohort Centrospermae, 

 Ranunculaceae, Magnoliaceae, Leguminosae, Rosaceae, Saxifra- 

 gaceae, Pittosporaceae, Polygalaceae, Rutaceae, Rhamnaceae, 

 Guttiferae, Thymelaeaceae, Combretaceae, Myrtaceae, Lecythi- 

 daceae, Araliaceae, Gramines, Liliaceae, and Gleicheniacese. 



The term saponin, though originally restricted to a specific 

 substance obtained from the root of Saponaria rubra and S. alba 

 is now applied to a large group of compounds, all of which 

 have properties similar to those possessed by the orginal 

 saponin. 



Physical and Chemical Properties. 



The saponins are mostly amorphous colloidal substances 

 which dissolve readily in water ; their aqueous solutions, if 



* Greshoff : " Kew Bulletin," 1909, 397 ; for summary of work on 

 saponins, see Winterstein and Maxim: " Helv. Chim. Acta," 1919. 2, 195. 



