USES OF SAPONINS 181 



plants of Phaseolus lunatus, it is present only in very small 

 quantities, or is entirely absent from the seeds of the culti- 

 vated plants. It is also present in Linum and many rubber- 

 yielding plants, such as Hevea braziliensis and species of 

 Manihot. Associated with it in its natural surroundings is 

 the enzyme phaseolunatase which is able to hydrolyse it to 

 acetone, glucose, and hydrocyanic acid,* from which it follows 

 that phaseolunatin is a glucose ether of acetone cyanhydrin. 



LOTUSIN. 



Lotusin, C 28 H 31 NO 16 , occurs in Lotus ardbicus. 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 28 H 31 N0 16 + 2H 3 = 2C 6 H 12 6 + HCN + C 15 H 10 O 6 



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 

 gf stock has been sustained by their consumption by cattle. 



SAPONINS. 



According to the researches of Greshoff,f the saponins are 

 very widely distributed in the higher plants ; he has identified 

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

 raceae, Saururaceae, Primulaceae, Loganiaceae, Oleaceae, Pole- 

 moniaceae, Proteaceae, 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, Gramineae, Liliaceae, and Gleicheniaceae. 



The term saponin, though originally restricted to a specific 



* Dunstan, Henry and Auld : "Proc. Roy. Soc.,Lond.," B., 1906,78,145,152. 

 fGreshoff : " Kew Bulletin," 1909, 397; for summary of work on saponins 

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



