ox THE CHEMICAL ASPECTS OF CYANOGENESIS IN PLANT?. M9 



was observed to produce prussic acid when ground and moistened with 

 water, and the acid was found to be derived from a glucoside, which 

 was named lotusin. This is pale yellow in colour, and has the formula 

 CjgHjiOiijN. When hydrolysed by a specific enzyme loiase, which occurs 

 in the same plant, or by boiling it with dilute hydrochloric acid, lotusin 

 furnishes two molecules of dextrose and one molecule each of prussic acid 

 and a yellow dye, lotoflavin. 



C,^H3,0,„N + 2H,0 = C„H,„0,. + HCN + 2C„H,p, 

 Lotusin Lotoflavin. Prussic Dextrose. 



acid. 



When decomposed by boiling with ddute alkalis the glucoside 

 furnishes ammonia and lotusinic acid. 



And the latter, when boiled with dilute hydrochloric acid, decomposes into 

 lotoflavin, dextrose, and heptogluconic acid. 



The dye lotoflavin is liberated as a final product both in the acid and 

 alkaline hydroyses of lotusin, and one of the dextrose residues is obtained 

 as heptogluconic acid in the alkaline hydrolysis. These reactions indicate 

 that the cyanogen radicle in lotusin must be associated with the sugar 

 residue, and that it is probably a lotoflavin ether of maltosecyanohydrin. 

 Lotoflavin also possesses a much more complicated structure than that of 

 similar decomposition products of cyanogenetic glucosides. It is isomeric 

 with the dyes luteolin and fisetin, obtained respectively from the yellow 

 dyestuff" 'weld' and 'young fustic'; and, like its isomerides, has been 

 shown to be a flavone derivative, and to difier from each of them in the 

 positions occupied by one of the four hydroxy 1 groups. The constitution 

 of lotusin may be represented as follows : — 



C'„H.,,0,„ CH- 



I 

 CN 



Maltosecyano- 

 hydrin residue. 



OH CO 



Lotoflavin residue. 



The precise position of attachment of the lotoflavin residue to the 

 gpgar-cyanohydrin residue has not been determined, 



rhaseolunatin. 



The cyanogenetic glucosides mentioned above include all those defi- 

 nitely known to contain a cyclic nucleus. Phaseolunatin differs from 

 these in having an aliphatic nucleus. 



It w^s fipst obtained from the beans of Phaseohis himijj,s, L., grown iti 



