1^2 PHYSIOLOGY OF NUTRITION 



cane sugar is there any transformation of the latter into starch; Bohm obtained 

 quite analogous results by artificially supplying sugar to the plant. 



§10. Glucosides."— Glucosidesi are chemical combinations of glucose (some- 

 times of other sugars) with various other substances, and they are spUt into their 

 component parts by the action of acids or glucoside-splitting enzymes. For 

 example, under the influence of emulsin, arbutin takes up water and produces 

 hydroquinone and glucose. This reaction is shown below :" 



I 1 



CH2OH— CHOH— CH— CHOH— CHOH— CH— OCeHiOH (arbutin) + 



, ' 1 



H2O (water) = CH2OH—CHOH—CH—CHOH—CHOH—CHOH (glucose) + 



HOC6H4OH (hydroquinone). 



Indican, a glucoside of the indigo plant, etc., forms glucose and indoxyl, 

 with the taking up of water: 



CvHeNC— O— CeHuOs (indican) + H2O (water) = 



/COH. 

 CeHiaOe (glucose) + CsHZ >CH (mdoxyl). 



Indoxyl oxidizes in the air, forming dark blue indigo tin (indigo blue) and water: 



2C8H7ON + 02 = 2H2O X Cl6Hio02N2. 



Indigotin has the structural formula, 



CeH/ >C=C( >C6H4. 



\NH/ \nH/ 



As a third example may be mentioned amygdalin, an a-^ glucoside of almond, 



peach, etc., which takes up water and splits into glucose, benzaldehyde and 



hydrocyanic acid: 



I O , 



CH2OH— CHOH— CH— CHOH - CHOH— CH— O— CH2— CHOH— 



CeHs 



CH— CHOH— CHOH— CH—O—CH (amygdaUn) + H2O (water) = 2C6H12O6 



I ' I 



CN 



(glucose) + CeHs — CHO (benzaldehyde) + HCN (hydrocyanic acid). 



Glucosides may undergo autolysis in the tissues. Thus, if leaves of Polygo- 

 gonum tinctorium are exposed to an atmosphere saturated with chloroform 

 vapor (which kills the cells), blue indigotin is formed in the tissues. The chlor- 

 ophyll may then be extracted by alcohol, leaving the leaves blue. When 



> Rijn, van, igoa. [See note 3, p. 295.] 



• This sectioti appears for the first time in the 7th Russian edition. — Ed. 



" For this and similar statements of formulas and reactions, see Haas and Hill, 1913. [See 

 note 3, p. 6.] Also see works on organic chemistry; an excellent short treatise for physio- 

 logical students is Bemthsen, A., A text-book of organic chemistry. Translated and edited 

 by J. J. Sudborough. New York. 1907. — Ed. 



