March, i9io. j NAG AL— THE ACTION OF OXIDASE ON ANTHOCYANIN. 



67 



The decolourization of the flower extract which contains 

 anthocj-anin, by means of high temperature 1 or by some other 

 causes is a well known fact and in such cases, the reaction is 

 reversible ; namely the colour reappears if the decolourizing 

 factor is removed. In the case here dealt with, however, the 

 reaction is not reversible. The decolourized mixture does not 

 recover its initial colour even if it is again reduced. Decolouri- 

 zation, therefore, does not seem due to the intra-molecular 

 changes but a complex molecule of anthocyanin 2 seems to be 

 destroyed. To illustrate, the following observation may be 

 mentioned. A few cc of an alcoholic solution (95 per cent) of 

 quercetin (1 : 1000) is reduced by means of magnesium powder 

 and hydrochloric acid with a drop of mercury, and to that 

 mixture, a small amount of 3 per cent hydrogen peroxide is 

 added. Within an hour, the colour of the mixture disappears 

 co npletely and leaves a clear yellow solution like the original 

 quercetin solution. It is again reduced in a similar manner as 

 before. The colour recovers slightly at first, but immediately 

 vanishes, and further reduction has no power to produce the 

 colour. A similar observation is made upon the aqueous and 

 alcoholic extract of the white potato flowers which contain a 

 flavone compound in a marked degree, so that a dec]) antho- 

 cyanin colour is formed when it is reduced. [fa small amount 

 of hydrogen peroxide is added to the extract previous to the 

 treatment, the anthocyanin colour vanishes as soon as it is 



1 Fitting, B.: X.its<lir. f. Bot. 4: 81, 1912. 



2 Cf. BniBATA, K., Bhtbata, V. and KASHIWAGI, [.: Jour, fharniiiceill. Sue-. 

 Japan. No 417. Nov. 1916. They give the following constitutional formula of antho- 

 cyanin (delphinidin) \vlii< li is prepare! I.v rcilucinj,' myriretin with iiiMLriH'Miiin and 

 acetic acid, after Werner's scheme: 



OH 



oir/\/\_/ \ ii 

 Mg J \_ / 



\/\/ oir ° ,r 

 OH OH 



Mr,!!,.,,,,, 



:; :: gm of dried material ia extracted by 50 cc 95 per cenl alcohol on ihe walei 

 bath. The reduction colour of the < prepared, matche fairlj well with thai 



of a 1 : 1000 qui rcetin olution 



I I! Os 



