4 I. NAGAI : 



to obtoin the flavone from the authcx-^auiu of Antirr/iinvm by the same 

 mamier jiist quoted, but failed. She obtained oiih- a j-ellowish brown solu- 

 tiou. 



HiUatOW aud Gies (1919)' obsen-ed the revei-sible c-olom- changes in the 

 soUition of flavone and anthocyanin isolated from the flower of tuhps by means 

 of nascent hydi'ogen and hydi'ogen peroxide respectively. 



The writer obseiTed that the coloured reduction product of quercetin, 

 mj-i'icetiu, apigeuin, and luteolin yielded a yellow solution when ti'eated with 

 hydrogen jjeroxide and in the ctise of the fii'st two, the original colom-s were 

 resumed by fru'ther reduction by means of hydi'ochloric acid and magnesium 

 jwwder. If, ho\\ever, the reduced, coloured solutions were decolourized l>v 

 an excess of hydrogen ^jeroside, the yellow solution so obtained failed to 

 recover the reddish hue by reduction. 



The aqueous exti-act of the Aiolet anthoc-yanin n"om the perigone leaf of 

 Iris Kcemjjfcri and the purple one fr'om the leaf of Perillo. nanhmensis were 

 also changed to yellow hj hydrogen peroxide and they yielded again an 

 orange red colom* b}- reduction but no initial liluish hue. 

 \ The red colour of the reduced solution of quercetin, quercitiin, and 

 myricetin were converted to yellow by the addition of an aqueous solution of 

 potassium permanganate, and the fm'ther addition finulh' rendered the solution 

 completely colomless. 



The mode of action of hydi'ogen peroxide and the oxidizing enzyme on 

 anthocyanin was studied colorimetiically. One of the difliculties here met 

 with, was the change in hue as the action proceeded. It is naturally to be 

 expected that yeUow colour should increase in depth as the anthocyanin is 

 converted to a flavone like substance and at the point where fifty per cent of 

 anthocyanin is converted to the j-ellow suljstauce, the cc)lüur of the solution 

 becomes about half wa\- between red and yello^^•, namely- orange. When 

 \iolet anthocyanin is used, the change iu hue is so distinct that no dii^ect 

 comparison can be made -tt-ith the standard colom-. With red and orange-red 

 ones, however, the change in hue does not take place in a marked degi'ee up 

 to a certain point, hence the approximate measm-ement Ijecomes possible. 



1. Haurow. 15. una Gies, W. J., Experimental Stiulics on TLint Pigments. Columbi.i Univ . 

 Proc. Soc. Exp. Biol. Meil. IG : 8, 1918, Review in Chem. .\bstract. 13 : 2695, 1919. 



