A GENETICO-PHYSIOLOGICAL STUDY ON THE FORMATION ETC. 
11 
2. The Action of Oxidizing Enzymes on Flatones. 1 
When the aqueous or alcoholic extracts of the plant tissues which are rich 
in flavone, are mixed with the freshly prepared pressed plant-juice containing 
the active oxidase, a marked brown to reddish brown colour is formed instantly. 
The more flavone the extract contains, the deeper is the colour produced. On 
standing, a brownish precipitate is formed and subsides. The production of 
that colouring matter is produced at the expense of the flavone contained in 
the extract. It can be proved by testing the intensity of the reduction colour 
of the extract at the beginning and at the end of the experiment. At the end 
of the experiment, a marked decrease in the flavone content can be seen by 
means of its reduction colour, whenever the brown coloiuing matter is formed. 
The extract of leaves, twigs, white flowers, fruits, and other parts of plants 
of different species were examined and in general, the parallelism in the 
depth of the brownish colour .produced by the oxidase and that of the 
reduction colora' of the extract w r as established. The brownish colouring matter 
thus formed has its colour intensified by the addition of alkali and, on the 
addition of acid diminishes or changes to yellow. The colour change just 
mentioned is very sensitive being performed in an indicator like manner. 
Pure chemical preparations were then tried and it was found that certain 
flavones and flavonols yielded a marked oxidation colour by the action of 
oxidizing enzymes. For example, myricetin, even in a comparatively dilute 
alcoholic solution, yielded a beautiful red colour immediately after the oxidase 
was added. The colour, how r ever, was unstable, and changed to brownish red 
and finally to brown. Quercetin and luteolin yielded also a deep red colour 
rapidly changing to browra. Kæmperol, apigenin, and tringin on the other 
hand, showed practically no change. In the former cases, the reduction colour 
when tested after being acted on by the enzyme, was decidedly less deep than 
that of the control or that of the initial one, while in the latter cases, practic¬ 
ally no difference was observed showing that the flavones remained unchanged. 
Glucosides gave less characteristic colour than non glucosides. Myricitrin 
1. The full account of the investigation will be published by the author jointly with Prof. 
K. Shibata. 
