A GF.NETICÜ-PHYSIOLOOICiU:. STt'DY OX THE FOUMATION ETC. H 



2. The Action of Oxidizko Enzymes ox Fiavoxes.' 



A\'lien the aqueous or nJwIiolic extracts of the plaut tissues which are lich 

 iu ihivoue, are uiixccl with the freshly prcpared ijressed i^laut-juice oontaiuing 

 the ivotive oxidase, a marked bi-own to reddish browu colour is formed iustautly. 

 The iiiuvt> ilaM)uo the extract contains, the deepar is the colour produced. On 

 standing, a brownish jirecipitate is formed and subsides. Thj production of 

 that colouring matter is produced at the expense of the flavone contained in 

 the exti-act. 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 mai'ked deci-ease in the flavone content can Ije seen by 

 means of its reduction colom-, whenever the brown coloiu'ing matter is formed. 



The extract of leaves, twigs, white flowei-s, fruits, and other parts of plants 

 of dLflerent species were examined and iu general, the parallelism iu the 

 depth of the l)rowuisli colour produced b}' tha osidasi and that of the 

 reduction colour of the extract was established. The In-owuish colouring luatter 

 thus formed has its colom- intensified l)y the addition of alkali aud, on tlie 

 addition of acid diminishes or changes to yellow. The colour chauge jast 

 mentioned is vei-y sensitive being performed in an indicator like maimer. 



Pure chemical preparations were then tried and it was fouud that certain 

 flavones and flavonols yielded a marked oxidation colour In' the action of 

 oxidizing enzymes. For example, m_^Ticetin, eveu iu a comparatively dilute 

 alcoholic solution, yielded a beautiful red colour immediately after the oxidase 

 was added. The colour, however, was unstable, and changed to brownish red 

 and finally to brown. Quercetin aud luteolin ^-ielded also a deep red colour 

 rapidly clianging to brown. Kasmperol, apigeuin, 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 decidedlj- less deep than 

 that of the control or that of the initial one, while iu the latter cases, practic- 

 iiWy no düTerence ^^■as observed showing that the flavones remained unchanged. 



Glucosides gave less characteristic colour than non glucosides. Mjricitriu 



1. Tbu till (iccoimt of the investigation will be published liy the author jointly with I'rof. 

 K. Shibata. 



