FLAVONE DERIVATIVES 



239 



tion with rhamnose or glucose as glucosides and in some cases 

 uncombined, and frequently are also associated with tannins. 



The mother substances from which all these substances 

 are derived and from which they derive their name are the 

 two compounds Flavone and Xanthone. 



CH— CH 



=CH 



CH 



YELLOW COLOURING MATTERS DERIVED FROM FLAVONE. 

 There are quite a considerable number of yellow substances 

 occurring in plants derived from Flavone, but only a few re- 

 presentative ones can be mentioned here in order to give some 

 idea of the constitution of these compounds. 



Chrysin, or dihydroxy-flavone, is a yellow colouring matter 

 occurring in several varieties of poplar, such as Populus nigra 

 and P. pyramidalis. 



O 



HO 



/\/ \ 



CH 



OH CO 

 Quercetm, or tetrahydroxy-flavonol * 



o OH 



^C / ^OH 



II N — / 



HO 



COH 



\/\ / 

 OH CO 



* Flavonol is the hydroxy! derivative of flavone ; the relationship between 

 the two substances is shown by the following formulje : — 

 O O 



c— 



II 



CH 



CO 



Flavone 



C — 



II 



COH 



CO 



Flavonol 



