200 



BIOCHEMICAL SYSTEMATICS 



FLAVONOLS 



These, like most of the flavonoids other than anthocyanins, 

 are colored yellow or cream or have hardly any color. The basic 

 flavonol nucleus is illustrated below. 



HO 



HO 



kaempferol 



Substitutions, similar to some of those illustrated in the anthocyanins, 

 also occur in the flavonol class. For example, other well known 

 flavonols are quercetin (analogous to the anthocyanin cyanidin), and 

 myricetin (analogous to the anthocyanin delphinidin). Flavonols are 

 common flavonoid constituents and, like the anthocyanins, widely 

 distributed. 



FLAVONES 



These are similar to flavonols but lack the 3-hydroxyl group. 



HO 



OH 



OH 



FLAVANONES 



HO O 



FLAVANONOLS 



HO 



HO O 



