Category:FL

FL: Flavonoid

Structural Characteristics

Flavonoid is a class of plant secondary metabolites that have two benzene rings (each called A-ring and B-ring) connected by a chain of three carbons (Figure 1).

The carbon chain, corresponding to the numbers 2,3,4 in Figure 1, is linked to a hydroxyl group in the A-ring to form the C-ring. The class of flavonoids are usually determined by the modification pattern of the C-ring (Table 1).

FLx		FLxy
FL1	Aurones and Chalcone	FL1A	Aurone
		FL1B	Auronol
		FL1C	Chalcone
		FL1D	Dihydrochalcone
FL2	Flavanone	FL2F	Flavanone
FL3	Flavone	FL3F	Flavone
FL4	Dihydroflavonol	FL4D	Dihydroflavonol
FL5	Flavonol	FL5F	Flavonol
FL6	Flavan	FL6F	Flavan
		FL63	Flavan 3-ol
		FL64	Flavan 4-ol
		FL6D	Flavan 3,4-diol
FL7	Anthocyanin	FL7A	Anthocyanin
		FL7D	3-Desoxyanthocyanin
FLI	Isoflavonoid	FLIA	Isoflavone
		FLIB	Isoflavanone
		FLIC	Isoflavan
		FLID	Pterocarpane
		FLIE	Coumestan
		FLIF	Rotenoid
		FLIG	Coumaranochromone
		FLIH	3-Arylcoumarin
		FLII	2-Arylbenzofuran
		FLIJ	alpha-Methoxynbenzoin
FLN	Neoflavonoid	FLNA	4-Arylcoumarin
		FLNB	4-Arylchroman
		FLNC	Dalbergiquinol
		FLND	Dalbergione
		FLNE	Neoflavene
		FLNF	Coumarinic acid

names	structure	class	description
Aurones and Chalcones	100px	FL1	The C-ring is absent (chalcones) or a 5-member ring (aurones).
Flavanone	100px	FL2
Flavone	100px	FL3
Dihydroflavonol	100px	FL4	Because many flavonols (FL5) are hydroxylated at their position 3, they form a different category in our classification.
Flavonol	100px	FL5
Flavan	100px	FL6
Anthocyanin	100px	FL7
Isoflavonoid	100px	FLI
Neoflavonoid	70px	FLN

Biosynthesis

Flavonoid is synthesized through the phenylpropanoid-acetate pathway in all higher plants. It is responsible for many biological activities including pigments, anti-oxidative or anti-allergic agents, and signaling elements in nodule formation. Some of them are quite familiar in our daily life.

Familiar examples. anthocyanin (blueberry), isoflavone (soybean), rutin (soba noodle), catechin (tea), flavan-diol (tea), naringeninchalcone (tomato), polyphenol (wine, cacao)