Category:FL5F

Flavonol

Upper classes : FL Flavonoid : FL5 Flavonol

Overview

Flavonols are most widespread of the flavonoids and the main dietary flavonols are: kaempferol, quercetin, isorhamnetin, and myricetin.

The majority of flavonol glycosides (including dihydroflavonols) are present as O-glycosides and not C-glycosides (see Glycosylation Patterns below). Most glycosides are 3-, 7-, 3'-, 4'-glycosides and their combinations. Only flavonols and flavones contain rare glycosidic sugars such as alloside (allose), mannoside (mannose), galacturonic acid (galacturonide), and apioside (this is found in isoflavone too).
Also, 2 flavonols (FL5FF8NS0002 FL5FF8NSH001) are exceptionally found from a fungus Aspergillus candidus.

Biosynthesis

Excerpt from the FL top page

	naringenin FLAVANONE		kaempferol	FLAVONOLS			quercetin		myricetin
	F3H (hydroxylase)	FLS:flavonol synthase (oxygenase)				FLS			FLS
DIHYDRO FLAVONOLS	dihydro-kaempferol	F3'H +OH in B-ring			dihydro-quercetin	F3'5'H +OH in B-ring			dihydro-myricetin

Major Plant Families

Patterns of Hydroxylation

The 5th and 6th digits of our flavonoid ID indicates the hydroxylation patterns of A-ring and B-ring (See the upper-right figure. The leftmost ring is A, rightmost is B), respectively. The following chart is spanned by these 2 digits. R indicates H or CH₃, and R' indicates H or R. Numbers are IUPAC positions. The value in each cell (such as GS: glycosilation only) corresponds to the 7th and 8th digits, which is explained at the bottom of this page.

Details of the 3rd Class: Hydroxylation pattern of A and B rings (5th and 6th digits)

Position of -OH (-OCH3) groups       6th digit → 5th digit ↓
		A (593 pages)	B (66 pages)	C (679 pages)	D (148 pages)	E (38 pages)	F (21 pages)	G (142 pages)	H (16 pages)	I (18 pages)	J (16 pages)	K (12 pages)	L (73 pages)	8 (23 pages)	9 (90 pages)
	A (992 pages)
	B (20 pages)
	C (114 pages)
	D (129 pages)
	E (284 pages)
	F (224 pages)
	G (95 pages)
	1 (42 pages)
	2 (14 pages)
	3 (14 pages)
	4 (2 pages)
	9 (5 pages)

Abbreviations used in the above chart

First Characters 

N not glycosylated; G O-glycoside; C C-glycoside; D both glycosides;

Second Characters 

S not modified; M alkylated; I prenylated; R cyclic-prenylated; F furanoFL; P pyranoFL; D furano and pyranoFL; N phenylpropanoid; C others;

Special Second Character only for Anthycyanin (FL7) 

A Galactosylated; L Glucosylated; O modified with other sugars;

Other Unusual Patterns

These types are not classified in the above chart.

Patterns of Glycosylation

The 7th and 8th digits of the flavonoid ID indicates the glycosylation, and other modification patterns, respectively. The following chart is spanned by these 2 digits. The value in each cell (such as AA for the standard form) corresponds to the 5th and 6th digits.