Category:FL3F

Latest revision as of 11:58, 15 July 2011

FL3F: Flavone

Upper classes : FL Flavonoid : FL3 Flavone

[edit] Overview

The basic structure of flavone is 2-phenylbenzopyrone, the same as flavonol. The word 'flavone' first appeard in 1895^[1], indicating its yellow color. luteolin, quercetin, kaempferol were widespread natural dyes before synthetic dyes were invented in 1856 ^[2]. As a dye, flavone requires a mordant to chelate positions 4 and 5 with metallic salts. Ferric chloride gives green with 5-hydroxyflavones and brown with 3-hydroxyflavones (flavonol). Chrysin was the first flavone to be isolated in a pure form. Many members in Asteraceae contain unique flavones, especially the genus Cirsium and Onopordum in the tribe Cardueae (or equivalently, Cynareae), commonly known as thistles.

Polymethoxylated flavones

Most flavones are not widely distributed and often 7-O-glycosylated. Major dietary sources are celery, parsley, and some herbs. In citrus species, polymethoxylated flavones such as tangeretin and nobiletin are found.

apigenin

luteolin

tangeretin

nobiletin

[edit] Structure

Flavones are commonly present in vacuoles as O- and/or C-glycosides. Most glycosides are 7-, 3'-, and 4'-glycosides. 5-glycoside is rare because the 5-hydroxyl group forms a hydrogen bond with the adjacent 4-carbonyl group. Flavone glycosides have been frequently used as chemotaxonomic markers^[3].
Isovitexin (C-glycosylflavone) acts as co-pigments of anthocyanins in Iris ensata Thunb. (Japanese iris flower)^[4]

1. ↑ S. von Kostanecki and J. Jambor, Ber. Deut. Chem. Ges. 28, 2302, 1895
2. ↑ J. Piccard, Ber. Deut. Chem. Ges. 6, 884 (1873); 7, 888 (1874); 10, 176 (1877)
3. ↑ Iwashina T & Hatta H: Flavonoid glycosides from leaves of Aucuba japonica and Helwingia japonica: Phytochemical relationship with the genus Cornus J. Jap. Bot. 72:337-346, 1997
   Reference:Iwashina_T:Ootani_S:,Phytochemistry,1990,29,3639
   Reference:Iwashina T:Kamenosono K:Ueno T:,Phytochemistry,1999,51,1109
4. ↑ Iwashina T, Kamenosono K, and Yabuya T: Isolation and identification of flavonoid and related compounds as co-pigments from the flowers of Iris ensata. J. Jap. Bot. 71:281-287

[edit] Major Plant Families

[edit] 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 (443 pages)	B (53 pages)	C (395 pages)	D (72 pages)	E (33 pages)	F (11 pages)	G (77 pages)	H (4 pages)	I (23 pages)	J (2 pages)	K (17 pages)	L (104 pages)	8 (83 pages)	9 (128 pages)
	A (776 pages)
	B (15 pages)
	C (101 pages)
	D (8 pages)
	E (213 pages)
	F (135 pages)
	G (88 pages)
	1 (50 pages)
	2 (16 pages)
	3 (6 pages)
	4 (1 pages)
	9 (36 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;

[edit] Other Unusual Patterns

These types are not classified in the above chart.

[edit] 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.