Structure-antioxidant activity relationships of flavonoids and phenolic acids

http://amborella.net/2010PlantSystematics/DATA/3-24-APG%202003%20Bot%20J%20Linn%20Soc%20APGII.pdf

An update of the Angiosperm Phylogeny Group classification for the orders and families of flowering plants: APG II

Flavonoids are nearly ubiquitous in plants and are recognized as the pigments responsible for the colors of leaves, especially in autumn. They are rich in seeds, citrus fruits, olive oil, tea, and red wine. They are low molecular weight compounds composed of a three-ring structure with various substitutions. This basic structure is shared by tocopherols (vitamin E). Flavonoids can be subdivided according to the presence of an oxy group at position 4, a double bond between carbon atoms 2 and 3, or a hydroxyl group in position 3 of the C (middle) ring. These characteristics appear to also be required for best activity, especially antioxidant and antiproliferative, in the systems studied. The particular hydroxylation pattern of the B ring of the flavonoles increases their activities, especially in inhibition of mast cell secretion. Certain plants and spices containing flavonoids have been used for thousands of years in traditional Eastern medicine. In spite of the voluminous literature available, however, Western medicine has not yet used flavonoids therapeutically, even though their safety record is exceptional. Suggestions are made where such possibilities may be worth pursuing.

Tom J. Mabry

Papers

Flavonol glycosides of Nerisyrenia (cruciferae)

Pseudoguaianolides and sesquiterpene glucoside from Gaillardia coahuilensis

Labdane diterpenes from Brickellia vernicosa

Flavonoids from Ageratina saltillensis

A sesquiterpene dilactone from Helianthus maximiliani