Structure flavonoids

Relationship between flavonoid structure and inhibition of phos-phatidylinositol 3-kinase a comparison with tyrosine kinase and protein kinase C inhibition Biochemical Pharmacology 53, 1649-57. 

CAO G, SOFIC E and prior r l (1997) Antioxidant and prooxidant behavior of flavonoids structure-activity relationships . Free Rad Biol Med, 22 (5), 749-60. 

MacGregor, J. T. Jurd, L. Mutagenicity of plant flavonoids structural requirements for mutagenic activity in Salmonella typhimurium. Mutat. Res. 1978, 54, 297-309. 

Flavonols and flavones have a double bond between C2 and C3 in the flavonoid structure and an oxygen atom at the C4 position. Furthermore, flavonols also have a hydroxyl group at the C3 position. Dihydroflavonols have the same structure as flavonols without the double bond between C2 and C3. 

Flavonoids are the largest class of phenylpropanoids in plants. The basic flavonoid structure is two aromatic rings (one from phenylalanine and the other from the condensation of three malonic acids) linked by three carbons (Fig. 3.6). Chalcone is converted to naringenin by the enzyme chalcone isomerase, which is a key enzyme in flavonoid synthesis. This enzyme, like PAL and chalcone synthase (CHS), is under precise control and is inducible by both internal and external signals. Naringenin is the... 

Walle UK and Walle T. 2002. Induction of human UDP-glucuronosyltransferase UGT1A1 by flavonoids-structural requirements. Drug Metab Dispos 30(5) 564-569. 

IR AND Raman Spectroscopic Techniques in Studies of Flavonoid Structures... 

The flavonoid modification enzymes for which DNA sequences are available, and which we have already discussed in this chapter, represent only a few of the expected activities. Heller and Forkmann tabulated 20 to 30 characterized enzymes, and given the variety of flavonoid structures identified, this must still be only a small portion of the existing activities. 

Miksicek RJ. Estrogenic flavonoids. Structural requirements for biological activity. Proc. Soc. Exp. Biol. Med. 208, 44-50, 1995. 

Sadik, C.D., Sies, H., and Schewe, T., Inhibition of 15-lipoxygenases by flavonoids structure-activity relations and mode of action, Biochem. Pharmacol., 65, 773, 2003. 

Moon, J.Y., Lee D.W., and Park, K.H., Inhibition of 7-ethoxycoumarin O-deethylase activity in rat liver microsomes by naturally occurring flavonoids structure-activity relationships, Xenobio-tica, 28, 117, 1998. 

In an interesting paper by Bernini et al., compounds with a flavonoid structure have been selectively oxyfunctionalized at the C-2 carbon atom by dimethyldioxirane (DMD). Products obtained in this way appeared to be useful starting materials to access anthocyani-dins. An example of this route is presented in Scheme 10.1. Here, 2,4-cw-flavane-4-acetate (A) was oxidized by DMD at room temperature, affording the corresponding C-2 hydroxy derivative (B) as the only product (63% yield). Further treatment of B with silica gel eliminated acetic acid to give C quantitatively. Then C was easily transformed into the flavylium salt (D) by simple addition of a 37% solution of HCl in water. 

OH-, OMe-groups C-methyl methylenedioxy groups C-prenylation (9-prenylation (dihydro)furanosubstitution pyranosubstitution complex cyclosubstitution aromatic substitution esterification chlorination. These residues may also occur combined in one flavonoid structure. 

Abbreviations such as -OH = hydroxyl, -OMe = methoxy, -Me = methyl are used throughout text and tables. Further abbreviations used to describe the flavonoid structure are explained in a footnote to Table 12.3. 

For details of the enzymes that further modify chalcone and other flavonoid structures by hydroxylation, methylation, glycosylation, and other processes, the review by Forkmann and Heller can be recommended. ... 

It is with great pleasure that we accepted the offer by CRC Press to assemble and edit this compilation of reviews on flavonoids and their properties and functions for the present volume. We considered the volume timely in that the last book of this general type, The Flavonoids — Advances in Research Since 1986 (edited by Jeffrey B. Harborne), appeared over a decade ago. Since then, advances in the flavonoid field have been nothing short of spectacular. These advances are particularly evident in the contributed chapters that cover the discovery of a variety of new flavonoids the application of advanced analytical techniques genetic manipulation of the flavonoid pathway improved understanding of flavonoid structures and physiological functions in plants and animals and, perhaps most importantly, the significance of flavonoids to human health. 

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