Flavones
Flavones (flavus = yellow), are a class of flavonoids based on the backbone of 2-phenylchromen-4-one (2-phenyl-1-benzopyran-4-one) shown on the right.
Natural flavones include Apigenin (4',5,7-trihydroxyflavone), Luteolin (3',4',5,7-tetrahydroxyflavone) and Tangeritin (4',5,6,7,8-pentamethoxyflavone), chrysin(5,7-OH), 6-hydroxyflavone, baicalein (5,6,7-trihydroxyflavone), scutellarein (5,6,7,4'-tetrahydroxyflavone), wogonin (5,7 -OH, 8 -OCH3). Synthetic flavones are Diosmin and Flavoxate.
Metabolism in humans
The enzyme encoded by the gene UGT1A8 has glucuronidase activity with many substrates including flavones.[1]
Intake and putative beneficial effects
Flavones are mainly found in cereals and herbs. In the West, the estimated daily intake of flavones is in the range 20–50 mg per day.[2] In recent years, scientific and public interest in flavones has grown enormously due to their putative beneficial effects against atherosclerosis, osteoporosis, diabetes mellitus and certain cancers.[3] Flavones intake in the form of dietary supplements and plant extracts has been steadily increasing.
Natural dietary flavones, found in parsley, celery, and citrus peels, reactivate DLC1 (Deleted in Liver Cancer 1) expression in breast cancer cell lines which have decreased DLC1 expression due to promoter hypermethylation, and may potentially be used as an anti-cancer agent for prevention and therapy of breast and other DLC1 downregulated cancers.[4]
Drug interactions
Flavones have effects on CYP (P450) activity [5][6] which are enzymes that metabolize most drugs in the body.
Organic chemistry
In organic chemistry several methods exist for the synthesis of flavones:
- the Allan–Robinson reaction
- the Auwers synthesis
- the Baker–Venkataraman rearrangement
- the Algar–Flynn–Oyamada reaction
Another method is the dehydrative cyclization of certain 1,3-diaryl diketones [7]
this particular study making use of an ionic liquid solvent and microwave irradiation.
Wessely–Moser rearrangement
The Wessely–Moser rearrangement (1930)[8] has been an important tool in structure elucidation of flavonoids. It involves the conversion of 5,7,8-trimethoxyflavone into 5,6,7-trihydroxyflavone on hydrolysis of the methoxy groups to phenol groups. It also has synthetic potential for example:[9]
This rearrangement reaction takes place in several steps: A ring opening to the diketone, B bond rotation with formation of a favorable acetylacetone-like phenyl-ketone interaction and C hydrolysis of two methoxy groups and ring closure.
External links
- Flavones at the US National Library of Medicine Medical Subject Headings (MeSH)
References
- ↑ Ritter JK, Chen F, Sheen YY, Tran HM, Kimura S, Yeatman MT, Owens IS (Mar 1992). "A novel complex locus UGT1 encodes human bilirubin, phenol, and other UDP-glucuronosyltransferase isozymes with identical carboxyl termini". J Biol Chem 267 (5): 3257–61. PMID 1339448.
- ↑ Cermak R, Wolffram S (October 2006). "The potential of flavonoids to influence drug metabolism and pharmacokinetics by local gastrointestinal mechanisms". Curr. Drug Metab. 7 (7): 729–44. doi:10.2174/138920006778520570. PMID 17073577.
- ↑ Cermak R (January 2008). "Effect of dietary flavonoids on pathways involved in drug metabolism". Expert Opin Drug Metab Toxicol 4 (1): 17–35. doi:10.1517/17425255.4.1.17. PMID 18370856.
- ↑ Ullmannova V, Popescu NC (2007). "Inhibition of cell proliferation, induction of apoptosis, reactivation of DLC1, and modulation of other gene expression by dietary flavone in breast cancer cell lines". Cancer Detect Prev. 31 (2): 110–8. doi:10.1016/j.cdp.2007.02.005. PMC 1950447. PMID 17418982.
- ↑ Cermak R, Wolffram S., The potential of flavonoids to influence drug metabolism and pharmacokinetics by local gastrointestinal mechanisms,Curr Drug Metab. 2006 Oct;7(7):729-44.
- ↑ Si D, Wang Y, Zhou YH, et al. (March 2009). "Mechanism of CYP2C9 inhibition by flavones and flavonols". Drug Metab. Dispos. 37 (3): 629–34. doi:10.1124/dmd.108.023416. PMID 19074529.
- ↑ Sarda SR, Pathan MY, Paike VV, Pachmase PR, Jadhav WN, Pawar RP (2006). "A facile synthesis of flavones using recyclable ionic liquid under microwave irradiation". Arkivoc xvi: 43–8.
- ↑ Wessely F, Moser GH (December 1930). "Synthese und Konstitution des Skutellareins". Monatsh. Chem. 56 (1): 97–105. doi:10.1007/BF02716040.
- ↑ Larget R, Lockhart B, Renard P, Largeron M (April 2000). "A convenient extension of the Wessely-Moser rearrangement for the synthesis of substituted alkylaminoflavones as neuroprotective agents in vitro". Bioorg. Med. Chem. Lett. 10 (8): 835–8. doi:10.1016/S0960-894X(00)00110-4. PMID 10782697.
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