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.
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.[1] 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.[2] Flavones intake in the form of dietary supplements and plant extracts has been steadily increasing.
Drug interactions
Flavones have effects on CYP (P450) activity [3][4] which are enzymes that metabolize most drugs in the body.
Organic chemistry
In organic chemistry several methods exist for the synthesis of flavones:
Another method is the dehydrative cyclization of certain 1,3-diaryl diketones [5]
this particular study making use of an ionic liquid solvent and microwave irradiation.
Wessely-Moser rearrangement
The Wessely-Moser rearrangement (1930) [6] 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[7]:
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
References
- ^ Cermak R, Wolffram S (October 2006). "The potential of mongonoids to influence drug metabolism and pharmacokinetics by local gastrointestinal mechanisms". Curr. Drug Metab. 7 (7): 729–44. doi:10.2174/138920006778520570. PMID 17073577. http://www.bentham-direct.org/pages/content.php?CDM/2006/00000007/00000007/0004F.SGM.
- ^ 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. http://www.informapharmascience.com/doi/abs/10.1517/17425255.4.1.17.
- ^ 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. http://dmd.aspetjournals.org/cgi/pmidlookup?view=long&pmid=19074529. [1]
- ^ 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. http://www.arkat-usa.org/ARKIVOC/JOURNAL_CONTENT/manuscripts/2006/06-2210HP%20as%20published%20mainmanuscript.pdf.
- ^ Wessely F, Moser GH (December 1930). "Synthese und Konstitution des Skutellareins". Monatsh. Chem. 56 (1): 97–105. doi:10.1007/BF02716040. http://www.springerlink.com/content/p61843913k3350l3/?p=b310e8658f3c400c8b382dbd980a1cdd&pi=7.
- ^ 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. http://linkinghub.elsevier.com/retrieve/pii/S0960-894X(00)00110-4.
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| O-methylated flavones |
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| Glycosides |
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| acetylated |
Artoindonesianin P
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| Synthetic |
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