Flavones
From Wikipedia, the free encyclopedia
Flavones 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.
Contents |
[edit] 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.
[edit] Drug interactions
Flavones have effects on CYP (P450) activity [3] [4]which are enzymes that metabolize most drugs in the body.
[edit] 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 [5]
this particular study making use of an ionic liquid solvent and microwave irradiation.
[edit] 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.
[edit] External links
[edit] References
- ^ 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:. 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:. 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:. 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:. 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:. PMID 10782697. http://linkinghub.elsevier.com/retrieve/pii/S0960-894X(00)00110-4.
|
||||||||
