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Quercetin

Names
IUPAC name 2-(3,4-dihydroxyphenyl)-3,5,7-trihydroxy-4H-chromen-4-one
Other names Sophoretin Meletin Quercetine Xanthaurine Quercetol Quercitin Quertine Flavin meletin
Identifiers
CAS Number	117-39-5
3D model (JSmol)	Interactive image
ChEMBL	ChEMBL50
ChemSpider	4444051
ECHA InfoCard	100.003.807
KEGG	C00389
PubChem CID	5280343
UNII	9IKM0I5T1E
CompTox Dashboard (EPA)	DTXSID4021218
InChI InChI=1S/C15H10O7/c16-7-4-10(19)12-11(5-7)22-15(14(21)13(12)20)6-1-2-8(17)9(18)3-6/h1-5,16-19,21HKey: REFJWTPEDVJJIY-UHFFFAOYSA-N InChI=1/C15H10O7/c16-7-4-10(19)12-11(5-7)22-15(14(21)13(12)20)6-1-2-8(17)9(18)3-6/h1-5,16-19,21HKey: REFJWTPEDVJJIY-UHFFFAOYAW
SMILES O=C1c3c(O/C(=C1/O)c2ccc(O)c(O)c2)cc(O)cc3O
Properties
Chemical formula	C15H10O7
Molar mass	302.236 g/mol
Density	1.799 g/cm
Melting point	316 °C
Except where otherwise noted, data are given for materials in their standard state (at 25 °C , 100 kPa). Y verify (what is  ?) Infobox references

Quercetin Template:IPA-en, a flavonol, is a plant-derived flavonoid found in fruits, vegetables, leaves and grains. It also may be used as an ingredient in supplements, beverages or foods.

Research

Several laboratory studies show quercetin may have anti-inflammatory and antioxidant properties, and it is being investigated for a wide range of potential health benefits.

Quercetin has been shown to increase energy expenditure in rats, but only for short periods (fewer than 8 weeks). Effects of quercetin on exercise tolerance in mice have been associated with increased mitochondrial biogenesis.

The American Cancer Society says while quercetin "has been promoted as being effective against a wide variety of diseases, including cancer," and "some early lab results appear promising, as of yet there is no reliable clinical evidence that quercetin can prevent or treat cancer in humans." In the amounts consumed in a healthy diet, quercetin "is unlikely to cause any major problems or benefits."

Adequate dietary intake of fruits and vegetables may reduce the risk of cancer. Research shows quercetin influences cellular mechanisms in vitro and, in animal studies, there is evidence from human population studies that quercetin may, in a very limited fashion, reduce the risk of certain cancers.

In laboratory studies of cells in vitro, quercetin produces changes that are also produced by compounds that cause cancer (carcinogens), but these studies do not report increased cancer in animals or humans. The U.S. Food and Drug Administration has not approved any health claims for quercetin. There is current early-stage clinical research on quercetin addressing safety and efficacy against sarcoidosis, asthma and glucose absorption in obesity and diabetes (February 2009).

Quercetin is the aglycone form of a number of other flavonoid glycosides, such as rutin and quercitrin, found in citrus fruit, buckwheat and onions. Quercetin forms the glycosides quercitrin and rutin together with rhamnose and rutinose, respectively. Quercetin is classified as IARC group 3 (no evidence of carcinogenicity in humans).

Occurrence

Quercetin is a naturally-occurring polar auxin transport inhibitor.

Foods rich in quercetin include black and green tea (Camellia sinensis; 2000–2500 mg/kg), capers (1800 mg/kg), lovage (1700 mg/kg), apples (44 mg/kg), onion, especially red onion (1910 mg/kg) (higher concentrations of quercetin occur in the outermost rings), red grapes, citrus fruit, tomato, broccoli and other leafy green vegetables, and a number of berries, including raspberry, bog whortleberry (158 mg/kg, fresh weight), lingonberry (cultivated 74 mg/kg, wild 146 mg/kg), cranberry (cultivated 83 mg/kg, wild 121 mg/kg), chokeberry (89 mg/kg), sweet rowan (85 mg/kg), rowanberry (63 mg/kg), sea buckthorn berry (62 mg/kg), crowberry (cultivated 53 mg/kg, wild 56 mg/kg), and the fruit of the prickly pear cactus. A recent study found that organically grown tomatoes had 79% more quercetin than "conventionally grown".

A study by the University of Queensland, Australia, has also indicated the presence of quercetin in varieties of honey, including honey derived from eucalyptus and tea tree flowers.

Biosynthesis

File:Biosynthesis of Quercetin.jpg The biosynthesis of quercetin is summarized in the above figure. Phenylalanine(1) is converted to 4-coumaroyl-CoA(2) in a series of steps known as the general phenylpropanoid pathway using phenyl ammonia-lyase, cinnamate-4-hydroxylase, and 4-coumaroylCoA-ligase. 4-coumaroyl-CoA(2) is added to three molecules of malonyl-CoA(3) to form tetrahydroxychalcone(4) using 7,2’-dihydroxy, 4’-methoxyisoflavanol synthase. Tetrahydroxychalcone(4) is then converted into naringenin(5) using chalcone isomerase. Naringenin(5) is then converted into eriodictyol(6) using flavanoid 3’ hydroxylase. Eriodictyol(6) is then converted into dihydroquercetin(7) with flavanone 3-hydroxylase, which is then converted into quercetin using flavanol synthase.

Possible medicinal properties

This section needs additional citations for verification. Please help improve this article by adding citations to reliable sources in this section. Unsourced material may be challenged and removed. Find sources: "Quercetin" – news · newspapers · books · scholar · JSTOR (February 2010) (Learn how and when to remove this message)

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From in vitro studies, quercetin has demonstrated significant anti-inflammatory activity by inhibiting both synthesis and release of histamine and other allergic/inflammatory mediators. In addition, it may have antioxidant activity and vitamin C-sparing action.

In vitro, cultured skin and prostate cancer cells were suppressed (compared to nonmalignant cells) when treated with a combination of quercetin and ultrasound.

It has also been claimed that quercetin reduces blood pressure in hypertensive and obese subjects in whom LDL cholesterol levels were also reduced.

An 8-year study found the presence of three flavonols — kaempferol, quercetin, and myricetin — in a normal diet was associated with 23% reduced risk of pancreatic cancer, a rare but frequently fatal disease, in tobacco smokers. There was no benefit in subjects who had never smoked or had previously quit smoking.

In mice, an oral quercetin dose of 12.5 to 25 mg/kg increased gene expression of mitochondrial biomarkers and improved exercise endurance.

An in vitro study showed quercetin and resveratrol combined inhibited production of fat cells.

A possible antagonistic interaction occurred in rats between quercetin and niacin (vitamin B₃) which, in sustained, high doses, produces a cutaneous reddening or flush.

Despite these preliminary indications of possible medicinal effects, quercetin has neither been confirmed as a specific therapeutic for any condition, nor has it been approved by any regulatory agency. A bioavailability study done on rats showed ingested quercetin is extensively metabolized into inactive phenolic acids, with more than 96% of the ingested amount excreted within 72 hours, indicating actual physiological roles, if they exist, involve quercetin in only minute amounts.

Drug interactions

Quercetin is contraindicated with some antibiotics; it may interact with fluoroquinolones (an antibiotic), as quercetin competitively binds to bacterial DNA gyrase. Whether this inhibits or enhances the effect of fluoroquinolones is not certain.

Quercetin is described as an inhibitor of CYP2C9. Sources are inconsistent as to whether quercetin is an inhibitor or inducer of CYP3A4. CYP2C9 and CPY3A4 are members of the cytochrome P₄₅₀ mixed-function oxidase system, and as such are enzymes involved in the metabolism of xenobiotics in the body. In either case, quercetin may alter serum levels, and potentially, effects of drugs metabolized by these enzymes.

In cattle, there is a synergystic interaction between bovine papillomavirus-2 infection and exposure to quercetin, promoting bladder neoplasia, clinically presenting as enzootic haematuria. A similar effect is seen on exposure to the bracken fern Pteridium aquilinum, and the chemical ptaquiloside found within it.

Glycosides

• Guaijaverin is the 3-O-arabinoside of quercetin.
• Hyperoside is the 3-O-galactoside of quercetin.
• Isoquercitin is the 3-O-glucoside of quercetin.
• Spiraeoside is the 4'-O-glucoside of quercetin.

See also

References

1. ^ Laura K. Stewart, Jeff L. Soileau, David Ribnicky, Zhong Q. Wang, Ilya Raskin, Alexander Poulev, Martin Majewski, William T. Cefalu, and Thomas W. Gettys (2008). "Quercetin transiently increases energy expenditure but persistently decreases circulating markers of inflammation in C57BL/6J mice fed a high-fat diet". Metabolism. 57.{{cite journal}}: CS1 maint: multiple names: authors list (link)
2. ^ J. Mark Davis, E. Angela Murphy, Martin D. Carmichael, and Ben Davis (2009), "Quercetin increases brain and muscle mitochondrial biogenesis and exercise tolerance", Am J Physiol Regul Integr Comp Physiol, 296{{citation}}: CS1 maint: multiple names: authors list (link)
3. Phys Ed: Is Quercetin Really a Wonder Sports Supplement? By Gretchen Reynolds. New York Times, October 7, 2009. Review of the research.
4. American Cancer Society, Quercetin
5. "Guidance for Industry: A Food Labeling Guide XI. Appendix C: Health Claims, 21 CFR 101.76 and 21 CFR 101.78, April 2008". US Department of Health and Human Services, Food and Drug Administration.
6. Neuhouser ML (2004). "Dietary flavonoids and cancer risk: evidence from human population studies". Nutr Cancer. 50 (1): 1–7. doi:10.1207/s15327914nc5001_1. PMID 15572291.
7. Murakami A, Ashida H, Terao J (2008). "Multitargeted cancer prevention by quercetin". Cancer Lett. 269 (2): 315–25. doi:10.1016/j.canlet.2008.03.046. PMID 18467024. {{cite journal}}: Unknown parameter |month= ignored (help)CS1 maint: multiple names: authors list (link)
8. Verschoyle RD, Steward WP, Gescher AJ (2007). "Putative cancer chemopreventive agents of dietary origin-how safe are they?". Nutr Cancer. 59 (2): 152–62. doi:10.1080/01635580701458186. PMID 18001209. {{cite journal}}: Unknown parameter |doi_brokendate= ignored (|doi-broken-date= suggested) (help)CS1 maint: multiple names: authors list (link)
9. Rietjens IM, Boersma MG, van der Woude H, Jeurissen SM, Schutte ME, Alink GM (2005). "Flavonoids and alkenylbenzenes: mechanisms of mutagenic action and carcinogenic risk". Mutat. Res. 574 (1–2): 124–38. doi:10.1016/j.mrfmmm.2005.01.028. PMID 15914212. {{cite journal}}: Unknown parameter |month= ignored (help)CS1 maint: multiple names: authors list (link)
10. van der Woude H, Alink GM, van Rossum BE; et al. (2005). "Formation of transient covalent protein and DNA adducts by quercetin in cells with and without oxidative enzyme activity". Chem. Res. Toxicol. 18 (12): 1907–16. doi:10.1021/tx050201m. PMID 16359181. {{cite journal}}: Explicit use of et al. in: |author= (help); Unknown parameter |month= ignored (help)CS1 maint: multiple names: authors list (link)
11. US FDA, Center for Food Safety and Nutrition, Qualified Health Claims Subject to Enforcement Discretion, April 2007
12. Clinicaltrials.gov, National Institutes of Health
13. USDA Database for the Flavonoid Content of Selected Foods
14. Crystal Smith, Kevin A. Lombard, Ellen B. Peffley, Weixin Liu (2003). "Genetic Analysis of Quercetin in Onion (Allium cepa L.) Lady Raider" (PDF). The Texas Journal of Agriculture and Natural Resource. 16. Agriculture Consortium of Texas: 24–8. Archived from the original (PDF) on February 25, 2007. {{cite journal}}: Unknown parameter |deadurl= ignored (|url-status= suggested) (help)CS1 maint: multiple names: authors list (link)
15. Sari H. Häkkinen; et al. (1999). "Content of the Flavonols Quercetin, Myricetin, and Kaempferol in 25 Edible Berries". Journal of Agricultural and Food Chemistry. 47 (6): 2274–9. doi:10.1021/jf9811065. PMID 10794622. {{cite journal}}: Explicit use of et al. in: |author= (help)
16. A. E. Mitchell, Y. J. Hong, E. Koh, D. M. Barrett, D. E. Bryant, R. F. Denison and S. Kaffka (2007). "Ten-Year Comparison of the Influence of Organic and Conventional Crop Management Practices on the Content of Flavonoids in Tomatoes". Journal of Agricultural and Food Chemistry. 55 (15): 6154–9. doi:10.1021/jf070344. PMID 17590007.{{cite journal}}: CS1 maint: multiple names: authors list (link)
17. Honey Research Unit
18. honey fingerprinting
19. Biosynthesis of quercetin.
20. Winkel-Shirley, Brenda (June 2001). "Flavonoid Biosynthesis. A Colorful Model for Genetics, Biochemistry, Cell Biology, and Biotechnology". Plant Physiol. 126 (2): 485–493. doi:10.1104/pp.126.2.485. PMC 1540115. PMID 11402179.
21. Paliwal S; Sundaram, J; Mitragotri, S (2005). "Induction of cancer-specific cytotoxicity towards human prostate and skin cells using quercetin and ultrasound". British Journal of Cancer. 92 (3): 499–502. doi:10.1038/sj.bjc.6602364. PMC 2362095. PMID 15685239.
22. Edwards RL, Lyon T, Litwin SE, Rabovsky A, Symons JD, Jalili T (1 November 2007). "Quercetin reduces blood pressure in hypertensive subjects". J. Nutr. 137 (11): 2405–11. PMID 17951477.{{cite journal}}: CS1 maint: multiple names: authors list (link)
23. Egert S; et al. (2009). "Quercetin reduces systolic blood pressure and plasma oxidised low-density lipoprotein concentrations in overweight subjects with a high-cardiovascular disease risk phenotype: A double-blinded, placebo-controlled cross-over study". Br J Nutr. 102 (7): 1065–1074. PMID 19402938. {{cite journal}}: Explicit use of et al. in: |author= (help)
24. Nöthlings U; et al. (2007). "Flavonols and pancreatic cancer risk". American Journal of Epidemiology. 166 (8): 924–931. doi:10.1093/aje/kwm172. PMID 17690219. {{cite journal}}: Explicit use of et al. in: |author= (help)
25. Davis JM, Murphy EA, Carmichael MD, Davis B. (2009). "Quercetin increases brain and muscle mitochondrial biogenesis and exercise tolerance". Am J Physiol Regul Integr Comp Physiol. 296 (4): R1071–7. doi:10.1152/ajpregu.90925.2008. PMID 19211721.{{cite journal}}: CS1 maint: multiple names: authors list (link)
26. Yang JY, Della-Fera MA, Rayalam S, Ambati S, Hartzell DL, Park HJ, Baile CA (2008). "Enhanced inhibition of adipogenesis and induction of apoptosis in 3T3-L1 adipocytes with combinations of resveratrol and quercetin". Life Sci. 82 (19–20): 1032–9. doi:10.1016/j.lfs.2008.03.003. PMID 18433793.{{cite journal}}: CS1 maint: multiple names: authors list (link)
27. Papaliodis D, Boucher W, Kempuraj D, Theoharides TC (2008). "The flavonoid luteolin inhibits niacin-induced flush". Brit J Pharmacol. 153 (7): 1382–87. doi:10.1038/sj.bjp.0707668. PMC 2437911. PMID 18223672.{{cite journal}}: CS1 maint: multiple names: authors list (link)
28. Mullen W; et al. (2008). "Bioavailability of quercetin-4'-glucoside in rats". J Agric Food Chem. 2456 (24): 12127–37. doi:10.1021/jf802754s. PMID 19053221. {{cite journal}}: Explicit use of et al. in: |author= (help); Unknown parameter |month= ignored (help)
29. Hilliard JJ, Krause HM, Bernstein JI; et al. (1995). "A comparison of active site binding of 4-quinolones and novel flavone gyrase inhibitors to DNA gyrase". Adv. Exp. Med. Biol. 390: 59–69. PMID 8718602. {{cite journal}}: Explicit use of et al. in: |author= (help)CS1 maint: multiple names: authors list (link)
30. Si Dayong, Wang Y, Zhou Y-H, Guo Y, Wang J, Zhou H, Li Z-S, Fawcett JP (2009). "Mechanism of CYP2C9 inhibition by flavones and flavonols" (PDF). Drug Metabolism and Disposition. 37 (3): 629–634. doi:10.1124/dmd.108.023416. PMID 19074529. {{cite journal}}: Unknown parameter |month= ignored (help)CS1 maint: multiple names: authors list (link)
31. Su-Lan Hsiu; Yu-Chi Hou; Yao-Horng Wang; Chih-Wan Tsao; Sheng-Fang Sue; and Pei-Dawn L. Chao (6 December 2002). "Quercetin significantly decreased cyclosporin oral bioavailability in pigs and rats". Life Sciences. 72 (3): 227–235. doi:10.1016/S0024-3205(02)02235-X.{{cite journal}}: CS1 maint: multiple names: authors list (link)
32. Judy L. Raucy (1 May 2003). "Regulation of CYP3A4 Expression in Human Hepatocytes by Pharmaceuticals and Natural Products". Drug Metabolism and Disposition. 31 (3): 533–539. doi:10.1124/dmd.31.5.533.

External links

• UMM Quercetin Info Page (University of Maryland Medical Center Website)

• Misleading articles from February 2010
• Flavonols
• Catechols
• Antioxidants
• Resorcinols
• Experimental medical treatments