Quercetin

Yellow needles (dilute alcohol, +2 water)

less than 1 mg/mL at 70 °F (NTP, 1992)

60

Very soluble in ether, methanol; soluble in ethanol, acetone, pyridine, acetic acid

Soluble in alcohol and glacial acetic acid; insoluble in water

In water, 60 mg/L at 16 °C

0.06 mg/mL at 16 °C

Sublimes (NTP, 1992)

Sublimes

When heated to decomposition it emits acrid smoke and irritating fumes.

601 to 603 °F (NTP, 1992)

316.5

316.5 °C

316 - 318 °C

Yellow needles from ethanol, dec 277-230 °C. Specific optical rotation: -83 deg at 20 °C/D (c = 0.2 in pyridine); UV max: 259, 364 nm (log epsilon 4.31, 4.39) /3-beta-Galactoside hemipentahydrate/

Quercetin appears as yellow needles or yellow powder. Converts to anhydrous form at 203-207 °F. Alcoholic solutions taste very bitter. (NTP, 1992)

Solid

164.7 Ų [M-H]- [CCS Type: DT; Buffer gas: N2; Ionization: ESI-; Dataset: TOXCAST; Source Identifier: DTXSID4021218]

158.98 Ų [M-H]- [CCS Type: DT; Method: single field calibrated with Agilent tune mix (Agilent)]；166.7 Ų [M+H]+ [CCS Type: DT; Method: single field calibrated with Agilent tune mix (Agilent)]

154.31 Ų [M+H-H2O]+ [CCS Type: TW; Method: calibrated with polyalanine and drug standards]；173.34 Ų [M+Na]+ [CCS Type: TW; Method: calibrated with polyalanine and drug standards]；169.75 Ų [M+Na]+ [CCS Type: TW; Method: calibrated with polyalanine and drug standards]；161.96 Ų [M+H]+ [CCS Type: TW; Method: calibrated with polyalanine and drug standards]

163.4 Ų [M+H]+ [CCS Type: TW; Method: calibrated with polyalanine and drug standards]

Yellow needles from dil alcohol. Becomes anhydrous at 95-97 °C. When anhydrous, decomposes at 314 °C; uv max (alcohol) 258, 375 nm (log epsilon 2.75, 2.75). One gram dissolves in 290 mL absolute alcohol, in 25 mL boiling alcohol. Soluble in glacial acetic acid; in aqueous alkaline solutions with yellow color. Practically insoluble in water. Alcoholic solutions taste very bitter. /Dihydrate/

Crystals; mp 123-125 °C; UV max (chloroform): 249, 343 nm (log epsilon 4.43, 4.14) /Pentabenzyl ether/

This chemical does not meet GHS hazard criteria for 1.3% (3 of 224) of reports.

Danger

H301 (97.3%): Toxic if swallowed [Danger Acute toxicity, oral]

P264, P270, P301+P316, P321, P330, P405, and P501 (click each P-code to see the statement)

Aggregated GHS information provided per 224 reports by companies from 3 notifications to the ECHA C&L Inventory.；Reported as not meeting GHS hazard criteria per 3 of 224 reports by companies.；There are 2 notifications provided by 221 of 224 reports by companies with hazard statement code(s).；Information may vary between notifications depending on impurities, additives, and other factors. The percentage value in parenthesis indicates the notified classification ratio from companies that provide hazard codes. Only hazard codes with percentage values above 10% are shown. For more detailed information, please visit ECHA C&L website.

Chemical: 4H-1-Benzopyran-4-one, 2-(3,4-dihydroxyphenyl)-3,5,7-trihydroxy-

4H-1-Benzopyran-4-one, 2-(3,4-dihydroxyphenyl)-3,5,7-trihydroxy-: Does not have an individual approval but may be used under an appropriate group standard

Quercetin: Does not have an individual approval but may be used under an appropriate group standard

Poison

Flash point data for this compound are not available; however, it is probably combustible. (NTP, 1992)

ACUTE/CHRONIC HAZARDS: When heated to decomposition this compound emits acrid smoke and irritating fumes. (NTP, 1992)

Ketones；Phenols and Cresols

DHHS/NTP; Toxicology & Carcinogenesis Studies of Quercetin in F344/N Rats (Feed Studies) Technical Report Series No. 409 (1992) NIH Publication No 92-3140

QUERCETIN is a strong antioxidant and a metal chelator. Promotes the formation of nitrosamines (NTP, 1992).

Sensitive to exposure to air and light. Insoluble in water.

Acute Tox. 3 (97.3%)

Fires involving this compound may be controlled with a dry chemical, carbon dioxide or Halon extinguisher. (NTP, 1992)

EYES: First check the victim for contact lenses and remove if present. Flush victim's eyes with water or normal saline solution for 20 to 30 minutes while simultaneously calling a hospital or poison control center. Do not put any ointments, oils, or medication in the victim's eyes without specific instructions from a physician. IMMEDIATELY transport the victim after flushing eyes to a hospital even if no symptoms (such as redness or irritation) develop.；SKIN: IMMEDIATELY flood affected skin with water while removing and isolating all contaminated clothing. Gently wash all affected skin areas thoroughly with soap and water. If symptoms such as redness or irritation develop, IMMEDIATELY call a physician and be prepared to transport the victim to a hospital for treatment.；INHALATION: IMMEDIATELY leave the contaminated area; take deep breaths of fresh air. IMMEDIATELY call a physician and be prepared to transport the victim to a hospital even if no symptoms (such as wheezing, coughing, shortness of breath, or burning in the mouth, throat, or chest) develop. Provide proper respiratory protection to rescuers entering an unknown atmosphere. Whenever possible, Self-Contained Breathing Apparatus (SCBA) should be used; if not available, use a level of protection greater than or equal to that advised under Protective Clothing.；INGESTION: DO NOT INDUCE VOMITING. If the victim is conscious and not convulsing, give 1 or 2 glasses of water to dilute the chemical and IMMEDIATELY call a hospital or poison control center. Be prepared to transport the victim to a hospital if advised by a physician. If the victim is convulsing or unconscious, do not give anything by mouth, ensure that the victim's airway is open and lay the victim on his/her side with the head lower than the body. DO NOT INDUCE VOMITING. IMMEDIATELY transport the victim to a hospital.；OTHER: Since this chemical is a known or suspected carcinogen you should contact a physician for advice regarding the possible long term health effects and potential recommendation for medical monitoring. Recommendations from the physician will depend upon the specific compound, its chemical, physical and toxicity properties, the exposure level, length of exposure, and the route of exposure. (NTP, 1992)

Quercetin tablets and capsules should be stored at room temp, away from heat, moisture, and direct light.

SMALL SPILLS AND LEAKAGE: Should a spill occur while you are handling this chemical, FIRST REMOVE ALL SOURCES OF IGNITION, then you should dampen the solid spill material with 60-70% ethanol and transfer the dampened material to a suitable container. Use absorbent paper dampened with 60-70% ethanol to pick up any remaining material. Seal the absorbent paper, and any of your clothes, which may be contaminated, in a vapor-tight plastic bag for eventual disposal. Solvent wash all contaminated surfaces with 60-70% ethanol followed by washing with a soap and water solution. Do not reenter the contaminated area until the Safety Officer (or other responsible person) has verified that the area has been properly cleaned.；STORAGE PRECAUTIONS: You should protect this chemical from exposure to light. Keep the container tightly closed under an inert atmosphere, and store under refrigerated temperatures. (NTP, 1992)

SRP: At the time of review, criteria for land treatment or burial (sanitary landfill) disposal practices are subject to significant revision. Prior to implementing land disposal of waste residue (including waste sludge), consult with environmental regulatory agencies for guidance on acceptable disposal practices.

Excerpt from ERG Guide 154 [Substances - Toxic and/or Corrosive (Non-Combustible)]:；IMMEDIATE PRECAUTIONARY MEASURE: Isolate spill or leak area in all directions for at least 50 meters (150 feet) for liquids and at least 25 meters (75 feet) for solids.；SPILL: Increase the immediate precautionary measure distance, in the downwind direction, as necessary.；FIRE: If tank, rail tank car or highway tank is involved in a fire, ISOLATE for 800 meters (1/2 mile) in all directions; also, consider initial evacuation for 800 meters (1/2 mile) in all directions. (ERG, 2024)

RECOMMENDED RESPIRATOR: Where the neat test chemical is weighed and diluted, wear a NIOSH-approved half face respirator equipped with a combination filter cartridge, i.e. organic vapor/acid gas/HEPA (specific for organic vapors, HCl, acid gas, SO2 and a high efficiency particulate filter). (NTP, 1992)

In human myelogenous leukemia cells, quercetin was reported to arrest growth of the cell by an incr in the uptake of vincristine, a chemotherapeutic agent.

Quercetin binds, in vitro, to the DNA gyrase site in bacteria. Therefore, theoretically, it can serve as a competitive inhibitor to the quinolone antibiotics which also bind to this site ... Because of the theoretical risk of genotoxicity in normal tissues in those using cisplatin along with quercetin, those using cisplatin should avoid quercetin supplements ... Bromelain and papain are reported to incr absorption of quercetin.

Quercetin has a pro-oxidant effect and will incr the iron-dependent DNA damage induced by bleomycin. Quercetin may reduce iron to the ferrous state, which allows bleomycin to complex more readily with oxygen and produce more efficient DNA damage. A biphasic pro-oxidant effect with bleomycin has been demonstrated. At low concn incr DNA damage was noted, and at higher doses less DNA damage was noted.

Concomitant use may reduce cyclosporine /or floroquinolones/ effectiveness.

For more Interactions (Complete) data for QUERCETIN (18 total), please visit the HSDB record page.

Quercetin supplements have not been linked serum aminotransferase elevations during therapy, although there have been few focused studies of its hepatic safety. Furthermore, there have been no published reports of clinically apparent liver injury attributable to quercetin. Indeed, many in vitro and in vivo studies have shown that quercetin protects against hepatic injury caused by drugs and toxins including acetaminophen and cancer chemotherapeutic agents. These hepatoprotective effects have not been demonstrated in prospective clinical trials in humans.；Likelihood score: E (unlikely cause of clinically apparent liver injury).；Other Names: Often a component in Bioflavonoid Extracts；Drug Class: Herbal and Dietary Supplements

TERRESTRIAL FATE: Based on a classification scheme(1), an estimated Koc value of 460(SRC), determined from a water solubility of 60 mg/L(2) and a regression-derived equation(3), indicates that quercetin is expected to have moderate mobility in soil(SRC). The estimated pKas of quercetin are 7.17, 8.26, 10.13, 12,30, and 13.11(4), indicating that this compound will partially exist in the anion form in the environment at neutral pH and anions generally do not adsorb more strongly to soils containing organic carbon and clay than their neutral counterparts(5). Volatilization of quercetin from moist soil surfaces is not expected to be an important fate process because it is an anion and anions do not volatilize(SRC). Quercetin is not expected to volatilize from dry soil surfaces(SRC) based upon an estimated vapor pressure of 2.8X10-14 mm Hg(SRC), determined from a fragment constant method(6). Quercetin's rapid degradation in soil(7) suggests that biodegradation may be an important environmental fate process(SRC).

AQUATIC FATE: Based on a classification scheme(1), an estimated Koc value of 460(SRC), determined from a water solubility of 60 mg/L(2) and a regression-derived equation(3), indicates that quercetin is not expected to adsorb to suspended solids and sediment(SRC). The estimated pKas of 7.17, 8.26, 10.13, 12,30, and 13.11(4) indicate quercetin will exist partially in the anion form at pH values of 5 to 9 and therefore volatilization from water surfaces is not expected to be an important fate process(5). According to a classification scheme(6), an estimated BCF of 61(SRC), from its water solubility(2) and a regression-derived equation(3), suggests the potential for bioconcentration in aquatic organisms is moderate(SRC). Quercetin's rapid degradation in soil(7) suggests that biodegradation may be an important environmental fate process in water(SRC).

ATMOSPHERIC FATE: According to a model of gas/particle partitioning of semivolatile organic compounds in the atmosphere(1), quercetin, which has an estimated vapor pressure of 2.8X10-14 mm Hg at 25 °C(SRC), determined from a fragment constant method(2), is expected to exist solely in the particulate phase in the ambient atmosphere. Particulate-phase quercetin may be removed from the air by wet or dry deposition(SRC). Quercetin contains chromophores that absorb at wavelengths >290 nm(4) and therefore may be susceptible to direct photolysis by sunlight(SRC).

Quercetin is a specific quinone reductase 2 (QR2) inhibitor, an enzyme (along with the human QR1 homolog) which catalyzes metabolism of toxic quinolines. Inhibition of QR2 in plasmodium may potentially cause lethal oxidative stress. The inhibition of antioxidant activity in plasmodium may contribute to killing the malaria causing parasites.

The concentration in onions varies widely depending on the type of onion. Those with colored skins ... contain 25,000-65,000 mg/kg quercetin mainly as the aglycone; however, onions with white skins have only traces of flavonols, e.g., 10 mg/kg quercetin in dry skins. The quercetin concentration decreases from the outer to inner scales, with the highest levels in the outer epidermis ...

Adapted from Table 1 & 2；Table: CONCENTRATION OF QUERCETIN AS ITS GLYCOSIDE IN PLANTS [Table#4628]

The following link will take the user to the National Toxicology Program (NTP) Test Agent Search Results page, which tabulates all of the "Standard Toxicology & Carcinogenesis Studies", "Developmental Studies", and "Genetic Toxicity Studies" performed with this chemical. Clicking on the "Testing Status" link will take the user to the status (i.e., in review, in progress, in preparation, on test, completed, etc.) and results of all the studies that the NTP has done on this chemical. [http://ntp-apps.niehs.nih.gov/ntp_tox/index.cfm?fuseaction=ntpsearch.searchresults&searchterm=117-39-5]

The Koc of quercetin is estimated as 460(SRC), using a water solubility of 60 mg/L(1) and a regression-derived equation(2). According to a classification scheme(3), this estimated Koc value suggests that quercetin is expected to have moderate mobility in soil. The estimated pKas of quercetin are 7.17, 8.26, 10.13, 12,30, and 13.11(4), indicating that this compound will partially exist in the anion form in the environment at neutral pH and anions generally do not adsorb more strongly to soils containing organic carbon and clay than their neutral counterparts(5).

Quercetin is the aglucon of quercitrin, of rutin, and other glycosides. It is widely distributed in the plant kingdom, especially in rinds and barks, in clover blossoms, and ragweed pollen and has been isolated from Rhododendron cinnabarinum Hook, Ericaceae(1)

Quercetin is widely distributed in the plant kingdom, where it occurs as a condensation product (a glycoside) with sugars ... Plants /that/ contain these glycosides are: Allium ascalonicum; Allium cepa (onion); Allium porrum (leek); Anethum graveolens; Apium graveolens; Asperagus officinalis (asparagus); Brassica chinensis; Brassica napus; Brassica oleracae var. butrytis subvar. cymosa; Brassica oleraceae var. buttata; Brassica oleraceae var. captata; Brassica oleraceae var. gemmifera (plants of cabbage and mustard); Capsicum annuum (ornamental pepper); Cichorium endivia (endive); Citrus paradisi (grapefruit); Fragaria ananassa; Humulus lupulus; Latuca sativa (lettuce); Malus pumila (apple); Malus silvestris; Mangifera indica (mango); Petroselinum crispum; Prunus armeniaca; Prunus avium; Prunus domestica (European plum); Raphanus sativus (radish); Rheum spp; Ribes L.; Ribes nigrum (blackcurrant); Ribes grossularia; Rubus L.; Rubus ideaus; Rumex acetosa; Sambuccus nigra (elder); Solanum tuberosum (potato); Solanum lycopersicum; Spinacea oleraceae (spinach); Vaccinium macrocarpum ... Quercetin has been isolated from grapes, Vitis vinifera (1.4 mg/kg, fresh fruit), from leaves of the 'huckleberry', Vaccinium myrtillus (11 g/kg, dry weight, for quercetin and its glucosides), and from the leaves of Rhododendron cinnabarinum Hook. ... China tea, Camellia sinensis, has been reported to contain relatively large amounts of triglycosides of quercetin ... The total concentration of kaempferol and quercetin glycosides in tea (unspecified variety) is >10,000 mg/kg. ... This compound occurs in bracken fern (Pteridium aquilinum) ... .

/HUMAN EXPOSURE STUDIES/ ... A double-blind, placebo-controlled study compared one gram daily of oral quercetin with placebo in 27 healthy subjects ... The study continued for 28 days, during which period subjects receiving quercetin achieved plasma quercetin level 23-fold higher than levels in those on placebo. The results showed no quercetin effect on serum total cholesterol, LDL-cholesterol, HDL-cholesterol or triglyceride levels. Nor was there any effect on other factors considered to be indicators of risk for cardiovascular/thrombogenic disease, including platelet aggregation, platelet thromboxane B2 production, blood pressure and resting heart rate. There was no effect on levels of (n-6) or (n-3) polyunsaturated fatty acids in serum or platelet phospholipids ...

/HUMAN EXPOSURE STUDIES/ Intravenous admin of doses greater than 945 mg/sq m has been associated with nephrotoxicity.

/SIGNS AND SYMPTOMS/ Adverse effects reported with oral quercetin include gastrointestinal effects such as nausea, and rare reports of headache and mild tingling of the extremities ... Intravenous admin of quercetin has been associated with nausea, vomiting, diaphoresis, flushing and dyspnea.

/ALTERNATIVE and IN VITRO TESTS/ Quercetin was reported to have 1% of the estrogenic activity of estradiol in HeLa cells transfected with the human estrogen receptor and the pERE-TK-CAT reporter plasmid ...

For more Human Toxicity Excerpts (Complete) data for QUERCETIN (13 total), please visit the HSDB record page.

Quercetin's production and use as an experimental antioxidant dietary supplement(1), cosmetic preservative(2), and natural dye(3) may result in its release to the environment through various waste streams(SRC).

AEROBIC: Quercetin, along with rutin and two of their decomposition products phloroglucinol and protocatechuic acid, were rapidly degraded in soil as indicated by less than 10% of their phenolic nuclei being detected in soil and 27-57% of their structural carbons remaining in soil after 9 weeks incubation(1).

ANAEROBIC: Approximately 2% of microorganisms isolated from a sandy soil that were sensitive to cadmium and zinc were able to grow on quercetin(1). Zinc-resistant microorganisms were not able to utilize this compound(1).

Quercetin

Group 3: Not classifiable as to its carcinogenicity to humans

Volume Sup 7: Overall Evaluations of Carcinogenicity: An Updating of IARC Monographs Volumes 1 to 42, 1987; 440 pages; ISBN 92-832-1411-0 (out of print)；Volume 73: (1999) Some Chemicals that Cause Tumours of the Kidney or Urinary Bladder in Rodents and Some Other Substances

1999

1998

Quercetin

Chemical: 4H-1-Benzopyran-4-one, 2-(3,4-dihydroxyphenyl)-3,5,7-trihydroxy-

4H-1-Benzopyran-4-one, 2-(3,4-dihydroxyphenyl)-3,5,7-trihydroxy-: Does not have an individual approval but may be used under an appropriate group standard

Quercetin: Does not have an individual approval but may be used under an appropriate group standard

Quercetin is a specific quinone reductase 2 (QR2) inhibitor, an enzyme (along with the human QR1 homolog) which catalyzes metabolism of toxic quinolines. Inhibition of QR2 in plasmodium may potentially cause lethal oxidative stress. The inhibition of antioxidant activity in plasmodium may contribute to killing the malaria causing parasites.

... The 5, 7, 3', 4'-hydroxyl groups on quercetin are capable of donating electrons to quench various radical oxygen species (ROS) and other radical species ... Oxygen radicals (superoxide, hydrogen peroxide, hydroxyl radicals, and other related radicals) ... are quenched by ... antioxidant systems, including antioxidant cmpd, which balance cellular redox status involved in cellular processes for cell homeostasis ... Generally, 3 criteria are considered to assess the antioxidant activity of flavonoids in vitro: first, B ring with 2 hydroxyl groups (adjacent), second, C ring with 2,3-double bond, 4-oxo, and 3-hydroxyl group, and third, A ring with 5,7-dihydroxyl groups. Quercetin meets all 3 criteria, indicating stronger antioxidant activity ... The flavonol was reported to prevent radicals from damaging carbohydrates, proteins, nucleotides, and lipids ... The glucuronide conjugates found in the plasma were also reported to have potent antioxidant activity, indicating that the activity may be retained depending on conjugation positions ...

Cytokines such as tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) can induce apoptosis in colon cancer cells through engagement of death receptors. Nevertheless, evading apoptosis induced by anticancer drugs characterizes many types of cancers. This results in the need for combination therapy. In this study ... whether the flavonoid quercetin could sensitize human colon adenocarcinoma cell lines to TRAIL-induced apoptosis /was investigated/ ... Quercetin enhanced TRAIL-induced apoptosis by causing the redistribution of DR4 and DR5 into lipid rafts. Nystatin, a cholesterol-sequestering agent, prevented quercetin-induced clustering of death receptors and sensitization to TRAIL-induced apoptosis in colon adenocarcinoma cells ... Qercetin, in combination with TRAIL, triggered the mitochondrial-dependent death pathway, as shown by Bid cleavage and the release of cytochrome c to the cytosol. Together /the/ findings propose that quercetin, through its ability to redistribute death receptors at the cell surface, facilitates death-inducing signaling complex formation and activation of caspases in response to death receptor stimulation. Based on these results, this study provides a challenging approach to enhance the efficiency of TRAIL-based therapies.

Previously /the authors/ reported that isoflavone (genistein) activated bone sialoprotein (BSP) gene transcription is mediated through an inverted CCAAT box in the proximal BSP gene promoter. The present study investigates the regulation of BSP transcription in a rat osteoblast-like cell line, ROS 17/2.8 cells, by quercetin and its conjugated metabolite quercetin 3-glucuronide. Quercetin and quercetin 3-glucuronide (5 uM) increased the BSP mRNA levels at 12 hr and quercetin upregulated the Cbfa1/Runx2 mRNA expression at 12 hr. From transient transfection assays using various sized BSP promoter-luciferase constructs, quercetin increased the luciferase activity of the construct (pLUC3), including the promoter sequence nucleotides -116 to -43. Transcriptional stimulations by quercetin were almost completely abrogated in the constructs that included 2 bp mutations in the inverted CCAAT and FRE elements whereas the CCAAT-protein complex did not change after stimulation by quercetin according to gel shift assays. Quercetin increased the nuclear protein binding to the FRE and 3'-FRE. These data suggest that quercetin and quercetin 3-glucuronide increased the BSP mRNA expression, and that the inverted CCAAT and FRE elements in the promoter of the BSP gene are required for quercetin induced BSP transcription.

Connexin proteins form gap junctions, which permit direct exchange of cytoplasmic contents between neighboring cells. Evidence indicates that gap junctional intercellular communication (GJIC) is important for maintaining homeostasis and preventing cell transformation. Furthermore, connexins may have independent functions including tumor growth suppression. Most tumors express less connexins, have reduced GJIC and have increased growth rates compared with non-tumorigenic cells. The purpose of this study was to determine whether common flavonoids, genistein and quercetin, increase connexin43 (Cx43) levels, improve GJIC and suppress growth of a metastatic human breast tumor cell line (MDA-MB-231). Quercetin (2.5, 5 ug/mL) and genistein (0.5, 2.5, 15 ug/mL) upregulated Cx43 but failed to increase GJIC. Cx43 localized to the plasma membrane following genistein treatment (2.5, 15 ug/mL). In contrast, Cx43 aggregated in the perinuclear region following quercetin treatment (0.5, 2.5, 5, 15 ug/mL). Both genistein (15 ug/mL) and quercetin (2.5, 5, 15 ug/mL) significantly reduced MDA-MB-231 cell proliferation. In summary, genistein and quercetin increase Cx43 and suppress MDA-MB-231 cell proliferation at physiologically relevant concentrations. These results demonstrate that genistein and quercetin are potential anti-breast cancer agents.

For more Mechanism of Action (Complete) data for QUERCETIN (12 total), please visit the HSDB record page.

One male and one female volunteer were given a diet containing quercetin glucosides (64.2 mg expressed as the aglycone) ... Half-lives /were/ 3.8 hr for the distribution phase and 16.8 hr for the elimination phase ... /Quercetin glucosides/

...The elimination half-life of quercetin is approx 25 hr.

The glycosides are hydrolyzed in the body to corresponding aglycones, which are then further metabolized by scission of the heterocyclic ring to give 3,4-dihydroxy-phenyl-substituted acids ... The site of ring scission depends on structure ... with flavonols (quercetin) scission occurs at the 1,2 & 3,4 bonds to yield homoprotocatechuic acid ... These acids are further metabolized by beta-oxidation of acyl side-chain, o-methylation & demethylation, & aromatic dehydroxylation.

o-Beta-hydroxyethylated derivatives of quercetin were isolated from urine samples & separated by HPLC. The 5,7,3',4'-tetra compd was separated from 3,7,3',4'-tetra derivative. The 7,3',4'-tri & 7'-mono compounds gave 1 common peak, separated from the peak for the 7,4'-di compd.

After oral admin to ACI rats, the absorbed (14)C-quercetin was rapidly excreted into the bile & urine within 48 hr as the glucuronide & sulfate conjugates of (14)C-quercetin, 3'-o-monomethyl quercetin & 4'-o-monomethyl quercetin. Efficient metabolism and elimination of quercetin may be one reason for the lack of carcinogenicity in rats.

The metabolites of quercetin flavonols identified in urine samples collected from two male volunteers who consumed their habitual diets for three days were 3,4-dihydroxyphenylacetic acid, meta-hydroxyphenylacetic acid, and 4-hydroxy-3-methoxyphenylacetic acid ...

For more Metabolism/Metabolites (Complete) data for QUERCETIN (10 total), please visit the HSDB record page.

Quercetin has known human metabolites that include Mikwelianin and Dihydroquercetin.；Quercetin is a known human metabolite of tamarixetin and Quercitrin.

Naturally occurring or synthetic substances that inhibit or retard oxidation reactions. They counteract the damaging effects of oxidation in animal tissues.

After oral administration of a single dose of 4 g quercetin to four male and two female volunteers, neither quercetin nor its conjugates was detected in the blood or urine during the first 24 hr; 53% of the dose was recovered in the feces within 72 hr. After a single intravenous injection of 100 mg quercetin to six volunteers, the blood plasma levels declined biphasically, with half-lives of 8.8 min and 2.4 hr; protein binding exceeded 98%. In the urine, 0.65% of the intravenous dose was excreted as unchanged quercetin and 7.4% as a conjugate within 9 hr; no further excretion occurred up to 24 hr ...

When 14C-quercetin was administered orally to ACI rats, about 20% of the administered dose was absorbed from the digestive tract, more than 30% was decomposed to yield 14-CO2 & about 30% was excreted unchanged in feces..

One male and one female volunteer were given a diet containing quercetin glucosides (64.2 mg expressed as the aglycone). The mean peak plasma concentration of quercetin was 196 ng/mL which was reached 2.9 hr after ingestion. The time-course of the plasma concentration of quercetin was biphasic, with half-lives of 3.8 hr for the distribution phase and 16.8 hr for the elimination phase. Quercetin was still present in plasma 48 hr after ingestion ... /Quercetin glucosides/

Autoradiographic analysis of a fasted rat 3 hr after administration of a single oral dose of 2.3 mg/kg (4-(14)C)quercetin showed that although most of the radiolabel remained in the digestive tract it also occurred in blood, liver, kidney, lung and ribs. After oral administration of 630 mg/kg of the labelled compound to rats, 34% of the radiolabel excreted within 24 hr ... was expired carbon dioxide, 12% in bile and 9% in urine; within 48 hr, 45% was recovered in the feces. Approximately 60% of the radiolabel in the feces was identified as unmetabolized quercetin ...

For more Absorption, Distribution and Excretion (Complete) data for QUERCETIN (9 total), please visit the HSDB record page.

Membrane

Dietary supplement

Quercetin has been used in ... dyes and as a veterinary drug.

Medicine, reported formation of epoxy resins on mixing with epichlorohydrin

Free-radical inhibiting antioxidant useful in cosmetics intended to protect the product from oxidative damage from UV radiation or singlet oxygen formation ... Use levels are normally about 0.1% and rarely exceed 0.2%.

For more Uses (Complete) data for QUERCETIN (8 total), please visit the HSDB record page.

Quercetin ... has been obtained for use as a natural coloring agent (Natural Yellow 10) by the rapid extraction of powdered quercitron bark with dilute ammonia and boiling of the extract with sulphuric acid ... The first successful synthesis of quercetin was reported in 1962 ... in which treatment of 2-methoxyacetyl phloroglucinol with O-benzylvanillic acid anhydride in triethylamine and then with potassium hydroxide produced 5,7-dihydroxy-4'-benzyloxy-3,3'- dimethexyflavone. The benzyl ether was cleaved with acetic acid-hydrochloric acid, and the methyl ethers were then cleaved with hydriodic acid to produce quercetin.

Isolation from Rhododendron cinnabarinum Hook, Ericaceae

/Isolation from/ bark of fir trees, also synthetically

Supplied as capsules & tablets

Glycosylated forms include rutin and quercetrin

Intravenous soln in ethanol or DMSO ...

Food Additives -> COLOUR -> JECFA Functional Classes

4H-1-Benzopyran-4-one, 2-(3,4-dihydroxyphenyl)-3,5,7-trihydroxy-: ACTIVE

Natural antioxidant ... Plant dye

Flavone dye ...(flavus , Latin for yellow) ... has lost commercial value since the advent of synthetic dyes in 1856