• YAKHAK HOEJI
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• v.35 no.5
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• pp.401-415
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• 1991

Effects of quercetin on the specific and non-specific immune responses were studied in vivo. Quercetin at a dose of 2.5, 5, 10, 20 and 40 mg/kg were orally administered to ICR male mice once daily for 28 consecutive days. Cyclophosphamide was injected intraperitoneally to ICR mice with a single dose of 5 mg/kg 2 days before secondary immunization. Mice were sensitized and challenged with sheep red blood cells (S-RBC). Immune responses were evaluated by humoral and cellular immune reponses and non-specific immune response. The results of this study were summarized as followings; 1. Quercetin significantly decreased the body weight, and introduced the atrophy of liver, spleen and thymus gland dose-dependently, but increased the numbers of white blood cell. 2. Querectin significantly depressed the hemagglutination titer, Arthus reaction and hemolytic plaque forming cell. 3. Quercetin significantly depressed the delayed type hypersensitivity and rosette forming cell. 4. Quercetin at a dose of 2.5, 5 and 40 mg/kg significantly depressed phagocytic activity. 5. Quercetin at a dose of 10 and 20 mg/kg significantly increased natural killer cell activity.

• Journal of Pharmaceutical Investigation
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• v.34 no.1
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• pp.15-21
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• 2004

The pharmacokinetics of orally administered verapamil (10 mg/kg) was studied in six rabbits after 20 min pretreatment with quercetin ad coadministration of quercetin (2.0 mg/kg, 1 mg/g and 20 mg/kg, respectively). Pretreatment with quercetin significantly (p < 0.01, p < 0.05) increased the plasma concentration of verapamil. However, coadministration of quercetin showed no significantly effect on the pharmacokinetic parameters of verapamil. The elimination rate constant $(K_{el})$ of verapamil pretreated with quercetin (1 mg/kg and 20 mg/kg) was significantly (p < 0.05) reduced compared with control. The area under the plasma concentration-time curve (AUC) and the peak concentration $(C_{max})$ of verapamil pretreated with quercetin (2.0 mg/kg, 10 mg/kg and 20 mg/kg) were increased significantly (p < 0.01, p < 0.05) compared with control. Pretreatment with quercetin (2.0 mg/kg, 10 mg/kg and 20 mg/kg) significantly (p < 0.01, p < 0.05) increased the relative bioavailability of verapamil to 159 - 219%. These results suggest that quercetin alters disposition of verapamil by inhibition of P-glycoprotein efflux pump and its first-pass metabolism. The dosage of verapamil should be adjusted when it is administered chronically with quercetin in a clinical situation.

• BMB Reports
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• v.56 no.9
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• pp.508-513
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• 2023

The phytochemical quercetin has gained attention for its anti-inflammatory and anti-tumorigenic properties in various types of cancer. Tumorigenesis involves the aberrant regulation of kinase/phosphatase, highlighting the importance of maintaining homeostasis. Dual Specificity Phosphatase (DUSP) plays a crucial role in controlling the phosphorylation of ERK. The current study aimed to clone the DUSP5 promoter, and investigate its transcriptional activity in the presence of quercetin. The results revealed that quercetin-induced DUSP5 expression is associated with the serum response factor (SRF) binding site located in the DUSP5 promoter. The deletion of this site abolished the luciferase activity induced by quercetin, indicating its vital role in quercetin-induced DUSP5 expression. SRF protein is a transcription factor that potentially contributes to quercetin-induced DUSP5 expression at the transcriptional level. Additionally, quercetin enhanced SRF binding activity without changing its expression. These findings provide evidence of how quercetin affects anti-cancer activity in colorectal tumorigenesis by inducing SRF transcription factor activity, thereby increasing DUSP5 expression at the transcriptional level. This study highlights the importance of investigating the molecular mechanisms underlying the anti-cancer properties of quercetin, and suggests its potential use in cancer therapy.

• Nutrition Research and Practice
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• v.5 no.1
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• pp.28-33
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• 2011

Limited information from human studies indicates that dietary quercetin supplementation influences blood lipid profiles, glycemic response, and inflammatory status, collectively termed cardiometabolic risks. We tested the hypothesis that quercetin-rich supplementation, derived from onion peel extract, improves cardiometabolic risk components in healthy male smokers in a randomized, double blinded, placebo-controlled parallel design. Randomly assigned subjects were instructed to take either the placebo (n=43) or 100 mg quercetin capsules each day (n=49) for 10 weeks. Anthropometric parameters and blood pressure were measured, and blood lipids, glucose, interleukin-6, and soluble vascular cell adhesion molecule-1 (sVCAM-1) were determined at baseline and after 10 weeks of quercetin supplementation. Quercetin-rich supplementation significantly reduced serum concentrations of total cholesterol (P<0.05) and LDL-cholesterol (P<0.01), whereas these effects were not shown in the placebo group. Furthermore, significant increases were observed in serum concentrations of HDL-cholesterol both in the placebo (P<0.005) and quercetin-rich supplementation group (P<0.001); however, changes in HDL-cholesterol were significantly greater in subjects receiving quercetin-rich supplementation than the placebo. Both systolic (P<0.05) and diastolic blood pressure (P<0.01) decreased significantly in the quercetin-rich supplementation group. Glucose concentrations decreased significantly after 10 weeks of quercetin-rich supplementation (P<0.05). In contrast, no effects of quercetin-rich supplementation were observed for the inflammatory markers-IL-6 and sVCAM-1. Daily quercetin-rich supplementation from onion peel extract improved blood lipid profiles, glucose, and blood pressure, suggesting a beneficial role for quercetin as a preventive measure against cardiovascular risk.

• Korean Journal of Poultry Science
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• v.42 no.1
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• pp.33-40
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• 2015

This study was conducted to investigate the effects of dietary quercetin on growth performance, blood biochemical parameters, immunoglobulin, and blood antioxidant activity in broiler chickens. Three hundred twenty one-day old Ross broilers were divided 8 treatments (C(-), basal diet; C(+), basal diet with antibiotics; vitamin E 20 IU; vitamin E 200 IU; quercetin 20 ppm; quercetin 200 ppm; methoxylated quercetin 20 ppm; methoxylated quercetin 200 ppm) with 4 replicates and 10 birds per replicate. Birds were reared for 35 days and their feed intake and weight gain were measured weekly. At 35d, eight birds of average weight from each replicate were selected for blood collection and analysis. Weight gain of birds in the groups fed quercetin was higher when compare to NC but there was no significant difference. In the serum, creatinine, BUN and AST in quercetin groups significantly decreased compared to those of control (NC and PC) (P<0.05). The contents of IgA and IgM were significantly lower in quercetin groups than those of NC (P<0.05). SOD like activity and MDA content tended to decrease in quercetin groups, however, there was no significant difference among treatments. In conclusion, supplemental quercetin to poultry diet could be positive aspect on performance and blood metabolites. Optimum adding levels was more than 20 ppm.

• Journal of Nutrition and Health
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• v.55 no.1
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• pp.36-46
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• 2022

Purpose: Quercetin is a polyphenolic flavonoid abundant in many fruits and vegetables. It has potential health-beneficial properties, such as antioxidant, anti-obesity, anti-cancer, anti-diabetic and anti-inflammatory effects. The purpose of this study was to investigate whether the lipid metabolism improvement effect of quercetin affected the regulation of AMP-activated protein kinase (AMPK) activity and microRNA (miR)-21 expression in the liver of mice fed a high-cholesterol diet. Methods: Male C57BL/6J mice were fed with normal diet, quercetin-free diet and diets containing 0.05% or 0.1% quercetin for six weeks. Hypercholesterolemia was induced by adding 1% cholesterol and 0.5% cholic acid to all diets. Serum and liver triglyceride (TG), and total cholesterol (TC) concentrations were analyzed using a commercial enzymatic colorimetric kit. AMPK activity was quantified using an AMPK kinase assay kit. The levels of miR-21 and genes involved in lipid metabolism were measured by real-time quantitative polymerase chain reaction. Results: Supplementation of quercetin reduced serum and hepatic TG and TC levels without changing body weight and food intake. Dietary quercetin significantly inhibited the mRNA levels of hepatic sterol-regulatory element binding protein-1c, acetyl-CoA carboxylase 1 and fatty acid synthesis, which are involved in hepatic lipogenesis. Dietary quercetin enhanced AMPK activity and suppressed miR-21 expression, promoting hepatic lipid accumulation. Conclusion: These results suggest that the lipid-lowering effect of quercetin on the serum and liver of mice may be partially mediated by the regulation of lipogenic gene expression, AMPK activity and miR-21 expression in the liver of mice fed a high-cholesterol diet.

• Asian-Australasian Journal of Animal Sciences
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• v.23 no.5
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• pp.588-597
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• 2010

We investigated the effect of quercetin on growth and plasma cholesterol level and the effects of quercetin pretreatment (Diet 1, 0%; Diet 2, 0.25%; and Diet 3, 0.5% quercetin) for 30 and 60 days on oxidative stress induced by hypo-osmotic conditions (17.5, 8.75, and 4 psu) in olive flounder. The weights of flounder were higher with Diet 3 than with Diet 1 and 2, which indicated that a high concentration (Diet 3) of quercetin was very effective in growth. Total cholesterol levels were lower with Diets 2 and 3 than with Diet 1, leading us to hypothesize that quercetin removed low-density lipoproteins from circulation and thereby reduced total cholesterol. To understand the antioxidant role of quercetin, we measured the mRNA expression and activities of superoxide dismutase (SOD) and catalase (CAT) and the $H_2O_2$ concentration in quercetin-treated flounder exposed to osmotic stress. The $H_2O_2$ concentration and the SOD and CAT expression and activity levels were lower in flounder fed with Diets 2 and 3 than with Diet 1, suggesting that quercetin directly scavenges reactive oxygen species to reduce oxidative stress. Furthermore, the plasma lysozyme activity and osmolality were higher with Diets 2 and 3 than with Diet 1, indicating that quercetin increases immune function and helps to maintain physiological homeostasis. Plasma cortisol was lower with Diets 2 and 3 than with Diet 1, suggesting the quercetin protects against stress. These results indicate that quercetin has hypocholesterolemic and antioxidant effects, increases immune function, and acts to maintain physiological homeostasis.

• Journal of the Korean Society of Food Science and Nutrition
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• v.34 no.4
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• pp.509-512
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• 2005

Changes in rutin and Quercetin contents of Gochujang, which was added buckwheat flour, were investigated during steaming and fermentation for 1 month. Not steamed buckwheat flour showed only in presence of rutin. But rutin decreased and quercetin increased after steaming. The koji of buckwheat flour showed maximum contents of rutin and Quercetin at 20 hours during fermentation. The rutin content of Gochujang made with koji of buckwheat flour decreased slightly during fermentation but the Quercetin content increased with decreasing contents of rutin, probably due to degradation of rutin. All rutin degraded completely in Gochujang made with koji of buckwheat flour after 20 days.

• Journal of Veterinary Science
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• v.23 no.2
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• pp.26.1-26.12
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• 2022

Background: Glutamate is the main excitatory neurotransmitter. Excessive glutamate causes excitatory toxicity and increases intracellular calcium, leading to neuronal death. Parvalbumin is a calcium-binding protein that regulates calcium homeostasis. Quercetin is a polyphenol found in plant and has neuroprotective effects against neurodegenerative diseases. Objectives: We investigated whether quercetin regulates apoptosis by modulating parvalbumin expression in glutamate induced neuronal damage. Methods: Glutamate was treated in hippocampal-derived cell line, and quercetin or vehicle was treated 1 h before glutamate exposure. Cells were collected for experimental procedure 24 h after glutamate treatment and intracellular calcium concentration and parvalbumin expression were examined. Parvalbumin small interfering RNA (siRNA) transfection was performed to detect the relation between parvalbumin and apoptosis. Results: Glutamate reduced cell viability and increased intracellular calcium concentration, while quercetin preserved calcium concentration and neuronal damage. Moreover, glutamate reduced parvalbumin expression and quercetin alleviated this reduction. Glutamate increased caspase-3 expression, and quercetin attenuated this increase in both parvalbumin siRNA transfected and non-transfected cells. The alleviative effect of quercetin was statistically significant in non-transfected cells. Moreover, glutamate decreased bcl-2 and increased bax expressions, while quercetin alleviated these changes. The alleviative effect of quercetin in bcl-2 family protein expression was more remarkable in non-transfected cells. Conclusions: These results demonstrate that parvalbumin contributes to the maintainace of intracellular calcium concentration and the prevention of apoptosis, and quercetin modulates parvalbumin expression in glutamate-exposed cells. Thus, these findings suggest that quercetin performs neuroprotective function against glutamate toxicity by regulating parvalbumin expression.

• Journal of Pharmaceutical Investigation
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• v.34 no.1
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• pp.29-34
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• 2004

The solubility and stability of quercetin in various vehicles were determined. The solubility of quercetin at $28^{\circ}C$ increased in the rank order of isopropyl myristate < oleyl alcohol < propylene glycol monolaurate < oleoyl macrogol­6 glycerides < linoleoyl macrogol-6 glycerides < propylene glycol laurate (PGL) < propylene glycol monocaprylate (PGMC) < polyethylene glycol-8 glyceryl linoleate < caprylocaproyl macrogol-6 glycerides < diethylene glycol mono ethyl ether (DGME). The addition of DGME to non-aqueous vehicles such as PGL ad PGMC markedly increased the solubility of quercetin. From the stability studies, it was found that quercetin was unstable due to rapid oxidation by dissoved oxygen. The addition of a combination of ascorbic acid and edetic acid (EDTA) at 0.1 % markedly decreased the degradation rates of quercetin in 40% polyethylene glycol 400 in saline. Quercetin was relatively unstable in non-aqueous vehicles such as PGL and PGMC alone, and PGL-PGMC co-solvent The degradation of quercetin in such non-aqueous vehicles was fast, depending on temperature. The addition of butylated, hydroxytoluene, butylated hydroxyanisole, citric acid and/or EDTA at 0.1 % was effective in retarding the degradation of quercetin.