• Nutrition Research and Practice
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• 제7권6호
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• pp.439-445
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• 2013

It has been shown that dysregulation of IGF-1 signaling is associated with tumor incidence and progression, whereas blockade of the signaling can effectively inhibit carcinogenesis. Although several mechanisms of anticancer activity of quercetin were proposed, molecular targets of quercetin have not been identified yet. Hence, we assessed the effect of quercetin on IGF-1 signaling inhibition in BK5.IGF-1 transgenic (Tg) mice, which over-expresses IGF-1 in the skin epidermis. A quercetin diet (0.02% wt/wt) for 20 weeks remarkably delayed the incidence of skin tumor by 2 weeks and reduced tumor multiplicity by 35% in a 7,12-dimethylbenz(a)anthracene (DMBA)-tetradecanoyl phorbol-13-acetate (TPA) two stage mouse skin carcinogenesis protocol. Moreover, skin hyperplasia in Tg mice was significantly inhibited by a quercetin supplementation. Further analysis of the MT1/2 skin papilloma cell line showed that a quercetin treatment dose dependently suppressed IGF-1 induced phosphorylation of the IGF-1 receptor (IGF-1R), insulin receptor substrate (IRS)-1, Akt and S6K; however, had no effect on the phosphorylation of PTEN. Additionally, the quercetin treatment inhibited IGF-1 stimulated cell proliferation in a dose dependent manner. Taken together, these data suggest that quercetin has a potent anticancer activity through the inhibition of IGF-1 signaling.

• 한국임상수의학회지
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• 제39권2호
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• pp.51-58
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• 2022

Quercetin, a flavonoid found in fruits and vegetables, exhibits a strong anti-inflammatory activity. The objective of this study was to examine the effect of quercetin on chemotactic activity of peripheral blood polymorphonuclear cells (PMNs) to culture supernatant from peripheral blood mononuclear cells (PBMCs) stimulated with lipopolysaccharide (LPS). In addition, we determined whether this effect is related to interleukin (IL)-8 and changes in cytoskeleton. The chemotactic activity of PMNs was evaluated by a modified Boyden chamber assay. Total cellular filamentous (F)-actin levels were measured by method of fluorescence microscopy. The levels of IL-8 mRNA and protein were measured by real time polymerase reaction method and enzyme-linked immunosorbent assay, respectively. Quercetin (0-50 µM) itself has no chemoattractant effect for PMNs. The culture supernatant from PBMCs (2 × 10⁶ cells/mL) treated with LPS (1 ㎍/mL) showed remarkable increase in chemotaxis of PMNs. However, this effect was reduced dose-dependently by treatment with quercetin. In addition, PBMCs treated with LPS revealed enhanced levels in IL-8 protein and mRNA. Co-treatment of LPS with quercetin (50 µM) in PBMCs decreased IL-8 production and expression. Treatment of quercetin (0-50 µM) on PMNs to rpIL-8 (10 nM) decreased dose-dependently the chemotactic activity of PMNs. Treatment of quercetin on PMNs to IL-8 also reduced their total cellular F-actin level. These results suggested that quercetin attenuates chemotactic activity of PMNs, which is mediated by down-regulation of IL-8 production from LPS-stimulated PBMCs and inhibition of F-actin polymerization in PMNs.

• 한국식품과학회지
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• 제50권4호
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• pp.391-399
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• 2018

생물전환기법과 유산균을 사용한 발효를 이용해 쿼세틴의 회수율 증가와 비배당체(aglycone) 형태로의 전환을 통해 체내 흡수율을 높이고 풍미가 향상된 기능성 양파음료를 개발하기 위한 연구를 수행하였다. 생물전환에 적합한 유산균과 효모를 발굴하고 외부환경 조건에 차이를 두어 쿼세틴의 비배당화 전환율을 최대화하는 조건을 확립하였다. 실험 결과를 바탕으로 L. casei, L. plantarum, K. lactis가 생물전환공정에 적합한 유산균으로 선별되었다. 양파 슬러리를 포함한 양파즙을 발효하였을 때 쿼세틴 농도는 초기 대비 K. lactis와 L. casei에서 각각 260%, 318%의 증가가 관찰되었으나, 48시간 이후에는 감소하는 것을 확인하였다. 또한 quercetin hexose와 quercetin di-hexose는 최대 141%까지 증가하여 발효가 진행되는 동안 전체 총 쿼세틴 양이 증가함을 알수 있었다. 양파즙의 초기 pH를 중성으로 조정하였을 때 비배당체 쿼세틴 농도는 초기에 빠르게 증가했으나 24시간 이후에는 발효가 지속됨에 따라 감소하였다. Quercetin hexose의 농도 또한 빠르게 감소해 비배당체 비율이 증가했지만 자체 농도가 감소해 중성 pH에서의 발효는 적절하지 않다고 판단하였다. 발효기를 이용한 대용량 발효 실험에서도 L. plantarum, L. casei와 K. lactis 모두 동일한 발효 효율을 유지함을 확인하였다. 그러나 식품으로서의 사용을 위한 열 살균 이후에는 유산균 발효 양파즙의 쿼세틴 배당체 농도가 급격히 감소하여 고온 고압 살균이 아닌 여과와 같은 다른 살균 공정이 필요하다고 판단했다. 이상의 결과를 바탕으로 식물성 유산균 발효를 통한 쿼세틴 함량 증가와 비배당체/배당체 비율의 증가를 확인하였고 고기능성 유산균/젖산균 발효 양파즙의 개발 가능성을 알 수 있었다.

• 대한약침학회지
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• 제19권2호
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• pp.163-166
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• 2016

Objectives: Quercetin is a flavonoid and an important dietary constituent of fruits and vegetables. In recent years, several pharmacological activities of quercetin, such as its neuroprotective activity and, more specifically, its anti-convulsant effects in animal models of epilepsy, have been reported. This study evaluated the role of quercetin pretreatment on gene expression of ${\gamma}$-amino butyric acid type A ($GABA_A$) receptor beta subunits in kainic acid (KA)-induced seizures in mice. Methods: The animals were divided into four groups: one saline group, one group in which seizures were induced by using KA (10 mg/kg) without quercetin pretreatment and two groups pretreated with quercetin (50 and 100 mg/kg) prior to seizures being induced by using KA. Next, the messenger ribonucleic acid (mRNA) levels of the $GABA_A$ receptor ${\beta}$ subunits in the hippocampus of each animal were assessed at 2 hours and 7 days after KA administration. Quantitative real-time polymerase chain reaction (RT-PCR) assay was used to detect mRNA content in hippocampal tissues. Results: Pretreatments with quercetin at doses of 50 and 100 mg/kg prevented significant increases in the mRNA levels of the ${\beta}_1$ and the ${\beta}_3$ subunits of the $GABA_A$ receptor at 2 hours after KA injection. Pretreatment with quercetin (100 mg/kg) significantly inhibited ${\beta}_1$ and ${\beta}_3$ gene expression in the hippocampus at 7 days after KA injection. But, this inhibitory effect of quercetin at 50 mg/kg on the mRNA levels of the ${\beta}_3$ subunit of the $GABA_A$ receptor was not observed at 7 days after KA administration. Conclusion: These results suggest that quercetin (100 mg/kg) modulates the expression of the $GABA_A$ receptor ${\beta}_1$ and ${\beta}_3$ subunits in the KA model of epilepsy, most likely to prevent compensatory responses. This may be related to the narrow therapeutic dose range for the anticonvulsant activities of quercetin.

• The Korean Journal of Physiology and Pharmacology
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• 제15권1호
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• pp.17-22
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• 2011

Quercetin mainly exists in the skin of colored fruits and vegetables as one of flavonoids. Recent studies show that quercetin, like other flavonoids, has diverse pharmacological actions. However, relatively little is known about quercetin effects in the regulations of ligand-gated ion channels. In the previous reports, we have shown that quercetin regulates subsets of homomeric ligand-gated ion channels such as glycine, 5-$HT_{3A}$ and ${\alpha}7$ nicotinic acetylcholine receptors. In the present study, we examined quercetin effects on heteromeric neuronal ${\alpha}3{\beta}4$ nicotinic acetylcholine receptor channel activity expressed in Xenopus oocytes after injection of cRNA encoding bovine neuronal ${\alpha}3$ and ${\beta}4$ subunits. Treatment with acetylcholine elicited an inward peak current ($I_{ACh}$) in oocytes expressing ${\alpha}3{\beta}4$ nicotinic acetylcholine receptor. Co-treatment with quercetin and acetylcholine inhibited $I_{ACh}$ in oocytes expressing ${\alpha}3{\beta}4$ nicotinic acetylcholine receptors. The inhibition of $I_{ACh}$ by quercetin was reversible and concentration-dependent. The half-inhibitory concentration ($IC_{50}$) of quercetin was $14.9{\pm}0.8\;{\mu}M$ in oocytes expressing ${\alpha}3{\beta}4$ nicotinic acetylcholine receptor. The inhibition of $I_{ACh}$ by quercetin was voltage-independent and non-competitive. These results indicate that quercetin might regulate ${\alpha}3{\beta}4$ nicotinic acetylcholine receptor and this regulation might be one of the pharmacological actions of quercetin in nervous systems.

• 생명과학회지
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• 제30권12호
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• pp.1101-1108
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• 2020

타타리메밀은 rutin, quercetin, kaempferol, myricetin 등의 플라보노이드를 함유하고 있는 곡물이다. 또한, 이러한 생리활성 물질은 곡물을 발아시키고 싹으로 재배하였을 경우 증가하는 경향을 가지게 된다. 이에 본 연구에서는 반응표면분석법을 활용하여 재배한 타타리메밀싹으로부터 생리활성 물질인 플라보노이드, rutin, quercetin, myricetin의 추출 함량이 최대로 되는 최적추출조건을 도출하였다. Box-Behnken design에 따라 함량에 영향을 끼칠 수 있는 독립변수로 추출온도(X1, 50~70℃), 추출시간(X2, 5~9 hr), 에탄올의 농도(X3, 60~90%)를 설정하였고, 종속변수로는 rutin, quercetin, myricetin 각각의 함량을 사용하였다. 각각의 함량에 대한 모델식의 R2은 0.95 이상으로 유의성을 가져 적합하다고 판단되었다. 적합성 결여 test에서의 p-value가 모두 0.1 이상을 나타내어 유의성이 기각되었고, 이는 모델이 추출조건을 잘 설명할 수 있음을 나타내었다. 최적화된 추출 방법은 추출온도 51.03℃에서 6.62시간 동안 69.16%의 에탄올을 이용하여 추출하는 것이었다. 최적 조건에서의 예측된 rutin, quercetin, myricetin의 함량은 각각 808.467, 193.296, 37.361 ㎍/ml이었다. 예상된 모델을 검증하기 위하여 최적화된 추출조건을 이용하여 10회 추출을 진행한 결과, rutin, quercetin, myricetin 함량이 각각 802.84±8.49 ㎍/ml, 193.76±2.80 ㎍/ml, 34.84±0.43 ㎍/ml으로 측정되었다 rutin과 quercetin는 예측치와 실험치가 유의적 차이를 보이지 않았지만, myricetin의 경우에는 예상된 값에 조금 미치지 못하는 값이 측정되었다.

• 한국식품과학회지
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• 제54권2호
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• pp.115-125
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• 2022

열풍건조로 제조된 껍질을 포함한 적양파 분말은 강력한 항산화제인 플라보노이드 함량이 생양파즙에 비해 약 22배로 고농도로 농축되어 있으며, 60-70% ethanol 농도에서 70℃, 2시간 추출시 가장 높은 수율을 나타내었다. 이때 추출된 플라보노이드의 함량은 DPPH radical 소거능과 상관계수 0.877의 높은 상관관계를 나타내었다. 적양파 분말의 플라보이드는 주로 quercetin 배당체인 Q3,4'G, Q4'G와 QA로 이루어져 있으며, 15:39:47의 비율로 구성되어 있었다. 염산, 젖산, 초산 등 다양한 종류의 산처리에 의해 적양파 분말 속 quercetin 배당체는 QA로 전환될 수 있었으며 저농도 초산용액에서 QA로 전환되는 비율이 높았다. 이는 적양파 분말에 포함된 glucosidase가 저농도 산용액에서 활성화되면서 일어나는 반응으로 사료되었다. 초산 처리초기에는 diglycoside인 Q3,4'G의 de-glycosylation이 급격히 일어났으며, 초산처리 6시간 이후에는 Q4'G의 분해와 함께 QA가 증가하여 24시간 경과 후에 최대 QA의 함량에 도달하였으며, QA의 증가는 DPPH radical 소거능과 유의적인 상관성(r=0.90)을 나타내어 생리활성의 증가를 나타내었다. 본 연구결과, 양파의 주요 플라보노이드인 quercetin 배당체는 저농도 초산 처리로 빠르고 간편하게 QA로 전환이 가능하였으며, 이와 더불어 생리활성의 증가도 도모할 수 있었다. 적양파 분말을 이용하여 저농도 산처리를 통하여 QA로의 전환률을 높이면, 고농도의 quercetin을 함유한 양파 소재의 개발이 가능할 것이며, 이를 통해 기능성 양파 가공품의 개발로 이어질 수 있을 것이다.

• Natural Product Sciences
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• 제8권3호
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• pp.77-82
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• 2002

An investigation of the methanolic extract of Maesa lanceolata leaves has led to the isolation of four novel flavonol glycosides characterised as myricetin 3-0-2', 3', 4'-triacetylxylopyranoside (1), quercetin $3-O-{\beta}-3'$, $6'-diacetylglucopyranosyl-(1{\longrightarrow}4)-{\alpha}-2'$, 3'-diacetylrhamnopyranoside (2), myricetin $3-O-xylopyranosyl-(1{\to}3)-{\alpha}-rhamnopyranoside$ (3) and quercetin $3-O-{\beta}-ga1actopyranosyl-(1{\to}4)-{\alpha}-rhamnopyranoside-7-O-{\beta}-galactopyranoside$ (4). Also isolated from the same extract were known flavonols; quercetin (5), myricetin (6), quercetin 3-O-xylopyranoside (7), quercetin $3-O-{\alpha}-rhamnopyranoside$ (8), myricetin $3-O-{\alpha}-rhamnopyranoside$ (9), myricetin $3-O-{\beta}-galactopyranoside$ (10) and quercetin 3-O-rutinoside (11).

• Journal of Microbiology and Biotechnology
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• 제30권1호
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• pp.11-20
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• 2020

Quercetin and its derivatives are important metabolites that belong to the flavonol class of flavonoids. Quercetin and some of the conjugates have been approved by the FDA for human use. They are widely distributed among plants and have various biological activities, such as being anticancer, antiviral, and antioxidant. Hence, the biosynthesis of novel derivatives is an important field of research. Glycosylation and methylation are two important modification strategies that have long been used and have resulted in many novel metabolites that are not present in natural sources. A strategy for modifying quercetin in E. coli by means of glycosylation, for example, involves overexpressing respective glycosyltransferases (GTs) in the host and metabolic engineering for increasing nucleoside diphosphate sugar (NDP-sugar). Still others have used microorganisms other than E. coli, such as Streptomyces sp., for the biotransformation process. The overall study of the structural activity relationship has revealed that modification of some residues in quercetin decreased one activity but increased others. This review summarizes all of the information mentioned above.

• Biomolecules & Therapeutics
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• 제17권1호
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• pp.43-46
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• 2009

The immunosuppressive properties of flavonoids were examined for the first time by testing their effects on T-cell-mediated antibody production, using a classical plague-forming cell (PFC) assay in mice. Among the tested flavonoids including naringenin, chrysin, flavonol, galangin, quercetin, morin, myricetin and biochanin A, only quercetin, orally administered at 25 mg/kg, significantly inhibited the number of IgMproducing PFCs induced by sheep red blood cells (SRBC). Interestingly, biochanin A (isoflavone) increased the number of PFCs, suggesting an immunostimulatory effect. The other flavonoids tested did not inhibit or enhance PFC response significantly. Quercetin was also found to show thymus atrophy dose-dependently at 5-500 mg/kg. All these results indicate that quercetin inhibits in vivo antibody production probably by inhibiting T-cell function.