Morphological and Morphometric Analysis, Apoptosis and Oxidative Stress Study in Hep 2 Cells Treated by Resveratrol or Quercetine / Análisis Morfológico y Morfométrico, Estudio de Apoptosis y Estrés Oxidativo en Células Hep 2 Tratadas con Resveratrol o Quercetina

SUMMARY: Resveratrol (RES) and quercetine (QRC), is a promising agent relevant for both cancer chemoprevention and treatment via several signaling pathways, involved in their anticancer activity related to its chemotherapeutic potential, associated with the induction of ROS generation in cancer cells, leading to apoptosis. In our study, we have summarized the mechanisms of action of RES and QRC, and their pharmacological implications and potential therapeutic applications in cancer therapy. After treatment of Hep 2 cells with QRC or RES, the death pathways such as the cytochrome c release, ERK1/2 and IRS-1 pathways were upregulated, while cell survival pathway, including PI3K/AKT were downregulated. The RES and QRC caused oncosis, cells hypertrophy, hypercondensatin of chromatin, rupture of the plasma membrane and nuclear membrane, and formation of apoptotic bodies. Morphometric measurements of some cellular and nuclear parameters showed that RES and QRC induced an increase in cells and nuclear size, the nucleocytoplasmic ratio remained below 1 (N-Cyt R < 1), sign of low nuclear activity. The RES and QRC induced apoptosis of Hep2 cells by increasing of oxidative stress markers, MDA, and by modulating detoxifying enzymes, CAT and SOD. Our study results prove antiproliferative and proapoptotic properties of quercetin and resveratrol with regard to larynx cancer.

Resveratrol (RES) y quercetina (QRC), es un agente prometedor y relevante tanto para la quimioprevención como para el tratamiento del cáncer a través de varias vías de señalización, involucrado en su actividad anticancerígena relacionada con su potencial quimioterapéutico, asociado con la inducción de la generación de especies reactivas del oxígeno (ROS) en células cancerosas, lo que lleva a apoptosis. En nuestro estudio, hemos resumido los mecanismos de acción de RES y QRC, y sus implicaciones farmacológicas y posibles aplicaciones terapéuticas en la terapia del cáncer. Después del tratamiento de las células Hep 2 con QRC o RES, las vías de muerte, tal como la liberación de citocromo c, las vías ERK1/2 e IRS-1, se regulaban positivamente, mientras que la vía de supervivencia celular, incluida PI3K/AKT, se regulaba negativamente. El RES y el QRC provocaron oncosis, hipertrofia celular, hipercondensación de la cromatina, rotura de la membrana plasmática y nuclear y formación de cuerpos apoptóticos. Las mediciones morfométricas de algunos parámetros celulares y nucleares mostraron que RES y QRC indujeron un aumento en las células y el tamaño nuclear, la proporción nucleocitoplasmática se mantuvo por debajo de 1 (N- Cyt R <1), signo de baja actividad nuclear. RES y QRC indujeron la apoptosis de las células Hep2 aumentando los marcadores de estrés oxidativo, MDA, y modulando las enzimas desintoxicantes, CAT y SOD. Los resultados de nuestro estudio demuestran las propiedades antiproliferativas y proapoptóticas de la quercetina y el resveratrol con respecto al cáncer de laringe.

Mechanisms mediating the inhibitory effects of quercetin against phthalates-induced testicular oxidative damage in rats / 南方医科大学学报

OBJECTIVE@#To explore the mechanism underlying the inhibitory effect of quercetin against testicular oxidative damage induced by a mixture of 3 commonly used phthalates (MPEs) in rats.@*METHODS@#Forty male Sprague-Dawley rats were randomly divided into control group, MPEs exposure group, and MPEs with low-, median- and high-dose quercetin treatment groups. For MPEs exposure, the rats were subjected to intragastric administration of MPEs at the daily dose of 900 mg/kg for 30 consecutive days; Quercetin treatments were administered in the same manner at the daily dose of 10, 30, and 90 mg/kg. After the treatments, serum levels of testosterone, luteinizing hormone (LH), follicle stimulating hormone (FSH), and testicular malondialdeyhde (MDA), catalase (CAT) and superoxide dismutase (SOD) were detected, and testicular pathologies of the rats were observed with HE staining. The expressions of nuclear factor-E2-related factor 2 (Nrf2), Kelch-like ECH2 associated protein 1 (Keap1) and heme oxygenase 1 (HO-1) in the testis were detected using immunofluorescence assay and Western blotting.@*RESULTS@#Compared with the control group, the rats with MPEs exposure showed significant reductions of the anogenital distance, weight of the testis and epididymis, and the coefficients of the testis and epididymis with lowered serum testosterone, LH and FSH levels (P < 0.05). Testicular histological examination revealed atrophy of the seminiferous tubules, spermatogenic arrest, and hyperplasia of the Leydig cells in MPEs-exposed rats. MPEs exposure also caused significant increments of testicular Nrf2, MDA, SOD, CAT and HO-1 expressions and lowered testicular Keap1 expression (P < 0.05). Treatment with quercetin at the median and high doses significantly ameliorated the pathological changes induced by MPEs exposure (P < 0.05).@*CONCLUSION@#Quercetin treatment inhibits MPEs-induced oxidative testicular damage in rats possibly by direct scavenging of free radicals to lower testicular oxidative stress and restore the regulation of the Nrf2 signaling pathway.

RANKL+ senescent cells under mechanical stress: a therapeutic target for orthodontic root resorption using senolytics / 国际口腔科学杂志·英文版

In dentistry, orthodontic root resorption is a long-lasting issue with no effective treatment strategy, and its mechanisms, especially those related to senescent cells, remain largely unknown. Here, we used an orthodontic intrusion tooth movement model with an L-loop in rats to demonstrate that mechanical stress-induced senescent cells aggravate apical root resorption, which was prevented by administering senolytics (a dasatinib and quercetin cocktail). Our results indicated that cementoblasts and periodontal ligament cells underwent cellular senescence (p21+ or p16+) and strongly expressed receptor activator of nuclear factor-kappa B (RANKL) from day three, subsequently inducing tartrate-resistant acid phosphatase (TRAP)-positive odontoclasts and provoking apical root resorption. More p21+ senescent cells expressed RANKL than p16+ senescent cells. We observed only minor changes in the number of RANKL+ non-senescent cells, whereas RANKL+ senescent cells markedly increased from day seven. Intriguingly, we also found cathepsin K+p21+p16+ cells in the root resorption fossa, suggesting senescent odontoclasts. Oral administration of dasatinib and quercetin markedly reduced these senescent cells and TRAP+ cells, eventually alleviating root resorption. Altogether, these results unveil those aberrant stimuli in orthodontic intrusive tooth movement induced RANKL+ early senescent cells, which have a pivotal role in odontoclastogenesis and subsequent root resorption. These findings offer a new therapeutic target to prevent root resorption during orthodontic tooth movement.

Single-cell profiling reveals a potent role of quercetin in promoting hair regeneration

Hair loss affects millions of people at some time in their life, and safe and efficient treatments for hair loss are a significant unmet medical need. We report that topical delivery of quercetin (Que) stimulates resting hair follicles to grow with rapid follicular keratinocyte proliferation and replenishes perifollicular microvasculature in mice. We construct dynamic single-cell transcriptome landscape over the course of hair regrowth and find that Que treatment stimulates the differentiation trajectory in the hair follicles and induces an angiogenic signature in dermal endothelial cells by activating HIF-1α in endothelial cells. Skin administration of a HIF-1α agonist partially recapitulates the pro-angiogenesis and hair-growing effects of Que. Together, these findings provide a molecular understanding for the efficacy of Que in hair regrowth, which underscores the translational potential of targeting the hair follicle niche as a strategy for regenerative medicine, and suggest a route of pharmacological intervention that may promote hair regrowth.

Enhancement of Annexin V in response to combination of epigallocatechin gallate and quercetin as a potent arrest the cell cycle of colorectal cancer / Aumento da anexina V em resposta à combinação de galato de epigalocatequina e quercetina como uma potente parada do ciclo celular do câncer colorretal

Abstract Colorectal cancer (CRC) is one of the most common cancers leading to comorbidities and mortalities globally. The rational of current study was to evaluate the combined epigallocatechin gallate and quercetin as a potent antitumor agent as commentary agent for therapeutic protocol. The present study investigated the effect of epigallocatechin Gallate (EGCG) (150mg) and quercetin (200mg) at different proportions on proliferation and induction of apoptosis in human colon cancer cells (HCT-116). Cell growth, colonogenic, Annexin V in addition cell cycle were detected in response to phytomolecules. Data obtained showed that, the colony formation was inhibited significantly in CRC starting from the lowest concentration tested of 10 µg/mL resulting in no colonies as visualized by a phase-contrast microscope. Data showed a significant elevation in the annexin V at 100 µg/mL EGCG(25.85%) and 150 µg/mL quercetin (48.35%). Moreover, cell cycle analysis showed that this combination caused cell cycle arrest at the G1 phase at concentration of 100 µg/mL (72.7%) and 150 µg/mL (75.25%). The combined effect of epigallocatechin Gallate and quercetin exert antiproliferative activity against CRC, it is promising in alternative conventional chemotherapeutic agent.

Resumo O câncer colorretal (CCR) é um dos cânceres mais comuns, levando a comorbidades e mortalidade em todo o mundo. O racional do presente estudo foi avaliar a combinação de galato de epigalocatequina e quercetina como um agente antitumoral potente como agente de comentário para protocolo terapêutico. O presente estudo investigou o efeito de galato de epigalocatequina (EGCG) (150 mg) e quercetina (200 mg) em diferentes proporções na proliferação e indução de apoptose em células de câncer de cólon humano (HCT-116). O crescimento celular, colonogênico, anexina V, além do ciclo celular foram detectados em resposta a fitomoléculas. Os dados obtidos mostraram que a formação de colônias foi inibida significativamente no CRC a partir da concentração mais baixa testada de 10 µg/mL, resultando em nenhuma colônia conforme visualizado por um microscópio de contraste de fase. Os dados mostraram uma elevação significativa na anexina V a 100 µg/mL de EGCG (25,85%) e 150 µg/mL de quercetina (48,35%). Além disso, a análise do ciclo celular mostrou que essa combinação causou parada do ciclo celular na fase G1 na concentração de 100 µg/mL (72,7%) e 150 µg/mL (75,25%). O efeito combinado da epigalocatequina galato e quercetina exerce atividade antiproliferativa contra o CCR, é promissor como agente quimioterápico alternativo convencional.

Estudo do potencial antiviral sobre Sars Cov-2 dos compostos identificados nas folhas do extrato bruto de Eugenia pyriformis / Study of the antiviral potential on Sars Cov-2 of compounds identified in the leaves of the gross extract of Eugenia pyriformis / Estudio del potencial antiviral sobre Sars Cov-2 de los compuestos identificados en las hojas del extracto crudo de Eugenia pyriformis

Eugenia pyriformis Cambess (Myrtaceae), conhecida popularmente como uvaia. Em seus frutos são encontrados compostos fenólicos com ação antioxidante e nas folhas foram detectados altos teores de flavonoides e taninos hidrolisados que se mostraram inibidor da protease de 2019 - nCoV e SARS-CoV. Neste sentido, o objetivo deste estudo foi a obtenção do extrato bruto das folhas, a análise da composição química e a possibilidade da ação antiviral frente ao SARS COV-2. O extrato bruto (EB) foi obtido a partir das folhas secas de E. pyriformis, pela técnica de maceração dinâmica com esgotamento do solvente (etanol 90º GL) e concentrado em evaporador rotativo. Seis gramas do EB foram fracionados em cromatografia em coluna, e eluído com hexano, diclorometano, acetato de etila e metanol, as frações foram concentradas em um evaporador rotativo (Tecnal TE-210). O EB e as frações foram identificadas por cromatografia líquida de alta eficiência à espectrometria de massas de alta resolução (CLAE-ESI/qTOF). A identificação química do extrato bruto e frações das folhas de E. pyriformis evidenciou a presença de compostos fenólicos destacando os ácidos fenólicos, flavonoides e taninos. De forma complementar, foi realizado um levantamento bibliográfico sobre a provável ação antiviral dos compostos fenólicos e taninos presentes nas folhas de uvaia. Os resultados evidenciaram que os flavonoides quercetina e kaempferol possuem ação antiviral quando se ligam a glicoproteína do envelope ou capsídeo viral interferindo na ligação e penetração do vírus na célula. Este resultado coloca as folhas de E. pyriformis na lista de plantas com ação antiviral.

Eugenia pyriformis Cambess (Myrtaceae), popularly known as uvaia. In its fruits, phenolic compounds with antioxidant action are found and in the leaves, high levels of flavonoids and hydrolyzed tannins were detected, which proved to be an inhibitor of the 2019 protease - nCoV and SARS-CoV. In this sense, the objective of this study was to obtain the crude extract of the leaves, the analysis of the chemical composition and the possibility of antiviral action against SARS COV-2. The crude extract (EB) was obtained from the dried leaves of E. pyriformis, by the dynamic maceration technique with solvent exhaustion (ethanol 90º GL) and concentrated in a rotary evaporator. Six grams of EB were fractionated in column chromatography, and eluted with hexane, dichloromethane, ethyl acetate and methanol, the fractions were concentrated on a rotary evaporator (Tecnal TE-210). EB and fractions were identified by high performance liquid chromatography using high resolution mass spectrometry (HPLC-ESI/qTOF). The chemical identification of the crude extract and fractions of E. pyriformis leaves evidenced the presence of phenolic compounds, highlighting phenolic acids, flavonoids and tannins. In addition, a bibliographic survey was carried out on the probable antiviral action of phenolic compounds and tannins present in uvaia leaves. The results showed that the flavonoids quercetin and kaempferol have antiviral action when they bind to the envelope glycoprotein or viral capsid, interfering with the binding and penetration of the virus into the cell. This result places E. pyriformis leaves in the list of plants with antiviral action.

Eugenia pyriformis Cambess (Myrtaceae), conocida popularmente como uvaia. En sus frutos se encuentran compuestos fenólicos con acción antioxidante y en las hojas se detectaron altos contenidos de flavonoides y taninos hidrolizados que demostraron inhibir la proteasa de 2019 - nCoV y SARS-CoV. En este sentido, el objetivo de este estudio fue obtener el extracto crudo de las hojas, el análisis de la composición química y la posibilidad de acción antiviral contra el SARS COV-2. El extracto crudo (EB) se obtuvo a partir de las hojas secas de E. pyriformis, mediante la técnica de maceración dinámica con agotamiento del disolvente (etanol 90º GL) y se concentró en evaporador rotatorio. Seis gramos de EB se fraccionaron en cromatografía en columna, y se eluyeron con hexano, diclorometano, acetato de etilo y metanol, las fracciones se concentraron en un evaporador rotatorio (Tecnal TE-210). El EB y las fracciones se identificaron mediante cromatografía líquida de alta resolución a espectrometría de masas de alta resolución (HPLC-ESI/qTOF). La identificación química del extracto crudo y de las fracciones de las hojas de E. pyriformis mostró la presencia de compuestos fenólicos destacando los ácidos fenólicos, los flavonoides y los taninos. De forma complementaria, se realizó un estudio bibliográfico sobre la probable acción antiviral de los compuestos fenólicos y los taninos presentes en las hojas de la uva. Los resultados mostraron que los flavonoides quercetina y kaempferol tienen acción antiviral cuando se unen a la glicoproteína de la envoltura o cápside viral, interfiriendo en la unión y penetración del virus en la célula. Este resultado sitúa a las hojas de E. pyriformis en la lista de plantas con acción antiviral.

Pharmacological action of quercetin against testicular dysfunction: A mini review / 中西医结合学报

The testis is an immune-privileged organ susceptible to oxidative stress and inflammation, two major factors implicated in male infertility. A reduction in the concentration and activities of testicular function biomarkers has been shown to correlate with impaired hypothalamic-pituitary-testicular axis and oxidative stress. However, the use of natural products to ameliorate these oxidative stress-induced changes may be essential to improving male reproductive function. Quercetin possesses several pharmacological activities that may help to combat cellular reproduction-related assaults, such as altered sperm function and reproductive hormone dysfunction, and dysregulated testicular apoptosis, oxidative stress, and inflammation. Studies have shown that quercetin ameliorates testicular toxicity, largely by inhibiting the generation of reactive oxygen species, with the aid of the two antioxidant pharmacophores present in its ring structure. The radical-scavenging property of quercetin may alter signal transduction of oxidative stress-induced apoptosis, prevent inflammation, and increase sperm quality in relation to the hormonal concentration. In this review, the therapeutic potential of quercetin in mediating male reproductive health is discussed.

Paracetamol poisoning induces acute liver injury in rats: inhibition of miR-155/cd45 axis-mediated antioxidant depletion and hepatotoxicity using quercetin and resveratrol / La intoxicación por paracetamol induce daño hepático agudo en ratas: inhibición de la depleción de antioxidantes mediado por el eje miR-155/cd45 y hepatotoxicidad usando quercetina y resveratrol

SUMMARY: Ingestion of an overdose of paracetamol (also called acetaminophen, or APAP) induces hepatotoxicity that can lead to liver failure. The link between the pro-inflammatory microRNA-155 (miR-155) and leukocyte infiltration (CD45) in APAP- antioxidant depletion and liver toxicity with and without the natural polyphenolic compounds, quercetin (QUR) plus resveratrol (RES) has not been previously studied. Therefore, acute hepatic injury was induced in rats by 2 g/kg APAP (single dose, orally) and another group started QUR (50 mg/kg) plus RES (30 mg/kg) treatment one week prior to APAP ingestion. Animals were culled 24 hours post the paracetamol treatment. APAP overdose induced hepatic and blood levels of miR-155 expression, CD45 (leukocyte common antigen) immunostaining, degenerated hepatocytes, and hepatic injury enzymes; alanine aminotransferase (ALT) and aspartate aminotransferase (AST), which were markedly decreased by QUR+RES. Whereas, APAP intoxication ameliorated liver tissue levels of the antioxidants, glutathione peroxidase and superoxide dismutase that were augmented by QUR+RES. Moreover, a significant (p<0.05) correlation between miR-155/CD45 axis and liver tissue injury was observed. These findings show that paracetamol intoxication augments miR- 155/CD45 axis-mediated modulation of antioxidants and liver injury in rats, and is protected by QUR+RES.

RESUMEN: La ingestión de una sobredosis de paracetamol (también llamado acetaminofeno o APAP) induce hepatotoxicidad que puede provocar insuficiencia hepática. El vínculo entre el microARN-155 proinflamatorio (miR-155) y la infiltración de leucocitos (CD45) en el agotamiento de APAP- antioxidante y la toxicidad hepática con y sin los compuestos polifenólicos naturales, quercetina (QUR) más resveratrol (RES) no ha sido previamente investigado. En este estudio, se indujo daño hepático agudo en ratas con 2 g/kg de APAP (dosis única, por vía oral) y otro grupo comenzó el tratamiento con QUR (50 mg/ kg) más RES (30 mg/kg) una semana antes de la ingestión de APAP. Los animales se sacrificaron 24 horas después del tratamiento con paracetamol. La sobredosis de APAP indujo niveles hepáticos y sanguíneos de expresión de miR-155, inmunotinción de CD45 (antígeno leucocitario común), degeneración de los hepatocitos y daño hepático enzimático; alanina aminotransferasa (ALT) y aspartato aminotransferasa (AST), disminuyeron notablemente con QUR+RES. Mientras que la intoxicación con APAP mejoró los niveles de antioxidantes, glutatión peroxidasa y superóxido dismutasa en el tejido hepático los que aumentaron con QUR+RES. Además, se observó una correlación significativa (p<0,05) entre el eje miR-155/CD45 y la lesión del tejido hepático. Estos hallazgos muestran que la intoxicación por paracetamol aumenta la modulación mediada por el eje miR-155/CD45 de los antioxidantes y la lesión hepática en ratas, y está protegida por QUR+RES.

Quercetin protects against acetaminophen-induced acute nephrotoxicity associated with the inhibition of biomarkers of acute kidney injury in rats / La quercetina protege contra la nefrotoxicidad aguda inducida por acetaminofén asociada con la inhibición de biomarcadores de lesión renal aguda en ratas

Acetaminophen (also called paracetamol, or APAP) causes acute kidney injury after accidental or intentional ingestion of a toxic dose of the drug. We tested whether the antioxidant and anti-inflammatory agent, quercetin (QUR) given alone can protect against acute nephrotoxicity induced by APAP overdose in a rat model of APAP-induced acute kidney injury. Rats were either given a single dose of APAP (2 g/kg) before being sacrificed after 24 hours or were pre-treated for 7 days with QUR (50 mg/kg) before being given a single dose of APAP and then sacrificed 24 hours post APAP ingestion. Kidneys were examined by light microscopy after staining with hematoxylin and eosin (H&E) and collected blood samples were assayed for biomarkers of oxidative stress, inflammation, and kidney injury. H&E stained sections of kidney from the model group of rats (APAP) showed substantial damage to the kidney architecture as demonstrated by widening of Bowman's space, tubular dilatation, vacuolization of tubular epithelium, and congested dilated blood vessels, which were partially protected by QUR. In addition, APAP significantly (p<0.05) increased blood levels of urea, creatinine, malondialdehyde (MDA), tumor necrosis factor-alpha (TNF-a), and interleukin-6 (IL-6), which were significantly (p<0.05) reduced by QUR. These results indicate that quercetin partially protects against APAP-induced acute kidney injury in rats, which is associated with the inhibition of biomarkers of oxidative stress and inflammation and kidney injury.

El acetaminofeno (también llamado paracetamol o DCI) causa daño renal agudo después de la ingestión accidental o intencional de una dosis tóxica del medicamento. En el estudio analizamos si el agente antioxidante y antiinflamatorio, la quercetina (QUR) administrada sola, puede proteger contra la nefrotoxicidad aguda inducida por sobredosis de DCI en un modelo de rata. Las ratas recibieron una dosis única de DCI (2 g / kg) antes de ser sacrificadas después de 24 horas o fueron pretratadas durante 7 días con QUR (50 mg / kg) antes de recibir una dosis única de DCI y luego sacrificadas 24 horas post ingestión. Los riñones se examinaron mediante microscopía óptica después de la tinción con hematoxilina y eosina (H&E) y las muestras de sangre recolectadas se analizaron para detectar biomarcadores de estrés oxidativo, inflamación y daño renal. Las secciones de riñón teñidas con H&E del grupo modelo de ratas (DCI) mostraron un daño sustancial a la arquitectura del riñón, como lo demuestra la ampliación del espacio de Bowman, la dilatación tubular, la vacuolización del epitelio tubular y los vasos sanguíneos dilatados congestionados, que estaban parcialmente protegidos por QUR. Además, DCI aumentó significativamente (p <0,05) los niveles sanguíneos de la urea, creatinina, malondialdehído (MDA), factor de necrosis tumoral alfa (TNF-a) e interleucina-6 (IL-6), los que fueron reducidos significativamente (p < 0,05) por QUR. Estos resultados indican que la quercetina protege parcialmente contra la lesión renal aguda inducida por DCI en ratas, asociada con la inhibición de biomarcadores de estrés oxidativo, inflamación y lesión renal.

Quercetina Melhora o Perfil Lipídico e Apolipoproteico em Ratos Tratados com Glicocorticóides em Altas Doses / Quercetin Ameliorates Lipid and Apolipoprotein Profile in High-Dose Glucocorticoid Treated Rats

Resumo Fundamento Os glicocorticóides (GCs) são amplamente prescritos para o tratamento de numerosos distúrbios clínicos devido às suas propriedades anti-inflamatórias e imunomoduladoras, e um dos efeitos indesejáveis mais comuns desses medicamentos é a dislipidemia. Objetivo Avaliar o efeito da quercetina, um flavonoide derivado de plantas, no perfil lipídico de ratos tratados com glicocorticóides em altas doses. Métodos Um total de 32 ratos Sprague-Dawley foram distribuídos aleatoriamente entre quatro grupos (8 ratos por grupo) e tratados por 6 semanas com uma das seguintes opções : (i) solução salina normal; (ii) 40 mg/kg de succinato sódico de metilprednisolona (MP); (iii) MP + 50 mg/kg de quercetina; (iv) MP + 150 mg/kg de quercetina. O MP foi injetado por via subcutânea e a quercetina foi administrada por gavagem oral 3 dias por semana. No final do estudo, o perfil lipídico dos animais foi medido através de kits enzimáticos. Os dados foram analisados e a significância estatística foi estabelecida em p <0,05. Resultados Os níveis séricos médios de colesterol total (CT), triglicerídeos (TG) e LDL aumentaram drasticamente em animais tratados com GC em comparação com o grupo controle. Ambas as doses de quercetina (50 e 150 mg/kg) melhoraram o CT (43% e 45%), LDL (56% e 56%) e TG (46% e 55%, respectivamente). A razão Apo B/A1 diminuiu mais de 20% após a ingestão de Anti-Inflamatory Agents. Conclusões Esses dados sugerem que a ingestão de quercetina Quercetin; induzida por glicocorticóides. (Arq Bras Cardiol. 2020; 115(1):102-108)

Abstract Background Glucocorticoids (GCs) are widely prescribed for the treatment of numerous clinical disorders due to their anti-inflammatory and immune-modulatory properties and one of the most common untoward effects of these drugs is dyslipidemia. Objective To evaluate the effect of quercetin, a plant-derived flavonoid, on the lipid profile of high-dose glucocorticoid treated rats. Methods A total of 32 Sprague-Dawley rats, were randomly distributed among four groups (8 rats per group) and treated for 6 weeks with one of the following: (i) normal saline; (ii) 40 mg/kg methylprednisolone sodium succinate (MP); (iii) MP + 50 mg/kg quercetin; (iv) MP + 150 mg/kg quercetin. MP was injected subcutaneously, and quercetin was administered by oral gavage 3 days a week. At the end of the study, the animals' lipid profile was measured by enzymatic kits. Data were analyzed and statistical significance was set at p<0.05. Results The mean serum total cholesterol (TC), triglyceride (TG) and LDL levels were drastically increased in GC-treated animals compared with the control group. Both doses of quercetin (50 and 150 mg/kg) ameliorated TC (43% and 45%), LDL (56% and 56%) and TG (46% and 55% respectively). Apo B/A1 ratio decreased more than 20% following quercetin intake and the decline in TC/HDL, TG/HL, LDL/HDL ratios were significant. Conclusions These data suggest that quercetin intake with both doses of 50 and 150 mg/kg could be considered as a protective agent for glucocorticoid-induced dyslipidemia. (Arq Bras Cardiol. 2020; 115(1):102-108.)

Acetaminophen induces alterations to the renal tubular ultrastructure in a rat model of acute nephrotoxicity protected by resveratrol and quercetin / El acetaminofeno induce alteraciones en la ultraestructura tubular renal en un modelo de rata con nefrotoxicidad aguda protegida por resveratrol y quercetina

Acetaminophen (also called paracetamol, or APAP) induced nephrotoxicity is reported after accidental or intentional ingestion of an overdose of the drug. Renal tubular ultrastructural alterations induced by APAP overdose associated with the induction of biomarkers of kidney injury have not been investigated before. Also, we investigated whether the combined polyphenolic anti-inflammatory and antioxidants agents, resveratrol (RES) and quercetin (QUR) can protect against APAP-induced acute kidney injury. The model group of rats received a single dose of APAP (2 g/kg), whereas the protective group of rats was pre-treated for 7 days with combined doses of RES (30 mg/kg) and QUR (50 mg/kg) before being given a single dose of APAP. All rats were then sacrificed one day post APAP ingestion. Harvested kidney tissues were prepared for transmission electron microscopy (TEM) staining and blood samples were assayed for urea, creatinine, and biomarkers of inflammation and oxidative stress. TEM images and blood chemistry analysis showed that APAP overdose induced kidney damage as demonstrated by substantial alterations to the proximal convoluted tubule ultrastructure, and a significant (p<0.05) increase in urea, creatinine, tumor necrosis factor-alpha (TNF-a), and malondialdehyde (MDA) blood levels, which were protected by RES+QUR. These findings indicate that APAP induces alterations to the renal tubular ultrastructure, which is inhibited by resveratrol plus quercetin, which also decreases blood levels of kidney injury biomarkers.

El objetivo de este trabajo fue estudiar la nefrotoxicidad inducida por acetaminofeno (también llamado paracetamol o APAP) después de la ingestión accidental o intencional de una sobredosis de la droga. Las alteraciones ultraestructurales tubulares renales inducidas por sobredosis de APAP asociadas con la inducción de biomarcadores de daño renal no se han investigado. Además, estudiamos si los agentes combinados antiinflamatorios y antioxidantes polifenólicos, el resveratrol (RES) y la quercetina (QUR) pueden proteger contra la lesión renal aguda inducida por APAP. El grupo modelo de ratas recibió una dosis única de APAP (2 g / kg), mientras que el grupo protector de ratas se trató previamente durante 7 días con dosis combinadas de RES (30 mg / kg) y QUR (50 mg / kg) antes de recibir una dosis única de APAP. Todas las ratas se sacrificaron un día después de la ingestión de APAP. Los tejidos renales fueron preparados para el análisis a través de la microscopía electrónica de transmisión (MET). En las muestras de sangre se determinaron la urea, creatinina y los biomarcadores de inflamación y estrés oxidativo. Las imágenes MET y el análisis químico de la sangre mostraron que la sobredosis de APAP inducía daño renal, como lo demuestran las alteraciones sustanciales en la ultraestructura del túbulo contorneado proximal, y además, de un aumento significativo (p <0,05) de la urea, creatinina, factor de necrosis tumoral alfa y niveles sanguíneos de malondialdehído, protegidos por RES + QUR. Estos hallazgos indican que APAP induce alteraciones en la ultraestructura tubular renal, inhibida por el resveratrol más quercetina, que también disminuye los niveles sanguíneos de biomarcadores de daño renal.

Suppression of hepatic apoptosis induced by acetaminophen using a combination of resveratrol and quercetin: an association of oxidative stress and interleukin-11 / Suspensión de la apoptosis hepática inducida por acetaminofén mediante una combinación de resveratrol y quercetina: una asociación de estrés oxidativo e interleucina-1

We sought to determine whether the combined polyphenolic compounds, resveratrol and quercetin can substantially protect against modulation of hepatic biomarkers of apoptosis and survival, p53-Bax axis and B-cell lymphoma 2 (Bcl-2) in an animal model of acetaminophen-induced acute liver injury via the association of oxidative stress and interleukin-11 (IL-11). The model group of rats received a single dose of acetaminophen (2 g/kg), whereas the protective group of rats was pre-treated for 7 days with combined doses of resveratrol (30 mg/kg) and quercetin (50 mg/kg) before being given a single dose of acetaminophen. All rats were then sacrificed 24 hours post acetaminophen ingestion. Acetaminophen overdose induced acute liver injury as demonstrated by profound liver parenchymal damage and increased levels of the liver injury enzymes, alanine aminotransferase (ALT) and aspartate aminotransferase (AST). Acetaminophen significantly (p<0.05) modulated malondialdehyde (MDA), p53, apoptosis regulator Bax, Bcl-2, IL-11, interleukin-6 (IL-6), ALT, AST, superoxide dismutase (SOD), and glutathione peroxidase (GPx), which were significantly protected by resveratrol plus quercetin. We further demonstrated a significant (p<0.01) correlation between IL-11 scoring and the levels of p53, Bax, Bcl-2, and MDA. Thus, resveratrol plus quercetin effectively protect against acetaminophen-induced apoptosis, which is associated with the inhibition of oxidative stress and IL-11.

En el estudio se intentó determinar si los compuestos polifenólicos combinados, el resveratrol y la quercetina pueden proteger sustancialmente contra la modulación de los biomarcadores hepáticos de apoptosis y supervivencia, el eje p53-Bax y el linfoma de células B 2 (Bcl-2) en un modelo animal de lesión hepática aguda inducida por acetaminofén, a través de la asociación del estrés oxidativo y la interleucina-11 (IL-11). El grupo modelo de ratas recibió una dosis única de acetaminofén (2 g / kg), mientras que el grupo protector de ratas fue tratado durante 7 días con dosis combinadas de resveratrol (30 mg / kg) y quercetina (50 mg / kg) antes de recibir una dosis única de acetaminofén. Todas los animales fueron sacrificados 24 horas después de la ingestión de acetaminofén. La sobredosis de acetaminofén indujo una lesión hepática aguda, como se observó en el daño profundo del parénquima hepático y el aumento de los niveles de las enzimas en la lesión hepática, alanina aminotransferasa (ALT) y aspartato aminotransferasa (AST). Acetaminofén moduló significativamente (p <0.05) malondialdehído (MDA), p53, regulador de apoptosis Bax, Bcl2, IL-11, interleucina-6 (IL-6), ALT, AST, superóxido dismutasa (SOD) y glutatión peroxidasa ( GPx), los que se encontraron significativamente protegidos por el resveratrol y quercetina. Además se determinó una correlación significativa (p <0.01) entre la puntuación de IL-11 y los niveles de p53, Bax, Bcl-2 y MDA. En conclusión, el resveratrol más la quercetina protegen de manera efectiva contra la apoptosis inducida por acetaminofén, asociada con la inhibición del estrés oxidativo y la IL-11.

Effect of quercetin on chondrocyte phenotype and extracellular matrix expression / 中国天然药物

Due to the poor repair ability of cartilage tissue, regenerative medicine still faces great challenges in the repair of large articular cartilage defects. Quercetin is widely applied as a traditional Chinese medicine in tissue regeneration including liver, bone and skin tissues. However, the evidence for its effects and internal mechanisms for cartilage regeneration are limited. In the present study, the effects of quercetin on chondrocyte function were systematically evaluated by CCK8 assay, PCR assay, cartilaginous matrix staining assays, immunofluorescence assay, and western blotting. The results showed that quercetin significantly up-regulated the expression of chondrogenesis genes and stimulated the secretion of GAG (glycosaminoglycan) through activating the ERK, P38 and AKT signalling pathways in a dose-dependent manner. Furthermore, in vivo experiments revealed that quercetin-loaded silk protein scaffolds dramatically stimulated the formation of new cartilage-like tissue with higher histological scores in rat femoral cartilage defects. These data suggest that quercetin can effectively stimulate chondrogenesis in vitro and in vivo, demonstrating the potential application of quercetin in the regeneration of cartilage defects.

Inhibition of paracetamol-induced acute kidney damage in rats using a combination of resveratrol and quercetin / Inhibición de daño renal agudo inducido por paracetamol en ratas usando una combinación de resveratrol y quercetina

Paracetamol (also called acetaminophen, or APAP) overdose causes acute damage to the liver and kidneys in both humans and experimental animal models via the induction of the oxidative stress pathway. We sought to determine whether the combined antioxidants and anti-inflammatory compounds, resveratrol (RES) and quercetin (QUR) can protect against kidney injury induced by a toxic dose of APAP in a rat model of APAP-induced acute kidney injury. Rats were either received a single dose of APAP (2 g/kg) before being sacrificed after 24 hours or were pre-treated for 7 days with combined doses of RES (30 mg/kg) and QUR (50 mg/kg) before being given a single dose of APAP and then sacrificed 24 hours post APAP ingestion. Harvested kidney tissues were prepared for light microscopy staining, and tissue samples were assayed for (i) biomarkers of oxidative stress and antioxidant, malondialdehyde (MDA) and superoxide dismutase (SOD); and (ii) biomarkers of inflammation, tumor necrosis factor-alpha (TNF-α) and interleukin-6 (IL-6). Hematoxylin and eosin (H&E) stained images showed that APAP overdose induced acute kidney injury as demonstrated by widening of glomeruli space (Bowman space), tubular dilatation, numerous cellular debris in the renal tubules with tubular epithelial degeneration, and vacuolization, which were effectively protected by RES+QUR except a partial protection of the glomeruli space was observed. In addition, APAP significantly (p<0.05) modulated tissue levels of MDA, SOD, TNF-α, and IL-6, which were protected by RES+QUR. Furthermore, a significant (p<0.0001) positive correlation was observed between glomeruli space and TNF-α, (r=0.8899), IL-6 (r=0.8986), and MDA (r=0.8552), whereas glomeruli space scoring versus SOD showed negative correlation (r= - 0.7870). We conclude that resveratrol plus quercetin substantially protects against APAP-induced acute kidney injury in rats, possibly via the augmentation of antioxidants and inhibition of oxidative stress and inflammation.

La sobredosis de paracetamol (también llamado acetaminofen o APAP) causa un daño agudo en el hígado y los riñones, tanto en humanos como en modelos animales experimentales, a través de la inducción de la vía del estrés oxidativo. Intentamos determinar si los antioxidantes y los compuestos antiinflamatorios combinados, el resveratrol (RES) y la quercetina (QUR) pueden proteger contra la lesión renal inducida por una dosis tóxica de APAP en un modelo de rata de lesión renal aguda inducida por APAP. Las ratas recibieron una dosis única de APAP (2 g / kg) antes de ser sacrificadas después de 24 horas o se trataron previamente durante 7 días con dosis combinadas de RES (30 mg / kg) y QUR (50 mg / kg), antes de ser tratadas, se administró una dosis única de APAP y luego fueron sacrificadas 24 horas después de la ingestión. Los tejidos renales recolectados se tiñeron con H-E y fueron observados a través de microscopía óptica. Las muestras de tejido se analizaron para (i) biomarcadores de estrés oxidativo y antioxidante, malondialdehído (MDA) y superóxido dismutasa (SOD); y (ii) biomarcadores de inflamación, factor de necrosis tumoral alfa (TNF-α) e interleucina-6 (IL-6). Las imágenes teñidas con H & E mostraron que la sobredosis de APAP indujo daño renal agudo como lo demuestra la ampliación del espacio glomerular, la dilatación tubular, numerosos desechos celulares en los túbulos renales con degeneración epitelial tubular y la vacuolización, que se protegieron eficazmente con RES + QUR Se observó una protección parcial del espacio glomerular. Además, APAP modificó significativamente (p <0.05) los niveles tisulares de MDA, SOD, TNF-α e IL-6, que estaban protegidos por RES + QUR. Además, se observó una correlación positiva significativa (p <0,0001) entre el espacio glomerular y el TNF-α, (r = 0,8899), IL-6 (r = 0,8986) y MDA (r = 0,8552), mientras que la puntuación del espacio glomerular versus SOD mostró correlación negativa (r = - 0,7870). Concluimos que el resveratrol más quercetina protege sustancialmente contra la lesión renal aguda inducida por APAP en ratas, posiblemente a través del aumento de antioxidantes y la inhibición del estrés oxidativo y la inflamación.

Photoprotection / photostabilizer potential in a quercetin sunscreens: determination of physical-chemical, safety and efficacy properties / Potencial fotoprotetor / fotoestabilizador de filtros solares associados à quercetina: ensaios físico-químicos e pré-clínicos

Ultraviolet radiation (UV) is related to the development of skin cancer and photoaging, also produces free radicals or reactive oxygen species (ROS) that cause premature aging. Therefore, sunscreens with extended UV protection capacity have been studied associated with antioxidant compounds. Different components can be incorporated with the purpose of improving, the photoprotection efficiency, as well as other cosmetic attributes, creating a multifunctional product. Among the compounds, there are some to be used from natural origin that are excellent, because it reduces the side effects and toxicity. Flavonoids are good examples of natural agents, because have demonstrated photoprotective antioxidant action in food and it is also promising for topical use. The aim of this work is to develop photoprotective formulations with quercetin, evaluating potential photoprotective and antioxidant of each formulation through tests already established and described in the literature, with emphasis on in vitro testing of potential photoprotective, antioxidant and security (het-cam); ex vivo antioxidant potential (tape-stripping). The results show us the photoprotective and antioxidant capacity of quercetin and the ideal concentration for this potential, thereby contributing to the synthesis of new molecules and development of new products, concerning stable, safe and effective exposure to solar UV radiation, preventing new incidences of skin cancer and reduction of photoaging

A radiação ultravioleta (UV) está relacionada ao desenvolvimento de câncer de pele e fotoenvelhecimento, também produz radicais livres ou espécies reativas de oxigênio (EROs) que causam o envelhecimento precoce. Portanto, protetores solares com capacidade de proteção UV amplo espectro foram estudados associados a compostos antioxidantes. Diferentes componentes podem ser incorporados com o objetivo de melhorar a eficiência da fotoproteção, assim como outros atributos cosméticos criando um produto multifuncional. Entre os compostos a serem utilizados, de origem natural são excelentes, pois reduzem os efeitos colaterais e a toxicidade. Os flavonóides são bons exemplos de agentes naturais, porque demonstraram ação antioxidante fotoprotetora nos alimentos e também são promissores para uso tópico. O objetivo deste trabalho é desenvolver formulações fotoprotetoras com quercetina, avaliando potenciais fotoprotetores e antioxidantes de cada formulação através de testes já estabelecidos e descritos na literatura com ênfase em ensaios in vitro de potenciais fotoprotetores, antioxidantes e de segurança (het-cam); potencial antioxidante ex vivo (tape-stripping). Os resultados nos mostram a capacidade fotoprotetora e antioxidante da quercetina e a concentração ideal para este potencial, contribuindo para a síntese de novas moléculas e desenvolvimento de novos produtos estáveis, seguros e eficazes em relação à exposição à radiação solar UV, prevenindo novas incidências de câncer de pele e redução do fotoenvelhecimento

Quercetina atenúa la virulencia de Staphylococcus aureus al disminuir la secreción de alfa toxina / Quercetin attenuates Staphylococcus aureus virulence by reducing alpha-toxin secretion

Alfa toxina, una proteína formadora de poros con actividad citotóxica, es uno de los principales factores de virulencia secretados por la mayoría de las cepas de Staphylococcus aureus. Se ha establecido la relevancia de esta proteína en la patogenia de la neumonía asociada a infecciones por S. aureus. Por lo tanto, la inhibición de la secreción de alfa toxina puede ser una alternativa en el control de las infecciones causadas por este microorganismo. En este trabajo mostramos que quercetina, un flavonoide de origen natural, inhibe de manera dosis dependiente la actividad hemolítica y disminuye la secreción de alfa toxina en sobrenadantes de cultivos de S. aureus sensible y resistente a meticilina. Además, quercetina previene de manera significativa el daño de células alveolares humanas cuando se co-cultivan con S. aureus. Nuestros datos sugieren que quercetina puede disminuir la virulencia de S. aureus al afectar la secreción de alfa toxina.

Alpha toxin, a pore-forming protein with cytotoxic activity, is one of the major virulence factors secreted by most strains of Staphylococcus aureus. The relevance of this protein in the pathogenesis of pneumonia associated with S. aureus infections has already been esta blished. Therefore, inhibiting alpha toxin secretion can be an alternative for controlling these infections. This study shows that quercetin, a naturally occurring flavonoid, inhibits hemolytic activity in a dose-dependent manner and reduces alpha toxin secretion in culture supernatants of methicillin-sensitive and methicillin-resistant S. aureus. Furthermore, quercetin significantly prevents damage to human alveolar cells when co-cultured with S. aureus. Our results suggest that quercetin can reduce S. aureus virulence by affecting alpha-toxin secretion.

Hyperin protects against cisplatin-induced liver injury in mice

Abstract Purpose: To evaluate the effect of hyperin in cisplatin-induced liver injury in mice. Methods: Mice were pretreated with hyperin at doses of 25 mg/kg and 50 mg/kg, respectively, for six days, and intraperitoneal injection of cisplatin (40 mg/kg) was administrated one hour after the final intragastrication of hyperin. Twenty-four hours later, blood and liver were collected for further research. Results: A single injection of cisplatin (40 mg/kg) for 24 h significantly increased serum alanine and aspartate aminotransferases (ALT/AST) and gamma glutamyl transferase (GGT) activities, whileas hyperin reversed cisplatin-induced such increases. Liver histopathological examination further demonstrated the protection of hyperin against cisplatin-induced liver injury. Further results showed hyperin reversed cisplatin-induced the increase in content of malondialdehyde (MDA) and the decrease in level of total antioxidant capacity (T-AOC) in liver. Moreover, hyperin increased the levels of superoxide dismutase (SOD), catalase (CAT), glutathione (GSH), glutathione peroxidase (GPx), glutathione-s transferase (GST) in cisplatin-induced liver. Conclusion: Hyperin inhibits cisplatin-induced hepatic oxidative stress, which contributes greatly to the amelioration of cisplatin-induced liver injury in mice.

Quercetin and rutin as potential agents antifungal against Cryptococcus spp / Quercetina e rutina: potenciais agentes para terapia antifúngica

Abstract Amphotericin B is a fungicidal substance that is treatment of choice for most systemic fungal infections affecting as cryptococcosis the immunocompromised patients. However, severe side effects have limited the utility of this drug. The aim of this study was to evaluate the antifungal effect of the combination of amphotericin B with quercetin or rutin and as a protective of citotoxic effect. The antifungal activity to amphotericin B, quercetin and rutin alone and in combination was determined in Candida sp and Cryptococcus neoformans strains. Cytotoxicity test on erythrocytes was performed by spectrophotometric absorbance of hemoglobin. The amphotericin B MIC was reduced when used in combination with quercetin or rutin to C. neoformans ATCC strain and reduced when combined with rutin to a clinical isolate of C. neoformans. In addition, the combination of quercetin with amphotericin B may reduce the toxicity of amphotericin B to red blood cells. Our results suggest that quercetin and rutin are potential agents to combine with amphotericin B in order to reduce the amphotericin dose to lessen side effects and improve antifungal efficacy.

Resumo A anfotericina B é uma substância fungicida e é o tratamento de escolha para a maioria das infecções fúngicas sistêmicas que afetam os pacientes imunocomprometidos, como a criptococose. No entanto, as severas reações adversas têm limitado a utilização desta droga. O objetivo deste estudo foi avaliar o efeito antifúngico e o potencial efeito protetor de citotoxicidade da combinação de anfotericina B com quercetina ou rutina. A atividade antifúngica de anfotericina B, quercetina e rutina, isoladamente e em combinação foi determinada em cepas de Candida sp e Cryptococcus neoformans. O teste de citotoxicidade em eritrócitos foi realizado por espectrofotometria, através da determinação da absorbância da hemoglobina. A concentração inibitória mínima da anfotericina B foi reduzida quando utilizada em combinação com a quercetina e rutina em C. neoformans ATCC e reduzida quando combinados com rutina em um isolado clínico de C. neoformans. Além disso, a combinação de quercetina com anfotericina B pode reduzir a toxicidade da droga em eritrócitos. Os resultados sugerem que quercetina e rutina são potenciais agentes para combinação com anfotericina B, a fim de reduzir a dose de anfotericina, diminuindo os efeitos colaterais e melhorando sua eficácia antifúngica.

Effect of the Parafunctional Occlusal Loading and Crown Height on Stress Distribution

The aim of this study was to assess, by the three-dimensional finite element method, the influence of crown-to-implant ratio and parafunctional occlusal loading on stress distribution in single external hexagon implant-supported prosthesis. Computer-aided design software was used to confection three models. Each model was composed of a block bone and an external hexagon implant (5x10.0 mm) with screw-retained implant prostheses, varying the height crown: 10, 12.5 and 15 mm. Finite element analysis software was used to generate the finite element mesh and to establish the loading and boundary conditions. Normal (200 N axial and 100 N oblique load) and parafunctional forces (1,000 N axial and 500 N oblique load) were applied. The results were visualized by von Mises and maximum principal stress. In comparison with the normal occlusal force, the parafunctional occlusal force induced an increase in stress concentration and magnitude on implant (platform and first threads) and screw (neck). The cortical bone showed the highest tensile stress under parafunctional force (oblique load). The stress concentration increased as the crown height increased. It was concluded that: increasing the C/I increased stress concentration in both implant components and cortical bone; parafunctional loading increased between 4-5 times the value of stresses in bone tissue compared with functional loading; the type of loading variation factor is more influential than the crown-to-implant factor.

O objetivo deste estudo foi avaliar, através do método dos elementos finitos tridimensionais, a influência do carregamento oclusal parafuncional e da altura da coroa na distribuição das tensões em próteses unitárias implantossuportadas de hexágono externo. Foram confeccionados três modelos com o auxílio de programas de desenho assistido. Cada modelo foi composto por um bloco ósseo da região molar mandibular, por um implante de tipo hexágono externo (5x10,0 mm) e por coroa com diferentes alturas: 10, 12,5 e 15 mm. Os modelos foram exportados para o programa de elementos finitos NEiNastran 9.0, para geração das malhas e estabelecer as condições de contorno. Aplicou-se uma carga funcional (200 N axial e 100 N oblíqua), bem como uma carga parafuncional (1.000 N axial e 500 N oblíqua). Os resultados foram visualizados por meio de mapas de Tensão de von Mises e mapas de Tensão Máxima Principal. O carregamento parafuncional induziu um aumento da área de distribuição e da magnitude das tensões no implante (plataforma e primeiras roscas) e parafuso (pescoço) em comparação com o carregamento funcional. A cortical óssea apresentou maiores áreas de tensão por tração sob carregamento parafuncional oblíquo. A concentração de tensões aumentou à medida que aumentou a altura da coroa. O aumento da altura da coroa induziu um aumento na concentração de tensões, tanto nos componentes do implante, quanto na cortical óssea; o carregamento parafuncional induziu um aumento entre 4-5 vezes da magnitude das tensões no tecido ósseo; o tipo de carregamento apresenta-se como um fator de variação mais influente do que a proporção coroa/implante.

Inhibitory effect of liposomal quercetin on acute hepatitis and hepatic fibrosis induced by concanavalin A

Immune response plays an important role in the development of hepatic fibrosis. In the present study, we investigated the effects of quercetin on hepatitis and hepatic fibrosis induced by immunological mechanism. In the acute hepatitis model, quercetin (2.5 mg/kg) was injected iv into mice 30 min after concanavalin A (Con A) challenge. Mice were sacrificed 4 or 24 h after Con A injection, and aminotransferase tests and histopathological sections were performed. Treatment with quercetin significantly decreased the levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST). Consistent with this observation, treatment with quercetin markedly attenuated the pathologic changes in the liver. A hepatic fibrosis model was also generated in mice by Con A challenge once a week for 6 consecutive weeks. Mice in the experimental group were treated with daily iv injections of quercetin (0.5 mg/kg). Histopathological analyses revealed that treatment with quercetin markedly decreased collagen deposition, pseudolobuli development, and hepatic stellate cells activation. We also examined the effects of quercetin on the nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) and transforming growth factor beta (TGF-β) pathways by immunohistochemistry and real-time reverse transcriptase-polymerase chain reaction (RT-PCR). NF-κB and TGF-β production was decreased after treatment with quercetin, indicating that the antifibrotic effect of quercetin is associated with its ability to modulate NF-κB and TGF-β production. These results suggest that quercetin may be an effective therapeutic strategy in the treatment of patients with liver damage and fibrosis.