槲皮素对大鼠非酒精性脂肪肝炎的治疗作用及其机制

目的 观察槲皮素对大鼠非酒精性脂肪肝炎(NASH)的治疗作用,以及槲皮素对NASH大鼠肝组织核因子-κB (NF-κB)及其下游转录因子表达水平的影响.方法 采用高脂饲料喂食6周,建立NASH大鼠模型.灌胃给予40～160 mg/kg槲皮素治疗4周.采用生化检测仪检测血清总胆固醇(TC)、甘油三酯(TG)、低密度脂蛋白胆固醇(LDL-C)、高密度脂蛋白胆固醇(HDL-C)、丙氨酸转氨酶(ALT)和天冬氨酸转氨酶(AST)水平.采用Western blotting法检测各组肝脏中NF-κB蛋白表达情况.采用RT-PCR技术检测各组肝脏中肿瘤坏死因子-α(TNF-α)、白细胞介素6(IL-6)和白细胞介素1β(IL-1β) mRNA的表达情况.结果 与高脂模型组相比,槲皮素各剂量组大鼠血清LDL-C、TC、AST水平显著降低.病理组织学检查结果表明,给予槲皮素治疗后,可明显减轻NASH大鼠肝脏脂肪变性和炎性细胞浸润;同时,还可明显降低TNF-o、IL-6和IL-1β mRNA以及NF-κBp65蛋白的表达,并呈一定的量效关系.结论 槲皮素对高脂饮食诱导大鼠NASH有明显治疗作用,作用机制可能与其抑制肝细胞脂质沉积和调控NF-κB通路有关.     

Oral supplementation of quercetin in PRRSV-1 modified-live virus vaccinated pigs in response to HP-PRRSV-2 challenge

This study evaluated the immunomodulatory effect of quercetin on improving cross protection of porcine reproductive and respiratory syndrome virus-1 (PRRSV-1) modified-live virus (MLV) vaccine against highly pathogenic (HP)-PRRSV-2 challenge. Ex vivo experiments demonstrated that quercetin significantly enhanced type I interferon-regulated genes (IRGs) and type I and II interferon (IFN), and significantly decreased pro- and anti-inflammatory cytokine expressions in HP-PRRSV-inoculated monocyte-derived macrophages. In vivo experiments divided pigs (4-week-old; n = 24) into four groups of six pigs. Group 1 and group 2 were immunized with PRRSV-1 MLV vaccine at 0 dpv (day post vaccination). Group 2 also received oral administration of quercetin at 0–49 dpv. Group 3 was injected with PRRSV-1 MLV vaccine solvent at 0 dpv. Group 4 served as strict control. Group 1–3 were challenged intranasally with HP-PRRSV at 28 dpv and immune and clinical parameters were monitored weekly until 49 dpv. Group 1 demonstrated significantly reduced HP-PRRSV viremia, rectal temperature and clinical scores, and significantly improved average daily weight gain (ADWG), compared to group 3. Group 2 demonstrated significantly increased IFN regulatory factor 3, stimulator of IFN genes, IFNα, and significantly decreased transforming growth factor beta (TGFβ) mRNA expressions, compared to group 1. The animals demonstrated significantly reduced HP-PRRSV viremia, but did not demonstrate any further improved PRRSV-specific antibody responses, rectal temperature, clinical scores, and ADWG as compared to group 1. Our findings suggest that quercetin up-regulates IRGs, IFNα, and down-regulates TGFβ mRNA expressions which may contribute to further reducing number of viremic pigs and HP-PRRSV viremia which were conferred by PRRSV-1 MLV vaccine. Our findings also suggest that quercetin may serve as an effective oral immunomodulator for improving cell-mediated immune defense to HP-PRRSV.     

Hyphenated LC-ABTS·+ and LC-DAD-HRMS for simultaneous analysis and identification of antioxidant compounds in Astragalus emarginatus Labill. extracts

The compounds in leaf and stem extracts of Astragalus emarginatus Labill. (AEL), a plant species used in traditional Lebanese medicine, were investigated for antioxidant properties. First, the activity of various extracts was assessed using the Trolox equivalent antioxidant capacity, oxygen radical absorption capacity, and 2,2-diphenyl-1-picryl-hydrazyl-hydrate assays. The extract obtained using 30% ethanol showed the greatest activity. The antioxidant compounds in this extract were screened using a hyphenated high-performance liquid chromatography-2,2-azinobis-(3-ethylbenzothiazoline-6-sulfonate) radical (ABTS^·+) system before being separated by ultra-high-performance liquid chromatography and identified using high-resolution mass spectrometry and ultra-violet-visible diode array detection. Approximately 40 compounds were identified. Hydroxycinnamates (caffeic, ferulic, and p-coumaric acid derivatives) and flavonoids (quercetin, luteolin, apigenin, and isorhamnetin derivatives) were the two main categories of the identified compounds. The active compounds were identified as caffeic acid derivatives and quercetin glycosides. In addition, the catechol moiety was shown to be key to antioxidant activity. This study showed that AEL is a source of natural antioxidants, which may explain its medicinal use.     

Quercetin protects against aluminium induced oxidative stress and promotes mitochondrial biogenesis via activation of the PGC-1α signaling pathway

The present investigation was carried out to elucidate a possible molecular mechanism related to the protective effect of quercetin administration against aluminium-induced oxidative stress on various mitochondrial respiratory complex subunits with special emphasis on the role of PGC-1α and its downstream targets, i.e. NRF-1, NRF-2 and Tfam in mitochondrial biogenesis. Aluminium lactate (10 mg/kg b.wt./day) was administered intragastrically to rats, which were pre-treated with quercetin 6 h before aluminium (10 mg/kg b.wt./day, intragastrically) for 12 weeks. We found a decrease in ROS levels, mitochondrial DNA oxidation and citrate synthase activity in the hippocampus (HC) and corpus striatum (CS) regions of rat brain treated with quercetin. Besides this an increase in the mRNA levels of the mitochondrial encoded subunits – ND1, ND2, ND3, Cyt b, COX1, COX3 and ATPase6 along with increased expression of nuclear encoded subunits COX4, COX5A and COX5B of electron transport chain (ETC). In quercetin treated group an increase in the mitochondrial DNA copy number and mitochondrial content in both the regions of rat brain was observed. The PGC-1α was up regulated in quercetin treated rats along with NRF-1, NRF-2 and Tfam, which act downstream from PGC-1α. Electron microscopy results revealed a significant decrease in the mitochondrial cross-section area, mitochondrial perimeter length and increase in mitochondrial number in case of quercetin treated rats as compared to aluminium treated ones. Therefore it seems quercetin increases mitochondrial biogenesis and makes it an almost ideal flavanoid to control or limit the damage that has been associated with the defective mitochondrial function seen in many neurodegenerative diseases.     

Quercetin and Ethanol Attenuate the Progression of Atherosclerotic Plaques With Concomitant Up Regulation of Paraoxonase1 (PON1) Gene Expression and PON1 Activity in LDLR−/− Mice

Background: As moderate wine drinking is atheroprotective, it is clinically relevant to elucidate its possible mechanism/s of action/s. Our objective is to demonstrate the potential benefits of the wine components, quercetin and ethanol, on the development of aortic plaques with parallel changes in antiatherogenic factors. Methods and Results: The effects of quercetin and ethanol on the development of aortic atherosclerotic lesions, liver PON1 gene expression, and serum PON1 activity were measured in LDLR^?/? mice on an atherogenic diet for 4 and 8 weeks. Depending on the duration and dosage of these modulators, 12.5 to 25 mg/dl quercetin (12.5Q to 25Q) and 18 to 25% ethanol, the magnitude of decreases in aortic lesions caused by moderate ethanol and quercetin ranged from 20 to 70% (p < 0.05 to p < 0.001) based on ultrasound biomicroscopy (UBM) analyses, and from 18 to 61% (p < 0.05 to p < 0.001) based on morphometric analyses. The composite plot of all the UBM and morphometric data showed significant correlation between these 2 methods (p = 0.0001, Pearson r = 0.79 for 4‐week treatment; p = 0.000004, Pearson r = 0.84 for 8‐week treatment). Concomitantly, 4‐week treatments with 12.5Q and 18% ethanol up regulated liver PON1 mRNA by 41% (p < 0.05) and 37% (p < 0.05), respectively, accompanied by 92% (p < 0.001) and 61% (p < 0.001) increases in serum PON1 activity, respectively. The corresponding values after 8‐week treatment with 12.5Q and 18% ethanol were 23% (p < 0.05) and 40% (p < 0.02) with respect to the up regulation of liver PON1 mRNA expression, while the stimulations of serum PON1 activity were 75% (p < 0.001) and 90% (p < 0.001), respectively. Conclusions: Based on these findings, we conclude that quercetin and moderate ethanol significantly inhibit the progression of atherosclerosis by up regulating the hepatic expression of the antiatherogenic gene, PON1, with concomitant increased serum PON1 activity.     

五羟黄酮调节肝癌HepG2细胞bax基因表达诱导细胞凋亡的实验研究

目的:探讨三磷酸肌醇( IP3) 和bax基因表达变化在五羟黄酮(Quercetin)诱导肝癌细胞凋亡中的作用。方法:以肝癌HepG2 细胞培养72 h为对照,以20，40，60，80μmol/L Quercetin作用于 HepG2 细胞72 h 时和60μmol/L Quercetin 作用于 HepG2 细胞 6，12，24，48，72 h，应用同位素试剂盒检测细胞IP3含量,RT-PCR分析bax mRNA表达，Western blotting 分析细胞bax蛋白表达,流式细胞仪检测细胞凋亡率。结果:各浓度的Quercetin作用于肝癌HepG2 细胞72 h，IP3含量显著低于对照组(P<0.01)，bax mRNA和bax蛋白表达显著高于对照组，细胞凋亡率显著高于对照组(P<0.01); 60 μmol/L Quercetin 作用于肝癌HepG2 细胞6，12，24，48，72 h,各时相IP3含量显著低于对照组(P<0.01）;12 h后bax mRNA和bax蛋白表达显著高于对照组，24 h后各时相细胞凋亡率为显著高于对照组（P<0.01）。结论:Quercetin能减少IP3生成,上调bax基因表达,诱导肝癌细胞凋亡。     

Involvement of P450s and nuclear receptors in the hepatoprotective effect of quercetin on liver injury by bacterial lipopolysaccharide

Abstract

Objective: Quercetin (Que), a flavonoid, possesses anti-inflammatory and antioxidant properties. It has been shown to protect against liver injury induced by various factors. This study was designed to investigate the underlying mechanism of its protective effect against lipopolysaccharide (LPS)- induced liver damage.

Methods: Mice were pretreated with Que for 7 consecutive days and then exposed to LPS. To study the hepatoprotective effect of Que, oxidative stress parameters, inflammatory cytokine levels in liver and serum liver function indexes were examined. Protein and mRNA expression of nuclear orphan receptors and cytochrome P450 enzymes were measured by Western Blotting and qPCR, respectively.

Results: Que significantly reduced circulating ALT, AST, ALP, and ameliorated LPS-induced histological alterations. In addition, Que obviously decreased markers of oxidative stress and pro-inflammatory cytokines. Furthermore, Que carried out the hepatoprotective effect via regulation of the expression of nuclear orphan receptors (CAR, PXR) and cytochrome P450 enzymes (CYP1A2, CYP2E1, CYP2D22, CYP3A11).

Conclusions: Our findings suggested that Que pretreatment could ameliorate LPS-induced liver injury.     

The effect of quercetin on iron overload and inflammation in β-thalassemia major patients: A double-blind randomized clinical trial

ObjectivesThe aim of this study was to determine whether quercetin can reduce iron overload and inflammation in thalassemic patients.MethodsEighty four patients were recruited to this study and randomly assigned to two groups: 42 patients received a 500 mg/day quercetin tablet and 42 others took a 500 mg/day starch placebo for 12 weeks. Demographic, anthropometric and biochemical evaluation were performed.ResultsANCOVA analysis revealed that compared to the control group, quercetin could reduce high sensitivity C-reactive protein (hs-CRP) (P = 0.046), iron (p = 0.036), ferritin (p = 0.043), and transferrin saturation (TS) (p = 0.008) and increase transferrin (p = 0.045) significantly, but it had no significant effect on total iron binding capacity (TIBC) (p = 0.734) and tumor necrosis factor α (TNF-α) (p = 0.310).ConclusionsQuercetin could ameliorate the iron status in thalassemia major, but its effect on inflammation is indistinctive.     

Quercetin promotes glioma growth in a rat model

We have previously demonstrated that quercetin (Quer), a polyphenol widely found in vegetables, decreased glioma cell growth in vitro. Here, we asked whether this compound could affect glioma growth in an in vivo rat glioma model. We found that daily intraperitoneal Quer (50 mg/kg) injections lead to a concentration of 0.15 μg of Quer per gram of brain tissue, which increased the tumor volume in a time dependent manner. We observed a small reduction in lymphocytic infiltration, a marker of good prognosis in gliomas that was accompanied by a small reduction in cell viability of peripheral T-cells. Moreover, after Quer treatment neither body weight alteration nor liver pathology markers were detected. Although in vitro studies and massive literature reports point to the antitumoral properties of Quer, the present results indicate that great caution has to be taken in the design of clinical trials and the indiscriminate use of this polyphenol as dietary supplement.