Protective effect of quercetin on experimental chronic cadmium nephrotoxicity in rats is based on its antioxidant properties

Oxidative stress can play a key role in Cd-induced dysfunctions. Quercetin is a potent oxygen free radicals scavenger and a metal chelator. Our aim was to study the effect of quercetin on Cd-induced kidney damage and oxidative stress as well as its mechanism of action. Wistar rats were distributed in four experimental groups: control rats; Cd; quercetin and Cd + quercetin. Renal toxicity was evaluated by measuring urinary excretion of proteins, albumin, glucose and enzymes markers of tubular necrosis, as well as plasma concentration of creatinine. Plasma TBARS concentration and activity of antioxidant enzymes in kidney were also measured. Renal cell damage was assessed by electron microscopy. Animals that received both Cd and quercetin showed a better renal function than those receiving Cd alone. Cd-induced tubular lesions were markedly reduced in rats that also received quercetin. Cd-induced increase in plasma TBARS was prevented by the administration of quercetin. Total plasma antioxidants and renal superoxide dismutase and glutathione-reductase activities were higher in the group that received Cd and quercetin than in rats that received Cd alone. Quercetin administration does not modify the renal content or the urinary excretion of Cd. In conclusion, quercetin treatment prevents renal tubular damage and increased oxidative stress induced by chronic Cd administration, most probably throughout its antioxidant properties.     

高效液相色谱法测定复方银杏叶片中银杏总黄酮的含量

目的建立复方银杏叶片中银杏总黄酮含量测定方法。方法采用高效液相色谱法,用Symmetry-C18色谱柱(250mm×4.6 mm,5μm),以甲醇-0.4%磷酸溶液(52∶48)为流动相,流速为1.0 ml.min-1,检测波长360 nm,柱温35℃。结果该法线性关系良好,平均加样回收率为98.35%,RSD为1.17%(n=5)。结论该法操作简便,分离效果好,结果准确,专属性强,可作为复方银杏叶片的质量控制方法。     

槲皮素铜（Ⅱ）配合物清除自由基活性的研究

目的研究槲皮素铜(Ⅱ)配合物的抗氧化作用。方法采用DPPH法和NBT法分别测定了槲皮素铜(Ⅱ)配合物对二苯代苦味肼基自由基(DPPH.)和超氧阴离子(O2-.)的清除作用。结果槲皮素铜(Ⅱ)配合物能有效清除DPPH.和O2-.,其清除能力均强于单独的槲皮素。结论槲皮素铜(Ⅱ)配合物是一种较强的自由基清除剂,具有较高的SOD活性。     

Role of Bax in quercetin-induced apoptosis in human prostate cancer cells

The aim of this study was to investigate the effect of quercetin, a flavonoid, on the apoptotic pathway in a human prostate cell line (LNCaP). We observed that treatment of cells for 24h with quercetin-induced cell death in a dose-dependent manner. A sustained inhibition of the major survival signal, Akt, occurred in quercetin-treated cells. Treatment of LNCaP cells with an apoptosis inducing concentration of quercetin (100 microM) resulted in a rapid decrease in the inhibitory Ser473 phosphorylation of Akt leading to inhibition of its kinase activity. Quercetin treatment (100 microM) also caused a decrease in Ser136 phosphorylation of Bad, which is a downstream target of Akt. Protein interaction assay revealed that during treatment with quercetin, Bcl-xL dissociated from Bax and then associated with Bad. Our results also show that quercetin decreases the Bcl-xL:Bax ratio and increases translocation and multimerization of Bax to the mitochondrial membrane. The translocation is accompanied by cytochrome c release, and procaspases-3, -8 and -9 cleavage and increased poly(ADP-ribose) polymerase (PARP) cleavage. Similar results were observed in human colon cancer HCT116Bax+/+ cell line, but not HCT116Bax-/- cell line. Interestingly, at similar concentrations (100 microM), quercetin treatment did not affect the viability or rate of apoptosis in normal human prostate epithelial cell line (PrEC) and rat prostate epithelial cell line (YPEN-1). Our results indicate that the apoptotic processes caused by quercetin are mediated by the dissociation of Bax from Bcl-xL and the activation of caspase families in human prostate cancer cells.     

HPLC法测定降脂宁胶囊中槲皮素的含量

目的:建立以高效液相色谱法测定降脂宁胶囊中槲皮素含量的方法。方法:色谱柱为Shim-packVP-ODSC18(150mm×4·6mm,5μm),流动相为甲醇-0·4%磷酸溶液(52:48),流速为0·8mL·min-1,检测波长为373nm。结果:槲皮素的进样量在0·0189～0·0566μg范围内与峰面积积分值呈良好的线性关系(r=0·9999);平均回收率为98·06%,RSD=1·73%(n=6)。结论:本方法简便、可靠、准确,可用于降脂宁胶囊的质量控制。     

8-Br-cAMP联合槲皮素对人食管癌Eca-109细胞的逆转化作用

目的探讨8-Br-cAMP与槲皮素联合用药对人食管癌Eca-109细胞逆转化的作用。方法将培养的Eca-109细胞随机分为4组:①8-Br-cAMP组(Br):加终浓度为2×10-5mol/L8-Br-cAMP;②槲皮素组(Q):加槲皮素终浓度为43μmol/L;③8-Br-cAMP和槲皮素共同作用组(Br+Q):加终浓度为2×10-5mol/L8-Br-cAMP和终浓度为43μmol/L的槲皮素;④对照组(C):仅加DMEM培养液(含10%胎牛血清)。同时培养48h后分别对以上4组细胞制备细胞滴片及硝酸纤维素膜滴膜两种标本,进行Caspase-3和PCNA的免疫组化和免疫斑点印迹实验;应用完整细胞原位斑点印迹杂交技术检测c-myc、野生型p53(wtp53)、p16和EGFR的基因表达;并进行分化细胞/增殖细胞计数。结果8-Br-cAMP与槲皮素联合或单独应用均可上调Caspase-3免疫反应信号的表达,下调PCNA免疫反应信号的表达;同时上调wtp53和p16基因的表达,下调c-myc和EGFR基因的表达;且分化细胞的比率显著提高。结论8-Br-cAMP与槲皮素联合用药或单独用药均可通过调控人食管癌Eca-109细胞癌基因和抑癌基因的表达对Eca-109细胞起到生长抑制和促分化的作用。     

五子衍宗片质量标准研究

目的建立五子衍宗片的质量标准。方法用薄层色谱法对处方中五味子、枸杞子进行鉴别;用HPLC法测定槲皮素的含量。结果薄层色谱鉴别分离度好,专属性强;,槲皮素的含量测定在0.04228~0.4228μg范围呈良好的线性关系,r=0.9999;平均回收率为98.03%,RSD=0.72%。结论建立的方法可靠、准确、专属性强,可有效地用于该制剂的质量控制。     

HPLC法同时测定楚雄臭菜中槲皮素和山奈酚的含量

目的建立HPLC法测定楚雄臭菜中的槲皮素和山奈酚含量的方法。方法采用色谱柱:InertSustain C18(250 mm×4.6 mm,5μm);以乙腈(A)-0.3%磷酸水溶液(B)为流动相进行梯度洗脱;流速:0.8 m L/min;检测波长:360 nm;柱温:30℃。结果槲皮素的进样量在0.034~0.272μg范围内(r=0.999 9)、山奈酚的进样量在0.039~0.317μg范围内(r=0.999 8)线性关系良好,槲皮素、山奈酚的平均回收率分别为99.33%(RSD=1.33%,n=6)、99.48%(RSD=1.85%,n=6)。结论本方法操作简便、快捷,稳定性高,重现性好,为楚雄臭菜药材的质量评价提供依据。     

翻白草中槲皮素的提取工艺优化及含量测定

目的:优选翻白草中槲皮素的最佳提取工艺,建立以高效液相色谱法测定其含量的方法。方法:采用超声波提取法,以槲皮素的提取含量为评价指标,以提取时间、料液比、乙醇浓度和提取次数为考察因素,通过正交试验筛选出最佳提取工艺;采用高效液相色谱法测定槲皮素的含量。结果:翻白草中槲皮素的最佳提取工艺为每次提取40min、料液比1∶15、80%的乙醇、提取3次;槲皮素检测浓度在0.004～0.020mg·mL-1(r=0.999 6)范围内与其峰面积积分值呈良好的线性关系,平均加样回收率为100.17%,RSD=2.27%(n=6)。结论:本方法简便、迅速,可为翻白草的进一步开发利用和有效性研究提供理论依据。     

Consumption of polyphenol concentrate with dietary fructo-oligosaccharides enhances cecal metabolism of quercetin glycosides in rats

Objective

We verified the hypothesis that the consumption of polyphenol concentrate (PC), rich in quercetin and its glycosides (36 g/100 g), in association with different dietary fiber matrices, that is, an easily fermentable fructo-oligosaccharides (FOS) or non-fermentable cellulose (CEL), causes a disparate adaptive response of the cecal microbial activity in rats. This in turn facilitates further utilization of biologically active polyphenolic compounds, which are not, as usual, digested in the foregut.

Methods

Four-week experimental feeding of male Wistar rats consisted of diets containing 5% FOS or CEL, as a source of dietary fiber, with or without 0.3% addition of PC.

Results

Positive changes in rat cecum were observed resulting from the ingestion of an FOS-containing diet, such as decreased pH and increased the production of short-chain fatty acids in the digesta, compared with a CEL-containing diet. The addition of PC to the FOS diet did not eliminate the positive effects of the latter, except for a slight increase in cecal pH and a decrease in microbial glycolytic activity. However, a simultaneous increase in the cecal butyrate pool was also observed. An adaptation process of the microflora enzymatic system to dieting with PC and FOS was proven in further enhanced susceptibility of rutin (quercetin 3-O-glucorhamnoside), hyperoside (quercetin 3-O-galactoside), and quercitrin (quercetin 3-O-rhamnoside) to hydrolysis by the cecal digesta solution.

Conclusion

Especially when consumed together, PC and FOS are important dietary factors affecting the susceptibility of quercetin glycosides to microbial metabolism in the cecum. The intensification of the hydrolysis of quercetin glycosides by dietary treatments leads also to the increased metabolism of quercetin itself.