Antioxidant and Vasodilatory Action of Grape Juices Produced in Different Regions of Brazil

Grapes and its derivatives (wines and juices) are rich in polyphenols that have high antioxidant and vasodilator capacity. These biological activities may vary in the juices marketed and produced in different regions of Brazil. Objectives: To determine the antioxidant and vasorelaxant effects of grape juice samples produced in different regions of Brazil. Methods: The content of phenolic compounds and antioxidant capacity were evaluated by the methods of Folin-Ciocalteau, DPPH, ABTS and a new electroanalytical approach (differential pulse voltammetry - DPV). Vasodilator effects were analyzed in isolated aorta from rats in an organ bath. Results: The samples from RJ and SP presented respectively the higher and lower phenolic content and also antioxidant capacity by the methods used (ABTS and DPPH). The results of the electrochemical index corroborate to the other tests, with the best results to RJ (21.69 ± 3.15 µA/V) and worse to the SP sample (11.30 ± 0.52 µA/V). In the vascular reactivity studies, the relaxation induced by each sample presented more distinct differences, following the order: RJ (87.9 ± 4.8%) > RS1 (71.6 ± 8.6%) > GO (56.2 ± 7.2%) > SP (39.9 ± 7.8%) > PR (39.4 ± 9.5%) > RS2 (19.5 ± 6.2%). Inhibition of endothelial NO practically abolished (p < 0.001) the relaxation for all samples, except one. Conclusion: The phenolic content and antioxidant capacity vary greatly among samples. The results obtained for the order of antioxidant activity were: RJ > RS1 > GO > RS2 > PR > SP. The juices were able to induce vascular relaxation at quite varied levels, and the RJ sample the most effective. The L-NAME practically blocked all samples except one (RS2)

Modulatory effect of baicalein on gene expression and activity of antioxidant enzymes in streptozotocin-nicotinamide induced diabetic rats

Oxidative stress plays the central role in the pathogenesis and progression of diabetic complications. The present study aims to investigate the beneficial effect of oral administration of flavone baicalein in streptozotocin-nicotinamide (STZ-NA) induced diabetic rats by measuring oxidative stress markers, antioxidant enzyme activities and expression analysis of antioxidant genes. Experimental diabetes was induced by a single intraperitoneal (i.p.) injection of STZ (55 mg /kg b.wt), 15 min after the i.p. administration of NA. At the end of the experimental period, thiobarbituric acid reactive substances (TBARS), activities of antioxidant enzymes and expression levels of superoxide dismutase (SOD), catalase (CAT), glutathione (GSH) and glutathione peroxidase (GPx) were measured in diabetic rats along with serum biochemical parameters namely total cholesterol (TC), total triglyceride (TG), aspartate transaminase (AST) alanine transaminase (ALT) and glycosylated hemoglobin (HbA1c). Oral administration of baicalein (40 mg/kg b.wt/day) demonstrated a significant ameliorative effect on all studied biochemical and oxidative stress parameters. Biochemical findings were corroborated by qPCR expression analysis which showed significant upregulation of antioxidant genes in diabetic rats. These results suggest that baicalein supplementation may reduce diabetes and its complications by suppressing oxidative stress and enhancing gene expression and antioxidant enzyme activities in diabetic rats.

Proventive effects of astaxanthin on metabolic cataract and its mechanism in type 1 diabetic rats / 中华实验眼科杂志

Background The pathogenesis mechanism of diabetic cataract has not been fully elucidated.Researches showed that multiple biological pathways participate in the pathogenesis of diabetic cataract,including oxidative stress.Astaxanthin can inhibit oxidative stress-mediated injury and lipid peroxidation.However,whether astaxanthin has the preventive effects on diabetic cataract is unclear.Objective This study was to investigate the preventive effects of astaxanthin on metabolic cataract in type 1 diabetic rats.Methods Thirty-eight 6-week-old SPF male SD rats were used in this study,and 1％ streptozocin was intraperitoneally injected to establish type 1 diabetic models in 30 rats,and 24 successful models were assigned to diabetic model group,low-dose astaxanthin group and high-dose astaxanthin group.Equal volume of normal saline solution was injected in the same way in 8 rats as the normal control group.Mixture foods containing 50 mg/(kg · day) or 100 mg/(kg · day) astaxanthin with olive oil and fodder were used continuously for 3 months in the rats of low-dose astaxanthin group and high-dose astaxanthin group,respectively,and mixture food of olive oil with fodder was used in the diabetic model group.Only fodder was used in the same way in the rats of the normal control group.The opacification of lens was examined by slit lamp section radiography system and graded on a scale of 1-5.The specimen of lens were prepared for the hematoxylin & eosin stain.The expression and lation of advanced glycosylation end products (AGEs) in the lens was examined using immunochemistry.The contents of oxidative stress-related indicators in the lens,such as AGEs,malonydialdehyde (MDA),catalase (CAT),superoxide dismutase (SOD) and mass fraction of glutathione (GSH),were assayed by ELISA.The experimental process complied with the national standard (Laboratory Animal Requirements of Environment and Housing Facilities [GB14925-2001]).Results The blood glucose levels of the rats were significantly higher in the diabetic model group,low-dose astaxanthin group and high-dose astaxanthin group than those in the normal control group at 2,4,6,8,10 and 12 weeks after modeling (all at P＜0.05),while the blood glucose levels of rats were not evidently different between low-dose astaxanthin group and high-dose astaxanthin group at various time points(all at P＞0.05).The rat lenses were transparent in the normal control group with scale of grade 1,and serious lens opacification was seen in the rats of the diabatic model group,with the scale of grade 5,while the rat lenses in the low-dose astaxanthin group and high-dose astaxanthin group were in grade 3-4.The contents of AGEs in the lenses were (7.23 ±0.50) μg/ml and (7.01 ±0.37) μg/ml,and M DA contents were (1.43 ± 0.22) mmol/L and (1.35±0.16)mmol/L in the low-dose astaxanthin group and high-dose astaxanthin group respectively,which were significantly lower than (7.61± 0.45) μg/ml and (1.62 ±0.42) mmol/L in the normal control group (all at P＜0.05).GSH contents in rat lenes were (272.70±12.53) ng/L and (283.52±16.17) ng/L,and SOD coneents were (55.45± 6.47) μmol/(min · L) and (56.73±5.12) μmol/(min · L),and CAT concents were (2.91 ±0.41) μmol/(min · L)and (3.02±0.13)μmol/ (min · L) in the low-dose astaxanthin group and high-dose astaxanthin group respectively,which were significantly higher than (241.52 ± 15.13) ng/L,(51.67 ± 5.45) μmol/(min · L) and (2.72 ± 0.27)μmol/(min · L) in the normal control group (all at P＜0.05).The GSH concent and SOD concent in rat lens were lower in the low-dose astaxanthin group than that in the high-dose astaxanthin group (both at P＜0.05).Conclusions Astaxanthin can postpone the pathogenesis and development of diabetic cataract in type 1 diabetic rats by antioxydative stress.

Induction of docosahexaenoic acid to expression of heme oxygenase-1 in retinal pigment epithelial cells / 中华实验眼科杂志

Background Oxydative stress is an important pathogenesis of age-related macular degeneration.Resent evidences indicate that docosahexaenoic acid (DHA) plays an important role during the development of retinal photoreceptor cells and protect the cells against oxydative stress by inducing the expression of heme oxygenase-1 (HO-1).However,whether DHA can induce the expression of HO-1 in human retinal pigment epithelium (RPE) cells is unelucidated.Objective This study was to investigate the effect of DHA on the expression of HO-1 in RPE cells and its molecular mechanism.Methods Human RPE cell line ARPE-19 was cultured in vitro and treated with 30,50,100 and 120 μmol/L DHA for 4 to 24 hours,respectively,and the cells were cultured without DHA as the control group.The cytotoxicity of DHA was detected by lactate dehydrogenase(LDH),and the expression of HO-1 mRNA and protein were detected by real-time PCR and Western blot assay,respectively.The enzymatic activity of HO-1 was detected by colorimetry.The reactive oxygen species (ROS) proportion in the cells was detected using fluorescence probe H2 DCFDA,and immunofluorescence technology was adopted to detect the nuclear translocation of nuclear facotor-E2-related factor 2 (Nrf2).The expression of Nrt2 protein in the cells was detected by Western blot after intervention of ROS inhibitor N-acetylcysteine (NAC) and transfection of Nrf2 small interfering RNA (siRNA).Results The LDH leakage rate was significantly different after 0,3,50,100 and 120 μmol/L DHA treated the cells for 24 hours (F=8.14,P＜0.05),and the LDH leakage rate in the 120 μmol/L DHA group was significantly higher than that of 0,30,50 and 100 μmol/L DHA group (all at P＜0.05).The relative expression levels of HO-1 mRNA and HO-1 protein or HO-1 enzymatic activity in the cells were significantly different among different concentrations of DHA group in 8 hours after treatment (F=16.24,P＜0.05;F=11.34,P＜0.05;F=11.81,P＜0.05),and the expressions of these factors were considerably higher in the 30,50 and 100 μ mol/L DHA group than those in the 0 μmol/L DHA group (all at P＜0.05).The ROS relative fluorescence intensity and nuclear Nrf2 positive cells proportion were statistically significant among different concentrations of DHA groups (F =11.08,P ＜ 0.05;F=16.42,P＜0.05),and the ROS relative fluorescence intensity and nuclear Nrf2 positive cells proportion were evidently higher in the 30,50 and 100 μmol/L DHA group than those in the 0 μmol/L DHA group (all at P＜0.05).The relative expression levels of HO-1 protein and the proportion of nuclear Nrf2 positive cells were significantly lower in the NAC pretreated 100 μmol/L DHA group than those in the 100 μmol/L DHA group.In addition,the HO-1 relative expression level and the positive cells proportion of nuclear Nrf2 were significantly lower in the of Nrf2 siRNA transfection group than those in the blank siRNA transfection group (both at P＜0.05).Conclusions DHA with concentration below 100 μ mol/L can protect RPE cells from oxidative stress by inducting the expression of HO-1 in the cells via ROS/Nrf2 pathway.