Soy isoflavone attenuates brain mitochondrial oxidative stress induced by ß-amyloid peptides 1-42 injection in lateral cerebral ventricle.

The aim of this study is to investigate whether soy isoflavone (SIF) reduces oxidative stress and improves the antioxidant ability in mitochondria of rat brain damaged by injection of beta-amyloid peptides 1-42 (Aß1-42). Forty Wistar rats were randomly divided into control, Aß1-42, SIF + Aß1-42, and SIF groups according to body weight. The rats in the SIF + Aß1-42 group and SIF group were intragastrically administered SIF suspension in 0.5% CMC-Na for 28 days, whereas the rats in control group and Aß1-42 group were administered the same volume of 0.5% CMC-Na. On day 14, the rats in the Aß1-42 group and SIF + Aß1-42 group were injected with Aß1-42 into the lateral cerebral ventricle with physiological saline. The rat brains were then sampled, and brain mitochondria were isolated. After this, the mitochondrial membrane potential (MMP) and mitochondrial redox state were measured. The contents of brain nuclear factor E2-related factor (Nrf2) and heme oxygenase-1 (HO-1) protein in brain tissue were quantitated by Western blot. The results showed that SIF maintained the MMP, elevated the reduced glutathione/oxidized glutathione (GSH/GSSG) ratio, and increased glutathione peroxidase (GPx) and manganese superoxide dismutase (MnSOD) protein expression in brain mitochondria. Additionally, SIF reversed the Aß1-42-induced downregulation of the protein expression of Nrf2 and HO-1 in brain tissue. These results indicated that SIF could alleviate the oxidative damage and maintain the redox imbalance in brain mitochondria damaged by Aß1-42. This might result from regulation of the Nrf2/HO-1 pathway.

Antagonizing effects of soybean isoflavones on ß-amyloid peptide-induced oxidative damage in neuron mitochondria of rats.

Soybean isoflavone (SIF) has been demonstrated to have neuroprotective effects induced by ß-amyloid peptides (Aß) through suppressing oxidative stress; however, the explicit mechanisms still remain uncovered. In the present study, 32 Wistar rats were randomly divided into four groups: an Aß1-42-treated group, a SIF + Aß1-42 group, a SIF-treated group and a control group. We measured the protein content of 8-hydroxydeoxyguanosine (8-OhdG) and mRNA expression of 8-oxoguanine DNA glycosylase (OGG1). The protein expression of OGG1, Bcl-xl, Bad, beta subunit of ATP synthase (ATPB) and pyruvate dehydrogenase (PDH) in brain was also measured. The results showed that the level of 8-OHdG in both SIF groups was significantly decreased compared to the Aß1-42-treated group (p < 0.05), while the mRNA and protein expression of OGG1 in the SIF + Aß1-42 groups were up-regulated compared with the Aß1-42-treated groups (p < 0.05). The expression of Bcl-xl was up-regulated in the SIF-treated group compared with the Aß1-42-treated groups (p < 0.05), while the expression of Bad was down-regulated in the two SIF-treated groups (p < 0.05). Aß1-42 significantly down-regulated the expression of ATPase and PDH proteins compared with the control group (p < 0.05). SIF reversed the down-regulation effects on the mitochondrial energy metabolic enzymes induced by Aß1-42 (p < 0.05) in the rats. These results suggest that SIF alleviate the oxidative stress in neurons and mitochondria of rat brains mediated by Aß1-42, and these protective effects might be associated with the regulation of OGG1, Bad, Bcl-xl, ATPB and PDH.

Flavonoids protect cerebrovascular endothelial cells through Nrf2 and PI3K from ß-amyloid peptide-induced oxidative damage.

ß-amyloid peptides (Aß) induced cerebrovascular dysfunction has been recognized as a vital factor involved in the pathogenesis of neurodegeneration. Genistein, a flavonoid, has antioxidative properties to prevent neurodegeneration induced by ß-amyloid peptides. In this study, we were investigating whether genistein could antagonize oxidative damage induced by ß-amyloid peptide 25-35 (Aß25-35) in bEND.3 cells, and also identifying the potential neuroprotective targets of genistein. Vitamin E was used as the positive control. The bEND.3 cells were pre-incubated with/out genistein or vitamin E for 2 h followed by the incubation with 25 µM A 25-35 for another 24 h. The reactive oxygen species (ROS), nitrotyrosine, cell redox state, mRNA or protein expressions of the factors on Nrf2 signaling pathway were measured after Aß25-35 treatment. The results showed that genistein alleviated the increase of ROS and nitrotyrosine production induced by Aß25-35, and maintained bEND.3 cell redox state by increasing GSH level and GSH/GSSG. Genistein could reverse the down-regulation of total protein and mRNA expression of NF-E2-related factor 2 (Nrf2), nuclear Nrf2, γ-glutamylcysteine synthetase (γ-GCS), phosphatidylinositol 3-kinase (PI3K) induced by Aß25-35; while PI3K inhibitor LY294002 could attenuate the activation effects of genistein on Nrf2, especially for the promotion of nuclear translocation. These results suggested that genistein could protect cerebrovascular endothelial cells from Aß25-35-induced oxidative damage. The potential mechanisms might be associated with the activation of Nrf2 signaling pathway by modulating PI3K activity.

The role of glutathione S-transferase M1 and T1 gene polymorphisms and fruit and vegetable consumption in antioxidant parameters in healthy subjects.

The correlation of glutathione S-transferase (GST) M1/T1 genetic polymorphisms with oxidative stress-related chronic diseases was proved recently. The aim of the present study was to investigate the association of GSTM1/T1 genetic polymorphisms with antioxidant biomarkers and consumption of fruits and vegetables (F&V) in healthy subjects. In this study, for conducting a 3 d dietary survey, 190 healthy adults were recruited. After DNA extraction, a multiple PCR method was used for GSTM1/T1 genotyping. A spectrophotometer method was applied for the determination of plasma total antioxidant capacity (T-AOC), vitamin C level and erythrocyte GST enzyme activity. A general linear model was used to compare the mean values of antioxidant parameters for different GSTM1/T1 genotypes and consumption of F&V. Polymorphisms of GSTM1/T1 had no effects on plasma T-AOC and vitamin C levels. Deletion of the GSTM1 gene decreased the erythrocyte GST activity. There was correlation between plasma T-AOC and consumption of F&V in the GSTM1⁻ or GSTT1⁺ subjects. A similar pattern was evident for erythrocyte GST activity in the GSTM1⁻ subjects. No association was found among consumption of F&V and GSTM1/T1 genotypes and plasma vitamin C level. Different consumption of F&V had no impact on plasma T-AOC and vitamin C levels in the GSTM1⁻/GSTT1⁺ or GSTM1⁻/GSTT1⁻ subjects. The erythrocyte GST activity was more sensitive to consumption of F&V in the individuals with the GSTM1⁻/GSTT1⁺ genotype. Association was found among GSTM1/T1 genotypes, antioxidant parameters and consumption of F&V. Large-scale and multiple ethnic studies are needed to further evaluate the relationship.

Genistein inhibits mitochondrial-targeted oxidative damage induced by beta-amyloid peptide 25-35 in PC12 cells.

The antioxidative properties of genistein (Gen) have been demonstrated by our previous studies and others, but its potential mechanism was not very clear. Because of the key role of mitochondria in oxidant production, we wondered if mitochondria were one of Gen's neuroprotective targets. In the present study we investigated whether Gen has protective effects on mitochondria damaged by Aß25-35. PC12 cells were pre-incubated with or without Gen for 2 h followed by the incubation with 20 µM Aß25-35 for another 24 h before mitochondrial membrane fluidity (MMF), mitochondrial membrane potential (MMP) , and mitochondrial redox state were measured. The results showed that Gen alleviated the decrease of MMF induced by Aß25-35, and maintained the MMP. Additionally, Gen promoted the mitochondrial antioxidative capability through increasing the GSH/GSSG ratio, GPx activity and MnSOD protein expression in mitochondria. Moreover, Gen reversed the changes of ChAT mRNA and AChE mRNA expression in cells induced by Aß25-35. These results suggested that Gen can protect the mitochondrial membrane and maintain redox state in mitochondria damaged by Aß25-35.

Impact of apple and grape juice consumption on the antioxidant status in healthy subjects.

It is reported that consumption of antioxidant-rich foods significantly increased plasma total antioxidant capacity (T-AOC) in humans. Also, it is proved that the antioxidants from plant foods improve the body's antioxidant defence by acting additively and synergistically. As a result, rational combination of antioxidant-rich foods is recommended to population in the prevention of oxidative stress-related diseases. Both apple and grape are antioxidant-rich fruits. In this study, 2 weeks dietary intervention study was carried out in 25 healthy subjects to investigate the influences of apple and grape juices consumption on body antioxidant status. Our results indicated that 2 weeks of apple and grape juice consumption increased the plasma T-AOC and decreased the concentration of malondialdehyde. However, no change was found in the content of plasma carbonyl. Erythrocyte glutathione peroxidase and catalase activities were enhanced by 2 weeks of fruit juice consumption; however, no change was found in the activity of erythrocyte superoxide dismutase. The in vitro comet assay results indicated that apple and grape juice consumption did not influence lymphocyte damage upon hydrogen peroxide treatment. Urinary 8-hydroxy-2-deoxyguanosine content was not affected by 2 weeks of fruit juice intervention. These findings indicated that concomitant intake of apple and grape juice was efficient in enhancing the body's antioxidant status.

[Effects of genistein and folic acid on neuronal membrane and mitochondrial membrane damaged by ß-amyloid peptides 31-35].

OBJECTIVE: To observe the neuro-protective effects of genistein (Gen) and folic acid (FA) on neurons membrane and mitochondrial membrane damaged by ß-amyloid peptides 31-35 (Aß31-35). METHODS: The primary cultured rat cerebral cortical neurons were randomly divided into DMEM (control), Aß31-35 (25 µmol/L), Gen (Gen 27 µg/ml), FA (FA 40 µg/ml) and Gen + FA (Gen 27 µg/ml + FA 40 µg/ml). Gen and/or FA were added two hours before Aß31-35 addition. After twenty four hours, MTT assay was performed to measure the viability of cultured neurons. Fluorescence polarization was performed to observe the neuron cell membrane fluidity. The mitochondrial membrane potential (MMP) was determined to investigate the alteration of mitochondrial structure and function of neurons by laser scanning confocal microscope and a flow cytometer was used to investigate the activation of mitochondrial permeability transition pore (MPTP). Each experiment was repeated three times. RESULTS: Compared with group Aß31-35 (0.845 ± 0.050, F = 4.931, P < 0.05), the absorbance was significantly higher in group Gen (0.982 ± 0.110, t = 3.523, P < 0.01), FA (0.947 ± 0.061, t = 2.745, P < 0.01) and Gen + FA (0.996 ± 0.090, t = 3.966, P < 0.01). The viscosity of cell neuron membrane in group Gen (1.75 ± 0.28, t = 2.085, P < 0.05), FA (1.66 ± 0.37, t = 2.357, P < 0.05) and Gen + FA (1.50 ± 0.20, t = 3.784, P < 0.05) was significantly lower than that in group Aß31-35 (2.11 ± 0.44, F = 5.529, P < 0.01), which indicated the cell membrane fluidity was significantly higher in group Gen and/or FA than that in group Aß31-35. MMP was significantly decreased by Aß31-35 (3.364 ± 1.140, t = 3.949, P < 0.01) when comparing to control group (6.383 ± 1.683), while it was significantly increased by Gen (5.286 ± 1.792, t = 2.406, P < 0.05), FA (5.884 ± 2.022, t = 2.887, P < 0.01) and Gen + FA (6.120 ± 2.124, t = 3.304, P < 0.01) when comparing to group Aß31-35 (F = 7.585, P < 0.01). MPTP was activated by Aß31-35 and Gen and/or FA could reverse this progress. CONCLUSION: Gen and/or FA could protect the neuronal and mitochondrial membrane from the impairment induced by Aß31-35.

Dietary exposure assessment of Chinese adults and nursing infants to tetrabromobisphenol-A and hexabromocyclododecanes: occurrence measurements in foods and human milk.

Tetrabromobisphenol A(TBBPA) and hexabromocyclododecane diastereoisomers (alpha, beta, and gamma-HBCD) were determined in 24 pooled human milk samples and 48 Chinese total diet study (TDS) samples collected in 2007. On the basis of ultra performance liquid chromatography-mass spectrometry (UPLC-MS/MS) analysis, levels of TBBPA ranged from < LOD to 5124 pg/g lipid weight (lw) in human milk and from < LOD to 2044 pg/g lw in TDS samples. The alpha-HBCD diastereoisomer, which ranged from < LOD to 2776 pg/g lw in human milk and from < LOD to 2224 pg/g lw in TDS samples, was generally the most abundant isomer comparing with beta- and gamma-HBCD. The average estimated daily intake (EDI) of TBBPA via human milk for nursing infants with a range 320-37240 pg/kg bodyweight (bw)/day was 5094 pg/kg bw/day, while that of sigmaHBCD was 5837 pg/kg bw/day with a range 670-17320 pg/kg bw/day. The medium bound (< LOD = 1/2LOD) EDI(TBBPA) for a "reference" man via animal origin foods was 256 pg/kg bw/day and EDI(sigmaHBCD) was 432 pg/kg bw/day. Meat and meat products were the main source in the total dietary intake of TBBPA and sigmaHBCD. Our research on the estimated daily intake of TBBPA and sigmaHBCD by the Chinese population indicated large variations in TBBPA and sigmaHBCD levels between provinces. Overall, our data indicate the Chinese EDI was lowerthan the EDI from similar studies in Europe.

Neuroprotective effects of genistein and folic acid on apoptosis of rat cultured cortical neurons induced by beta-amyloid 31-35.

Genistein and folic acid have been reported respectively to protect against the development of cognitive dysfunction; however, the underlying mechanism(s) for this protection remain unknown. In this report, the mechanism(s) contributing to the neuroprotective effects of genistein and folic acid were explored using rat cortical neuron cultures. We found that genistein and folic acid, both separately and collaboratively, increased cell viability and mitochondrial membrane potential in beta-amyloid (Abeta) 31-35-treated neurons. Furthermore, reduced percentage of comet cells and shortened tail length were observed in the neurons treated with genistein or folic acid. A more significant reduction in tail length of the comet neurons was observed in the co-administered neurons. RT-PCR analysis of the cultured cortical neurons showed down-regulated expression of p53, bax and caspase-3, but up-regulated expression of bcl-2 in the three neuroprotective treatment groups compared with neurons from the Abeta31-35 solo-treated group. In a nuclear dyeing experiment using Hoechst 33342, we found that both genistein and folic acid prevent neuronal apoptosis. Collectively, these findings suggest that the mechanism underlying the neuroprotection of genistein and folic acid singly or in combination observed in cultured cortical neuron studies might be related to their anti-apoptotic properties.

[Lead and cadmium pollution in edible fungus sold in Beijing].

OBJECTIVE: To investigate the lead and cadmium pollution in edible mushrooms sold in Beijing. METHODS: 146 samples of 14 species were collected form 25 markets during the period of Mar. through May, 2007 in Beijing. The pollution of lead and cadmium were analyzed respectively according to the standard of GB/T5009. 12-2003 and GB 7096-2003. RESULTS: The content of lead and cadmium in edible mushrooms was ND--1.592 mg/kg, ND--0.550 mg/kg, respectively, both lower than the allowable content prescribed by The National Ministry of Health. CONCLUSION: The contents of lead and cadmium in the mushrooms marketed in Beijing are in safe ranges. It is worthy of mentioning the variation coefficients of heavy metal concentrations existing in edible mushrooms.