The single and combined effects of two abundant flavonoids, namely quercetin and genistein, were investigated according to their ability to inhibit the oxidation of methyl linolenate via Fenton's pathway. Antioxidative activity was determined by oxidizing methyl linolenate suspended in a buffer solution with either Fe2+ (50 microM) or Cu2+ (50 microM) and hydrogen peroxide (0.01 mM) without or with a flavonoid sample (10 or 20 microM). Lipid peroxidation products were measured by the thiobarbituric acid (TBA) assay and the amounts of thiobarbituric acid-reactive substances (TBARS) were calculated from a calibration curve using 1,1,3,3-tetraethoxypropane as the standard. Both quercetin and genistein at the 10 or 20 microM level decreased lipid peroxidation significantly compared with their respective controls. Of the two flavonoids tested, quercetin had a more marked effect on inhibiting lipid peroxides. Peroxidation products for the control samples were higher for the Fe2+-treated samples compared with the Cu2+ samples. Combination of both flavonoids at the same dose levels continued to decrease lipid peroxidation, the effect being the same for both metal ions. The data suggest that the combined flavonoids offered better protection than the single treatments and this may be attributed to the better radical scavenging or increased chelating capabilities of the combined over the single treatments. The differences in peroxide levels for the single treatment of quercetin compared with the genistein-treated samples may reflect the structural differences between these compounds in combating oxidative stress.

Key indicatorsSingle-crystal X-ray study T = 90 K Mean '(C±C) = 0.004 A Ê R factor = 0.025 wR factor = 0.052 Data-to-parameter ratio = 16.9For details of how these key indicators were automatically derived from the article, see

Obesity has been reported to be a risk factor for some types of cancer, such as prostate and lung. The AKT or PI3K-AKT is a signal transduction pathway that promotes survival and growth in response to extracellular signals. The aim of this study was to investigate the effects of two flavonoids, quercetin and kaempferol, and exogenous glutathione (GSH) on the expressions of phospho- and total-AKT levels in 3T3-L1 preadipocytes. Glyceraldehyde 3-phosphate dehydrogenase (GAPDH) levels were measured in the treated samples and used as the internal standard. 3T3-L1 preadipocytes were exposed to each flavonoid and GSH at concentrations of 0, 5, 10, 15, 20, and 25 µM, and the levels of phospho- and total-Akt were measured by the MILLIPLEX MAP mates protocol, based on the Luminex xMAP technology (Millipore Corp., St. Charles, MI, USA). GAPDH levels in the preadipocytes were not significantly different at the doses tested for the flavonoids and exogenous GSH. However, significant (p <.05) decreases in phospho-AKT levels in cells treated with quercetin, kaempferol, and GSH at certain doses were observed compared to their respective controls. Total-AKT levels showed the same profile for all the tested compounds. Significant (p <.01) differences were observed for kaempferol (15-25 µM), quercetin at 10 and 20 µM, and GSH at 10 µM compared to their respective controls. Findings suggest that exposure of 3T3-L1 preadipocytes to quercetin, kaempferol, and GSH may block the activation of AKT, suggesting the role such compounds play in cell differentiation in 3T3-L1 cells.

The purpose of the present study was to investigate the effect of perfusion with a medium containing 12 or 24 micrograms Cadmium (as CdCl2) per ml on this metal's accumulation, transfer rate and metallothionein (MT) level. The experiments were performed with an isolated lobule of a dually-perfused human term placenta. Placental cell integrity and viability were characterised by their morphology and metabolic function, manifested in the tissue's electron microscopic structure and glucose and oxygen (O2) consumption, respectively. Perfusion with 24 micrograms Cd/ml medium for 5 h resulted in significant elevation in MT. The transfer rate of Cd to the fetal side of the placenta was very slow, and not until 40 min after the addition of Cd into the maternal side was a significant increase in the metal's level observed in the fetal perfusate. Thereafter, the level of the metal increased gradually and reached a steady state about 1 h later, at a level which was less than 1/20th of its concentration in the maternal perfusate. There was a 60-fold increase in Cd level in the cytosolic fraction obtained from the Cd-treated samples. At 12 micrograms Cd/ml no significant changes were noted in morphology, metabolic function and MT content. None of the Cd levels caused a significant change in O2 and glucose consumption, in spite of the fact that with the higher Cd dose the microstructure of the tissue showed some pathological changes. The observed elevation in MT may provide the fetus some protection against the harmful effects of the metal.

The effects of flavonoids quercetin and genistein were investigated according to their potency to inhibit the oxidation of U937 cells via Fenton's pathway through the analysis of lipid peroxides and glutathione (GSH) levels. Human leukemia (U937) cells from the American Type Culture Collection were maintained at 37 degrees C for 24 h under 5% CO2 tension in RPMI-1640 medium containing 10% fetal bovine serum and 50 units ml(-1) each of penicillin and streptomycin. Cells were oxidized with iron 50 microM) or copper (50 microM) in H2O2 (0.01 mM) without or with a flavonoid sample (10 or 20 microM) for the lipid peroxidation studies. The GSH levels were measured (GSH Kit) before and after oxidation as above with different concentrations of flavonoids (0-40 microM). Lipid peroxide was measured by the thiobarbituric acid assay. Both quercetin and genistein at either the 10 or 20 microM level decreased lipid peroxidation significantly compared with their respective controls (P < 0.01). Lipid peroxides by Fe compared to the Cu-treated samples did not differ significantly from each other. However, the combination of flavonoids at the doses tested significantly (P < 0.001) decreased lipid peroxides, the effect being the same for both metal ions. The GSH levels increased significantly before exposure to the metal ions (for the different doses for the differences between the flavonoid samples and their respective untreated levels). For quercetin and genistein the increases in GSH above their untreated levels were 4.5, 8.3, 11.7 and 15 and 3.8, 7.9, 12.5 and 14.6 nmol 10(-6) cells, respectively, for the 5-40 microM levels tested for each flavonoid. Following the exposure to the metal ions, GSH levels remained almost the same for the different concentrations for each of the flavonoids tested but significantly above all of the controls and same for those of the untreated samples. The results indicate that both flavonoids inhibited lipid peroxides and the inhibition may be attributed to the prevention of loss of intracellular GSH levels in U937 cells.