In vitro exposure to quercetin and genistein alters lipid peroxides and prevents the loss of glutathione in human progenitor mononuclear (U937) cells

Abstract

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.

Lipid peroxides and glutathione status in human progenitor mononuclear (U937) cells following exposure to low doses of nickel and copper

“…U937 cells incubated for 24 hours with either Cu 2+ or Ni 2+ and oxidized through Fenton’s pathway resulted in significant increases in lipid peroxides, confirming the generation of these hydroxyl-like reactive species, causing the increases in the amounts of lipid peroxides as has previously observed by us and others (Boadi et al, 2003, 2005; Valko et al, 2005). It is interesting to note that Cu 2+ increased lipid peroxides more, compared to that of Ni 2+ .…”

“…U937 cells, obtained from American Type Culture Collection (ATCC; Manassas, Virginia, USA), were maintained at 37°C under a 5% CO 2 atmosphere in RPMI 1640 medium containing 10% fetal bovine serum and 50 U/mL each of penicillin and streptomycin (Subramanian et al, 1999). Cells were treated with 0, 5, 10, and 20 µM of Ni 2+ and/or Cu 2+ and H 2 O 2 (0.01 mM) (Boadi et al, 2005) and incubated for 24 hours at 37°C. Control incubations contained all reagents except the metals.…”

“…Lipid peroxides were analyzed by the thiobarbituric acid (TBA) assay in samples, following the treatments as previously described (Boadi et al, 2005), with some slight modifications described below. Cells in a 1.5 × 10 6 /well concentration from the various treatment groups were washed three times in RPMI 1640 medium, as described above, to remove residual metals before the analysis of lipid peroxides.…”

Genistein Induces Estrogen-Like Effects in Ovariectomized Rats but Fails to Increase Cardiac GLUT4 and Oxidative Stress

“…This role of genistein is also confirmed in soy-deficient diets, which cause mitochondrial levels of glutathione to decrease as a result of increased production of reactive oxygen species. [40][41][42][43][44] In contrast with these studies, our data failed to show an increase in cardiac GSH content with genistein treatment. However, this does not suggest that the oxidative stress capacity of genistein-treated hearts is limited because we recently reported that a 2-day treatment period increases tolerance of hearts to severe ischemia.…”

Quercetin reduces chromosome aberrations induced by atrazine in the Allium cepa test

“…Abel et al [2004] reported that atrazine is biotransformed by human and mouse hepatic GS S-transferases, and most probably this mechanism is the same in plants. Quercetin could act by regenerating GSH, as reported by Boadi et al [2005] for human cell lines. Flavonoids increase the intracellular GSH level by transactivation of the g-glutamylcysteine synthetase (GCS) catalytic subunit promoter; this effect may be exerted in part through GCS gene regulation, and also may contribute to the disease-preventing effects of fruits and vegetables [Myhrstad et al, 2002].…”