Erythrocyte Antioxidant System Research Articles

Modulation of the Human Erythrocyte Antioxidant System by the 5- and 6-Membered Heterocycle-Based Nitroxides.

Nitroxides are stable radicals consisting of a nitroxyl group, >N-O•, which carries an unpaired electron. This group is responsible for the paramagnetic and antioxidant properties of these compounds. A recent study evaluated the effects of pyrrolidine and pyrroline derivatives of nitroxides on the antioxidant system of human red blood cells (RBCs). It showed that nitroxides caused an increase in the activity of superoxide dismutase (SOD) and the level of methemoglobin (MetHb) in cells (in pyrroline derivatives) but had no effect on the activity of catalase and lactate dehydrogenase. Nitroxides also reduced the concentration of ascorbic acid (AA) in cells but did not cause any oxidation of proteins or lipids. Interestingly, nitroxides initiated an increase in thiols in the plasma membranes and hemolysate. However, the study also revealed that nitroxides may have pro-oxidant properties. The drop in the AA concentration and the increase in the MetHb level and in SOD activity may indicate the pro-oxidant properties of nitroxides in red blood cells.

Altered insulin secretion dynamics relate to oxidative stress and inflammasome activation in children with obesity and insulin resistance

BackgroundInsulin resistance (IR) is considered the main driver of obesity related metabolic complications, and is related to oxidative stress and inflammation, which in turn promote each other. There is currently no specific definition of IR in children, rather, that for adult population is used by pediatric endocrinologists instead. Altered insulin secretion dynamics are associated with worse metabolic profiles and type 2 diabetes mellitus development, thus we aimed to test whether insulin response relates to oxidative stress and inflammation in children.MethodsWe conducted a case–control study, including 132 children classified as follows: 33 children without obesity (Lean); 42 with obesity but no IR according to the American Diabetes Association criteria for adults (OBIR-); 25 with obesity and IR and an early insulin response to an oral glucose tolerance test (OGTT) (EP-OBIR +); 32 with obesity, IR, and a late insulin peak (LP-OBIR +); and studied variables associated with lipid and carbohydrate metabolism, oxidative stress, inflammation and inflammasome activation.ResultsThe measured parameters of children with obesity, IR, and an early insulin response were similar to those of children with obesity but without IR. It was late responders who presented an impaired antioxidant system and elevated oxidative damage in erythrocytes and plasma, and inflammasome activation at their white blood cells, despite lower classical inflammation markers. Increased uric acid levels seems to be one of the underlying mechanisms for inflammasome activation.ConclusionsIt is insulin response to an OGTT that identifies children with obesity suffering oxidative stress and inflammasome activation more specifically. Uric acid could be mediating this pathological inflammatory response by activating NLRP3 in peripheral blood mononuclear cells.Graphical

Erythrocytic antioxidant system in the administration of new coordination compounds thiosemicarbazide derivatives

Background: Currently, there is a growing interest in new local coordination compounds (CC), which demonstrated antitumor properties, but their influence on the erythrocyte antioxidant system has not been studied. The aim of the study: to study the effects of CC, thiosemicarbazide derivatives –TIA-160, CMT-67 and CMJ-33 on indices of the antioxidant system indicators in erythrocytes peripheral blood in vivo experiments. Material and methods: The action of CC on superoxide dismutase, catalase, total antioxidant capacity was evaluated on a group of 34 white rats, randomly divided into 4 groups: the first control group was injected subcutaneously with saline. The other groups (2 – TIA-160, 3 – CMT-67 and 4 – CMJ-33) were given subcutaneously 3 times a week for 30 days, 0.1µM / kg CC. Results: It was established that the TIA-160 compound demonstrated the highest capacity to induce the expression of erythrocyte catalase that exceeded the control level of 1.8, which did not correlate with the enzymatic superoxide dismutase (SOD) activity. Thus, this study showed that there are differences in the mechanisms of action of thiosemicarbazone derivatives. Conclusions: The influence of tested CC on the indices of the antioxidant system is selective. This selectivity may be the base to their strong selective antiproliferative and cytotoxic action on tumor cells, but not on healthy ones.

Deneysel Diyabette Döteryum Azlığının Eritrositler Üzerine Etkisi

In the development of diabetic complications, oxidative stress caused by hyperglycemia plays an important role. Deuterium depletion has protective effect against cellular damage and tumor suppressor effect in cancer cell lines. The purpose of this study was to examine and evaluate the effect of deuterium depletion on erythrocyte oxidant and antioxidant system parameters in experimental diabetes induced by streptozotocin (STZ) in rats. On the 30th or 40th day after STZ injection, blood samples were taken and blood glucose levels were measured. Erythrocyte hemolysates were also prepared. Lipid peroxidation and glutathione levels and glutathione-S-transferase, superoxide dismutase and catalase enzyme activities of erythrocytes were determined. At the 30 or 40 day periods, deuterium depleted water (DDW) consumption had differently affected oxidant-antioxidant parameters of erythrocytes. The clear effect of deuterium depletion in drinking water from 150 ppm to 85 ppm was observed in glutathione levels and it increased erythrocyte glutathione levels in both the control and diabetic groups. In conclusion, deuterium depletion may have protective effects on diabetes induced oxidative stress. Further studies are needed to be done to determine the mechanism of action and the useful dosage and the application period of DDW.

Evaluation of physico-chemical properties and biocompatibility of new surface functionalized Fe3O4 clusters of nanoparticles

In this research, magnetic nanoclusters of Fe3O4 (MNC) were synthesized by solvothermal method using different organic acids as surfactants such malic acid, aspartic acid and sodium tartrate in order to obtain new nanostructured materials with applications in medicine. The interaction process of these acids on the surface of magnetic nanoclusters is important in understanding the change induced on the surface properties of the obtained MNC. Structural analysis and physico-chemical characterization of the new synthesized materials were performed by means o X-ray photoelectron spectroscopy (XPS), transmission electron microscopy, zeta potential and magnetic measurements to provide their spherical shape, stability and specific functional groups and the influence of the surfactants on their magnetic properties. XPS core level and valence band photoemission spectra for all investigated samples is discussed in terms of changes induced in the electronic structure linked to variation of the Fe2+ cations at the samples surface. This is of fundamental importance to better understand the electronic structure and magnetism of the obtained MNC in order to tailor their electronic properties by surface engineering for specific biomedical applications. The biological effects of MNC in rat blood were studied by hemolysis and erythrocyte antioxidant systems (superoxide dismutase and catalase) showing no negative effect on the cells.

Lipid Peroxidation and Antioxidant System in Erythrocytes of Brucella Vaccinated and Challenged Goats

Lipid Peroxidation and Antioxidant System in Erythrocytes of Brucella Vaccinated and Challenged Goats

Dietary glutamine improves the function of erythrocytes through its metabolites in juvenile carp (Cyprinus carpio var. Jian)

An 8-week feeding trial was conducted to determine the effect of dietary glutamine (Gln) on the erythrocyte function in juvenile Jian carp. The results indicated that dietary Gln caused significant increases in haematocrit, erythrocyte count, haemoglobin concentration, mean corpuscular volume and mean corpuscular haemoglobin content in carp blood. Dietary Gln caused significant decreases in the levels of superoxide anion, hydrogen peroxide, met-haemoglobin, malonaldehyde and protein carbonyl and increases in the level of reduced glutathione and the activities of Na+, K+-ATPase and lactate dehydrogenase in carp erythrocytes. These results demonstrated that dietary Gln could improve the function of erythrocytes in fish. Meanwhile, the present study explored the effect of dietary Gln on hydroxyl radical (OH)-induced apoptosis in carp erythrocytes. We found that dietary Gln prevented the OH-induced apoptosis by inhibiting the generation of reactive oxygen species and the oxidation of cellular components, and restoring the non-enzymatic and enzymatic antioxidant activities in fish erythrocytes. These results revealed that the effects of Gln on the function may be closely associated with apoptosis in fish erythrocytes. Moreover, our data suggested that dietary Gln raised the levels of alanine (Ala), citrulline (Cit) and proline (Pro) in plasma of carp. We then examined the protective effects of Ala, Cit and Pro at the physiological concentrations in OH-induced carp erythrocytes. The results indicated that Ala, Cit or Pro at the physiological concentrations suppressed apoptosis and the oxidation of cellular components, and restored the GSH antioxidant system in the OH-induced carp erythrocytes. Moreover, the combination of Ala, Cit and Pro at the physiological concentrations produces a greater protective effect than their individual effects in fish erythrocytes. These results displayed that the effects of Gln on erythrocytes are at least partly dependent on that of its metabolites in fish. Ala, Cit, Pro and their combination could serve as an antioxidant or apoptosis-inhibitor in fish.

Effect of arsenic acid withdrawal on hepatotoxicity and disruption of erythrocyte antioxidant defense system.

We investigated the effects of withdrawal from Sodium arsenite (NaAsO2) on the hepatic and antioxidant defense system in male Wistar rats using a before and after toxicant design. Rats were orally gavaged daily with varying doses of NaAsO2 for a period of 4 weeks. One half of the population was sacrificed and the remaining half had the toxicant withdrawn for another further 4weeks. Biochemical and immunohistochemical techniques were used to assess the impact of withdrawal on the erythrocyte and hepatic systems. Exposure of Wistar rats to NaASO2 led to a significant (p<0.05) increase in hepatic and erythrocyte markers of oxidative stress (malondialdehyde, thiol contents and hydrogen peroxide generation). Concurrently, there was a significant (p<0.05) increase in hepatic and erythrocyte antioxidant enzymes (glutathione-S-transferase, glutathione peroxidase and superoxide dismutase) following exposure. Withdrawal from NaAsO2 exposure led to a decline in both erythrocyte and hepatic markers of oxidative stress and together with a significant improvement in antioxidant defense system. Histopathology and immunohistochemistry revealed varying degrees of recovery in hepatocyte ultrastructure alongside increased expression of the pro-survival protein Kinase B (Akt/PKB) after 4 weeks of NaAsO2 withdrawal. Conclusively, withdrawal from exposure led to a partial recovery from oxidative stress-mediated hepatotoxicity and derangements in erythrocyte antioxidant system through Akt/PKB pathway.

SO4= uptake and catalase role in preconditioning after H2O2-induced oxidative stress in human erythrocytes.

Preconditioning (PC) is an adaptive response to a mild and transient oxidative stress, shown for the first time in myocardial cells and not described in erythrocytes so far. The possible adaptation of human erythrocytes to hydrogen peroxide (H2O2)-induced oxidative stress has been here verified by monitoring one of band 3 protein functions, i.e., Cl-/HCO3- exchange, through rate constant for SO4= uptake measurement. With this aim, erythrocytes were exposed to a mild and transient oxidative stress (30min to either 10 or 100μM H2O2), followed by a stronger oxidant condition (300- or, alternatively, 600-μM H2O2 treatment). SO4= uptake was measured by a turbidimetric method, and the possible role of catalase (CAT, significantly contributing to the anti-oxidant system in erythrocytes) in PC response has been verified by measuring the rate of H2O2 degradation. The preventive exposure of erythrocytes to 10μM H2O2, and then to 300μM H2O2, significantly ameliorated the rate constant for SO4= uptake with respect to 300μM H2O2 alone, showing thus an adaptive response to oxidative stress. Our results show that (i) SO4= uptake measurement is a suitable model to monitor the effects of a mild and transient oxidative stress in human erythrocytes, (ii) band 3 protein anion exchange capability is retained after 10 μM H2O2 treatment, (iii) PC response induced by the 10 μM H2O2 pretreatment is clearly detected, and (iv) PC response, elicited by low-concentrated H2O2, is mediated by CAT enzyme and does not involve band 3 protein tyrosine phosphorylation pathways. Erythrocyte adaptation to a short-term oxidative stress may serve as a basis for future studies about the impact of more prolonged oxidative events, often associated to aging, drug consumption, chronic alcoholism, hyperglycemia, or neurodegenerative diseases.

Protective effects of resveratrol against hypoxanthine-xanthine oxidase-induced toxicity on human erythrocytes

An in vitro model of erythrocyte damage induced by hypoxanthine-xanthine oxidase (HX-XOD) was developed. The protective effects of resveratrol, a main component of red wine, were evaluated using this model. The results showed that resveratrol treatments maintained erythrocyte morphological and structural integrity, inhibited the formation of methaemoglobin, and suppressed the release of lactate dehydrogenase. Further investigation found that resveratrol attenuated the HX-XOD-induced reactive oxygen species generation, preserved erythrocyte antioxidant enzymes (SOD, CAT and GSH-Px) activities and increased GSH level. Also, resveratrol regulated the pyruvate kinase activity and pyruvate concentration, preserving the normal functioning of erythrocyte membrane ATPases (Na+/K+-ATPase and Ca2+/Mg2+-ATPase). This study established an ideal cellular model for the research of erythrocyte antioxidant system, and revealed the protective mechanisms of resveratrol on human erythrocyte. The results of this study provided novel evidences for further researches on the utilization of resveratrol as a protector on human erythrocyte.

Effect of melatonin on antioxidant enzyme activities in blood erythrocytes of rats during acute emotional stress

The effect of the epiphyseal hormone melatonin on the activity of antioxidant enzymes, glutathione peroxidase (GPx), glutathione reductase (GR), and Cu/Zn-superoxide dismutase (Cu/Zn-SOD) was studied in peripheral blood erythrocytes of behaviorally passive and active Wistar rats. Acute emotional stress was modeled by immobilization of animals for1 h with simultaneous electrocutaneous stimulation. Basal activity of antioxidant glutathione enzymes in erythrocytes of behaviorally passive rats was higher than that in active animals. Administration of melatonin (2 mg/kg, intraperitoneally) was accompanied by a decrease in the activity of GPx and GR in erythrocytes from non-stressed passive animals. After experimental stress, passive rats demonstrated a significant increase in the activity of Cu/Zn-SOD and GPx in peripheral blood erythrocytes. The absence of stress-induced changes in functional activity of antioxidant defense enzymes in the blood of behaviorally active animals suggests a relatively constant oxidative status of tissues in these animals under stress conditions. Melatonin administration had little effect on stress-induced changes in functional activity of the erythrocyte antioxidant system in passive rats. Active specimens pretreated with melatonin before stress exposure were characterized by activation of study antioxidant enzymes. Quantitative parameters of the erythrocyte antioxidant defense enzymes did not differ in behaviorally active and passive rats subjected to experimental stress after melatonin injection. Thus, exogenous melatonin abolishes differences in the activity of study antioxidant enzymes in erythrocytes of animals with different behavioral parameters under basal conditions and after experimental stress. In passive rats melatonin mainly reduced the initial tension of oxidative processes. By contrast, administration of this hormone to active specimens is followed by an increase in functional activity of the antioxidant enzyme system under conditions of acute stress.

Effect of long-term intake of aspartame on serum biochemical parameters and erythrocyte oxidative stress biomarkers in rats

Aspartame is one of the most widely used artificial sweeteners globally. Data concerning acute toxicity of aspartame is controversial, and knowledge on its chronic effect is limited. The present study evaluates the effect of long-term intake of aspartame on serum biochemical parameters and erythrocyte antioxidant defence system in rats. Male Wistar rats, weighing 150–175 g, were randomly divided into one control group and three experimental groups. The control group received only drinking water, whereas the experimental groups were orally administered with aspartame at the concentrations of 50, 500 and 1000 mg/kg b.wt respectively for 180 days. Results showed that administration of aspartame (1000 mg/kg b.wt) caused a significant increase in the levels of serum total bilirubin (P < 0.05). The activity of glutathione peroxidase and glutathione reductase was significantly reduced in the erythrocytes of rats that had received aspartame (1000 mg/kg b.wt) (P < 0.05). Glutathione was significantly decreased in 500 mg/kg (P < 0.05) and 1000 mg/kg (P < 0.001) aspartame groups. It can be concluded from these observations that long-term consumption of aspartame leads to dose-dependent increase in free radical production and produces impairment in antioxidant status in erythrocytes mainly through alterations in glutathione-dependent system.

Effect of melatonin on the activities of antioxidant enzymes in blood erythrocytes of rats during acute emotional stress

The effect of the epiphyseal hormone melatonin on the activity of antioxidant enzymes, glutathione peroxidase (GPx), glutathione reductase (GR), and Cu/Zn-superoxide dismutase (Cu/Zn-SOD) was studied in peripheral blood erythrocytes of behaviorally passive and active Wistar rats. Acute emotional stress was modeled by immobilization of animals for1 h with simultaneous electrocutaneous stimulation. Basal activity of antioxidant glutathione enzymes in erythrocytes of behaviorally passive rats was higher than that in active animals. Administration of melatonin (2 mg/kg, intraperitoneally) was accompanied by a decrease in the activity of GPx and GR in erythrocytes from non-stressed passive animals. After experimental stress, passive rats demonstrated a significant increase in the activity of Cu/Zn-SOD and GPx in peripheral blood erythrocytes. The absence of stress-induced changes in functional activity of antioxidant defense enzymes in the blood of behaviorally active animals suggests a relatively constant oxidative status of tissues in these animals under stress conditions. Melatonin administration had little effect on stress-induced changes in functional activity of the erythrocyte antioxidant system in passive rats. Active specimens pretreated with melatonin before stress exposure were characterized by activation of study antioxidant enzymes. Quantitative parameters of the erythrocyte antioxidant defense enzymes did not differ in behaviorally active and passive rats subjected to experimental stress after melatonin injection. Thus, exogenous melatonin abolishes differences in the activity of study antioxidant enzymes in erythrocytes of animals with different behavioral parameters under basal conditions and after experimental stress. In passive rats melatonin mainly reduced the initial tension of oxidative processes. By contrast, administration of this hormone to active specimens is followed by an increase in functional activity of the antioxidant enzyme system under conditions of acute stress.

The relationship between the pro-oxidant and antioxidant system status of patients with multiple myeloma and the disease stage.

Disturbances of the erythrocyte antioxidant system presented by LPO intensification were detected in patients with multiple myeloma. Plasma concentrations of MDA in these patients were close to normal due to effective work of the nonenzymatic antioxidant system. Activities of antioxidant enzymes in the plasma were reduced, while catalase activity was high, and ceruloplasmin content did not differ from the control, this indicating suppression of the enzymatic component of the antioxidant system. In erythrocytes, the level of reduced glutathione was low, especially at stage III of the disease. Changes in SOD and catalase activities were similar to those in the plasma, while activities of glutathione-dependent enzymes were comparable to those in normal human erythrocytes.

Effect of Chewing Catha edulis with Amphetamine-Like Effect on Erythrocyte Antioxidant System

Chewing Catha edulis leaves (Khat) that has amphetamine-like effect is of highly concern in Yemen and the Horn of Africa as most of the population chewing this plant. Unfortunately, farmers used to apply pesticides for better production of this plant. The present study has been designed to assess the activity of erythrocyte cholinesterase and the antioxidant defense system of male Khat chewers in Thamar city, Yemen. Erythrocytes of twenty male Khat chewers and twenty controls (non-Khat chewers) were prepared, and the activities of butyrylcholinesterase (BChE) and catalase (CAT) were estimated along with the measuring levels of reduced glutathione (GSH), total thiols (T-SH) and protein thiols (P-SH). The blood indices were also measured in both groups. A decrease in the activities of BChE and CAT was observed in the erythrocyte concomitant with reductions in the levels of GSH, T-SH and P-SH of Khat chewers group as compared to non-Khat chewers group. These alterations in the antioxidants resulted in changes in some blood indices of Khat chewers group. The present study shows that chewing C. edulis with amphetamine-like effect along with pesticide applied to the plant might be responsible for the production of oxidants, which lead to decrease the antioxidant system of erythrocytes of C. edulis chewers.

Failure of recovery from lead induced hepatoxicity and disruption of erythrocyte antioxidant defence system in Wistar rats

Lead acetate (PbA) is one of the major environmental contaminants with grave toxicological consequences both in the developing and developed countries. The liver and erythrocyte antioxidant status and markers of oxidative were assessed. Exposure of rats to PbA led to significant decline (p<0.05) in hepatic and erythrocyte glutathione peroxidase (GPx), glutathione S-transferase (GST), catalase (CAT), superoxide dismutase (SOD), and reduced glutathione (GSH) content. Similarly, malondialdehyde (MDA) and H2O2 concentrations were significantly (p<0.05) elevated. Histopathology and immunohistology of liver of rats exposed to PbA showed focal areas of necrosis and COX-2 expression after 6 weeks of PbA withdrawal. Taken together, hepatic and erythrocytes antioxidant defence system failed to recover after withdrawal of the exposed PbA for the period of the study. In conclusion, experimental animals exposed to PbA did not recover from hepatotoxicity and disruption of erythrocyte antioxidant defence system via free radical generation and oxidative stress.

Lipid Peroxidation and Antioxidant System in Erythrocytes of Patients with Renal Cell Carcinoma

For evaluation lipid peroxidation and antioxidant status of red blood cells, 150 patients with locally advanced renal cell carcinoma were examined. The content of conjugated dienes, MDA, and reduced glutathione and activities of SOD, catalase, and glutathione metabolism enzymes were determined. It was found that the balance between pro- and anti-oxidants in patients with kidney cancer differed significantly from that of healthy people and little changed during the observation.

Ethanol induced adaptive changes in blood for the pathological and toxicological effects of chronic ethanol consumption in humans

Alcohol consumption is associated with a number of toxicological changes in blood and the oxidant-antioxidant system. The present study was performed to investigate the alcohol induced toxicological, pathological changes in blood and an adaptive role of erythrocyte antioxidant system in chronic alcoholics. Human male volunteers aged 44±6 years with similar dietary habits were divided into two groups, namely non-alcoholic controls and chronic alcoholics. We measured hematological parameters, erythrocyte lipid peroxidation, NO production, erythrocyte antioxidant and liver function test enzyme activities. Alcoholics had increased erythrocyte nitric oxide levels and also elevated erythrocyte lipid malondialdehyde (MDA) concentrations. Strikingly, increments in reduced glutathione and markedly increased activities of certain antioxidant enzymes such as glutathione reductase (GR), superoxide dismutase (SOD), and another related enzyme G-6 phosphate dehydrogenase (G6-PDH) with no alterations in the activities of glutathione S-transferase (GST), glutathione peroxidase (GPx), and catalase (CAT) in chronic alcoholics were observed compared to controls. Furthermore, erythrocyte NO levels were positively correlated with lipid peroxidation, SOD, GSH, GR and G6PDH in chronic alcoholics. In addition, increased AST/ALT ratio and a significant increase in WBC and platelets were also noticed. Together, these results indicate that, antioxidants and defense enzymes appear to be rendering protection as a consequence of chronic adaptation in alcoholics.

Cytokines and Oxidative Stress Status Following a Handball Game in Elite Male Players

Background. Handball is considered an intermittent sport that places an important stress on a player's aerobic and anaerobic metabolism. However, the oxidative stress responses following a handball game remain unknown. We investigated the responses of plasma and erythrocyte antioxidant system and oxidative stress biomarkers following a single handball game. Methods. Fourteen male elite Brazilian handball athletes were recruited in the present study. Blood samples were taken before, immediately, and 24 hours after the game. Results. After the game and during 24 hours of recovery, the concentration of all oxidative stress indices changed significantly in a way indicating increased oxidative stress in the blood (thiol groups and reduced glutathione decreased, whereas TBARS and plasma antioxidant capacity was increased) as well as in erythrocyte (increased levels of TBARS and protein carbonyls). Erythrocyte antioxidant enzyme activities were also significantly changed by handball. Muscle damage indices (creatine kinase and lactate dehydrogenase) increased significantly after exercise. In addition, IL-6 increased after the game, whereas TNF-α decreased during recovery. Conclusion. This study demonstrates that a single handball game in elite athletes induces a marked state of oxidative stress evidenced by the oxidative modification in plasma and erythrocyte macromolecules, as well as by changes in the enzymatic and nonenzymatic antioxidant system.

Subacute chlorpyrifos-induced oxidative stress in rat erythrocytes and the protective effects of catechin and quercetin

This study examined the effects of chlorpyrifos in the rat erythrocyte antioxidant system and evaluated the ameliorating effects of catechin and quercetin on the oxidative damage induced by chlorpyrifos. Sexually mature male Wistar rats were given chlorpyrifos (5.4 mg/kg, 1/25 of the oral LD 50), catechin (20 mg/kg), quercetin (20 mg/kg), catechin plus chlorpyrifos, and quercetin plus chlorpyrifos daily via gavage for four weeks. No statistical differences were found in the catechin-only and quercetin-only groups compared with the control group. By the end of the fourth week, chlorpyrifos alone increased the levels of malondialdehyde (MDA) and decreased superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) activities compared with the control group in rat erythrocytes. In the catechin-plus-chlorpyrifos and quercetin-plus-chlorpyrifos groups, there were statistically significantly decreased MDA levels and increased SOD, CAT, and GPx activities compared with the chlorpyrifos-only group. Thus, it appears that catechin and quercetin ameliorate chlorpyrifos-induced oxidative stress in rat erythrocytes in vivo.