Oxidative Damage In Erythrocytes Research Articles

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

Improving functional properties of rice protein isolates by hydrolysis using alcalase enzyme and assessing bioactivities of hydrolysates

AbstractBackgroundDeveloping value‐added products from rice grains is becoming increasingly significant to enhance productivity from excess rice grains. Therefore, the objective of this study was to improve the functional properties of rice protein from four rice varieties, namely, RRF‐127, RRF‐105, Swarna, and Protezin by enzymatic hydrolysis, and also to evaluate bioactivities like antioxidant, ACE, and DPP‐IV inhibitory activities of the hydrolysates.ResultsThe alcalase hydrolysis increased protein solubility to >80% in the pH range of 4–10. The foaming capacity and stability of rice protein hydrolysates (RPHs) improved with the increase in pH. The hydrolysis significantly improved the emulsification activity index (EAI) in the pH range of 5–9. The hydrolysates showed antioxidant activity, namely, ABTS•+radical scavenging, reducing power, and metal ion chelation. RRF‐105 was found to possess the most potent antioxidant capacity among the hydrolysates. RPH could alleviate oxidative damage in erythrocytes, and their protective effects were concentration‐dependent. The hydrolysates had stronger inhibition of ACE and DPP‐IV enzymes. Protezin exhibited the highest ACE inhibition (63%), while Swarna demonstrated the most effective DPP‐IV inhibition (66%).ConclusionHydrolysis with alcalase improved the functional and bioactive properties of rice proteins, indicating that RPH could serve as a source of bioactive peptides or as a functional ingredient with potential properties.

Protective Effect of Bee Products Against Oxidative Damage in Erythrocytes

The positive effects of bee products on human health are due to their antioxidant composition. However, their possible protective efficacy against t-butylhydroxyperoxide (t-BHP)-induced oxidative damage on human erythrocytes has not been investigated. Our aim in this study is to investigate whether propolis, pollen and royal jelly have protective efficacy against t-BHP-induced oxidative damage in isolated erythrocytes. Propolis and pollen samples collected from various regions of Turkey were extracted by mixing with various solvents (water and ethanol). Commercially purchased royal jelly was also extracted with water. The erythrocytes collected from 15 volunteers were centrifuged and packaged by washing with isotonic saline. All RBC packets were pooled together. The final erythrocyte packet was divided into seven groups as control, water extract of propolis, ethanolic extract of propolis, water extract of pollen, water extract of royal jelly, positive control (quercetin) and t-BHP groups. Erythrocytes were first treated with extracts of bee products and then t-BHP was added. Protective activities of bee products were investigated by malondialdehyde (MDA), total oxidant capacity (TOS), total antioxidant capacity (TAS), superoxide dismutase (SOD) and catalase (CAT) activities. Statistically, one way ANOVA and post-hoc Tukey tests were applied. As a result of the study, it was found that all bee products contributed to keeping MDA levels close to the control group. (p

Effects of simulated gastrointestinal digestion on chickpea protein, and its hydrolysate physicochemical properties, erythrocyte haemolysis inhibition, and chemical antioxidant activity

Chickpea protein and its hydrolysates have good antioxidant activity. Proteins and peptides are degraded and modified in the gastrointestinal tract before being digested and absorbed, a process that changes their physicochemical and biological properties. Changes in structure and antioxidant capacity of the chickpea protein and its hydrolysates after simulated gastrointestinal digestion were studied. The secondary structure, amino acid composition, and chemical antioxidant activity of chickpea protein and its hydrolysates were determined, and their protective effects on AAPH-induced erythrocyte oxidative damage were studied. Results showed that chickpea protein hydrolysate was easier to be digested by the gastrointestinal tract than chickpea protein. After digestion, the chemical antioxidant capacity of chickpea protein and its hydrolysates increased in a dose-dependent manner, and showed a protective effect against erythrocytes AAPH-induced oxidative damage. Chickpea protein and its hydrolysates can be used as natural antioxidants to promote healthy digestion.

Intracellular free calcium concentration and oxidative damage in erythrocytes from workers occupationally exposed to organophosphate pesticides

Intracellular free calcium concentration and oxidative damage in erythrocytes from workers occupationally exposed to organophosphate pesticides

The flavonoids fisetin, apigenin, kaempferol, naringenin, naringin regulate respiratory activity and membrane potential of rat liver mitochondria and inhibit oxidative processes in erythrocytes.

Flavonoids, secondary plant metabolites, represent the most abundant heterogeneous group of phytochemicals. The aim of this study to compare antioxidant activity and regulatory properties of several representatives of different classes of flavonoids, fisetin, apigenin, kaempferol, naringenin, naringin, using liver mitochondria and erythrocytes as research objects. In the concentration range of 2.5-25 μM fisetin, apigenin, kaempferol, naringenin, and naringin dose-dependently prevented oxidative damage of erythrocytes induced by 700 μM tert-butyl hydroperoxide: accumulation of lipid peroxidation (LPO) products and oxidation of glutathione GSH. The IC50 values corresponding to the flavonoid concentration inhibiting the LPO process in erythrocyte membranes by 50%, were 3.9±0.8 μM in the case of fisetin, 6.5±1.6 μM in the case of kaempferol, 8.1±2.1 μM in the case of apigenin, 37.8±4.4 μM in the case of naringenin, and 64.7±8.6 μM in the case of naringin. The antioxidant effect of flavonoids was significantly higher in the membrane structures compared to the cytoplasm of cells. All flavonoids studied (10-50 μM) effectively inhibited the respiratory activity of isolated rat liver mitochondria and, with the exception of kaempferol, stimulated Ca²⁺-induced dissipation of the mitochondrial membrane potential. Cyclosporine A and ruthenium red inhibited flavonoid-stimulated Ca²⁺-dependent membrane depolarization, thus indicating that the mitochondrial calcium uniporter and the mitochondrial permeability transition pore opening were involved in the flavonoid effects. Flavonoids, as the redox-active compounds with antioxidant properties, are able to regulate mitochondrial potential and respiratory activity, and prevent mitochondrial oxidative stress. They can be considered as effective pharmacological agents or nutraceuticals.

Protective effect of rutin against thiram-induced cytotoxicity and oxidative damage in human erythrocytes

Thiram is a fungicide that is used to prevent fungal diseases in seeds and crops and also as an animal repellent. The pro-oxidant activity of thiram is well established. Rutin is a flavonoid glycoside present in many fruits and plants and has several beneficial properties, including antioxidant effects. We have previously shown that thiram causes oxidative damage in human erythrocytes. The present study was designed to evaluate the protective effect of rutin against thiram-induced damage in human erythrocytes. Treatment of erythrocytes with 0.5 mM thiram for 4 h increased the level of oxidative stress markers, decreased antioxidant power and lowered the activity of antioxidant and membrane bound enzymes. It also enhanced the generation of reactive oxygen and nitrogen species (ROS and RNS) and altered the morphology of erythrocytes. However, prior treatment of erythrocytes with rutin (0.5, 1 and 2 mM) for 2 h, followed by 4 h incubation with 0.5 mM thiram, led to a decrease in the level of oxidative stress markers in a rutin concentration-dependent manner. A significant restoration in the antioxidant power and activity of antioxidant enzymes was observed upon the treatment of erythrocytes with 1 and 2 mM rutin. Pre-incubation with rutin lowered the generation of ROS and RNS which will reduce oxidative damage in erythrocytes. The thiram-induced changes in cell morphology and activity of membrane-bound enzymes were also attenuated by rutin. These results suggest that rutin can be used to mitigate thiram-induced oxidative damage in human erythrocytes.

Antioxidant capacity of Myrciaria cauliflora seed extracts by spectrophotometric, biochemical, and electrochemical methods and its protective effect against oxidative damage in erythrocytes.

This study aimed to investigate the antioxidant activity of extracts obtained from jabuticaba (Myrciaria cauliflora) seeds. Ethanolic (ETJS), methanolic (MEJS), aqueous (AQJS), and propanone (PRJS) extracts was assessed by measuring spectrophotometrically their ability to scavenge DPPH· , ABTS·+ , HOCl, and O2 ·- radicals. Electrochemical methods were employed, and the obtained data presented a good correlation with the radical scavenging results. The extracts were also able to attenuate lipid peroxidation induced by Fe2+ ions in phospholipids due to their chelation ability. The extracts protected human erythrocytes against oxidative cellular damage caused by AAPH, which was confirmed by using FESEM analysis. PRJS extract demonstrated the highest effect in all assays used in this work. Our findings prove that jabuticaba seeds are an important source of antioxidants which act by different mechanisms. This study opens new frontiers regarding the use of this fruit byproduct as a food additive. PRACTICAL APPLICATIONS: Jabuticaba seeds are usually discarded as waste by food industries, but they are rich in bioactive products and present interesting biological properties. Herein, we demonstrated that their extracts show remarkable antioxidant power against different reactive oxygen species, which are involved in several human pathologies. In this way, this by-product can be further used in the development of products to protect the human body against diseases related to oxidative stress.

Deterministic flow cytometry: Rapid erythrocyte rheological profiling from a drop of whole blood

The loss of erythrocyte deformability (ED) is part of the etiology of a wide range of diseases. Current measures of ED are limited by the complexity of laboratory-based methods, insensitivity and the need for a venous blood draw. Here, we introduce a deterministic flow cytometry (DFC) assay for label-free measurements of the size of erythrocyte and ED. The assay can be completed within 2 min using only 10 μL whole blood collected via finger pricking, suitable for point-of-care measurements for clinical profiling of neonates, infants and children. Our results show that the unique C-shaped DFC is a sensitive and easy-to-use tool, which can detect not only the biphasic effect of ethanol and oxidative damage of erythrocytes but also significant individual-dependent variability and dose dependence under the phenazine methosulfate (PMS) stimuli. We also demonstrated the application of DFC for the assessment of sensitive erythrocyte changes in sepsis induced rats.

Effects of selenylation modification on the antioxidative and immunoregulatory activities of polysaccharides from the pulp of Rose laevigata Michx fruit

Selenylation modification has been widely utilized to improve the activity of polysaccharides and to develop novel sources of selenium (Se) supplements. A purified pulp polysaccharide of Rose laevigata Michx fruit (PPRLMF-2) was selenized into Se-PPRLMF-2 in this study. PPRLMF-2 + Se was formulated by Na2SeO3 according to the Se content of Se-PPRLMF-2. To investigate the effects of selenylation modification on the structure and functions of PPRLMF-2, the characteristics, antioxidative and immunoregulatory activities of PPRLMF-2 before and after selenylation were compared. The results showed that compared with PPRLMF-2, Se-PPRLMF-2 became an irregular fibrous network, and its Mw decreased and C-6 substitution predominated in 13C NMR spectra. Se-PPRLMF-2 significantly increased chemical antioxidant activity and reduced the oxidative damage of erythrocytes, which was not due to Se alone. Se-PPRLMF-2 significantly increased immunomodulatory activity on macrophages, which was related to Se alone. Se-PPRLMF-2 could be a good potential source of antioxidants, immune enhancers and dietary Se supplements.

Effect of Linseed Oil Supplementation on Lipid Peroxidation and Antioxidant Capacity in Pregnant Overfed Obese Rats and Their Offspring

Effect of Linseed Oil Supplementation on Lipid Peroxidation and Antioxidant Capacity in Pregnant Overfed Obese Rats and Their Offspring

Oxidative damage of canine erythrocytes after treatment with non-steroidal anti-inflammatory drugs.

To investigate oxidative erythrocyte damage in dogs treated with different non-steroidal anti-inflammatory drugs. Case-controlled prospective observational study using blood obtained from dogs presenting for lameness examinations or standard surgical procedures to a private referral clinic. Sampling was performed from April 2018 to July 2019. Groups comprised dogs receiving either metamizole (dipyrone) (22 dogs), carprofen (20 dogs) or meloxicam (20 dogs) for a minimum of 10 days. Dogs with gastrointestinal hemorrhage were excluded from the study. A complete hematological, as well as a basic biochemical profile were performed in every dog. Pappenheim stained blood smears were evaluated for eccentrocytes and brilliant cresyl blue stained smears for Heinz bodies. EDTA blood was frozen at -80°C immediately after sampling for measurement of superoxide dismutase and gluthathione peroxidase activity at an external laboratory. Hemoglobin concentration, superoxide dismutase and gluthathione peroxidase activities, reticulocyte count, eccentrocyte and Heinz body numbers were determined prospectively as key parameters for further statistical assessment with Kruskal-Wallis test and Dunn's multiple comparisons test. Dogs receiving metamizole showed a significant increase in eccentrocyte (median 14.5/500 cells vs. 0/500 cells in the other groups, p < 0.0001) and reticulocyte number (median 191.4 × 109/l vs. 31.6-37.9 × 109/l, p < 0.0001) and a significant decrease in hemoglobin concentration (median 8.4 mmol/l vs. 10.1-10.5 mmol/l, p < 0.0003). No significant difference in superoxide dismutase and gluthathione peroxidase activities was observed between dogs receiving metamizole and the other groups. Heinz bodies were not found in any of the dogs. Treatment with metamizole for 10 or more days resulted in decreased hemoglobin concentration, eccentrocytosis and reticulocytosis in dogs in this study. This might be a sign of increased oxidative damage caused by this drug. Prolonged metamizole therapy should be evaluated critically in patients already affected by severe illness or underlying anaemia.

Chemical and Antioxidant Characterization of the Portuguese Heather Honey from Calluna vulgaris

The Calluna vulgaris honey produced in Portugal, concerning its phenolic compounds and abscisic acids profiles, as well as its antioxidant activity and the protective effect against oxidative damage in human erythrocytes were herein performed for the first time. The phenolic and abscisic acid profiles were tentatively identified by LC-MS/MS (17 compounds). The total content of phenolics and abscisic acids was 15,446.4 µg/g of honey extract, with catechin derivatives and abscisic acids being major constituents. The highest scavenging capacity was found against reactive nitrogen species. Additionally, the honey extract prevented ROO•-induced oxidative damage in erythrocytes collected from human blood, by inhibiting hemolysis, lipid peroxidation and hemoglobin oxidation. In conclusion, C. vulgaris honey contains high content of catechin derivatives and abscisic acids that may be responsible for its biological activity, characterized by a strong antioxidant capacity, which adds up to the nutritional value of this delicacy.

Dose-Dependent Oxidative Damage in Erythrocytes and Hepatic Tissue of Wistar Rats Concurrently Exposed with Arsenic and Quinalphos: a Subacute Study.

Concurrent exposure to a multitude of environmental toxicants pose serious health hazard to humans and animals. The present investigation was conceptualized to determine deleterious effects of concomitant subacute arsenic and quinalphos exposure on antioxidant responses of liver and erythrocytes of Wistar rats. Fifty-four Wistar rats were divided into nine groups with six animals in each. Animals were exposed to either quinalphos (1/100th and 1/10th of LD50) through oral gavage daily or arsenic (50 and 100ppb) in drinking water alone and in combination for 28days. While treatment with different toxicants alone also significantly reduced hemoglobin concentration, hepatic biomarkers and levels of antioxidant parameters as compared with control values, concomitant exposure significantly (P < 0.05) elevated levels of hepatic transaminases and alkaline phosphatase. Moreover, along with significant depletion in activities of SOD, CAT, TTH, AChE, and enzymes of glutathione complex, a significant enhancement of lipid peroxidation was also recorded in liver and erythrocytes in co-exposed animals in a dose-dependent manner when compared with exposure to individual toxicant. More severe alterations occurred in hepatic histo-architecture of rats receiving combined treatment as compared with those treated with either toxicant. Results indicated that oxidative damage in erythrocytes was more than that ofthe liver of rats on concomitant exposure of arsenic and quinalphos in a dose-dependent manner. In nutshell, our results revealed that combined treatment of quinalphos with arsenic potentiated toxic effects of either toxicant on antioxidant machinery of liver and erythrocytes and hepatic histomorphology of exposed Wistar rats.

Relationship between Changes in Hematological Parameters, Levels of Acute Phase Proteins and Redox Homeostasis during Acute Babesia canis Infection in Dogs

Abstract Hemolysis and systemic acute inflammation characterize canine babesiosis caused by the intraerythrocytic protozoan parasite Babesia canis. Our hypothesis was that blood redox homeostasis of patients that suffered acute B. canis infection might be disturbed even after treatment with imidocarb-dipropionate and successful clinical recovery. Eight owner dogs with acute B. canis infection were used for this study. We analyzed the complete blood count, acute phase proteins (ceruloplasmin, haptoglobin, paraoxonase-1) in the serum, antioxidant enzymes (catalase and glutathione peroxidase) in the erythrocytes, and oxidative stress markers (malondialdehyde in erythrocytes and thiol groups in serum) at presentation and 15 days after treatment. Results were evaluated by corresponding statistical tests. At presentation, anemia, low/normal leukocyte count and severe thrombocytopenia occurred together with increased ceruloplasmin, haptoglobin levels within the reference interval, decreased paraoxonase-1 and compromised antioxidant defense in the red blood cells. After treatment and successful clinical recovery, hematological values generally fitted within the reference intervals, acute phase proteins were within the physiological levels in the majority of cases and the activities of the antioxidant enzymes were increased. However, elevated malondialdehyde levels indicated increased oxidative damage of erythrocytes that remained as a deleterious sequel despite a successful clinical recovery of the dogs.

Alleviation Effects of Diosmetin on H2O2-Induced Oxidative Damage in Human Erythrocytes

Free radicals (FRs) are formed in the high amounts result of the metabolic imbalance in cells and tissue. These radicals-induced oxidative damages constitute the basis of many diseases. Organisms have antioxidant defence systems (ADS) to eliminate the destructive effects of the oxidative damage. In addition to these antioxidant systems, dietary flavonoids have the antioxidant effect and the protective role against oxidative damage. In the present study, it was investigated whether a flavonoid derived diosmetin (10, 50, and 100 µM) have the elimination potential on hydrogen peroxide (H2O2)-induced oxidative damage in erythrocyte culture by using biomarkers such as lipid peroxidation (LP) level, catalase (CAT), total superoxide dismutase (SOD) activity and changes of SOD isozymes containing the manganese SOD (Mn SOD) and the cupper-zinc SOD (CuZn SOD). CAT, total SOD, Mn SOD and CuZn SOD activities showed a serious decline with H2O2 treatment, but diosmetin addition significantly increased their activities. While the H2O2 application critically increased LP products in erythrocytes, diosmetin considerably reduced these oxidative damage products. In conclusion, it has been determined that diosmetin can moderate oxidative damage in human erythrocytes by activating or protecting the ADS.

Poisoning in domestic cats in Brazil: toxicants, clinical signs, and therapeutic approaches

ABSTRACT This study evaluated the most common toxic agents affecting domestic cats, the clinical signs of toxicity, and the therapeutic approaches for recovery. A survey on poisoning in cats was conducted among small animal veterinary practitioners from 2017 to 2018. Of the 748 completed questionnaires, 543 (72.6%) were evaluated. Pesticides and household cleaning supplies were the most common causes of poisoning in cats. The toxicant groups included pesticides and household cleaning supplies (organophosphates), human drugs (acetaminophen), plants/plant derivatives (lily), and veterinary drugs (tramadol). The major clinical signs for these four groups of toxicants were (1) acetaminophen poisoning, which caused oxidative erythrocyte damage; (2) muscarinic and nicotinic cholinergic syndrome, which resulted from organophosphate poisoning; (3) acute kidney injury, which resulted from intoxication of lily; and (4) serotonin syndrome, which resulted from tramadol toxicosis. Interventions for treating poisoning in cats were based on the clinical presentation of animals. In the present study, the significant toxins identified to be dangerous for cats were characterized using the obtained data in Brazil as well as the main associated clinical signs and therapy recommended by veterinarians.

To Research the Effects of Storage Time on Autotransfusion based on Erythrocyte Oxygen-Carrying Capacity and Oxidative Damage Characteristics

Autotransfusion refers to a blood transfusion method in which the blood or blood components of the patient are collected under certain conditions, returned to himself when the patient needs surgery or emergency after a series of storing and processing. Although autotransfusion can avoid blood-borne diseases and adverse reactions related to allogeneic blood transfusion, a series of structural and functional changes of erythrocytes will occur during extension of storage time, thus affecting the efficacy of clinical blood transfusion. Our research was aimed to explore the change of erythrocyte oxygen-carrying capacity in different storage time, such as effective oxygen uptake (Q), P50, 2,3-DPG, Na+-K+-ATPase, to detect membrane potential, the change of Ca2+, and reactive oxygen species (ROS) change of erythrocytes. At the same time, Western blot was used to detect the expression of Mitofusin 1 (Mfn1) and Mitofusin 2 (Mfn2) proteins on the cytomembrane, from the perspective of oxidative stress to explore the function change of erythrocytes after different storage time. This study is expected to provide experimental data for further clarifying the functional status of erythrocytes with different preservation time in patients with autotransfusion, achieving accurate infusion of erythrocytes and improving the therapeutic effect of autologous blood transfusion, which has important clinical application value.

Effects of N-Acetylcysteine and N-Acetylcysteine Amide on Erythrocyte Deformability and Oxidative Stress in a Rat Model of Lower Extremity Ischemia-Reperfusion Injury.

N-acetylcysteine (NAC) is an antioxidant which works as a free radical scavenger and antiapoptotic agent. N-acetylcysteine-amide (NACA) is a modified form of NAC containing an amide group instead of a carboxyl group of NAC. Our study aims to investigate the effectiveness of these two substances on erythrocyte deformability and oxidative stress in muscle tissue. Materials and Methods. A total of 24 Wistar albino rats were used in our study. The animals were randomly divided into five groups as control (n: 6), ischemia (n: 6), NAC (n: 6), and NACA (n: 6). In the ischemia, NAC, and NACA groups, 120 min of ischemia and 120 min of reperfusion were achieved by placing nontraumatic vascular clamps across the abdominal aorta. The NAC and NACA groups were administered an injection 30 min before ischemia (100 mg/kg NAC; 100 mg/kg NACA; intravenous). Blood samples were taken from the animals at the end of the ischemic period. The lower extremity gastrocnemius muscle was isolated and stored at −80 degrees to assess the total antioxidant status (TAS), total oxidant status (TOS), and oxidative stress index (OSI) values and was analyzed. Results. The erythrocyte deformability index was found to be statistically significantly lower in rats treated with NAC and NACA before ischemia-reperfusion compared to the groups that received only ischemia-reperfusion. In addition, no statistically significant difference was found between the control group and the NAC and NACA groups. The groups receiving NAC and NACA before ischemia exhibited higher total antioxidative status and lower total oxidative status while the oxidative stress index was also lower. Conclusion. The results of our study demonstrated the protective effects of NAC and NACA on erythrocyte deformability and oxidative damage in skeletal muscle in lower extremity ischemia-reperfusion. NAC and NACA exhibited similar protective effects on oxidative damage and erythrocyte deformability.

Interaction of Catechins with Human Erythrocytes.

The aim of this study was to characterize the interaction of chosen catechins ((+)-catechin, (−)-epigallocatechin (EGC), and (−)-epigallocatechin gallate (EGCG)) with human erythrocytes and their protective effects against oxidative damage of erythrocytes. Uptake of the catechins by erythrocytes was studied by fluorimetry, their interaction with erythrocyte membrane was probed by changes in erythrocyte osmotic fragility and in membrane fluidity evaluated with spin labels, while protection against oxidative damage was assessed by protection against hemolysis induced by permanganate and protection of erythrocyte membranes against lipid peroxidation and protein thiol group oxidation. Catechin uptake was similar for all the compounds studied. Accumulation of catechins in the erythrocyte membrane was demonstrated by the catechin-induced increase in osmotic resistance and rigidification of the erythrocyte membrane detected by spin labels 5-doxyl stearic acid and 16-doxyl stearic acid. (−)-Epigallocatechin and EGCG inhibited erythrocyte acetylcholinesterase (mixed-type inhibition). Catechins protected erythrocytes against permanganate-induced hemolysis, oxidation of erythrocyte protein thiol groups, as well as membrane lipid peroxidation. These results contribute to the knowledge of the beneficial effects of catechins present in plant-derived food and beverages.