M.Y. Burak Çimen

Free radical metabolism in human erythrocytes

As the red cell emerges from the bone marrow, it loses its nucleus, ribosomes, and mitochondria and therefore all capacity for protein synthesis. However, because of the high O(2) tension in arterial blood and heme Fe content, reactive oxygen species (ROS) are continuously produced within red cells. Erythrocytes transport large amount of oxygen over their lifespan resulting in oxidative stress. Various factors can lead to the generation of oxidizing radicals such as O(2)(-), H(2)O(2), HO in erythrocytes. Evidence indicates that many physiological and pathological conditions such as aging, inflammation, eryptosis develop through ROS action. As such, red cells have potent antioxidant protection consisting of enzymatic and nonenzymatic pathways that modify highly ROS into substantially less reactive intermediates. The object of this review is to shed light on the role of ROS both at physiological and pathological levels and the structural requirements of antioxidants for appreciable radical-scavenging activity. Obviously, much is still to be discovered before we clearly understand mechanisms of free radical systems in erythrocytes. Ongoing trends in the field are recognition of undetermined oxidant/antioxidant interactions and elucidation of important signaling networks in radical metabolism.

Effects of cigarette smoking with different tar content on erythrocyte oxidant/antioxidant status.

Abstract In this study, the effects of cigarettes with differing tar content on erythrocyte oxidant/antioxidant status was investigated. Malondialdehyde (MDA) as an indicator of oxidant status and superoxide radical scavenger activity (SSA) as an indicator of antioxidant status were measured in erythrocytes from 20 smokers and 10 non‐smoker controls. Ten of the 20 smoking subjects smoked five cigarettes with full flavour low tar (FFLT with 12 mg tar) and the others smoked five cigarettes with full flavour high tar (FF with 23 mg tar) over 1 hour. Initial blood samples from both groups at fasting, followed by further samples from smokers at 1.5 hours and 3 hours after smoking. Initial erythrocyte MDA level and SSA activity were found to be higher in the smoking groups compared to non‐smokers. Furthermore, both parameters were significantly higher at the 1.5‐hour and 3‐hour erythrocyte samples when compared to initial values in the FFLT group. However, there were no statistically significant differences between SSA values established at different times in FF group. Results suggest that smoking causes oxidant load in the erythrocytes. Although a compensatory mechanism (i.e. increased SSA activities) develops in the FFLT group after smoking, this cannot prevent peroxidation reactions (i.e. increased MDA levels) in the erythrocytes. As to the types of cigarettes, both seem to have oxidant potential, but oxidation degree in the FFLT group is higher than that of FF group. These results suggest that antioxidant supplementation to smokers might be beneficial to decrease cellular oxidation damages.

Antioxidant Defense Potential of Rabbit Renal Tissues after ESWL: Protective Effects of Antioxidant Vitamins

Antioxidant defense potential, malondialdehyde (MDA) levels, and relative hydroxyl radical (OH·) concentrations were measured in order to establish the effects of extracorporeal shock wave lithotripsy (ESWL) on free radical production and antioxidant defense potential of the rabbit kidney tissues. Electron microscopic examination was also performed to observe ultrastructural changes. The antioxidant defense potential of the ESWL-treated tissues was found to be reduced, and the MDA levels increased as compared with controls. Vitamin (vitamin E plus C combination) pretreatment ameliorated antioxidant defense potential in part, prevented increases in MDA levels in the ESWL-treated tissues, and increased the antioxidant defense potential in the control kidney tissues. After ESWL, a significant amount of OH· radical was measured in the affected tissue. This revealed the source of oxidant stress and peroxidation reactions in the ESWL-treated kidney tissue. Vitamin pretreatment caused significant reduction in the OH· radical concentration. In the electron microscopic investigation, some significant subcellular changes, such as endothelial injury, loss of foot processes, damage of glomerular basal membrane, etc., were observed in the ESWL-treated renal tissue slices. Vitamin pretreatment to a great extent prevented formation of these subcellular changes. Our results suggest that the antioxidant capacity of the kidney tissue was reduced after ESWL treatment and that the tissue was exposed to oxidant stress. Vitamin pretreatment exerted significant protection against the radical damage.

Plasma reactive oxygen species activity and antioxidant potential levels in rosacea patients: correlation with seropositivity to Helicobacter pylori

Background  Recent studies have suggested that there might be an etiologic role for Helicobacter pylori (HP) in rosacea. HP is a Gram‐negative bacterium that colonizes the gastric mucosa, increases the generation of reactive oxygen species (ROS), and decreases plasma antioxidants such as ascorbic acid.

In vivo effects of meloxicam, celecoxib, and ibuprofen on free radical metabolism in human erythrocytes.

Abstract One of the major groups of chemical mediators involved in the inflammatory response is the prostaglandins, which are synthesized from arachidonic acid by the enzyme cyclooxygenase. The aim of this study is to compare the in vivo effects of celecoxib, meloxicam, and ibuprofen on the activities of catalase (CAT), glutathione peroxidase (GSHPx), superoxide dismutase (SOD) as well as malondialdehyde (MDA), and antioxidant potential levels (AOP) in human erythrocytes. Patients diagnosed as osteoarthritis were included in the study. Patients were treated with Celecoxib (200 mg/d) (n = 12), Meloxicam (15 mg/d) (n = 12), and Ibuprufen (1200 mg/d) (n = 9) for 21 days. SOD, CAT, GSHPx activities, MDA, and AOP levels were investigated in human erythrocyte haemolysates. SOD activity and AOP levels were significantly decreased in all NSAID groups when we compared the values before and after 21 days of celecoxib, meloxicam, ibuprofen treatment. There were no significant difference in CAT, GSHPx activities, and MDA levels before and after treatment in each group. Decreased SOD activities are thought to be related with the increased superoxide anion. Decreased AOP levels may indicate impairment in the total antioxidant defence system. These NSAIDs have similar effects on free radical metabolism on human erythrocytes; despite some difference in action mechanisms.

Reduced antioxidant defense capacity in myocardial tissue from guinea pigs treated with 5-fluorouracil

Antioxidant defense capacity was investigated in myocardial tissue from guinea pigs treated with 5-fluorouracil (5-FU) at a dose of 400 mg/kg/d daily for 5 d administered intraperitonally. Treatment with 5-FU lowered the activities of cardiac superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) accompanied by higher catalase (CAT) activity. Further, antioxidant potential (AOP) values were lower but oxidation resistance (OR) and malondialdehyde (MDA) levels were higher in the 5-FU-treated tissue. With regard to myocardial iron (Fe) and copper (Cu) levels, no significant differences were found between the groups. Results suggest that 5-FU treatment causes impairment in the myocardial antioxidant defense system and leads to cardiac peroxidation. It has been postulated that these changes might be responsible for the 5-FU cardiotoxicity seen in some patients, and antioxidant therapy might provide a therapeutic advantage.Antioxidant defense capacity was investigated in myocardial tissue from guinea pigs treated with 5-fluorouracil (5-FU) at a dose of 400 mg/kg/d daily for 5 d administered intraperitonally. Treatment with 5-FU lowered the activities of cardiac superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) accompanied by higher catalase (CAT) activity. Further, antioxidant potential (AOP) values were lower but oxidation resistance (OR) and malondialdehyde (MDA) levels were higher in the 5-FU-treated tissue. With regard to myocardial iron (Fe) and copper (Cu) levels, no significant differences were found between the groups. Results suggest that 5-FU treatment causes impairment in the myocardial antioxidant defense system and leads to cardiac peroxidation. It has been postulated that these changes might be responsible for the 5-FU cardiotoxicity seen in some patients, and antioxidant therapy might provide a therapeutic advantage.

The effects of cyclosporine on antioxidant enzyme activities and malondialdehyde levels in rabbit hepatic tissues

Possible molecular mechanisms leading to cyclosporine-induced hepatotoxicity has not been cleared yet. Therefore, investigation of antioxidant status of hepatic tissues exposed to cyclosporine A (CsA) and of free radical involvement in the CsA-induced hepatotoxicity seems of importance. For this aim, 20 rabbits were used in the study. In each group (control, CsA, CsA plus vitamin and, vitamin only) there were 5 animals. CsA was given orally (25 mg/kg/day) for 10 days. Vitamins E (100 mg/kg/ day) and C (200 mg/kg/day) combination was injected intramuscularly. After 10th day, animals were killed, and livers were prepared for the enzymatic assays. Activities of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and catalase (CAT) and, malondialdehyde (MDA) levels were determined in the supernatant fractions. Lowered SOD, unchanged GSH-Px and, increased CAT activities and MDA levels were detected in hepatic tissues of rabbits treated with CsA as compared with controls. In the CsA plus vitamin group, SOD activity was found to be higher, GSH-Px and CAT activities unchanged and MDA levels lower than the CsA group. In the vitamin-treated group, all of the enzyme activities were higher than the controls but MDA levels were unchanged. Correlation analysis revealed some significant differences between the groups. Results suggest that cyclosporine impairs the antioxidant defense system and thus, leads to oxidant stress and peroxidation in rabbit hepatic tissues. It has been established that this process can be prevented by antioxidant vitamin supplementation.

Blood oxidant/antioxidant status of atherosclerotic patients

In the present study, it is aimed to investigate oxidant/antioxidant status of plasma and erythrocytes from atherosclerotic patients and to establish the possible role of oxidant stress in the formation and progression of atherosclerosis. Antioxidant potential (AOP) values and malondialdehyde (MDA) levels were studied in erythrocyte and plasma samples from 40 atherosclerotic patients and 38 healthy controls. A total of 13 subjects in each group were smokers. AOP was found unchanged in erythrocytes but lower in plasma samples (P<0.0005) from atherosclerotic patients as compared with those of the controls. MDA levels were however higher in erythrocyte hemolysate (P<0.025), erythrocyte membrane (P<0.0005) and blood plasma samples (P<0.0005) from atherosclerotic patients than those of the controls. Moreover, AOP was found to be lower in plasma samples of smoker patients than that of non-smoker patients (P<0.05). In the control group, erythrocyte MDA level was higher in smoker group than that of non-smoker group (P<0.05). Results reveal the presence of oxidant stress in the blood samples from patients with atherosclerosis. It seems antioxidant therapy might give beneficial results for atherosclerotic patients.

The Effect of Red Wine on Blood Antioxidant Potential

We investigated the effects of red wine on blood antioxidant potential in an attempt to elucidate molecular mechanisms concerning the possible protective role of red wine in atherosclerosis. Volunteer subjects in the study group consumed a standard meal and drank red wine (5 mg/kg) while controls consumed the same meal and drank water. Over 4 1/2 hours, blood samples were taken, and malondialdehyde (MDA) and antioxidant potential (AOP, obtained from MDA levels before and after superoxide radical attack) values were measured in the plasma and erythrocytes. We found that AOP values of plasma and erythrocyte samples from the study group were at their highest after 1 1/2 hours and then declined to basal values at 4 1/2 hours. There were no statistically significant differences between the basal AOP values of the study group and the control group. With regard to MDA levels, gradual increases were seen in the plasma of the control group during the 3 hours after food, but no changes were seen in the plasma of the study group in this period. Although there were increases in erythrocyte MDA levels of both groups over 3 hours, the MDA production rate was significantly higher in the control group. Our results suggest that red wine causes significant increases in AOP values of plasma and erythrocytes, which may prevent cellular peroxidation reactions and lessen atherosclerotic complications through inhibition of LDL.

Oxidant/Antioxidant Status of Erythrocytes from Patients with Chronic Renal Failure: Effects of Hemodialysis

Objective: It has been suggested that oxidative processes may be increased in patients with chronic renal failure (CRF), and that this is a possible factor contributing to the development of anemia and atherosclerosis, characteristic complications of CRF. The aim of this study was to investigate erythrocyte oxidant/antioxidant status in patients with CRF and to elucidate possible effects of hemodialysis on erythrocyte antioxidant system. Methods: Fasting blood samples were obtained from 33 patients with CRF and from 12 healthy controls. Of the patients, 17 subjects were under regular hemodialysis. Values of the activities of antioxidant enzymes, namely superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), catalase (CAT) and antioxidant potential, nonenzymatic superoxide radical scavenger activity (NSSA) and levels of thiobarbituric acid reagent substances (TBARS) were measured in the erythrocytes from both patients and controls. Results: Antioxidant potential and NSSA values were found to be significantly decreased, while TBARS levels were increased in the erythrocytes of patients. SOD activity was found to be unchanged, but GSH-Px and CAT activities were significantly lower in the patient group. Moreover, the erythrocyte TBARS level in the hemodialysis group was higher than in the controls and nonhemodialysis patients. Conclusion: The results suggest that antioxidant potential is reduced due to impaired antioxidant system in erythrocytes from patients with CRF and that oxidant stress causes significant peroxidation. Hemodialysis is determined to further increase oxidative reactions. These changes seem to contribute to the occurrence of some complications of CRF. Therefore, it has been suggested that antioxidant supplementation may give beneficial results for these patients.