Aspirin impairs antioxidant system and causes peroxidation in human erythrocytes and guinea pig myocardial tissue

This study aims to investigate possible effects of aspirin treatment on cellular oxidant/antioxidant system. In the first part of the study, 15 guinea pigs were given aspirin at three different doses (2200, 440 and 10 mg/kg/day) for 30 days and five were fed on the same diet without aspirin. After a month, animals were killed and their hearts were removed for use in analyses. In the other part, after fasting blood samples were obtained from 11 volunteer subjects, they were given aspirin (approximately 10 mg/kg/day) for 30 days and second blood samples were obtained after 1 month. Five volunteer subjects also participated as placebo control. Oxidant/antioxidant parameters, namely superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), catalase (CAT), malondialdehyde (MDA), nonenzymatic superoxide scavenger activity (NSSA), susceptibility to oxidation (SO) and antioxidant potential (AOP) values, were assayed in the samples. Antioxidant system was found to be impaired in the heart tissue from guinea pigs and in the erythrocytes from volunteer subjects. AOP and NSSA values were lower and MDA higher after aspirin treatment in both heart tissues and erythrocytes. In guinea pig heart tissue, SO was lower, but GSH-Px and CAT were unchanged after aspirin treatment. In human erythrocytes, SO was unchanged, but GSH-Px and CAT activities were increased after aspirin treatment. Changes in guinea pig heart tissues from animals treated with higher aspirin doses were more drastic relative to those of human erythrocytes, but no meaningful differences were observed between analysis parameters of control and lower-dose (10 mg/kg/day) aspirin-treated animals. Our results suggest that high-dose aspirin exerts significant toxicity to guinea pig myocardium and normal dose aspirin may cause peroxidation in the human erythrocytes due to its oxidant potential. We suppose that antioxidant supplementation may be beneficial for the people using aspirin for longer periods in order to prevent peroxidation damages.

Acute effects of smoking of cigarettes with different tar content on plasma oxidant/antioxidant status

In this study, acute effects of two different types of cigarette smoking on plasma oxidant/antioxidant status were investigated. For this purpose, malondialdehyde (MDA) levels and antioxidant potential (AOP) values were measured in the plasma samples before and after cigarette smoking at fasting. After the first blood sample was obtained, second and third samples were withdrawn at 1.5 h and 3 h. In the first group, subjects smoked five cigarettes with full flavor (FF), and in the second group, five cigarettes with full-flavor low tar (FFLT). Quality classification is made mainly on the basis of tar content of the products. The cigarette with 23 mg tar is defined as FF and that with 12 mg tar as FFLT. MDA level was found to be significantly increased in the 1.5-h plasma samples of both groups, but the increase was greater in the FF group. AOP values, however, were found to be lower in the 3-h plasma samples of both groups, but the decrease was greater in the FF group compared with the FFLT group. It appears that acute smoking causes oxidant stress in blood plasma once exposed to smoke, and then this effect (MDA) begins to decrease. On the other hand, AOP is lowered due to oxidant stress created by smoke. With regard to the types of cigarettes, the FF product seems to be more oxidant than the FFLT product. Our results suggest that antioxidant supplementation might be beneficial for the smokers to cope with the oxidant load derived from cigarette smoke. It is also clearly seen from these results that cigarette manufacturers should reduce tar/nicotine ratio in their products in order to lessen the toxic effects of smoking without causing increased need to smoke.

High-temperature effects on antioxidant systems and toxic product formation in nutritional oils

In this study, effects of high-temperature heating on antioxidant defense potential (AOP) and malondialdehyde (MDA) levels were investigated in several types of oils ingested by humans. Natural olive oil, refined olive oil, sunflower oil, and soy oil were examined. High-temperature heating to 180 degrees C significantly decreased AOP. This was accompanied by a significant increase in MDA levels. The observed changes were quantitatively greater in soy and sunflower oil compared to olive oil. The loss in antioxidant defense potential and elevation in peroxidation products may be associated with enhanced disease processes.

Isoflurane impairs antioxidant defence system in guinea pig kidney

PURPOSE

To investigate whether free radical metabolism is changed due to isoflurane treatment and, if so, to elucidate the role of changed free radical metabolism in the nephrotoxicity.

MATERIALS AND METHODS

Fifteen guinea pigs were used in the study. Five were treated with isoflurane in oxygen, five with oxygen and five were controls. Animals were exposed to isoflurane and oxygen three times. Each treatment was performed for 30 min once a day for three consecutive days. Activities of free radical enzymes, superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px); values of antioxidant parameters, antioxidant potential (AOP), non-enzymatic superoxide radical scavenger activity (NSSA) and oxidation resistance (OR) and, level of an oxidant parameter namely, malondialdehyde (MDA) were determined in the renal tissues of the groups. Blood was also obtained for serum creatinine and urea analyses.

RESULTS

AOP, NSSA, SOD and CAT activities were decreased; (0.0188 +/- 0.0026 vs 0.0156 +/- 0.0015, P < 0.025; 8.72 +/- 1.80 vs 6.40 +/- 1.22, P < 0.05; 76.71 +/- 18.54 vs 52.79 +/- 11.68, P < 0.025; 71.26 +/- 15.58 vs 55.39 +/- 8.83; P < 0.05, respectively) but, MDA level, OR value and GSH-Px activities increased (10.89 +/- 1.57 vs 15.87 +/- 2.97, P < 0.01; 0.84 +/- 0.34 vs 2.28 +/- 1.39, P < 0.05; 1.45 +/- 0.83 vs 3.45 +/- 1.20, P < 0.01, respectively) in kidney tissues from isoflurane-treated group compared with controls. No differences were observed between control and oxygen groups with regard to all analysis parameters except GSH-Px.

CONCLUSION

Isoflurane impairs the antioxidant defence system and this oxidant stress may play a part in the isoflurane-induced renal toxicity.

Comparison of antioxidant potentials of red wine, white wine, grape juice and alcohol

Antioxidant potential (AOP) and non-enzymatic superoxide radical scavenger activity (NSSA) values of red wine, white wine, grape juice and ethyl alcohol were assessed and values were compared. The effects of these beverages on serum AOP and NSSA values were also measured in vitro. Red wine, white wine and grape juice exert strong antioxidant activity in similar degrees and all produce significant effects on serum AOP and NSSA values. However, ethyl alcohol does not have either AOP or NSSA, nor does it have an effect on serum AOP or NSSA values. AOP values (nmol/ml h) of red wine, white wine and grape juice were 20.8 +/- 4.2, 23.2 +/- 4.0 and 24.6 +/- 4.8, respectively. NSSA values (U/ml) of red wine, white wine and grape juice were 30.4 +/- 6.8, 26.8 +/- 5.6 and 32.6 +/- 5.8, respectively. There were no statistically meaningful differences between AOP and NSSA values of the groups (p > 0.05 for all). Results suggest that red wine, white wine and grape juice all have high antioxidant potential to protect cellular structures against peroxidation reaction owing to their rich phenolic contents.