Effects of low doses of essential oils on the antioxidant status of the erythrocytes, liver and the brain of mice

We studied the effects of essential oils from oregano and clove and a mixture of lemon essential oil and a ginger extract on the antioxidant state of organs in intact and three experimental groups of Balb/c mice. We found that in vivo essential oils were efficient bioantioxidants when mice were treated with it for 6 months even at very low doses, such as 300 ng/day. All studied essential oils inhibited lipid peroxidation (LPO) in the membranes of erythrocytes that resulted in increasing membrane resistance to spontaneous hemolysis, decreasing membrane microviscosity, maintenance of their integrity, and functional activity. The essential oil significantly decreased the LPO intensity in the liver and the brain of mice and increased the resistance of liver and brain lipids to oxidation and the activity of antioxidant enzymes in the liver. The most expressed bioantioxidant effect on erythrocytes was observed after clove oil treatment, whereas on the liver and brain, after treatment with a mixture of lemon essential oil and a ginger extract.     

The relationship between total sialic acid levels and antioxidant status in the tadpoles of Bufo viridis and Rana ridibunda ridibunda

Total sialic acid levels (TSA), antioxidant enzymes activities such as superoxide dismutase (SOD), catalase (CAT) and lipid peroxidation (LPO) levels were investigated during the developmental period in tadpoles of the predominantly terrestrial amphibian B. viridis and the predominantly aquatic amphibian R. r. ridibunda. Maximum TSA levels were observed in B. viridis and R. r. ridibunda at the fifth and third week of their development, respectively. SOD and CAT activity variations during development in B. viridis were higher than in R. r. ridibunda. Although SOD activity in B. viridis was higher than R. r. ridibunda at the eighth week, SOD activity increased 19.2-fold in R. r. ridibunda and 10.4-fold in B. viridis between the first and eighth week. CAT activity in R. r. ridibunda did not significantly change (p>0.001) until the fifth week then increased, whereas in B. viridis CAT increased after the third week. In contrast to the rise in the antioxidant enzyme activities, LPO levels tended to decrease during the developmental period. Levels of LPO showed a similar trend until the third week for both species. The minimum LPO levels in B. viridis and R. r. ridibunda were 23+/-1.2 and 146+/-7.3 nmol MDA g(-1) tissue, at the eighth week, respectively. While decreasing LPO levels correlated with increasing antioxidant enzyme activities, TSA tended to decrease after reaching a maximum point.     

Dynamics of oxidation stress markers during long-term antiorthostatic hypokinesia: A retrospective study

Nine volunteers aged 27 to 42 participated in an experiment with 370-day antiorthostatic hypokinesia at–5°C, and their blood serum samples were tested for the concentrations of lipid peroxidation (LPO) derivatives, including diene conjugates (DCs), malonic dialdehyde (MDA), and Schiff bases (SBs), and indices of the antioxidant defense system, including the tocopherol (TP) concentration and total antioxidant activity (AOA). The subjects were divided into two groups, which differed in physical training regimen and prophylaxis measures. Initial LPO steps were inhibited in both of the groups by 54–73% from day 50, while the level of SBs, which are final LPO products, decreased by 50–61% by day 230 and remained much the same up to the end of the experiment. The MDA and SB concentrations decreased by a factor of 1.6–2.3 during recovery. Total AOA decreased as an aftereffect during recovery to a level far lower than physiologically normal. Based on the significant inhibition of free-radical LPO throughout the experiment, long-term adaptation to simulated hypogravity was accompanied by a pronounced decrease in biological oxidation and caused severe stress. Substantial long-term readaptation stress developed during recovery after 370-day antiorthostatic hypokinesia, as was evident from the facts that the LPO activity was almost halved, TP concentration significantly increased, and the functional reserves of water-soluble antioxidants were exhausted. Lack of LPO activation was assumed to reflect adequate compensation in the subjects.     

Changes in metabolic processes in humans during a 120-day antiorthostatic hypokinesia

The activities of organ- and tissue-specific diagnostically significant enzymes, including aspartate aminotransferase, alanine aminotransferase, γ-glutamyl transferase, alkaline phosphatase, total and prostatic acid phosphatase, glutamate dehydrogenase, choline esterase, amylase, lactate dehydrogenase, oxybutyrate dehydrogenase, and creatin phosphokinase (muscular and cardiac isoenzymes), as well as the concentrations of total cholesterol and the cholesterol of high- and low-density lipoproteins, the ratios of their concentrations, and the level of triglycerides, were studied during an experiment with 120-day antiorthostatic (?7°) hypokinesia (ANOH) in the blood of six volunteers (men, 21 to 36 years old). In addition, the indices of lipid peroxidation (LPO) and antioxidant activity were determined, including the concentrations of diene conjugates, malonic dialdehyde, Schiff bases and tocopherol, and the total antioxidant activity. It was found that a 120-day ANOH in this experiment did not result in the formation of deep metabolic shifts accompanied by unfavorable changes in organs and tissues. The changes in cholesterol metabolism during hypokinesia were expressed in the redistribution of cholesterol fractions with the dominance of atherogenic forms and a higher risk of atherogenesis. All of the observed metabolic changes were easily reversible and eliminated during the first month of the recovery period. No signs of a higher intensity of free-radical processes were observed during any of the examination periods due to activation of the antioxidant defense system.     

Stress induced injury and antioxidant enzymes in relation to drought tolerance in wheat genotypes

The role of plant antioxidant system in water stress tolerance was studied in three contrasting wheat genotypes. Water stress imposed at different stages after anthesis resulted in a general increase in lipid peroxidation (LPO) and decrease in membrane stability index (MSI), and contents of chlorophylls (Chl) and carotenoids (Car). Antioxidant enzymes like glutathione reductase and ascorbate peroxidase significantly increased under water stress. Genotype C 306, which had highest glutathione reductase and ascorbate peroxidase activity, also showed lowest LPO and highest MSI, and Chl and Car contents under water stress in comparison to susceptible genotype HD 2329, which showed lowest antioxidant enzyme activity as well as MSI, Chl and Car contents and highest LPO. HD 2285 which is tolerant to high temperature during grain filling period showed intermediate behaviour. Thus, the relative tolerance of a genotype to water stress as reflected by its comparatively lower LPO and higher MSI, Chl and Car contents is closely associated with its antioxidant enzyme system. This revised version was published online in August 2006 with corrections to the Cover Date.     

Role of the antioxidant system in adaptation of ducks to postnatal development conditions

The peculiarities of antioxidant system functioning of duck organism were exposed in postnatal ontogenesis. The liver tissues and blood plasma of daily ducks are characterized by high LPO level, that leads to changes of superoxide dismutase, catalase, glutathione peroxidase activity. The level of LPO products declines, but disforming of adapt mechanism breaks the coordinating function of enzymes while vitamin A and E provision are deficient sience 7 till 42 days age. In the 8 and 10 ontogenesis weeks the LPO intensification depends on lipid content increase. Perhaps, it is a response on energy need growth of duck organism in forming feather period.     

Effects of seawater acidification and salinity alterations on metabolic,osmoregulation and oxidative stress markers in Mytilus galloprovincialis

The impacts of seawater acidification and salinity shifts on metabolism, energy reserves, and oxidative status of mussels have been largely neglected. With the aim to increase the current knowledge for the mussel Mytilus galloprovincialis a 28-day chronic test was conducted during which mussels were exposed to two pH (7.8 and 7.3; both at control salinity 28) and three salinity (14, 28 and 35, at control pH, 7.8) levels. After exposure to different conditions, mussels electron transport system activity, energy reserves (protein and glycogen content) carbonic anhydrase activity, antioxidant defences and cellular damage were measured. Results obtained showed that mussels exposed to seawater acidification presented decreased metabolic capacity that may have induced lower energy expenditure (observed in higher glycogen, protein and lipids content at this condition). Low pH condition induced the increase of carbonic anhydrase activity that was related to acid-base balance, while no significant activation of antioxidant defence mechanisms was observed resulting in higher LPO. Regarding the impacts of salinity, the present study showed that at the highest salinity (35) mussels presented lower metabolic activity (also related to lower energetic expenditure) and an opposite response was observed at salinity 14. Carbonic anhydrase slightly increased at stressful salinity conditions, a mechanism of homeostasis maintenance. Lower metabolic activity at the highest salinity, probably related to valves closure, helped to mitigate the increase of LPO in this condition. At low salinity (14), despite an increase of antioxidant enzymes activity, LPO increased, probably as a result of ROS overproduction from higher electron transport system activity. The present findings demonstrated that Mytilus galloprovincialis oxidative status and metabolic capacity were negatively affected by low pH and salinity changes, with alterations that may lead to physiological impairments namely on mussels reproductive output, growth performance and resistance to disease, with ecological and economic implications.Indicators: Physiological and biochemical changes in Mytilus galloprovincialis in response to low pH and salinity changes     

Effect of the substances "Ammivit" and "cerloplasmin" on lipid peroxidation products level and of antioxidant system indicators under irradiation

It has been shown, that the total X-ray irradiation in the dozes of 0.5 and 1 Gy influences on the content of lipid peroxidation products and enzymatic activity of antioxidant system in rat spleen and thymus cells. The influence of preparations "AMMIVIT" and "Ceruloplasmin" on these processes is investigated also. So, the animals feeding by the vitamin concentrate "AMMIVIT" have lead to increase of MDA level (a final product of lipid peroxidation) and the overactivity of some antioxidant enzymes in rat spleen and thymus cells. Injection of the preparation "Ceruloplasmin" to experimental animals up 1 hour before the irradiation has normalized LPO intensity and activity of AO enzymes.     

Malathion-induced Oxidative Stress in Rat Brain Regions

Malathion is a pesticide with high potential for human exposure. However, it is possible that during the malathion metabolism, there is generation of reactive oxygen species (ROS) and malathion may produce oxidative stress in intoxicated rats. The present study was therefore undertaken to determine malathion-induced lipid peroxidation (LPO), protein carbonylation and to determine whether malathion intoxication alters the antioxidant system in brain rats. Malathion was administered intraperitoneally in the acute and chronic protocols in the doses of 25, 50, 100 and 150 mg malathion/kg. The results showed that LPO in brain increased in both protocols. The increased oxidative stress resulted in an increased in the activity of antioxidant enzymes such as superoxide dismutase (SOD) and catalase (CAT), observed in cortex, striatum in the acute malathion protocol and hippocampus in the chronic malathion protocol. Our results demonstrated that malathion induced oxidative stress and modulated SOD and CAT activity in selective brain regions.     

Biological activities of the natural imidazole-containing peptidomimetics n-acetylcarnosine, carcinine and L-carnosine in ophthalmic and skin care products

Apart from genetically programmed cell aging, different external aggressors related to oxidative stress and lipid peroxidation (LPO) can accelerate the skin aging phenomenon. Oxidative stress associated with the formation of lipid peroxides is suggested to contribute to pathological processes in aging and systemic diseases known as the risk factors for cataract. Despite the fact that L-carnosine-related peptidomimetics N-acetylcarnosine (N-acetyl-beta-alanyl-L-histidine) (NAC) and carcinine (beta-alanylhistamine) are metabolically related to L-carnosine and have been demonstrated to occur in tissues of many vertebrates, including humans, these compounds were shown resistant toward enzymatic hydrolysis. A series of related biocompatible imidazole-containing peptidomimetics were synthesized in order to confer resistance to enzymatic hydrolysis and ex vivo improvement of protective antioxidative properties related to L-carnosine. The included findings revealed a greater role of N-acetylcarnosine (NAC) and carcinine ex vivo in the prolongation and potentiation of physiological responses to the therapeutical and cosmetics treatments with L-carnosine as antioxidant. 3-D molecular conformation studies proposed the antioxidant activity of peptidomimetics (carcinine, L-prolylhistamine, N-acetylcarnosine, L-carnosine) for metal ion binding, quenching of a number free radicals, and binding of hydroperoxide or aldehyde (including dialdehyde LPO products) in an imidazole-peroxide adducts. NAC can act as a time release (carrier) stable version of L-carnosine during application in ophthalmic pharmaceutical and cosmetics formulations which include lubricants. Carcinine, L-prolylhistamine show efficient deactivation of lipid hydroperoxides monitored by HPLC and protection of membrane phospholipids and water soluble proteins from the lipid peroxides-induced damages. This activity is superior over the lipophilic antioxidant vitamin E. The biologically significant applications of carnosine mimetics were patented by Dr. Babizhayev and the alliance Groups (WO 2004/028536 A1; WO 94/19325; WO 95/12581; WO 2004/064866 A1).     

Does underwater rugby stimulate the over-production of reactive oxygen species?

Antioxidant enzymes in erythrocytes such as superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px) and antioxidant sex hormone oestradiol in serum and malondialdehyde (MDA) production as a marker of lipid peroxidation in erythrocytes were investigated in male and female underwater rugby (UWR) players. Results showed that except for GSH-Px activity in female players, all antioxidant enzymes increased significantly (p < 0.05) after an UWR game. It was interesting to note that while the concentration of oestradiol in female players did not change, it increased significantly (p < 0.05) in male players. Lipid peroxidation (LPO) levels in female players as well as oestradiol concentration did not change significantly (p > 0.05) whereas LPO levels in male players increased significantly (p < 0.05) compared to pre-exercise values. In conclusion, the results showed that underwater rugby can stimulate over-production of ROS and antioxidant systems and affect oestradiol levels in male players. Because of increased LPO levels observed in male players, complex antioxidant supplementation including co-factors of antioxidant enzymes such as Cu, Zn, Fe, Se and antioxidant vitamins such as vitamin C and E may be recommended to players before the UWR game.     

Characteristics of some stages of energy metabolism and antioxidant system in bone marrow myeloid cells and leukocytes from piglets

The age changes of enzymes of activity catalyzing several links of energy metabolism (hexokinase, phosphofructokinase, pyruvate kinase, lactate dehydrogenase, glucose-6-phosphate dehydrogenase, NADP-isocitrate dehydrogenase, cytochrome c-oxidase) and antioxidant system (superoxide dismutase and glutathione reductase) in bone marrow myeloid cells and blood leukocytes of pig in the 10-day period after birth were investigated. The bone marrow cells and leukocytes of the new born piglets were characterized by low intensity of oxidative steps of energy metabolism as well as by low activity of antioxidant enzymes. In the period of neonatal adaptation reorganization of energy metabolism, particularly, intensification of oxidative processes in the investigated cells occurred. It included the pentose phosphate way and cytochrome c-oxidase activation. During the neonatal period of development the functional activity of antioxidant enzymes in the investigated cells of piglets increased.     

Modification of biochemical parameters of gentamicin nephrotoxicity by coenzyme Q10 and green tea in rats

The present study was designed to investigate the possible potential protective role of coenzymeQ10 (CoQ10; 10 mg/kg/day, ip) and/or green tea (GT; 25mg/kg/day, po) against gentamicin (GM) nephrotoxicity. Marked increase in the level of serum urea. creatinine and lipid peroxidation (LPO) content was found after administration of gentamicin (80 mg/kg/day, ip) for eight days along with significant decrease in the antioxidant enzymes, superoxide dismutase (SOD), reduced glutathione (GSH), catalase (CAT) as well as brush border enzymes (Na+/K+ ATPase, Mg(+2)ATPase and Ca2+ ATPase).Treatment with CoQ10 or green tea alone with GM showed significant decrease in serum urea, creatinine and tissue LPO content and significant increase in antioxidant and membrane bound enzymes. Combined treatment with CoQ10 and green tea was more effective in mitigating adverse effect of GM nephrotoxicity. The present work indicated that CoQ10 and green tea due to their antioxidant activity modified the biochemical changes occurred during gentamicin nephrotoxicity and thus had a potential protective effect.     

The variation of antioxidant defense system of Streptomyces sp. M4018 with respect to carbon sources

The effect of glycerol, glucose, and starch as carbon sources on the antioxidant defense system such as superoxide dismutase (SOD) and catalase (CAT) activities, pyruvate levels, and membrane lipid peroxidation (LPO) levels of Streptomyces sp. M4018, after isolation from the rhizosphere samples of Colutea arborescens and identification as a strain of S. hiroshimensis based on phenotypic and genotypic characteristics, were investigated. As an antioxidant defense enzyme, SOD activities increased up to 20 g/L of glycerol and 15 g/L of starch, while they showed negative correlation with glucose concentration. CAT activity variations of glycerol- and glucose-supplemented mediums showed significant positive correlations with the trend of SOD activities. However, CAT activity, in contrast to SOD, in Streptomyces sp. M4018 tended to decrease as the starch concentration increased. The production of pyruvate increased with respect to glycerol and starch up to 15 g/L, while it was positively correlated with glucose concentration. The highest pyruvate production was seen at 20 g/L glucose. Membrane LPO levels were negatively correlated with the activities of SOD and CAT enzymes, and the minimum LPO level was determined at 5 g/L of glucose, where SOD and CAT activities reached their maximum levels. Nevertheless, the higher SOD and CAT activities in a wider range of incubation period compared to the beginning by resulting in insignificant increases in membrane LPO levels showed the unusual antioxidant response capacities of the in Streptomyces sp. M4018 against the potentially deleterious effects of reactive oxygen species (ROS) for glycerol, glucose, and starch as carbon sources.     

Effects of Se, Cu and Se + vitamin E deficiency on the activities of CuZnSOD, GSH-Px, CAT and LPO levels in chicken erythrocytes

Antioxidant enzymes and vitamins provide a defence against the damage of cells by reactive oxygen species in living systems. The effect of Cu, Se and vitamin E deficiencies on the antioxidant enzyme activities and lipid peroxide levels of chicken erythrocytes were investigated during 6 weeks of a depletion diet. CuZnSOD activity and the plasma Cu level of the Cu-deficient group which was fed a diet containing 0.2 mg Cu x kg(-1) were reduced to 62 and 71% respectively. GSH-Px activity of the Se-deficient group was decreased by 46% but by 21% in the Cu-deficient group. CAT activity values of Se- and Cu-deficient groups were increased by 28 and 10% respectively. The maximum increase of LPO levels in erythrocyte membranes was observed as 32% for the Se+E-deficient group. The LPO level of the Cu-deficient group which had decreased CuZnSOD and GSH-Px activity, was also observed to be significantly increased when compared with the controls (p < 0.05).     

The inhibition stage of lipid peroxidation during stress

Stress is shown to induce at first the generalized inhibition of lipid peroxidation (LPO), and then the activation of LPO. In brain and blood serum of rats subjected to continuous footshock as well as to restraint stress LPO products decreased and superoxide scavenging activity increased during the initial period of stress, after 1 hour of footshock LPO indices nearly reached normal values, and after 2 hours of footshock the accumulation of LPO products and decrease of superoxide scavenging activity were seen. LPO inhibition was accompanied by accumulation of easy oxidizable brain phospholipids and by depletion of brain cholesterol, during LPO activation brain cholesterol content and cholesterol-phospholipid ratio increased. The content of LPO products--fluorescent Schiff bases in blood plasma of women suffering from algomenorrhea at first decreased (O-12 h) and then dramatically increased (12-24 h) after a onset of pain at the beginning of menstruation. The data suggest that the stage of LPO inhibition precedes its activation during stress.     

Radioprotective mechanism of Podophyllum hexandrum during spermatogenesis

RP-1, a herbal preparation of Podophyllum hexandrum has already been reported to provide protection against whole body lethal gamma irradiation (10 Gy). It has also been reported to render radioprotection to germ cells during spermatogenesis. Present study was undertaken to unravel the cellular and molecular mechanism of action of RP-1 on testicular system in strain 'A' mice. Various antioxidant parameters such as thiol content, glutathione peroxidase (GPx), glutathione reductase (GR), glutathione-S-transferase (GST) enzyme activity, lipid peroxidation (LPO) and total protein levels were investigated. Thiol content was seen to increase significantly (p < 0.05) in both RP-1 alone and RP-1 pretreated irradiated groups over the irradiated groups at 8, 16 and 24 h. Irradiation (10 Gy) significantly decreased GPx, GST and GR activity in comparison to untreated control but RP-1 treatment before irradiation significantly (p < 0.05) countered radiation-induced decrease in the activity of these enzymes. Radiation-induced LPO was also found to be reduced at all time intervals by RP-1 treatment before irradiation. As compared to irradiated group the protein content in testicular tissue was increased in RP-1 pretreated irradiated group at 4 and 16 h significantly (p < 0.05). Comets revealed by single-cell gel electrophoresis were significantly longer (p < 0.001) in irradiated mice than in unirradiated control. RP-1 treatment before irradiation, however, rendered significant increase (p < 0.05) in comet length over the corresponding control and irradiated group initially at 4 h but at later time points, this was reduced significantly (p < 0.01) as compared to the irradiated group. RP-1 treatment alone rendered shorter comets at 8, 16 and 24 h than irradiated groups (p < 0.001). This study implies that RP-1 offers radioprotection at biochemical and cytogenetic level by protecting antioxidant enzymes, reducing LPO and increasing thiol content.     

The influence of season on oxidant-antioxidant status in trained and sedentary subjects

The association between oxidative stress and cardiovascular diseases is a widely accepted fact today. Generally, men have a higher risk of cardiovascular incidents and mortality from acute myocardial infarction and strokes. We have examined sport-associated circannual rhythms of oxidant and antioxidant processes by measuring plasma LPO, erythrocyte SOD, CAT, Gpx activity and plasma hormonal status in both sedentary and long-term trained men and women. We have shown seasonal variations in both oxidant and antioxidant status in all examined groups. The largest difference was observed in the oxidant status between sedentary men and women during autumn and winter, which is considered a period of high coronary risk for men. Sport decreased LPO in trained men in autumn, while the same effect in trained women was shifted towards summer. These data state that regular, long-term physical exercise training induces adaptive responses that confer protection against oxidative stress, as well as the beneficial effect of exercise with regard to season, particularly in men during a period of high coronary risk (autumn and winter, respectively) and in women during summer.     

Myocardial antioxidant status and oxidative stress after combined action of exercise training and ethanol in two different age groups of male albino rats

The interaction of exercise training and ethanol on the myocardial antioxidant enzymes and the oxidative stress markers was investigated in the Wistar strain male albino rats. We also tested the interactive effects of exercise training and ethanol on the age-associated free radical production and antioxidant defense system. We found a significant decrease (p<0.05) in the activity levels of superoxide dismutase (SOD) and catalase (CAT) in the myocardium of old rats when compared to young rats by 26% and 58%, respectively, suggesting the onset of age-dependent decrease in the myocardial antioxidant enzyme system. In contrast to the decreased antioxidant enzyme activity, xanthine oxidase (XOD) and lipid peroxidation (LPO) levels were elevated, suggesting the age-induced oxidative stress. Exercise training significantly (p < 0.05) elevated the activities of SOD, CAT, XOD and LPO levels in both the age groups of animals. Ethanol consumption significantly lowered the SOD and CAT activities in both the age groups, whereas a significant increase was observed in the XOD and LPO levels. In contrast, the combination of exercise training plus ethanol lowered XOD and LPO levels in both the age groups of rats compared to ethanol treated rats. A significant (p < 0.05) increase in the activities of SOD and CAT was reported in the rats treated with the combination of exercise training plus ethanol. This increase was more pronounced in the younger rats than the older rats. The findings of the present investigation on the potential role of antioxidant enzymes to counter the ethanol-induced pro-oxidants showed an increase with the interaction of exercise training. With age, a decrease in the antioxidant enzyme capacity was observed. This reveals that the old age rats were more affected to the pro-oxidants when compared to the young age rats. In conclusion it is demonstrated that two months treadmill endurance exercise training is beneficial to both young and old rats in improving antioxidant defense to challenge the oxidative stress in the myocardial tissue and thereby successfully countering the free radical production due to ethanol intoxication.     

Effects of temperature and dietary protein level on hepatic oxidative status of Senegalese sole juveniles (Solea senegalensis)

Effects of 55 and 45% dietary protein levels (55P and 45P diets, respectively) and temperature (12 and 18°C) on hepatic activity of superoxide dismutase (SOD), catalase, glutathione peroxidase, glutathione reductase (GR), glucose-6-phosphate dehydrogenase and lipid peroxidation (LPO) levels of Solea senegalensis juveniles were studied. Further, effects of acute thermal shocks provoked by a drop (18°C to 12°C) or a rise (12°C to 18°C) of water temperature on sole oxidative state was also evaluated. Dietary protein reduction increased LPO levels though no major alterations were found on antioxidant enzyme activities between dietary treatments. At 12°C GR activity was higher and SOD activity was lower than 18°C but LPO levels were not affected. In both thermal shock cases, LPO levels increased in 55P group, probably due to insufficient antioxidant enzyme activation. In contrast, fish of 45P group under acute exposition to warmer and colder temperature exhibited no substantial changes and a significant decrease on LPO levels, respectively, along with no major changes in antioxidant enzymes. Overall, results suggest that independently of rearing temperatures 45P group was more susceptible to oxidative stress than 55P group. Thermal shock either due to rise or drop of temperature seemed to induce oxidative stress in 55P group.