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In this study, isolated hepatocytes of pearl mullet (Alburnus tarichi) were exposed to bisphenol A (BPA) at concentrations of 25, 50, 100, and 200 μM for 24 h. Moreover, an in vitro antioxidant concentration of vitamin C (50 μM) was administrated to the culture medium along with the BPA exposures. Next, the antioxidant defense system parameters were analyzed. According to the results, the highest concentration of BPA (200 μM) proved to be severely toxic for the cells. The increased activities of superoxide dismutase (SOD) and glutathione-S-transferase (GST), the fluctuated activities of glutathione peroxidase (GPx), and the decreased content of reduced glutathione (GSH) were compared to the control group after the BPA exposures. Vitamin C co-administration was found to cause further increases in the SOD, GPx, and GST activities in some of the experimental groups and vitamin C could not restore the GSH content. Malondialdehyde (MDA) levels were observed to be unaffected in all exposure groups. These results show that BPA causes alterations in the antioxidant defenses of the isolated fish hepatocytes. In addition, vitamin C co-administration along with BPA was found to be non-protective against BPA-induced oxidative stress, consequently, aggravated a negative BPA impact.

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Alteration of the antioxidant system may be related to lead (Pb) hepatotoxicity. This study was carried out to investigate the possible beneficial effect of thymoquinone (TQ), the major active ingredient of volatile oil of Nigella sativa seeds, against Pb-induced liver antioxidant defense system impairment. Adult male rats were randomized into four groups: control group received no treatment, Pb group was exposed to 2000 ppm of Pb acetate in drinking water, Pb-TQ group was cotreated with Pb plus TQ (5 mg/kg/day, per os) and TQ group receiving only TQ. All treatments were applied for five weeks. TQ alone did not induce any significant changes in the enzymatic and non-enzymatic antioxidant status. By contrast, Pb exposure significantly decreased not only reduced glutathione level, but also superoxide dismutase, glutathione peroxidase, catalase and glutathione reductase activities in the liver tissue. Interestingly, when coadministrated with Pb, TQ significantly improved the affected antioxidant parameters. In conclusion, our results indicate a protective effect of TQ against Pb-induced liver antioxidant capacity impairment and suggest that this component might be a clinically promising alternative in Pb hepatotoxicity.

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Cao, L., Leers-Sucheta, S., Azhar, S. (2004) Aging alters the functional expression of enzymatic and non-enzymatic antioxidant defence system in testicular rat Leydig cells. J. Steroid Biochem. Mol. Biol. 88

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The effects of crude oil (Szeged-Algyő, Hungary) and oil fractions (F1: rich in aromatics; F2 fraction: free from aromatics) were investigated on liver CYP1A isoenzymes and antioxidant defence system following their i.p. injection into different freshwater fish species: carp ( Cyprinus carpio L.), silver carp ( Hyphothalmichtys molitrix V.), and European eel ( Anquilla anquilla ). A dose of 2 mL kg −1 crude oil enhanced EROD activity 8-fold in carp and only 5-fold in eel after 3 days. Oil fraction F1 caused only a 2-fold induction in EROD activity only in carp, while F2 fraction caused significant inhibition in all three investigated fish species. The antioxidant parameters [lipid peroxidation (LP), catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx), glutathione (GSH)] were measured following the treatment. A decrease of 50% in CAT activity was observed after oil treatment. The GSH level enhanced, resulting the protective effects against LP. The same dose of crude oil but a longer duration time resulted in lower CYP1A induction in carp and antioxidant parameters had returned close to control. In all treatments the EROD isoenzymes proved to be more sensitive and the effects of oil treatment showed species to be different. Carp proved to be more sensitive than eel or silver carp.

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Aerobic rice offers an attractive alternative approach over transplanting system as it consumes less water with low labour expenses. Flag leaf of six rice cultivars, viz. PR 120, PR 115, PR 116, Feng Ai Zan, PAU 201 and Punjab Mehak 1 was analysed for antioxidant defence mechanism and polyamine catabolism under the aerobic and the transplanting conditions. Ascorbate peroxidase (APX), guaiacol peroxidase (GPX), catalase (CAT), superoxide dismutase (SOD), diamine oxidase (DAO) and polyamine oxidase (PAO) activities increased gradually from tillering to anthesis stage and then declined towards maturity stage under both planting conditions. Apparently, contents of ascorbic acid, α-tocopherol, proline and polyamines (PAs) also revealed similar trend. The aerobic condition elevated activities of PAO, SOD as well as contents of PAs, lipid peroxide and H2O2 whereas the transplanting condition had higher levels of APX, GPX, CAT and total antioxidant activities and contents of ascorbate, α-tocopherol and proline. Cultivars Feng Ai Zan, PR 115 and PR 120 exhibited superior tolerance over other cultivars by accumulating higher contents of PAs with increasing levels of PAO and SOD activities under the aerobic condition. However, under the transplanting condition PR 116 and PAU 201 showed higher activities of antioxidative enzymes with decreasing contents of lipid peroxide and H2O2. We infer that under the aerobic condition, enhancement of PAs and PAO activity enabled rice cultivars to tolerate oxidative stress, while under the transplanting condition, antioxidative defence system with decreasing of lipid peroxide content was closely associated with the protection of flag leaf by maintaining membrane integrity. In crux, results indicated that H2O2 metabolic machinery was strongly up-regulated especially at the anthesis stage.

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The present study was aimed to investigate the effect of different ultraviolet radiation doses on the growth, and antioxidant enzymes of three cultivars of soybean ( Glycine max L.) (‘Giza-22’, ‘Giza-35’ and ‘Giza-111’). The seeds were grown in plastic pots equally filled with a mixture of pre-sieved sandy loam soil, peat-moss and vermiculite (2: 1: 1) for two weeks. The planted pots were divided into four groups and exposed to white light (1,100 Lux) (control), 3.2, 6.4 and 12.8 KJ m −2 d −1 UV A+B radiation, respectively, for 30 days and then harvested. The results indicated that shoot dry weight was decreased with increasing UV A+B radiation doses; it was found that supplementation of UV A+B radiation increased root dry weight in all studied cultivars of soybean plants. With referring to oxidative stress, it was found that increasing UV radiation induced significant increases in H 2 O 2 concentration, lipid peroxidation and cell death (as ion leakage) in soybean cultivars. Increasing supplemental doses of ultraviolet radiations significantly induced reductions in all studied antioxidants (catalase, peroxidase and superoxide dismutase (SOD) activities and glutathione content).

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Use of plant hormones as seed priming agents is known to improve the field performance especially under stressful conditions like salinity. A pot experiment was conducted to study the effects of seed priming of two wheat (Triticum aestivum L.) cultivars Auqab-2000 (salt tolerant) and MH-97 (salt sensitive) under saline (15 dS m−1) and non-saline (2.75 dS m−1) conditions. For priming seeds were soaked in aerated water (hydropriming), and solutions of kinetin (Kin; 25 mg L−1), or salicylic acid (SA; 50 mg L−1) for 12 h. All the priming treatments significantly reduced the adverse effects of salinity in terms of improving final emergence, growth and grain yield of both cultivars. Seed priming with SA and Kin improved salt tolerance in both wheat cultivars by the activation of antioxidants, i.e. superoxide dismutase (SOD) and catalase (CAT) to counterbalance the oxidative damage. Albeit, Na+ and Cl contents increased due to salinity, all priming strategies lowered the accumulation of Na+ and enhanced the accumulation of K+ in leaves of both cultivars. The results suggest that priming with SA followed by kinetin successfully improved fitness of wheat plants exposed to salt stress.

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, C. (2005b) Vulnerability of the mid aged rat myocardium to the age-induced oxidative stress: Influence of exercise training on antioxidant defense system. Free Radical Research 39 , 1211

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289 292 Buzadžić, B., Blagojevic, D., KoraĆ, B., Saicic, Z. S., Spasic, M. B., Petrović, V. M. (1997) Seasonal variation in the antioxidant defense system of the brain of the

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. Upregulation of antioxidant enzyme activity in Coleus suggests the existence of a strong antioxidant defense system in these two species with respect to drought stress. However, C. amboinicus has shown to possess a better antioxidative defense system than

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