الفهرس 
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Abstract
Exposure of biological systems to ultraviolet A (UVA) and the xenoestrogen bisphenol-A (BPA) can induce the formation of reactive oxygen species (ROS) which can cause oxidative damage to major constituents of cells .When ROS overcome antioxidant defence, the damage occurs in the cells. Therefore, The ability of two diet-derived flavonoids (i.e., the flavanone naringenin and the flavanol quercetin) to protect from oxidative stress will be investigated. For this purpose, sixty adult male albino rats of similar weights and ages were chosen as an animal model for the present study. Quercetin (QE) and naringenin (NG) were administered intraperitoneally in a dose of 10 mg/kg body weight. BPA was injected intraperitoneally to rats in a dose of 20 µg/kg body weight. All compounds were administered to rats 1 h before the irradiation periods. The UV groups were irradiated every day for 4 h with UVA during periods reached to 60 days. The experimental animals were randomely divided into ten groups each of 6 rats as follows:
A – NON-UV groups
1. NON-UV control (-) group was considered as negative control.
2. BPA group was injected with bisphenol A.
3. BPA+QE group was treated with both BPA and QE.
4. BPA+NG group was received both BPA and NG.
B – UV groups
5. UVA control (+) group was exposed to UVA.
6. UVA+QE group was injected with QE, then subjected to UVA.
7. UVA+NG group was treated with NG, then subjected to UVA.
8. UVA+ BPA group was injected with BPA, then subjected to UVA.
9. UVA-BPA+QE group was administered with both BPA and QE, then subjected to UVA.
10. UVA-BPA+NG group was treated with both BPA and NG, then subjected to UVA.
Blood was taken 15, 30, 45 and 60 days post-treatment to evaluate the protective role of QE and NG through estimation of the following parameters :
1. Glutathione peroxidase (GPx), superoxide dismutase (SOD), catalase (CAT) and glutathione S-transferase (GST).
2. Thiobarbituric acid reactive substances (TBARS), reduced glutathione (GSH) , total thiols, tocopherol and carotene.
3. Blood haemoglobin, glucose, urea, total protein, albumin, lipid profile and liver functions (AST &ALT), in addition to ALP and LDH.
4. Sex hormones (testosterone and estradiol)
5. Body, liver, kidneys, spleen, lungs, heart, brain and testes weights.
The main results obtained from this study could be summarized as follows :
1. The level of TBARS content was significantly increased in rats treated with BPA, UVA and BPA+UVA whereas the levels of GSH and plasma thiols were significantly decreased when compared with normal rats. However, administration of QE or NG along with BPA, UVA and BPA+UVA significantly decreased the levels of lipid peroxidation products and maintains the levels of GSH and plasma thiols.
2. A significant increase in the activities of SOD was observed in rats treated with BPA and UVA+PBA when compared to control rats. Also, significant increases in the activities of SOD were found in all groups receiving NG.
3. A significant decrease in the activities of CAT and GPx was recorded in animals treated with BPA, UVA and BPA+UVA meanwhile, administration of QE or NG resulted in normal activities of these enzymes similar to non-exposed control group.
4. The mean values of total cholesterol, LDL-C and triglycerides were significantly elevated in rats treated with BPA, UVA and UVA+BPA compared with the corresponding values of the control rats group. Whilst a significant decline was shown in the mean values of HDL-C. However, administration of QE or NG was found to be effective in controlling alterations in these tested parameters.
5. It has been found that BPA, UVA and UVA+BPA caused a significant elevation in serum ALT, AST, ALP, LDH and plasma GST activities. Meanwhile, these changes were noticeably ameliorated by QE or NG.
6. A significant reduction was observed in serum testosterone, estradiol and testes weights due to UVA and BPA treatment. It could be noticed that dministration of NG appears to be a useful approach to rectify these changes.
In conclusion, the results obtained from the present study revealed that UVA and BPA affect enzymatic and non-enzymatic antioxidant defense systems that led to a remarkable change in some biochemical parameters. Also, the findings provide experimental evidence that quercetin and naringenin exerted beneficial and diversity potential effective role on the antioxidant defence systems.