الفهرس 
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Abstract
Cataracts, the opacification of the eye lens, are the most common cause of blindness, accounting for almost half of all cases worldwide. Selenite-induced cataract is a cataract model mainly dependent on oxidative stress. Functional foods are foods with demonstrated physiological benefits similar in appearance to conventional foods, consumed as part of the usual diet and reduce the risk of chronic diseases beyond basic nutritional functions. Garlic, onion, broccoli and soybean possess strong antioxidant protective effects by their abilities to scavenge free radicals. Flavonoids and organosulfur compounds are the two major classes of secondary metabolites found in them and are believed to promote beneficial health effects. In the present study a special attention was made on the protective role of these functional foods against selenite-cataract development and oxidative stress.
A commercial diet from the animal house of Research Institute of Ophthalmology was used as basal diet. Powdered garlic, onion, broccoli and soybean were used as diet supplements. Total phenolic compounds of garlic, onion, broccoli and soybean powders were determined.
Ten Wister albino rat mothers were housed with their pups (Sixty five rat pups weighing 25±4 g) in ten cages. The rat pups were classified into ten groups.
Group 1: Normal control (6 pups) received basal diet.
Group 2: Cataract (8 pups), received basal diet.
Group 3: Normal fed on garlic (6 pups), received basal diet containing 5% garlic powder.
Group 4: Cataract fed on garlic (7 pups), received basal diet containing 5 % garlic powder.
Group 5: Normal fed on onion (6 pups), received basal diet containing 10% onion powder.
Group 6: Cataract fed on onion (6 pups), received basal diet containing 10% onion powder.
Group 7: Normal fed on broccoli (7 pups), received basal diet containing 10% broccoli powder.
Group 8: Cataract fed on broccoli (6 pups), received basal diet containing 10% broccoli powder.
Group 9: Normal fed on soybean (6 pups), received basal diet containing 25% soybean powder.
Group 10: Cataract fed on soybean (7 pups), received basal diet containing 25% soybean powder.
A protecting dose of 1ml of 5% garlic, 10% onion, 10% broccoli, and 25% soybean solution were given to rat pups in groups 4, 6, 8, and 10 respectively. Rat pups in groups 2, 4, 6, 8 and 10 were injected subcutaneously with a single dose of sodium selenite (30µmol/kg body weight). Then rat mothers were taken away from the cages of their pups. The progression of cataract in all cataract groups was under examination till the end of the experiment and opacities observed were graded into four stages according to severity of cataract.
At the end of the experiment (two months) blood samples were collected and the eyes were enucleated. Catalase (CAT), superoxide dismutase (SOD) activities, total antioxidant capacity (TAO), reduced glutathione (GSH), malondialdehyde (MDA) and nitric oxide (NO) were assessed in both blood and lenses. Fas ligand (FAS-L) as apoptotic marker was also assessed in the blood and lenses. The levels of serum lipid profile, serum glucose and blood hemoglobin were determined in rats’ blood. The crystalline lens protein patterns on sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) were identified and analyzed by computerized program.
Ophthalmic examination of rat eyes involves identifying the type and severity of cataract. Slit-lamp examination showed cataract development in group (2) after four days of sodium selenite injection and cataract was aggravated with progression of the experiment. At the end of experiment, all lenses were clear in normal control rats, while all the rats (100%) in selenite cataract group developed bilateral stage 4 cataract. The groups whose diet was supplemented with different functional foods (groups 4, 6, 8 and10) manifested lower maturation of selenite cataract to 85.7%, 83.3%, 83.3%, and 71.3% of lenses concerning to garlic, onion, broccoli and soybean consumption, respectively. On the other hand 14.3%, 16.7%, 16.7%, and 28.7% of lenses displayed stage 1 cataract in all previous treated groups, respectively.
Biochemical assessment revealed the following results:
•Sodium selenite injection increased oxidative stress in term of significant reduction in the activities of the antioxidant enzymes catalase and superoxide dismutase as well as total antioxidants and reduced glutathione in both blood and lenses of cataractous rats. Meanwhile, the content of lipid peroxides, expressed as malondialdehyde, and nitric oxide were significantly elevated in rats` blood and lenses in response to selenite injection. Apoptosis, represented as Fas-ligand was also increased due to oxidative stress induced by sodium selenite. On the other side, serum lipid profile parameters, total lipids, triacylglycerols, total cholesterol and low density lipoprotein-cholesterol; were significantly increased as compared to normal control group. Moreover, serum glucose level was significantly increased, while hemoglobin didn’t show any significant difference as compared to normal control group.
•Administration of garlic to cataractous rats significantly improved blood and lenses catalase and superoxide dismutase activities and total antioxidants and reduced glutathione levels as compared to cataract group. Furthermore, 5% garlic containing diet reduced both serum and lenses oxidative stress parameters, malondialdehyde, and nitric oxide as compared to cataract group. Fas-ligand was also significantly decreased reflecting prevention of apoptosis. Due to the effect flavonoids and organosulfur compounds present in garlic, serum total lipids, triacylglycerols, total cholesterol, low density lipoprotein-cholesterol and serum glucose in cataract group fed on garlic were significantly reduced as compared to cataract group. Garlic administration also appeared to enhance all the previously mentioned parameters except for hemoglobin in normal group fed on garlic as compared to normal control group.
•Onion administration elevated catalase and superoxide dismutase activities, total antioxidants and reduced glutathione in both blood and lenses of cataract group than that in cataract group without onion administration. Furthermore, the levels of malondialdehyde, nitric oxide, and fas-L were lower in both blood and lens than that in cataract group. Also, serum lipid profile parameters were significantly improved in response to administration of 10% onion containing diet. Meanwhile, high density lipoprotein-cholesterol didn’t show any significant difference in both normal and cataract groups fed on onion as compared to normal control and cataract groups, respectively. Furthermore, glucose level was markedly lowered while hemoglobin didn’t show significant difference in cataract group fed on onion as compared to cataract group. Administration of 10% onion containing diet to normal rats improved the antioxidant status, lipid profile as well as glucose level as compared to normal control group.
• Broccoli containing diet significantly elevated both lenses and serum catalase, superoxide dismutase activities, total antioxidants and reduced glutathione in cataract group as compared to cataract group without broccoli administration. Conversely, the mean levels of lens and serum malondialdehyde, nitric oxide and fas-ligand were significantly lowered in cataract group fed on broccoli than that in cataract group. Additionally, serum total lipids, triacylglycerols, total cholesterol, low density lipoprotein-cholesterol and serum glucose were significantly decreased in cataract fed on broccoli group as compared to cataract group without broccoli administration. Broccoli administration also enhanced most of the previously mentioned parameters in normal group fed on broccoli as compared to normal control group. This effect was attributed to the flavonoids, sulforaphane and xanthophylls present in broccoli.
•Finally, soybean administration elevated the levels of catalase and superoxide dismutase activities, total antioxidants and reduced glutathione in both blood and lenses of cataract group than that in cataract group without soybean administration. Moreover, the changes in the levels of malondialdehyde, nitric oxide, and fas-ligand were lower in both serum and lensrs than those in cataract group. Also, serum lipid profiles were significantly improved in response to administration of 25% soybean containing diet Furthermore, glucose level was markedly lowered while hemoglobin didn’t show significant difference in cataract group fed on soybean as compared to cataract group. Administration of 25% soybean containing diet to normal rats improved antioxidant status, lipid profile as well as glucose level as compared to normal rats without soybean administration.
•SDS-polyacrylamide gel electrophoresis profile of lenses water soluble protein fraction showed that the normal control lens crystallines displayed the presence of 7 peaks covering the molecular weight range 14-29 KDa. Meanwhile, The selenite-induced cataract profile revealed the reduction of the soluble lens protein peaks to 4 fractions which covered the molecular weight range 15-29 KDa. Moreover, water soluble proteins showed decreased intensity of the four bands in the cataractous group. The distributions of proteins in the cataract group fed on garlic and onion were nearly similar to that of the normal control lenses. In spite of selenite injection, either 5% garlic and 10 % onion consumption were able to recover peaks to 7 fractions with the same intensities as normal fractions ranging between 14-30 KDa. Broccoli also recovered peaks to 7 fractions with the same intensities. On the other hand soybean administration performed improvement on selenite cataract lens proteins. Peaks intensities were ameliorated to 7 fractions as compared to cataractous fractions. However, peaks intensities were not recovered to be similar to normal peaks.
The data revealed that, in spite of the fact that all the four functional foods under investigation in the present study are rich in different antioxidents, garlic and onion seemed to be the most powerful anticataract and antioxidant agents followed by broccoli which is strong antioxidant as well. However, soybean showed effective protection from oxidative stress and cataract enough to be recommended for dietary consumption along with garlic, onion and broccoli.