Role of antioxidant enzymes in oxidative stress and immune response evaluation of aspartame in blood cells of wistar albino rats

Aspartame is most commonly found in low calorie beverages, desserts and table top sweeteners added to tea or coffee. It is widely consumed by humans who are diabetic and who are under weight loss regime. Aspartame is rapidly and completely metabolized in humans and experimental animals to aspartic acid (40%), phenylalanine (50%) and methanol (10%). Methanol, a toxic metabolite is primarily metabolized by oxidation to formaldehyde and then to formate these processes are accompanied by the formation of superoxide anion and hydrogen peroxide. This study focus is to understand whether the oral administration of aspartame (40 mg/kg.bw) for 15 days, 30 days, and 90 days have any effect on membrane bound ATPase’s and oxidant-antioxidant imbalance, neutrophils function and humoral immunity. To mimic human methanol metabolism, folate deficient animals were used. After 15 days of aspartame administration, animals shows a significant change in membrane bound ATPase’s and showed a significant increase in lipid peroxidation and nitric oxide level along with the increase in free radical production as indicated by the increase in both enzymatic (superoxide dismutase, catalase, glutathione peroxidase) and non-enzymatic (reduced glutathione and vitamin C) antioxidant level. However, after repeated long term administration (30 days and 90 days) the generation of reactive free radicals overwhelmed the antioxidant defense as indicated by an increase in lipid peroxidation with the decrease in antioxidants level. This study concludes that administration of aspartame (40 mg/kg.bw) causes oxidative stress by altering the oxidant/antioxidant balance in blood cells, which also alter the neutrophil function and humoral immunity of aspartame treated wistar albino rats.