Aspartame l aspartyl l phenylalanine

Aspartame (l-aspartyl l-phenylalanine methylester) is a dipeptide artificial sweetener that is widely used as a non-nutritive sweetener in various food products [1]. The increased market of dietary products and the development of new synthetic sweetening compounds have not been sufficiently explored. Thus, to verify the risks and benefits of a substance present in our day-by-day use, like aspartame, leads us to worry about the actions of its metabolites (aspartic acid, phenylalanine and methanol) to our physical system [2], [3]. Clinically, chronic exposure to aspartame was reported to cause headache, blurred vision, epileptic tits and R-848 tumors as well as eye problems, numbness, insomnia, memory loss, nausea, slurred speech, personality changes, loss of energy, hyperactivity, hearing problems, neurological and behavioural disturbances [4]. Information available on the aspartame-induced toxicity at various levels is limited [5], [6]. Moreover, most of the studies on aspartame have been carried out to understand the mechanisms of toxicity [5], [6], [7], [8] and cancer [9], [10]. Several studies on laboratory animals have been made to verify aspartame's toxicity. Recently, a very large experiment confirmed that it is a multipotential carcinogenic agent when given at a daily dose of 20mg/kg body weight, an amount well below the acceptable daily dose of 40mg/kg body weight [11]. Relatively small amount of aspartame can significantly increase methanol levels [12]. Methanol is being increasingly recognized as a substance that damages the liver cells where it is oxidized to formaldehyde and latter to formate [13]. The toxic effects of formate result from inhibition of cytochrome oxidase complex at the end of the respiratory chain in mitochondria [14]. Also, methanol intoxication is associated with mitochondrial damage and increased microsomal proliferation, resulting in increased production of oxygen radicals [15], [16]. Of all the organs in the body, the CNS takes more than its share of oxidative abuse. This is associated with the abundance of redox active transition metal ions, and the relative death of antioxidant defence system [17]. Ashok and Sheeladevi [18] have also reported that chronic methanol exposure, which is a by-product of aspartame, may be responsible for the alteration observed in the free radical-scavenging system. The metabolism of xenobiotic to a large extent takes place in the liver. The by-products of such metabolism sometimes are more toxic than the initial substance. This could lead to hepatic damage and the emergence of hepatic disorders [19]. Although renal excretion is the major process for the removal of toxic substances, renal participation in the assimilation of many substances, including aspartame, has not been considered. Bearing in mind their indiscriminate utilization, the understanding of how certain peptides are metabolized by the kidney, may fill in up to now existing gaps in the understanding of their morphometric effects on this organ [20]. In experiments on rodents, which were given radiolabelled aspartame, labelled protein and DNA accumulated in the brain, liver, kidneys and other tissues after ingestion of either 20mg/kg or 200mg/kg of aspartame. [13] However, these scientists were not directly measuring formaldehyde, but simply measuring the levels of some by-product of the methanol from aspartame [21]. The severity of clinical findings in methanol intoxication correlated better with formate levels [22]. Formate is metabolized twice as fast in the rat as in the monkey [23]. The rodents do not develop metabolic acidosis during methanol poisoning, owing to their high liver folate content and in order to create similar results in human beings, only folate-deficient rodents are required to accumulate formate in order to develop acidosis [24], [25]. Hence, in order to mimic the human situation, a folate deficiency status is induced by administering MTX. This present study aims to evaluate the long-term effect of aspartame (75mg/kg) administered orally, on liver and brain antioxidant status, plus histopathological changes in liver and renal cortex in Wistar strain albino rats.