Non-enzymatic glycation of lens proteins and haemoglobin-inhibition by pyruvate: an in-vivo study

Aim: Previous studies have demonstrated that pyruvate can prevent protein g lycation and oxidative stress under in-vitro conditions. The aim of this st udy was to examine the in-vivo effectiveness of this metabolite against gly cation of lens crystallins and haemoglobin in galactosemic rats. Methods: Sprague-Dawley rats were maintained on a 30% or 50% galactose-cont aining diet in the absence or presence of 2% or 5% pyruvate in food and wat er, respectively. The animals were killed subsequently and the extent of gl ycation of lens crystallins and haemoglobin was determined using an affinit y column chromatograpic technique. Results: Maintenance of rats on the high galactose diet resulted in a signi ficant increase in glycation of both the proteins. The increase was faster and more substantial in the animals maintained on the 50% galactose diet th an that in the animals fed a 30% galactose diet. The increase in the latter was also very significant. Supplementation with pyruvate inhibited the pro cess. Conclusion: The inhibition is attributable to a competitive binding of pyru vate to the protein NH2 groups as well as to the antioxidant effect of the compound. The studies therefore suggest that this and other alpha-keto-acid s may be physiologically useful in minimizing glycation and oxidative stres s induced tissue pathology by the hyperglycaemic conditions, such as diabet es and galactosemia. The results are also considered pharmacologically sign ificant.