Keywords: amino acids, antioxidants, free radicals, photocatalysis, radical oxygen species, degradability, TiO2, glycine, alanine, histidine, proteins, environment, health
Protective action of antioxidants against amino acids degradation caused by free radicals
It is known that, in the human body, disequilibrium between free radical production and the human system defence, based on enzymatic and antioxidants actions, can produce an oxidative stress status and bring about a biochemical modification and a pathological status. Free radicals cannot be eliminated from the organism because they are continuously produced, but it is possible to control their concentrations. This paper describes the evaluation the effect of oxygen free radicals on amino acids, such as glycine, alanine and histidine, especially as the expression of their interaction with proteins. The first aim has been to develop two analytical methods (potentiometric and conductometric) to measure the amino acid degradability in the presence of radical oxygen species; the second one is to evaluate the short- and long-time action of antioxidants at different concentrations. To estimate the antioxidant capability, free radicals have been produced by the system xanthine/xanthineoxidase in the solution containing one of the three considered amino acids in the presence or absence of the antioxidant.