Antiradical Activity of Different Antioxidants Depending on pH and Polarity of Model System Detected by Photochemiluminescence Method

摘要

A pH-dependence of antiradical activity of natural antioxidants compared with synthetic ones has been studied by the method of photochemiluminescence using luminol as photosensitizer. The main kinetic parameters of antioxidants: constant of inhibition (K_(InH))_(eff), stoichiometric coefficient (f) and the initial rates of free radicals generation — (Wi)_(eff) in the measuring systems have been calculated from PCL-curves obtained. It was found that (K_(InH))_(eff) increased in several times at high pH while the stoichiometric coefficient decreased for natural water-soluble antioxidants giving lag-phase in PCL curves - ascorbic and uric acids as compared with standard Trolox. The value of (K_(InH)_(eff) diminished at high pH for water-soluble glutathione and increased for lipid-soluble α-tocopherol, both inhibited PCL integrally. It was obtained that value of (Wi)_(eff) increased at high pH in water-buffer system and at in more polar mixed system. It was shown that polarity of measuring system increased the value of (K_(InH)_(eff) of water-soluble antioxidants. It was concluded that antiradical activity of different antioxidants (except glutathione) increases at higher pH and polarity of the model system.