HEPARINS AS ESSENTIAL ANTIOXIDANTS

Chronically inflamed tissues contain significant concentrations of oxy gen radicals, possibly generated by transition metal species such as F e(II) and Cu(I). In addition, the pH of such tissues may well be lower than that of normal counterpart tissues. In this communication, the e ffect of variation of pH on the antioxidant activity of caeruloplasmin (a copper-containing acute-phase protein possessing important ferroxi dase and other antioxidant activities) and of heparin are reported. He parin, unlike caeruloplasmin, retains antioxidant activity at low pH. Heparins possess a variety of metal cation-binding chemical groups all owing them to bind damaging Cu(I) and Fe(II) ions and consequently pre vent their redox involvement in oxygen radical-generating Fenton react ions. In conclusion, heparins may function as endogenous antioxidants and sequestration and/or oxidation by them, of ions such as Fe(II), ma y contribute to their effectiveness.