HEPARIN PROTECTION AGAINST FE2-MEDIATED AND CU2+-MEDIATED OXIDATION OF LIPOSOMES()

Heparin (HE) exhibited a protective effect on liposome peroxidation in duced by Fe2+ and Cu2+, decreasing the formation of both conjugated di enes and thiobarbituric acid reactive substances (TBARS) in a dose-dep endent manner. The antioxidant activity was more relevant in the oxidi zing system employing Fe2+ and H2O2 and generating the highly reactive (OH)-O-. radical. The analysis of liposome size distribution by quasi elastic laser light scattering showed that: (1) the native structure o f the particles was completely lost after exposure to Fenton reagent; (2) the presence of HE in the reaction mixture completely prevented th e peroxidative damage on liposomes. Thus, HE acts as an antioxidant fa ctor on membrane lipid bilayer. This suggests that HE, released from m ast-cell granules during inflammatory processes, might locally protect the cell membrane from the oxidative injuries.