OXIDATIVE EFFECTS AFTER PHOTODYNAMIC THERAPY IN RATS

Abstract

The oxidative effects of photodynamic therapy (PDT) with 5-aminolevulinic acid (5-ALA) and chitosan (CS) were evaluated in Wistar rats s. c. inoculated with Walker 256 carcinoma. The animals were irradiated with red light (?=685 nm, D=50 J/cm2, 15 min) 3h after i.p administration of 250 mg/kg b.w. 5-ALA, 1.5-mg/kg b.w. CS or an associated treatment of 5-ALA and CS. The levels of lipid peroxides and protein carbonyls were determined in plasma and tumor tissues. The antioxidant capacity of plasma and tumor tissues as well as the antioxidant enzymes (superoxide dismutase, catalase and glutathione peroxidase) activities in erythrocytes and tumors were assessed. 24hs after the treatment, in 5-ALA treated animals the levels of lipid peroxides and protein carbonyls were significantly increased both in plasma and tumors. 5-ALA PDT decreased the erythrocyte antioxidant enzymes activities. An associated treatment with CS and 5-ALA produced the reduction of the lipid peroxides and protein carbonyls in plasma and the recovery of antioxidant enzymes activities. These results suggest the antioxidant properties of CS