RESUMO
Logistic response of antioxidants to lipid peroxide concentration in carbon tetrachloride toxicity in rabbit liver was evaluated. Carbon tetrachloride (CCl4), ethanol extracts of Chromolaena odorata (ETECO), sylimarin (a known hepatoprotective agent) and water, were used to induce variations in the oxidant/antioxidant balance in the test and control animals. This was used as a model to study the delicate balance between the activities and/or the intracellular concentrations of these antioxidants and lipid peroxide. Concentrations of lipid peroxidation product (malondialdehyde) were estimated to access the degree of oxidation of the polyunsaturated fatty acids in the liver tissue. Glutathione (GSH) concentration was estimated to capture the non-enzymatic antioxidant concentration, while glutathione-s-transferase (GST), superoxide dismutase (SOD), and catalase (CAT) activities were assayed in the liver to assess the enzymatic antioxidant activities. Results obtained from this study showed that the concentrations of lipid peroxidation product (malondialdehyde) varied in a logistic fashion with the nonenzymatic antioxidant (glutathione) and the enzymatic antioxidants (glutathione-stransferase, superoxide dismutase, and catalase). The concentration of the peroxidation product and the concentration/activity of the antioxidants were inversely related, maintaining a highly logistic relationship (R2 = 0.99). The non-enzymatic antioxidant (GSH) concentration and the enzymatic antioxidant (GST, SOD, and CAT) activities were found to be directly related in a sigmoidal manner (R2 = 0.98). These observations indicated that oxidant/antioxidant concentrations and activities in a rabbit liver tissue is tightly related and mathematically associated.