To examine whether Δ9-THC/sesame oil can attenuate the oxidative stress known to be involved in the pathogenesis of arthritis, levels of MDA, a major biomarker of lipid peroxidation and activities of antioxidant enzymes such as SOD and catalase as well as concentration of nonenzymatic antioxidant GSH, were determined in liver homogenates. The gene discussed is CAT; the disease is arthritic joint disease.