SOD1 and colitis: Figure 4(b) shows that the MPO activity of colitis animals was markedly higher than that of the naive group. SASP and MRS treatment all affected the inhibition of MPO activity. Additionally, the activities of endogenous antioxidants SOD and GSH were detected and found to be decreased in the AA group compared with those in the control group (Figure 4(c) and 4(d)).