Meanwhile, when comparing the colitis + melatonin (5 mg/kg) group to the colitis group without treatment, a significant decline in MPO (P < 0.0001) (− 26.44%) and MDA (P < 0.001) (− 36.38%) levels, as well as a significant increase (P < 0.001) (+ 63.78%) in GSH levels, were noted. Here, MPO is linked to colitis.