Protective effect of 3-methyl-1-phenyl-2-pyrazolin-5-one, a free radical scavenger, on acute toxicity of paraquat in mice

Abstract

Paraquat poisoning results in damages of multiple organs including liver, kidney and lung, and antioxidants have been proven to have protective effects. As a novel free radical scavenger, 3-methyl-1-phenyl-2-pyrazolin-5-one (MCI-186), was introduced to clinical use recently, its protective effect was studied on acute toxicity of paraquat in male ddY mice. When paraquat (175 mg/kg) were given orally, the survival rate was only 8% on the 6th day of paraquat ingestion in Control Group mice. Protective effect of MCI-186 was most evident and the survival rate was 42% on the 6th day and 38% on the 14th day of paraquat ingestion, respectively, when mice were treated immediately. A delay of 30 min in treatment resulted in an abrupt reduction of the survival rate. These results suggested that MCI-186 used in acute phase of paraquat intoxication might serve as a clinically available antidote for attenuating paraquat toxicity.