Abstract
The hemolytic action of the onion extract against canine erythrocytes was investigated. Onion-exposed erythrocyte suspension or hemolysate underwent rapid oxidation of hemoglobin to methemoglobin and subsequent denaturation leading to the formation of Heinz bodies. During the process of hemoglobin breakdown, the presence of superoxide radical (O-2) was demonstrated by using co-oxidation of epinephrine to adrenochrome. Carboxyhemoglobin was resistant to oxidation by the onion extract, and there was no liberation of superoxide. Superoxide dismutase (SOD), catalase, reduced glutathione (GSH) or mannitol had no effect on hemoglobin oxidation, suggesting that activated oxygens, O-2, H2O2 and ·OH were not involved in oxidation of the heme iron (Fe2+). Oxyhemoglobin is deduced to be a source of both methemoglobin and O-2, and their production which is accelerated by the onion extract is assumed to be a primary step of erythrocyte breakdown. Osmotic fragility of the red cell membrane increased markedly during exposure to the onion extract, and significant inhibition by SOD and catalase manifested that O-2 and its derivative H2O2 were both responsible for the damage of the cell membrane.
