MPP⁺ Toxicity in E. Coli Under Aerobic and Anaerobic Conditions

Abstract

MPP⁺ and paraquat (PQ⁺²) are two structurally analogous and highly toxic pyridinium compounds. The mechanism of PQ⁺² toxicity is best understood in the bacterial model system. While numerous studies, in a variety of systems, have indicated the causative role of free radicals and other oxygen-derived active species in PQ⁺² toxicity, this question is yet unresolved in the case of MPP'. In this study we have used the E. coli model and have demonstrated that MPP⁺ is toxic to bacterial cells in a dose and time dependent modes. Additionally, it is shown that only in the presence of molecular oxygen, bacterial inactivation occurred. The protective effects of the chemical scavenger -mannitol -and of histidine are presented. These results are in complete accord with a free radical mechanism for MPP⁺ toxicity.

Key Words:

• HPTP
• free radicals
• pyridinium compounds
• hydrogen peroxide
• E. coli