Preparation and characterization of Mn-salophen complex with superoxide scavenging activity

Area of Science:

• Inorganic Chemistry
• Biochemistry
• Microbiology

Background:

• Superoxide radicals are reactive oxygen species implicated in cellular damage.
• Superoxide dismutase (SOD) enzymes detoxify superoxide radicals.
• Developing synthetic SOD mimics is crucial for understanding oxidative stress and potential therapeutic interventions.

Purpose of the Study:

• To synthesize and characterize a manganese(III)-salophen complex.
• To evaluate the superoxide scavenging and SOD-like activity of the synthesized complex.
• To investigate the effect of the Mn-salophen complex on the growth of *Escherichia coli* SOD double mutants.

Main Methods:

• Synthesis of Mn(III)-salophen complex using manganese(III) acetate dihydrate and salophen.
• Spectroscopic analysis (visible absorption) to confirm complex formation and stoichiometry.
• Xanthine-xanthine oxidase/cytochrome c assay to determine SOD-like activity.
• Growth studies of *E. coli* SOD double mutant (*sodA-sodB-*) in minimal medium with varying concentrations of the complex.

Main Results:

• A red-brown Mn(III)-salophen complex was successfully prepared with a 1:1 Mn to salophen stoichiometry.
• The complex exhibited significant SOD-like activity (1450 units/mg salophen), which was partially inhibited by EDTA.
• The Mn-salophen complex (5-10 microM) significantly enhanced the aerobic growth of *E. coli* SOD double mutants, while higher concentrations (50 microM) were inhibitory.

Conclusions:

• The synthesized Mn(III)-salophen complex possesses potent SOD-like activity.
• This complex can rescue the growth defect of *E. coli* lacking endogenous SOD enzymes.
• Mn-salophen complex shows promise as a potential therapeutic agent against oxidative stress-related conditions.