Fenton reactions in lipid phases.

Area of Science:

• Biochemistry
• Lipid Chemistry
• Metal Catalysis

Background:

• Metal catalysis of lipid oxidation was traditionally confined to cell surfaces.
• Conflicting iron (Fe3+ vs. Fe2+) chelate activities challenge this view.

Purpose of the Study:

• To investigate the role of iron complex solubility in lipid phases on initiating lipid oxidation.
• To determine if Fenton-like reactions occur within lipid environments.

Main Methods:

• Quantified partitioning of iron complexes into purified lipids (oleic acid, methyl linoleate) using atomic absorption spectroscopy.
• Investigated Fenton-like reactions in lipid phases using H2O2, iron, reducing agents, and spin-trapping with electron paramagnetic resonance (EPR).

Main Results:

• Iron salts and chelates showed varying solubilities in lipids, with significant partitioning into oleic acid.
• Solubilities were lower in methyl linoleate.
• Hydroxyl radical adducts were detected in oleic acid, but secondary peroxyl radicals predominated in lipid esters.

Conclusions:

• Lipid phase solubility of iron complexes is critical for their catalytic effectiveness in lipid oxidation.
• Fenton-like reactions and hydroxyl radical production may occur within lipid phases, but their significance varies by lipid type and iron complex.