Metformin Protects Human Insulin from Fructosylation: An In Vitro Biochemical Study

Area of Science:

• Biochemistry
• Protein Chemistry
• Metabolic Diseases

Background:

• Fructose can glycate proteins, forming Advanced Glycation End Products (AGEs) through Schiff base and Amadori product formation.
• These processes induce oxidative stress, alter protein structure and morphology, and can lead to amyloidogenesis.
• Metformin is a key drug for type 2 Diabetes Mellitus (T2DM).

Purpose of the Study:

• To investigate the protective effects of metformin against fructosylation-induced structural changes and amyloid aggregation in human insulin.
• To evaluate metformin's potential to counteract the detrimental effects of fructosylation on insulin's conformation and function.

Main Methods:

• Utilized spectroscopic techniques (UV-Vis, fluorescence, CD) to assess insulin structure.
• Quantified protein modifications (carbonyl content, fructosamine) and amino acid residue integrity (lysine, arginine).
• Employed electron microscopy and dynamic light scattering to analyze morphological changes and aggregation patterns.

Main Results:

• Metformin demonstrated a concentration-dependent restoration of fructosylated insulin's structure and conformation.
• Thioflavin-T fluorescence assays and electron microscopy confirmed metformin's ability to inhibit insulin fibril formation.
• Dynamic light scattering indicated metformin preserves insulin's hydrodynamic radius, and it acts as an antioxidant protecting amino acid residues.

Conclusions:

• Metformin effectively protects insulin against fructosylation-induced structural, conformational, and aggregation-related damage.
• These findings highlight metformin's potential role in preserving insulin's biological activity and mitigating risks associated with protein aggregation.
• Further research is warranted to elucidate the molecular mechanisms underlying metformin's protective effects on insulin sensitivity and cellular pathways.