Glycation is regulated by isoflavones.

Area of Science:

• Food Chemistry
• Biochemistry
• Nutritional Science

Background:

• The Maillard reaction (MR) is a non-enzymatic browning process crucial in food chemistry and implicated in aging and diabetic complications.
• Soy isoflavones are known for their antioxidant properties, prompting investigation into their potential to inhibit MR.

Purpose of the Study:

• To investigate the anti-glycative effects of purified soy isoflavones (genistin, genistein) and a soy isoflavone-rich extract on the Maillard reaction.
• To elucidate the potential mechanisms by which soy isoflavones might modulate protein glycation.

Main Methods:

• Model systems using soy protein glycinin and fructose under alkaline conditions.
• Quantification of free amino groups (OPA assay), bound carbohydrates (phenol-sulfuric acid assay), N(ε)-(carboxymethyl)lysine (UPLC-MS), and fluorescent advanced glycation end products (AGEs).
• Pre-incubation of glycinin with isoflavones before initiating the Maillard reaction.

Main Results:

• Individual soy isoflavones (genistin, genistein) at 10 μg mL⁻¹ showed no significant effect on protein glycation (p > 0.05).
• A soy isoflavone-rich extract (containing 2.5 mg mL⁻¹ total flavonoids) significantly reduced bound carbohydrates (20%, p < 0.05) and AGE formation (>80%, p < 0.05).

Conclusions:

• Purified soy isoflavones genistin and genistein are ineffective in preventing Maillard reaction-induced protein glycation.
• Soy isoflavone-rich extracts demonstrate significant anti-glycative potential, likely through mechanisms involving conjugation, antioxidant activity, and dicarbonyl trapping.
• These extracts may be valuable in producing glycated protein conjugates with reduced AGE formation.