Natural thiol ergothioneine: a potential anti-glycation agent for bovine serum albumin and its mode of action

The Maillard reaction is ubiquitous in food processing, imparting desirable color and flavor. However, excessive protein glycation leads to the formation of advanced glycation end products (AGEs) and protein cross‑linking, causing nutritional loss and potential hazards. This study aimed to evaluate the anti‑glycation effect and mechanism of the natural thiol compound ergothioneine (EGT, 0.02–0.5 mg/mL) using bovine serum albumin (BSA) as a model and glucose, fructose, or methylglyoxal as inducers, with aminoguanidine as the positive control. EGT dose‑dependently inhibited the production of early (fructosamine), middle (reactive dicarbonyls), and late (total fluorescent AGEs, pentosidine) glycation products across all three glycation systems. It also reduced protein oxidative modification and cross‑linked aggregation, as shown by thioflavin T fluorescence, SDS‑PAGE, and measurements of formylkynurenine, kynurenine, and tyrosine. EGT exhibited strong radical scavenging activity against DPPH and ABTS, with scavenging rates of 66.3% and 86.2% at 0.5 mg/mL, respectively. Molecular docking revealed that EGT binds directly to the hydrophobic pocket of BSA near known glycation hotspots (e.g., Lys‑350 and Lys‑455). At 0.5 mg/mL, EGT showed higher overall inhibitory activity than aminoguanidine(AG) in several assays, which we attribute to its multi-mechanistic action compared with the single-mechanism action of AG. Ergothioneine inhibits protein glycation through multiple mechanisms: direct binding to BSA, radical scavenging, and carbonyl trapping. As a natural and safe thiol compound, it holds promise for developing anti‑glycation functional foods and provides theoretical support for optimizing food processing technologies to minimize AGEs formation.