Investigating the non-covalent interactions between rutin and superoxide dismutase: Focus on thermal stability, structure, and in vitro digestion

Rutin is prone to degradation during processing, highlighting the need for a suitable protein system for its delivery. This study evaluated the effects of pH and concentration ratios on the interaction between rutin and superoxide dismutase (SOD), aiming to develop a suitable non-covalent delivery system. The highest thermal stability was observed at pH 4 with a rutin-to-SOD concentration ratio of 5:1, where the melting temperature (Tm) reached 67.8°C, and the half-life was 176 min. Infrared spectroscopy and particle size analysis revealed that rutin has minimal impact on the secondary structure of SOD; however, high concentrations of rutin influence the quaternary structure of SOD, leading to aggregation. Molecular docking and molecular dynamics simulations further confirmed that the interaction between rutin and SOD occurs through hydrogen bonding and hydrophobic interactions, with pH altering their binding sites. At pH 5 and pH 6, the digestive stability of the SOD-rutin complex was the highest. This study provides a theoretical basis for the preparation of highly stable SOD-rutin complexes and identifies a new protein system for the stabilization of rutin. • Hydrophobic interactions and hydrogen bonds were the main forces in the interaction between SOD and rutin. • The hydrophobic interactions between SOD and rutin were significantly influenced by pH. • The thermal stability of the SOD-rutin complex was influenced by pH and concentration ratios. • The digestive stability of complex can be enhanced by adjusting the pH and incorporating rutin.