Maillard reaction products between chitosan/alginate: antioxidant and enzyme inhibitory potential

Abstract

The Maillard reaction products (MRPs) derived from Chitosan (Cs) and Alginate (Alg) have gained attention for their potential bioactivity, yet their antioxidant, enzyme inhibitory, and photoprotective properties remain under explored. This study aims to investigate the formation and bioactivity of Cs/Alg MRPs, focusing on their structural characteristics and functional properties. Chitosan and alginate solutions (1:1 v/v) were heated at 100 °C for 3 and 6 h at pH 4.5 to produce MRPs (Cs/Alg (3 h) and Cs/Alg (6 h)). Structural changes were confirmed using FTIR, UV–Vis spectroscopy, XRD, TGA, and zeta potential measurements. Remarkably, the MRPs demonstrated significant antioxidant activity, with Cs/Alg (3 h) and Cs/Alg (6 h) showing ABTS⁺ scavenging activity (IC50 = 27.27 and 29.85 µg mL⁻¹, respectively) and Cs/Alg (6 h) exhibiting the highest DPPH scavenging capacity (IC50 = 484.73 µg mL⁻¹). In the FRAP assay, both chitosan and Cs/Alg (3 h) displayed comparable reducing power (IC50 = 38.21 and 38.39 µg mL⁻¹, respectively), while Cs/Alg (6 h) was most effective in the phenanthrolin assay (IC50 = 92.47 µg mL⁻¹). Chitosan alone showed the highest H₂O₂-scavenging activity (IC50 = 3.88 µg mL⁻¹). Additionally, Cs/Alg (6 h) demonstrated notable photoprotective activity, achieving an SPF index of 44.89. The MRPs also exhibited significant inhibition of polyphenol oxidase (PPO) and α-amylase, with Cs/Alg (6 h) showing superior α-amylase inhibition (IC50 = 139.17 µg mL⁻¹). These findings highlight the potential of Cs/Alg MRPs as multifunctional agents with applications in food preservation, cosmetics, and pharmaceuticals, owing to their potent antioxidant, enzyme inhibitory, and photoprotective properties.

Graphical Abstract