β-Lactoglobulin-exopolysaccharide complex: Structural characterization, antioxidant activity in LPS-induced oxidative...

Lactobacillus exopolysaccharides (EPS) have been widely used in fermented food and health care products due to their good biological activities. In this study, EPS derived from Lactobacillus plantarum A106 and β-lactoglobulin (β-Lg) were used to prepare β-Lg-EPS complex, and the structure and antioxidant activity of the complex were studied. The results indicated that the incorporation of EPS with β-Lg could quench the inherent fluorescence of β-Lg and change the conformation and secondary structure, finally improving the thermal stability. Moreover, addition of EPS changed the spherical structure of β-Lg, and the structure of β-Lg-EPS complexes appeared blocky and dendritic. Both ζ potential and particle size of β-Lg-EPS complex were decreased regardless of proportions between β-Lg and EPS. The dispersion system was the most uniform and stable when the ratio of β-Lg to EPS was 10:1. Moreover, β-Lg-EPS complex presented a higher free radical scavenging rate than that of native β-Lg, 64.47 ± 2.77 % for DPPH, 90.09 ± 0.42 % for ABTS⁺ and 26.74 ± 0.56 % for ·OH, respectively. Moreover, β-Lg-EPS complex could alleviate oxidative damage and exert its antioxidant activity by improving cell viability and SOD activity, reducing ROS level, restoring mitochondrial membrane potential and improving apoptosis of LPS-induced RAW264.7 cells.