Characterization, antioxidant and antibacterial activity of neutral polysaccharides from oyster (Crassostrea rivularis)

Crassostrea rivularis are the main edible economic shellfish rich in bioactive substances. Therefore, Crassostrea rivularis resources have high development prospects. This study aimed to analyze the biological activity of neutral oyster polysaccharide powder (OPS-1) to enhance the comprehensive utilization value of oysters. OPS-1 was purified from Crassostrea rivularis by hot water agglutination using DEAE-cellulose column chromatography. Experimental results showed that OPS-1 was predominantly composed of 97.41 g/100g glucose, linked by a β-glycosidic bond, and exhibited a triple-helical conformation with a molecular weight of 954.32 kDa. OPS-1 solution is relatively stable with 15.87 ± 0.66 mV of zeta potential. In addition, OPS-1 has good thermal properties and a high antioxidant capacity. The median inhibitory concentrations (IC₅₀ values) of OPS-1 on DPPH radicals, ABTS⁺ radicals, OH radicals, and Fe²⁺ chelating ability were 0.23, 2.96, 2.68 and 2.33 mg/mL, respectively. Meanwhile, OPS-1 could inhibit the growth of common food-borne pathogenic bacteria (Escherichia coli, Salmonella Typhimurium, and Staphylococcus aureus). The inhibition zone sizes were not significantly different from penicillin (p > 0.05). These findings indicate that OPS-1 may be a novel natural antioxidant and antimicrobial agent derived from animal sources, providing a rationale for further investigating oyster polysaccharides.