Microwave-assisted extraction, physicochemical characterization and bioactivity of polysaccharides from Camptotheca acuminata fruits.

Microwave-assisted extraction of polysaccharides from Camptotheca acuminate (CAPs) was optimized by response surface methodology. The optimal parameters were as follows: microwave power, 600 W; liquid-solid ratio, 40:1 g/mL; extraction time, 14 min; and extraction temperature, 70 °C. Under these conditions, the yield of CAPs reached up to 8.61%. CAP-3, an acidic polysaccharide with a molecular weight of 121.34 kDa, was separated and purified from CAPs, which was only composed of glucose and mannose. CAP-3 exhibited strong antioxidant activity against DPPH (IC₅₀: 0.78 mg/mL), hydroxyl radicals (IC₅₀: 0.84 mg/mL) and also showed synergistic antioxidative effect with ascorbic acid in vitro. Meanwhile, CAP-3 could protect plasmid DNA from oxidative damage. Moreover, CAP-3 could improve immunomodulatory activity of RAW264.7 cells through promoting the phagocytosis and nitric oxide release. Therefore, CAP-3 had a strong potential in functional food, pharmaceuticals and cosmetics industries.