Rheological Properties and Antioxidant Activities of Polysaccharide from Toddalia Asiatica Lam

OBJECTIVE To investigate the antioxidant effects and rheological properties of polysaccharide from Toddalia asiatica Lam (TALP). METHODS Extracted TALP by the water-extracting and achohol-precipitating method, collected and purified the sample. The influences of concentration, pH, temperature, metal ions and other factor on viscosity of TALP were measured by rheometer. Compared with Vc, the in vitro antioxipant activities were studied by the Fenton method and DPPH radical scavenging. RESULTS TALP flow behavior was affected by its concentration, pH, temperature, cation type and concentration. Specifically, the viscosity of TALP solution increased with the mass concentration of TALP. The viscosity of TALP solution at pH 4.0 or pH 9.0 was obviously lower than that at pH 7.0. The add of Na⁺ significantly increased the viscosity of TALP solution, however, the viscosity of TALP solution got lower when the concentration of Na⁺ increased from 0.5% to 1.0%. The viscosity of TALP solution was decreased when Ca²⁺ was added, and the viscosity was lower when the concentration of Ca²⁺ was higher. The viscosity of TALP solution quickly dropped at the temperature among 20-60℃, because of its bad temperature resistance. The scavenging rate on 2 free radicals of TALP solution (10.0 mg·mL^-1) was nearly with 2.0 mg·mL^-1 Vc. CONCLUSION The aqueous TALP solution is a typical of non-Newtonian pseudoplastic fluid. Antioxidant activity assay indicates that TALP has favorable antioxidant activity.