Abstract
OBJECTIVES: In this study, Dioscorea preussii root tuber hemagglutinin was purified and its physicochemical properties were determined. The antioxidative and anti-hemolytic activities of the hemagglutinin were also investigated. MATERIALS AND METHODS: The hemagglutinating assay was used to detect the presence of lectin in the phosphate-buffered saline extract of the D. preussii root tuber. The lectin was purified using ammonium sulfate fractionation and molecular sieve chromatography. The optimum pH and temperature were determined. In addition, antioxidant activity was assessed using 2,2 diphenylpicrylhydrazyl (DPPH) radical scavenging, metal chelating, ferric reducing antioxidant power (FRAP), and lipid peroxidation inhibition assays. Red blood cells subjected to oxidative damage caused by H(2)O(2) were employed to evaluate their antihemolytic ability. RESULTS: Starch inhibited hemagglutinin activity. Dioscorea preussii hemagglutinin (DPH) maintained full hemagglutinating activity from 30 °C to 60 °C and pH 5-13. Ethylene diamine tetraacetic acid did not affect the hemagglutinating activity of hemagglutinin. All denaturing agents (Guanidine-HCl, urea, and β-mercaptoethanol) reduced the hemagglutinating activity of the hemagglutinin to different degrees. The hemagglutinin scavenged the DPPH radical and chelated iron metal with half maximum inhibitory concentration (IC(50)) of 0.727 ± 0.035 mg/mL and 0.583 ± 0.078 mg/mL, respectively, while the FRAP assay showed that it contained 76 mg of ascorbic acid equivalent per gram of the purified hemagglutinin. In the absence of hemolytic agents and at lower concentration tested, hemagglutinin showed positive membrane integrity protection. CONCLUSION: This study provides information on the antioxidant properties of D. preussii root tuber hemagglutinin as well as its cell membrane protective ability. The lectin is a starch-binding, which makes it a novel lectin.