Preparation of Astragalus membranaceus lectin and evaluation of its biological function.

Astragalus membranaceus lectin (AML) was abstracted as a supposedly novel agglutinin of 67 kDa from the seeds of Astragalus membranaceus. The seeds of Astragalus membranaceus were treated with acetate, ammonium sulfate precipitation, and purified by HiTrap SP XL ion column and Superdex G25 gel filtration chromatography to obtain the AML. AML contained 16.4% sugar, ~70% polar amino acids and ~30% hydrophobic amino acids. The AML exhibited agglutination activity toward human and animal erythrocytes, particularly human blood type O and rabbit erythrocytes. It also exhibited acid/alkali resistance and thermal denaturation above 64°C. Compared with human normal liver HL-7702 cells, different concentrations of AML (6.25, 12.50, 25.00 and 50.00 µg/ml) exhibited superior inhibitory effects on the growth of SGC-7901, HepG2 and H22 carcinoma cell lines, and displayed marked antibacterial effects on bacteria; the half maximal inhibitory concentration for B. dysenteriae, S. aureus and E. coli were 85.4, 80.2 and 65.3 µg/ml, respectively.