Thesis (M.Sc.)--Chulalongkorn University, 2008

In this research, a plant lectin from seeds of Archidendron jiringa Nielsen. was extracted with Tris-HCl pH 7.2 buffer containing 0.15 M NaCl after the seed was defatted with acetone. The protein was precipitated with 90% ammonium sulfate and purified using affinity chromatography on ConA Sepharose. The molecular mass of purified lectin was 35.7 kDa as estimated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The purified lectin showed no specificity in its ability to hemagglutinate human (A, B, AB and O) erythrocytes and indiscriminately agglutinate rabbit, rat, mouse, guinea pig, goose and sheep. Hemagglutination activity of lectin was markedly affected at pH 8. It was heat stable below 45oC for 30 min. The activity was decreased to 50% when heated at 40oC for 120 min and rapidly fully inactivated at 70oC. It was found that A. jiringa lectin required divalent metal cations (Ca2+, Mg2+, and Mn2+) for hemagglutination activity. The purified lectin had an internal amino acid sequences composition which was similar to that of mannose-glucose specific lectin family. The purified A. jiringa lectin inhibited growth of Fusarium oxysporum, Exserohilum turicicum and Colectrotrichum cassiicola at the concentration of > 5.66 µg. The 4.97 µg of purified lectin was led to the 52.29% of α-glucosidase inhibitory activity. A. jiringa lectin showed no cytotoxicity for five cell lines.