Thesis (M.Sc.)--Chulalongkorn University, 2009

A lectin was purified from the rhizomes of Curcuma amarissima Roscoe by aqueous extraction, fractionation with 80% saturated ammonium sulphate, and a combination of affinity and gel chromatography on ConA Sepharose and Superdex G-75, respectively. The molecular mass of the purified lectin was of 32.4 kDa, as estimated by SDS-PAGE. This purified lectin contains 33.21% of carbohydrate and show the specific activity for rabbit and rat erythrocytes but not for mouse, guinea pig, goose, sheep and human blood groups (A, B, AB and O) erythrocytes This lectin is stable at temperatures below 40 degerss calsius, but the hemagglutinating activity was reduced to halved when it was heated up to 45-85 degerss calsius and completely lost activity at 95 degerss calsius. Surprisingly, the hemagglutinating activity is more stable at 80 degerss calsius than at 70 degerss calsius, and was rapidly inactivated at 90 degerss calsius. It showed a maximum hemagglutination activity within the pH range of 8-11. Metal ions including Hg [superscript 2+], Co[superscript 2+], and EDTA can inhibit its activity whereas Mg [superscript 2+], Mn [superscript 2+], Fe [superscript 2+] and Ca [superscript 2+] were no effect. The deduced amino acid sequence of an internal tryptic peptide sequence of this purified lectin showed sequence similarity (homology) to other members of the leucoagglutinating phytohemagglutinin precursor family, whilst the complete lectin inhibited the in vitro growth of three plant pathogenic fungi, Fusarium oxysporum, Exserohilum turicicum, Colectrotrichum cassiicola, at a concentration of 17.5 to 35 µg, and four microbial, B. subtilis, C. albican, E. coli, and S. aureus at concentration ≥ 0.446, 0.446, 0.223, 0.892 mg/ml, respectively. Furthermore, this lectin showed in vitro cytotoxicity against the BT474 breast cancer cell line with IC[subscript 50 ] of ~21.2 micro gram Additionaly, IC[subscript 50 ] for an alpha-glucosidase activity is 0.073 mg/ml protein.