Purification and characterization lectin from the rhizome of kaempferia parviflora wall. ex. baker

Abstract

A lectin was isolated from the rhizomes of black galingale (Kra Chai Dam), Kaempferia parviflora Wall. Ex. Baker, using, in sequential order, ammonium sulfate precipitation, Concanavalin A affinity chromatography and Sephacryl S-100 gel filtration chromatography. The molecular weight of the purified lectin (or monomeric subunit) was estimated to be about 41.7 kDa by reducing SDS-PAGE analysis. The lectin showed hemagglutinating activity against, in order of the strongest activity, rabbit >> sheep > goose = rat > mouse = guinea pig = human O group > human A = B = AB group erythrocytes. In terms of hemagglutination activity, the optimal pH range of the K. parviflora lectin was between pH 6 - 8 and it was active up to 75℃. Furthermore, the purified K. parviflora rhizome lectin preparation at 18 - 36 µg /0.3 square cm disc was able to inhibit the growth of the plant pathogenic fungi, Exserohilum turcicum, Fusarium oxysporum and colectrotrichum cassicola, on potato dextrose agar (PDA) plates, and showed potentially non-selective antibacterial activity since it inhibited the growth of both gram positive (Bacillus subtilis and Staphylococcus aureus) and gram negative (Pseudomonas aeruginosa) bacteria with a minimum inhibitory concentration (MIC) of 0.184, 1.270 and 1.270 mg/ml, respectively. Finally, this purified lectin also exhibited a strong alpha-glucosidase inhibitory activity, but with a relatively high IC[subscript 50] value of 0.04 µg/ml.