Optimization strategy for purification and isolation of active lectin from Colocasia esculenta L. Schott rhizome

Abstract

Lectins are non-enzymatic proteins that attach to carbohydrates and exhibit diverse biological activities and are found in Colocasia esculenta rhizomes. This study determined the optimal conditions for purifying and isolating lectin from C. esculenta rhizome. The methods involved the preparation of crude extracts with variations of salting in, salting in followed by salting out, and precipitation with phosphate buffer saline (PBS), then all extracts were analyzed with sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Purification and isolation were carried out using ion exchange chromatography with pH variations of 8.3, 7.2, and 9.6. The isolates were evaluated using the bicinchoninic acid method, SDS-PAGE, and hemagglutination test. The results of SDS-PAGE showed that the best extraction method involved the use of PBS as indicated by the presence of a prominent band at ~12.5kDa. During pH optimization for purification, the best isolate was obtained at pH 9.6. This was observed by the appearance of a single band with ~12.5kDa MW on 12% SDS-PAGE gel and occurrence of an agglutination reaction at the hemagglutination stage. The total protein content of lectins ranged from 1284.83 to 2947.33 μg/mL. The C. esculenta rhizome contains lectins as active protein compounds. The best isolation condition is by extraction with PBS solvent and purification using ion exchange chromatography at pH 9.6.