A novel Polygonatum Lectin (GPL) was isolated from the rhizomes Georgian endemic plant Polygonatum obtusifolium Miscz. using a combination of gel-filtration chromatography on Toyopearl HW-55 column, affinity chromatography on glutaraldehyde fixed rabbit erythrocyte column and conventional protein purification techniques. GPL had a special agglutinating activity with rabbit trypsin-treated erythrocytes at a minimum concentration of 0.000095 mg/ml. Using the marker proteins and analytical gel-filtration, molecular weight of the native GPL was established, which corresponded to 30 kDa. Using electrophoresis of marker proteins on polyacrylamide gradient gel (10-25%), in the presence of SDS, it has been showed that GPL dissociated into subunits, migrates as a single band and its molecular mass corresponds to 15 kDa. Thus it was concluded that GPL consists of two same subunits and has homodimer quaternary structure. MTT analyses method showed growth inhibition effect of GPL on short- term (48 h) primary cancer cell culture derived from human skin, lung, ovarian and breast cancer. Carbohydrate αmethyl-mannopyranoside inhibited cytotoxic and cancer cell agglutination activity of GPL. Cancer cell agglutination and growth inhibitory effects of various concentration of GPL were lost at the corresponding level with the lose of mannose-binding activity, indicating that there may be a close link between the agglutinating activity and anti- proliferative property of GPL. It was suggested that cytotoxic effect of GPL on cancer cells should be mediated by its specific interaction with αmethyl-mannopyranoside containing cell membrane surface receptors inducing destruction of cancer cells.
Keywords : Polygonatum obtusifolium Miscz. rhizomes, mannose-specific lectin, isolation, properties, anticancer activity.