A New Galactose-Specific Lectin from Clerodendrum infortunatum

The ethno-medical significance of Clerodendrum genus raises the interest towards the characterization of its seed lectin by inexpensive and most effective technique. The focus of this study is the purification, characterization, and evaluation of the antioxidant and antiproliferative potential of a galactose-specific lectin from Clerodendrum infortunatum L. seeds. The crude extract, homogenized in 6 volumes of the saline containing 10 mM β-mercaptoethanol was subjected to pigment removal by Toyopeal HW-55 column prior to ammonium sulfate fractionation (40-80 %).The crude protein extract was then loaded to the gel filtration column Sephadex G-200 followed by affinity chromatography using activated galactose coupled Sepharose-4B. The SDS-PAGE analysis showed a single band of about 30 kDa which further determined by MALDI-TOF analysis. The MALDI-TOF spectra revealed that Clerodendrum infortunatum lectin (CIL) is a homo-tetramer of 120 kDa consisting of four identical subunits of 30 kDa. The haemagglutination inhibition assay was done with purified lectin by many sugars, among which N-acetyl-D-galactosmine (NAG), D-galactose and lactose exhibited high inhibition. NAG showed the highest inhibition amongst the tested sugars, having the minimum inhibitory concentration of about 0.97 mM. The lectin exhibited a moderate antioxidant activity with an IC50 value of 6.1 ± 0.1 mg.mL-1 and induced cell death with IC50 of 82.8 μg.mL-1 against human gastric cancer cell line, AGS, indicated the potential of CIL for clinical and therapeutic applications. The present study demonstrated the moderate ability of the CIL to inhibit the growth of human gastric cancer cells, AGS either by causing cytotoxic or anti-proliferative effects. Thus, CIL due to its remarkable properties may be considered as a potential bio-molecule in tumor research and glycobiology.