Antibacterial,antifungal and in vivo anticancer activities of chitin-binding lectins from Tomato (Solanum lycopersicum) fruits

A mixture of chitin-binding lectins from Tomato (Solanum lycopersicum) fruits, designated as Tomato chitin-binding lectins (TCLs), was isolated through affinity chromatography using an acetylated chitin column. Molecular weights of TCLs were determined to be 30 to 115 KDa which possessed mild toxicity with an LC₅₀ value of 521 µg/ml examined by the brine shrimp nauplii toxicity assay. Strong antibacterial activity of TCLs was found against Escherichia coli, Staphylococcus aureus and Shigella boydii at a concentration of 500 µg/ml by using disc diffusion method. Minimum inhibitory concentrations (MIC) of TCLs against Staphylococcus aureus and Escherichia coli were found to be 200 µg/ml and 140 µg/ml, respectively whereas minimum bactericidal concentrations (MBC) against the same bacterial species were 840 and 600 µg/ml, respectively. TCLs also exerted antibiofilm activity (53.32% at 250 μg/ml) against Escherichia coli. Strong antifungal activity of TCLs against Aspergillus niger was found at 600 µg/ml whereas the lectin mixture agglutinated A. niger spores at 200 µg/ml. TCLs exhibited 19.63% and 59.91% anti-proliferative activity against Ehrlich ascites carcinoma (EAC) cells in vivo in Swiss albino mice when intraperitonealy injected at doses 1.0 mg/kg/day and 2.0 mg/kg/day, respectively for five consecutive days. Morphological changes of apoptosis in EAC cells under fluorescence microscope and alteration of the expression of apoptosis-related genes (Fas, Caspase 8 and Caspase 3) had also been observed. MTT assay showed 27.61%, 38.74% and 49.23% of in vitro anticancer activity of the tomato lectins at concentrations of 37.5, 75 and 150 µg/ml, respectively.