Study of Biological Properties of Chitin-binding Lectins from Potato Species (Solanum tuberosum) Cultivated in Bangladesh

Abstract

Chitin-binding lectins were isolated from the tubers of two local varieties of potatoes (Solanum tuberosum) - 'Deshi' and 'Sheelbeelati' cultivated in Bangladesh. The approximate molecular mass of the Deshi Potato lectin mixtures were 22±1 kDa and 24±1 kDa whereas for Sheelbilatee potato lectins, those were 21±1 kDa and 23±1 kDa determined by SDS-PAGE. Both the lectin mixtures showed strong agglutination activity to mice blood as the minimum agglutination concentration was 4 μg/ml and possessed strong antibacterial activity against Escherichia coli (0157:Hl 8), Listeria monocytogenes, Salmonella enteritidis and Shigella boydii at the dose of 5 μg/ml. In a bacterial agglutination study it was found that only Salmonella enteritidis was very sensitive to the presence of Sheelbilatee lectins whereas Deshi potato lectins could not agglutinate any bacteria. The lectins exerted marked growth inhibition against the same set of pathogenic bacteria at different concentrations and the Sheelbilatee potato lectins were found more active than the Deshi potato lectins against every bacteria in almost every concentration. In an antifungal assay, both the lectin mixtures had notable antifungal activity against the tested fungal species Rhizopus sp., Penicillium sp. and Aspergillus niger. A quite high LC50 value of 75 μg/ml for Sheelbeelati potato lectins indicates cellular cytotoxicity whereas the LC5 o value for Deshi potato lectin was 90 μg/ml. Both the protein mixtures inhibited the growth of Ehrlich's Ascites carcinoma (EAC) cells in vivo at the dose of 1.38 mg/Kg/day by 83.04% and 79.84%. A mechanism study based on the measurement of ð€€¼-lactamase efficiency of the protein mixtures against two bacterial species showed that both Sheelbilatee and Deshi potato lectins were weakly positive against E. coli but failed to show any positivity against Klebsiella pneumoniae. Another mechanism study showed that both the protein mixtures have marked inhibitory effect on the biofilm production of Pseudomonas aeruginosa in a concentration-dependent manner. In a structural stability study, the measurement of fluorescence spectra indicated the possible structural similarities in the two lectin mixtures. The number of Tryptophan residues may be higher in the Deshi potato lectins than the Sheelbilatee lectins and these lectins may be calcium-independent in nature.