EVALUATION OF THE ANTIBACTERIAL ACTIVITY OF LECTINS FROM Canavalia maritima (ConM) AND Dioclea rostrata (DRL) IN STANDARD AND MULTI-RESISTANT STRAINS OF Staphylococcus aureus AND Escherichia coli
Antibiotic. Lectins. Modulation. Bacterial resistance
Lectins attract a lot of interest because of their unique properties to bind specifically and reversibly to glycans without changing the structure of either, and to bind cells. Due to these properties they have several functions, including antibacterial and modulating activity. Staphylococcus aureus and Escherichia coli are pathogenic microorganisms of great clinical concern, due to the nosocomial infections they can cause, besides being resistant to several drugs. Thus, isolating biomolecules with antibacterial potential is very promising to enable a future drug able to act against these strains. The aim of this study was to isolate lectins from Dioclea rostrata (DRL) and Canavalia maritima (ConM) seeds and test their antibacterial and modulatory potential against standard multidrug-resistant strains of S. aureus and E. coli. DRL and ConM lectins were purified by affinity chromatography on a Sephadex G-50 column. The hemagglutinating activity was performed using 3% rabbit erythrocytes, inhibition of hemagglutinating activity using 0.1 M glucose and protein denaturation by heating. The microbiological tests were performed in order to verify the MIC capable of inhibiting bacterial growth as well as the modulation test with antibiotics. The lectins tested presented a Minimum Inhibitory Concentration above or equal to 1024 µg/mL. They did not show clinically significant activity on bacterial growth directly. The modulatory effects of ConM and DRL lectins in combination with the antibiotics Ampicillin, Norfloxacin and Gentamicin were verified. ConM showed synergistic effect, significantly enhancing the activity of all antibiotics in resistant strains of E. coli, however it was indifferent for S. aureus. With DRL it was also possible to verify a synergism in combination with all antibiotics for E. coli, on the other hand, in S. aureus, it showed a synergistic effect only when combined with the antibiotic gentamicin. Finally, the lectins in the study were able to act synergistically in combination with the antibiotics against resistant strains of S. aureus and E. coli, lowering their concentrations in use.