Atividade citotóxica, bacteriostática e aglutinante para leishmania de ConM: uma lectina isolada das sementes do feijão de praia – Canavalia marítima (Aubl.) Thou. (1813)

Abstract

Plant seeds are reservoirs of molecules with great potential for development of bioproducts and for this reason special attention has been directed in the search of bioactive proteins with antimetabolic and pharmacological properties action. Plant lectins are proteins with biological activities related to defense, but that can be used, heterologously as interfering with the metabolism of other organisms. A Canavalia marítima seeds lectin (CML) was purified in two steps by ammonium sulfate fractionation followed by affinity chromatography on Sephadex G-50 column. CML was analyzed by SDS-PAGE and part of its amino acid sequence determined by mass spectrometry. The 20 resulting residues identified showed 100% identity with conm. ConM was tested against erythrocytes of human peripheral blood and it was observed absence of toxicity when incubated with up to 1000 µg/mL of protein. Since against mononuclear cells, the lectin was not significantly toxic at concentrations of 1, 2.5 and 5 µg/mL, but it was from concentration 7 µg/mL. Against RAEC lineage protein showed no significant toxicity with 25 µg/mL of protein. Other cytotoxicity assays revealed that CONM is toxic for the tumor cell lines A549, 786-0, HT-29 and HeLa in the range between 24 and 72 hours, particularly at concentrations of 5, 7 and 10 µg/mL. ConM was still able to agglutinate promastigotes of Leishmania spp at concentrations of 6.25 µg/mL. About action against Candida spp any of the tested concentrations (1 to 500 µg/ml) was able to interfere with growth. When evaluated bacteriostatic activity, ConM in concentrations ranging from 0.39 to 400 µg/mL did not inhibit the growth of Escherichia coli, but the concentration of 25 µg/mL proved active aganist Staphylococcus aureus, reducing its growth by 75%. Based on these data, the lectin corresponds to a isolectin ConA-like, and its anti-tumor properties, bacteriostatic and binder for Leishmania need to be further investigated for its biotechnological potential exploited.