Identificação e purificação de uma lectina de folhas de Jatropha multifida L.

Abstract

The interest in medicinal plants has increased progressively, since their constituents can provide a variety of products of economic importance. The species Jatropha multifida is a plant belonging to the family Euphorbiaceae used in folk medicine in the healing of wounds and ulcers, as a purgative and antipyretic, for the treatment of oral candidiasis, gonorrhoea, skin and urinary infections. Among the various biomolecules that can have these properties, lectins stand out for presenting biotechnological applications such as antimicrobial, immunomodulatory, mitogenic, insecticidal, antitumor and anti-inflammatory activity. Lectins are proteins that have at least one non-catalytic domain with the ability to bind reversibly to carbohydrates with high specificity, being found from microorganisms to animals and vegetables. This work aimed to identify and purify a lectin from the leaves of Jatropha multifida. For this, the leaf extract (10%, w/v) was prepared in three different solutions: 0.15 M NaCl, 50 mM Tris-HCl pH 8.0 and 50 mM sodium phosphate pH 7.2 for 16 h. The extraction performed with 50 mM Tris-HCl pH 8.0 showed the highest hemagglutinating activity (HA: 512) as well as the highest protein content (3.152 mg/mL). The extract was then subjected to saline fractionation with ammonium sulfate in different concentrations (0-20%, 20-40%, 40-60% and 60-80%), with F0-20% being the only one that presented HA (2048). The hemagglutination assay were performed with a 2.5% (v/v) suspension of rabbit erythrocytes in 0.15 M NaCl treated with alsevier solution. Then, the F0-20% was chromatographed on a chitin column equilibrated with 0.15 M NaCl. The fractions eluted with 0.5 M acetic acid that demonstrated HA were then collected and dialyzed against Milli-Q water and twice against 50 mM Tris-HCl pH 8.0 for 6 h. Lectin demonstrated greater specificity for glucose and maltose, but also showed affinity for N-acetylglycosamine, ribose and sucrose. To verify the purity of the lectin, the sample was analyzed by 10% polyacrylamide gel electrophoretic method under non-reducing and denaturing conditions, using sodium dodecyl sulfate, where it was possible to visualize a protein band. Thus, a lectin of J. multifida leaves was identified and purified by chitin column chromatography, stimulating future studies on its characterization and biotechnological potential.