Luana Cassandra Breitenbach Barroso Coelho

Lectins, versatile proteins of recognition: a review

Abstract The nomenclature, structure, mode of action and applications of lectins are reviewed. This group of proteinaceous macromolecules has the property of interacting with carbohydrates through binding sites to create complexes. Such complex formation is dependent upon the particular lectin and its specificity for certain carbohydrate structures. The review deals with the vast array of these known lectins with emphasis on recent literature, and covers such additional aspects as occurrence, purification, specificity, and records the recent advances that have been made in the field since the original discovery of erythrocyte agglutination by plant extracts, and the original extensive work on the original lectin concanavalin A.

Effect of Moringa oleifera lectin on development and mortality of Aedes aegypti larvae

Aedes aegypti larvae have developed tolerance to many insecticides used for mosquito control. Moringa oleifera seeds contain a water-soluble lectin (WSMoL) and this paper reports the effect of M. oleifera seed extracts (MoE(1-15)) and WSMoL on development and survival of A. aegypti larvae. WSMoL peptide from in-gel trypsin digestion is also described. MoE(1-15) showed hemagglutinating activity and WSMoL had similarity with flocculating proteins from M. oleifera seeds. MoE(1) and MoE(3) delayed larval development which stopped in the third instar (L3) in MoE(6) and MoE(15). Significant (p<0.0001) larval mortality was only detected in MoE(15). Native WSMoL showed larvicidal activity (LC(50) 0.197 mg mL(-1)) and heated lectin, without hemagglutinating activity, did not kill fourth instar (L4) larvae. Optical microscopy showed that live L4 from MoE(1) presented underlying epithelium, increased gut lumen and hypertrophic segments; dead L4 from WSMoL were absent of underlying epithelium, had increased gut lumen and hypertrophic segments. The presence of hemagglutinating activity in the extracts suggests that soluble lectin promotes the delay of larval development and mortality; furthermore, the absence of larvicidal activity in heat-denatured WSMoL strengthens the involvement of lectin in this activity mechanism.

Novel core(polyester)-shell(polysaccharide) nanoparticles: protein loading and surface modification with lectins

This study describes new lectin-decorated or protein-loaded nanoparticles with a hydrophobic poly(epsilon-caprolactone) (PCL) core and a hydrophilic dextran (Dex) corona. In this view, a family of block Dex-PCLn copolymers was first synthesized, consisting of a Dex backbone to which n preformed PCL blocks were grafted. The ability of these new copolymers to form nanoparticles was evaluated in comparison with a series of PCL homopolymers of various molecular weights (2000, 10,000 and 40,000 g/mole). Two different nanoparticle preparation methods have been developed and tested for their efficacy to incorporate proteins. For this, three proteins were used: a model protein, bovine serum albumin (BSA), a lectin from leaves of Bauhinia monandra (BmoLL) and Lens culinaris (LC) lectin. All these proteins were successfully incorporated in nanoparticles with a mean diameter around 200 nm. Lectins could also be adsorbed onto the surface of Dex-PCLn nanoparticles. Surface-bound BmoLL conserved its hemagglutinating activity, suggesting the possible application of this type of surface-modified nanoparticles for targeted oral administration. Caco-2 cellular viability was higher than 70% when put in contact with Dex-PCLn nanoparticles, even at concentrations as high as 660 microg/ml.

Purification and partial characterization of two lectin isoforms fromCratylia mollis mart. (camaratu bean)

Two additional electrophoretically distinct molecular forms, isoforms (iso) 2 and 3, with lectin properties were isolated fromCratylia mollis Mart, seeds (FABACEAE), by extraction with 0.15M NaCl and ammonium sulfate fractionation, followed by chromatography on Sephadex G-75 and Bio-Gel P-200 (iso 2), as well as CM-Cellulose and Sephadex G-75 (iso 3). Both isoforms were human group nonspecific and showed distinct specificity. Polyacrylamide gel electrophoresis resolved iso 2 and 3 in polypeptides of apparent mol wts 60 and 31 kDa, respectively; a distinct isoelectric focusing pattern was obtained for iso 2 and 3, under denaturing and reducing conditions.

Purification of a lectin from Eugenia uniflora L. seeds and its potential antibacterial activity

Aims:  The aim of this work was to analyse the antimicrobial properties of a purified lectin from Eugenia uniflora L. seeds.

Coagulant and antibacterial activities of the water-soluble seed lectin from Moringa oleifera

Aims:  The aim of this work was to analyse the coagulant and antibacterial activities of lectin isolated from Moringa oleifera seeds that are used for water treatment.

Larvicidal activity of lectins from Myracrodruon urundeuva on Aedes aegypti

Aedes aegypti transmits etiologic agents of yellow fever and dengue. Vaccine for dengue virus is not available and vector control is essential to minimize dengue incidence. This report deals with the larvicidal activity of lectins isolated from Myracrodruon urundeuva bark (MuBL) and heartwood (MuHL). The lectins were isolated by ammonium sulphate treatment of crude extracts followed by chromatography on chitin. MuBL and MuHL were evaluated by electrophoresis under native (PAGE) and denaturing conditions (SDS-PAGE). Carbohydrate specificity of lectins was evaluated by hemagglutinating activity (HA) inhibition assay using N-acetyl-d-glucosamine and by affinity chromatography on N-acetyl-D-glucosamine immobilized in agarose gel. Larvicidal activity against A. aegypti was investigated with the extracts, salt fractions and isolated lectins. MuBL and MuHL were characterized by PAGE as basic proteins of molecular masses of 14.0 and 14.4 kDa, respectively. The interaction of lectins with N-acetylglucosamine was detected by inhibition of HA by monosaccharide and lectin adsorptions on N-acetyl-D-glucosamine matrix. All M. urundeuva preparations promoted larvae mortality. LC16, LC50 and LC84 values of 0.077, 0.125, 0.173 for MuBL and 0.03, 0.04 and 0.05 mg/mL for MuHL were obtained. To our knowledge this is the first report of larvicidal activity of lectins against A. aegypti.

Antibacterial and antifungal activities of Myracrodruon urundeuva heartwood

The aim of this work was to isolate a lectin from Myracrodruon urundeuva heartwood and to evaluate its antimicrobial activity against bacteria and fungi that attack plants, including woods. The lectin was isolated from heartwood through affinity chromatography on a chitin column monitored by hemagglutination assay. The lectin inhibited Gram-negative and Gram-positive bacteria and was more effective than antifungal Cercobin in growth inhibition of phytopathogenic fungi. The detected antimicrobial activity reveals the possible role of the lectin in the resistance of M. urundeuva heartwood against deteriorative biological agents. The M. urundeuva lectin is the first bioactive peptide found in heartwood, probably stored as a chemical protection against biodegradation.

Simple method to purify milligram quantities of the galactose-specific lectin from the leaves of Bauhinia monandra.

Leaves of Bauhinia monandra Kurz. (pata-de-vaca, pulse) contain a relatively high concentration of a galactose-specific lectin (BmoLL). More than 2 mg of BmoLL were obtained from 5 g of leaf powder when a 10% (w/v) extract was submitted to 60% ammonium sulphate fractionation followed by guar gel affinity chromatography. The purified lectin ran slowly as a single broad band on non-denaturing electrophoresis. Under denaturing and reducing conditions, it appeared as a major subunit of apparent molecular weight 33 kDa, positive to carbohydrate staining, and a non-glycosylated polypeptide (26 kDa). Column fractions containing the peak of BmoLL eluted from the affinity chromatography, each containing the 33 and 26 kDa polypeptides. The highest agglutination activity of BmoLL was found with glutaraldehyde-treated rabbit erythrocytes; fresh and glutaraldehyde-treated human erythrocytes of blood groups B and AB were also agglutinated, whereas those form groups A and O were not.

Binding evaluation of Isoform 1 from Cratylia mollis lectin to human mammary tissues

The phenomenon of altered carbohydrates in transformed cell surfaces has been studied through histochemical techniques using lectins. Specific binding patterns to normal and transformed mammary tissues were evaluated by Isoform 1 fromCratylia mollis lectin (Cra Iso 1). Protocols using a direct method, incubation of Cra Iso I conjugated to peroxidase (Cra Iso 1-Per) with mammary tissues, followed by diaminobenzidine and hydrogen peroxidase interaction, were performed. Neoplastic tissues, marked by Cra Iso 1, showed a higher intensity of staining than normal ones, in comparison withCanavalia ensiformis lectin, Concanavalin A (Con A), conjugated to peroxidase (Con A-Per). The assay with Cra Iso 1 also indicated a possible utilization of this lectin to characterize normal and transformed mammary cells.