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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. Methods and Results:  The water‐soluble M. oleifera lectin (WSMoL) was separated from nonhemagglutinating components (NHC) by chitin chromatography. WSMoL fluorescence spectrum was not altered in the presence of ions that are often present in high concentrations in polluted waters. Seed extract, NHC and WSMoL showed coagulant activity on a turbid water model. Both NHC and WSMoL reduced the growth of Staphylococcus aureus, but only WSMoL caused a reduction in Escherichia coli. WSMoL was also more effective in reducing the growth of ambient lake water bacteria. Conclusions:  Data obtained from this study indicate that WSMoL is a potential natural biocoagulant for water, reducing turbidity, suspended solids and bacteria. Significance and Impact of the Study:  Moringa oleifera seeds are a material effective in the treatment of water.

Bauhinia bauhinoides cruzipain inhibitor (BbCI) and Bauhinia bauhinioides kallikrein inhibitor (BbKI) are cysteine and serine proteinase inhibitors structurally homologous to plant Kunitz-type inhibitors, but are devoid of disulfide bridges. Based on cDNA sequences, we found that BbKI and BbCI are initially synthesized as a prepropeptide comprising an N-terminal signal peptide (19 residues), the mature protein (164 residues) and a C-terminal targeting peptide (10 residues). Partial cDNAs encoding the mature enzymes plus N-terminal His-tags and thrombin cleavage sites were expressed in E. coli and the soluble proteins were purified by one-step nickel affinity chromatography. After thrombin cleavage, both proteins exhibited potent inhibitory activities toward their cognate proteinases like the wild-type proteins. BbCI inhibits human neutrophil elastase ( K i(app) 5.3 nM), porcine pancreatic elastase ( K i(app) 40 nM), cathepsin G ( K i(app) 160 nM) and the cysteine proteinases cruzipain ( K i(app) 1.2 nM), cruzain ( K i(app) 0.3 nM) and cathepsin L ( K i(app) 2.2 nM), while BbKI strongly inhibits plasma kallikrein ( K i(app) 2.4 nM) and plasmin ( K i(app) 33 nM). Circular dichroism spectra of BbCI and BbKI were in agreement with the beta-trefoil fold described for Kunitz inhibitors. The inhibitory potency of both BbCI- and BbKI-type inhibitors suggests that other, non-covalent interactions may compensate for the lack of disulfide bridges.

The saline extract of Bauhinia bauhinioides dry seeds was shown to inhibit cruzipain, a cysteine proteinase from Trypanosoma cruzi. The inhibitory activity was assigned to a protein with 164 amino acid residues and molecular mass of 18 034 Da that was purified by chromatography on DEAE-Sephadex, trypsin-Sepharose (removal of trypsin inhibitors), Mono Q and a reversed-phase C4 column. The primary structure is homologous to other plant Kunitz-type inhibitors, but it lacks cysteine residues and therefore the disulfide bridges. No methionine residue was identified by amino acid sequencing. The inhibition of cruzipain fits into a slow-tight binding mechanism with a low dissociation constant (Ki 1.2 nM). The studied Bauhinia protein also inhibits cruzain (Ki 0.3 nM), a C-terminally truncated recombinant species of cruzipain. Cathepsin L, a cysteine proteinase with high homology to cruzipain, is also inhibited (Ki 0.22 nM), but not cathepsin B, papain, bromelain or ficin.

BackgroundStudies have suggested that soluble factors in plasma from patients with active (aBD) and inactive (iBD) Behçet’s disease (BD) stimulate neutrophil function. Soluble CD40 ligand (sCD40L) is an important mediator of inflammation in BD. Its expression and effect on neutrophil oxidative burst and neutrophil extracellular trap (NET) release have not been characterized. In this study, we sought to investigate the role of plasma and the CD40L pathway on NET release and the oxidative burst profile in patients with aBD and iBD.MethodsNeutrophils and peripheral blood mononuclear cells (PBMCs) were obtained from patients with aBD (n = 30), patients with iBD (n = 31), and healthy control subjects (HCs; n = 30). sCD40L plasma concentration was determined in individual samples. A pool of plasma for each group was created. In some experiments, plasma pools were treated with recombinant CD40 (rhCD40-muIg) for sCD40L blockade. NET release and H2O2/O2 − production were determined after stimulation with phorbol 12-myristate 13-acetate, sCD40L, or plasma pool. Flow cytometric analysis was performed to evaluate the expression of (1) CD40, Mac-1, and phosphorylated NF-κB p65 on neutrophils and monocytes and (2) CD40L on activated T cells and platelets. CD40L gene expression in PBMCs was determined by qRT-PCR.ResultssCD40L plasma levels were significantly higher in patients with iBD (median 17,234, range 2346–19,279 pg/ml) and patients with aBD (median 18,289, range 413–19,883 pg/ml) than in HCs (median 47.5, range 33.7–26.7 pg/ml; p < 0.001). NET release was constitutively increased in BD compared with HC. NET release and H2O2/O2 − were higher after stimulation with sCD40L or BD plasma and decreased after sCD40L blockade. Mac-1 expression was constitutively increased in neutrophils of patients with aBD (88.7 ± 13.2% of cells) and patients with iBD (89.2 ± 20.1% of cells) compared with HC (27.1 ± 18.8% of cells; p < 0.01). CD40 expression on phagocytes and CD40L expression on platelets were similar in the three groups. PBMCs as well as nonactivated and activated CD4+ T cells from patients with BD showed higher CD40L expression.ConclusionsPlasma from patients with aBD exerts a stimulus on NET release and oxidative burst, probably induced by sCD40L.Electronic supplementary materialThe online version of this article (doi:10.1186/s13075-017-1443-5) contains supplementary material, which is available to authorized users.