A salinidade e o déficit hídrico são os fatores abióticos que têm afetado acentuadamente a produção de espécies vegetais de importância socioeconômica nas regiões áridas e semi-áridas. Portanto, o objetivo do presente trabalho foi de avaliar os efeitos do cloreto de sódio (NaCl) e do polietilenoglicol (PEG 6000), agentes estressores comumente utilizados para simular os estresses salino e hídrico, respectivamente, na germinação de sementes de cártamo (Carthamus tinctorius L.), uma oleaginosa da família Asteraceae. A germinação foi conduzida em sistema de rolo, com delineamento experimental de sete tratamentos osmóticos (controle; "0,450; "0,852; "1,271 MPa), sendo três com concentrações isosmóticas de NaCl (100; 200 e 300mM) e PEG (188,35; 267,75 e 357,24 g/L), e cada tratamento com seis repetições. Durante a germinação, foram avaliados parâmetros como a porcentagem de germinação, o índice de velocidade de germinação (IVG), e três dias após o semeio, foram registrados o índice de crescimento relativo da radícula (ICRR) e a massa fresca dos eixos das plântulas. A porcentagem de germinação e o IVG não sofreram alterações significativas no tratamento osmótico de "0,450 MPa induzido por NaCl quando comparado com o controle, enquanto no mesmo tratamento, induzido pelo PEG, estes dois parâmetros apresentaram uma intensa diminuição e um leve aumento, respectivamente. O ICRR e a massa das plântulas apresentaram diminuições proporcionais à redução do potencial osmótico ao utilizar ambos os compostos. Com base nos resultados alcançados, pôde-se concluir que a germinação de sementes de cártamo é influenciada pelo tipo de estresse aplicado e sua respectiva dose. Adicionalmente, o estresse osmótico induzido por PEG 6000 é mais agressivo que o salino, e potenciais osmóticos mais baixos ("0,851 e "1,271 MPa) são limitantes para a germinação desta espécie.

Lectins are proteins, or glycoproteins, capable of reversibly binding to specific mono- or oligosaccharides via a noncatalytic domain. The Diocleinae subtribe presents lectins with high structural similarity, but different effects based on biological activity assays. This variability results from small structural differences. Therefore, in this context, the present study aimed to perform a structural analysis of the lectin from Dioclea lasiophylla Mart. ex Benth seeds (DlyL) and evaluate its inflammatory effect. To accomplish this, DlyL was purified in a single step by affinity chromatography on Sephadex G-50 matrix. DlyL primary structure was determined through a combination of tandem mass spectrometry and DNA sequencing. DlyL showed high similarity with other species from the same genus. Its theoretical three-dimensional structure was predicted by homology modelling, and the protein was subjected to ligand screening with monosaccharides, oligosaccharides and complex N-glycans by molecular docking. Stability and binding of the lectin with α-methyl-d-mannoside were assessed by molecular dynamics. DlyL showed acute inflammatory response with hypernociceptive effect in the paw edema model, possibly by interaction with glycans present at the cell surface.

A native lectin (nPELa), purified from seeds of the species Platypodium elegans, Dalbergieae tribe, was crystallized and structurally characterized by X-ray diffraction crystallography and bioinformatics tools. The obtained crystals diffracted to 1.6Å resolution, and nPELa structure were solved through molecular substitution. In addition, nPELa has a metal binding site and a conserved carbohydrate recognition domain (CRD) similar to other Dalbergieae tribe lectins, such as PAL (Pterocarpus angolensis) and CTL (Centrolobium tomentosum). Molecular docking analysis indicated high affinity of this lectin for different mannosides, mainly trimannosides, formed by α-1,3 or α-1,6 glycosidic bond, as evidenced by the obtained scores. In addition, molecular dynamics simulations were performed to demonstrate the structural behavior of nPELa in aqueous solution. In solution, nPELa was highly stable, and structural modifications in its carbohydrate recognition site allowed interaction between the lectin and the different ligands. Different modifications were observed during simulations for each one of the glycans, which included different hydrogen bonds and hydrophobic interactions through changes in the relevant residues. In addition, nPELa was evaluated for its nociceptive activity in mice and was reported to be the first lectin of the Dalbergieae tribe to show CRD-dependent hypernociceptive activity.

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Using a rat model of peritonitis, we herein report the inflammatory effect induced by the lectin isolated from Vatairea guianensis (VGL) seeds in the context of interactions between VGL and both toll-like receptor 4 (TLR4) and tumor necrosis factor receptor 1 (TNFR1). Peritoneal macrophages were stimulated with VGL for dose-dependent gene expression and release of TNF-α. In vivo results showed that VGL (1 mg/kg; intraperitoneal) induced peritonitis in female Wistar rats. Leukocyte migration, macrophage activation, and protein leakage were measured 3 and 6 hours after induction.In vitro, peritoneal macrophages were stimulated with VGL for gene expression and TNF-α dosage (mean ± SEM (n = 6), analysis of variance, and Bonferroni's test (P < .05)). In silico, VGL structure was applied in molecular docking with representative glycans. It was found that (a) VGL increases vascular permeability and stimulates leukocyte migration, both rolling and adhesion; (b) lectin-induced neutrophil migration occurs via macrophage stimulation, both in vitro and in vivo; (c) lectin interacts with TLR4 and TNFR1; and (d) stimulates TNF-α gene expression (RT-PCR) and release from peritoneal macrophages. Thus, upon lectin-glycan binding on the cell surface, our results suggest that VGL induces an acute inflammatory response, in turn activating the release of peritoneal macrophages via TNF-α and TLR and/or TNFR receptor pathways.