Galactomannan of Delonix regia seeds modulates cytokine expression and oxidative stress eliciting anti-inflammatory and healing effects in mice cutaneous wound.

The galactomannans property of forming viscous solutions, along with the traditional use of Delonix regia as anti-inflammatory, antinociceptive and wound healing, justify the investigation of the healing mechanism of Delonix regia galactomannan (GM-DR) in a model of excisional cutaneous wound. GM-DR (% 0.01-1) was topically applied to the wounds of female Swiss mice during 14 days. The wound healing effect of GM-DR was evaluated by the following parameters: wound closure and clinical signs (hyperemia, edema and exudate by macroscopy, nociception by analgesimetry), oxidative stress markers (malondialdehyde - MDA, reduced glutathione - GSH) by ELISA, histopathological (HE and Picrosirius red), and histomorphometric (collagenesis, blood vessels, polymorphonuclear, mononuclear, fusiform cells) and immunohistochemistry (inflammatory and growth factor mediators) by tissue microarrayer. GM-DR reduced wound area (7-14th day) and hypernociception (6 h - 5th day), leukocyte infiltration (2 -7th days), expression and levels of IL-1ß (2th day), IL-6 (2th day), MDA (44% - 2th day), and increased fusiform cells, granulation tissue, collagen deposition, GSH (25 - 50%, 2-5th day), expression of the transforming growth factor beta (TGF-ß) (7-10th day) and smooth muscle alpha actin (α-SMA) (7-14th day). In conclusion, GM-DR accelerates the mice healing process acting both in the inflammatory and proliferative phases.

Exploring the carbohydrate-binding ability of Canavalia bonariensis lectin in inflammation models.

Lectins are a group of proteins of non-immune origin recognized for their ability to bind reversibly to carbohydrates. Researchers have been intrigued by oligosaccharides and glycoconjugates for their involvement as mediators of complex cellular events and then many biotechnological applications of lectins are based on glycocode decoding and their activities. Here, we report a structural and biological study of a ConA-like mannose/glucose-specific lectin from Canavalia bonariensis seeds, CaBo. More specifically, we evaluate the binding of CaBo with α-methyl-D-mannoside (MMA) and mannose-1,3-α-D-mannose (M13) and the resultant in vivo effects on a rat model of acute inflammation. A virtual screening was also carried out to cover a larger number of possible bindings of CaBo. In silico analysis demonstrated the stability of CaBo interaction with mannose-type ligands, and the lectin was able to induce acute inflammation in rats with the participation of the carbohydrate recognition domain (CRD) and histamine release. These results confirm the ability of CaBo to interact with hybrid and high-mannose N-glycans, supporting the hypothesis that CaBo's biological activity occurs primarily through its interaction with cell surface glycosylated receptors.

Heterologous production of α-chain of Dioclea sclerocarpa lectin: Enhancing the biological effects of a wild-type lectin.

Lectins from Diocleinae subtribe species (family Leguminosae) are of special interest since they present a wide spectrum of biological activities, despite their high structural similarity. During their synthesis in plant cells, these proteins undergo post-translational processing resulting in the formation of three chains (α, ß, γ), which constitute the lectins' subunits. Furthermore, such wild-type proteins are presented as isolectins or with different combinations of these chains, which undermine their biotechnological potential. Thus, the present study aimed to produce a recombinant form of the lectin from Dioclea sclerocarpa seeds (DSL), exclusively constituted by α-chain. The recombinant DSL (rDSL) was successfully expressed in E. coli BL21 (DE3) and purified by affinity chromatography (Sephadex G-50), showing a final yield of 74 mg of protein per liter of culture medium and specificity for D-mannose, α-methyl-mannoside and melibiose, unlike the wild-type protein. rDSL presented an effective vasorelaxant effect in rat aortas up to 100% and also interacted with glioma cells C6 and U87. Our results demonstrated an efficient recombinant production of rDSL in a bacterial system that retained some biochemical properties of the wild-type protein, showing wider versatility in sugar specificities and better efficacy in its activity in the biological models evaluated in this work.

Per oral rat treatment with glyconjugate fractions of Genipa americana leaves protects thrombus formation.

: The current study evaluated the effect of the arabinogalactan-glycoconjugate fractions (FI and FII) isolated from Genipa americana leaves given per oral in rat hemostasis protocols. Rats received daily treatment with FI or FII during 7 days and were evaluated for coagulation, platelet aggregation, venous thrombosis and bleeding tendency 1 h after the last treatment. FII prolonged in 5.5-fold the rat plasma coagulation time (activated partial thromboplastin time test). FI inhibited by 46% the platelet aggregation. Both FI and FII prevented thrombus formation by 33 and 28%, respectively. However, the bleeding time was not altered by any fractions, showing an advantage in relation to acetylsalicylic acid or warfarin that increased the bleeding time in 3.6 and 2.9-fold, respectively. Per oral treatment with the arabinogalactan-glyconjugate fractions FI and FII of G. americana leaves in rats prevents thrombus formation, being devoid of hemorrhagic risk. These results bring novel therapeutic possibilities for thromboembolic diseases.

Contribution of the carbohydrate-binding ability of Vatairea guianensis lectin to induce edematogenic activity.

Vatairea guianensis lectin (VGL), Dalbergiae tribe, is a N-acetyl-galactosamine (GalNAc)/Galactose (Gal) lectin previously purified and characterized. In this work, we report its structural features, obtained from bioinformatics tools, and its inflammatory effect, obtained from a rat paw edema model. The VGL model was obtained by homology with the lectin of Vatairea macrocarpa (VML) as template, and we used it to demonstrate the common characteristics of legume lectins, such as the jellyroll motif and presence of a metal-binding site in the vicinity of the carbohydrate-recognition domain (CRD). Protein-ligand docking revealed favorable interactions with N-acetyl-d-galactosamine, d-galactose and related sugars as well as several biologically relevant N- and O-glycans. In vivo testing of paw edema revealed that VGL induces edematogenic effect involving prostaglandins, interleukins and VGL CRD. Taken together, these data corroborate with previous reports showing that VGL interacts with N- and/or O-glycans of molecular targets, particularly in those presenting galactosides in their structure, contributing to the lectin inflammatory effect.

Polysaccharide rich fractions from barks of Ximenia americana inhibit peripheral inflammatory nociception in mice Antinociceptive effect of Ximenia americana polysaccharide rich fractions

Abstract Ximenia americana L., Olacaceae, barks are utilized in folk medicine as analgesic and anti-inflammatory. The objective was to evaluate the toxicity and antinociceptive effect of polysaccharides rich fractions from X. americana barks. The fractions were obtained by extraction with NaOH, followed by precipitation with ethanol and fractionation by ion exchange chromatography. They were administered i.v. or p.o. before nociception tests (writhing, formalin, carragenan-induced hypernociception, hot plate), or during 14 days for toxicity assay. The total polysaccharides fraction (TPL-Xa: 8.1% yield) presented 43% carbohydrate (21% uronic acid) and resulted in two main fractions after chromatography (FI: 12%, FII: 22% yield). FII showed better homogeneity/purity, content of 44% carbohydrate, including 39% uronic acid, arabinose and galactose as major monosaccharides, and infrared spectra with peaks in carbohydrate range for COO- groups of uronic acid. TPL-Xa (10 mg/kg) and FII (0.1 and 1 mg/kg) presented inhibitory effect in behavior tests that evaluate nociception induced by chemical and mechanical, but not thermal stimuli. TPL-Xa did not alter parameters of systemic toxicity. In conclusion, polysaccharides rich fractions of X. americana barks inhibit peripheral inflammatory nociception, being well tolerated by animals.

Modulator effect of a polysaccharide-rich extract from Caesalpinia ferrea stem barks in rat cutaneous wound healing: Role of TNF-α, IL-1ß, NO, TGF-ß.

ETHNOPHARMACOLOGICAL RELEVANCE: In folk medicine stem barks of Caesalpinia ferrea (Caesalpinioideae) are used to treat enterocolitis, rheumatism and wounds and in experimental procedures, its aqueous extracts demonstrated antiulcer, anti-inflammatory, analgesic, and healing effects. AIM OF THE STUDY: The healing mechanism of the polyssacharide-rich extract of C. ferrea stem barks (TPL-Cf) was investigated in a model of excisional cutaneous wound in Wistar rats. MATERIALS AND METHODS: Excisional wounds received topical treatment with TPL-Cf (0.025-0.1%) during 21 days. Hypernociception, macroscopical, histological and immunohistochemical parameters were evaluated and analyzed by ANOVA, Bonferroni and Kruskal-Wallis tests, followed by Dunn and Chi-Square tests. RESULTS: TPL-Cf (0.1%) reduced wound area and hypernociception, and increased wound contraction. TPL-Cf reduced leukocyte infiltration and vascular permeability, and stimulated fibroblasia, angiogenesis, well formed granulation tissue, collagen deposition and epithelial layer formation. TPL-Cf reduced TNF-α expression and the levels of PGE2 (73%-day 5), IL-1 (42%-day 2), MDA (38%-day 5), total protein (53%-day 2; 73%-day 5) and MPO activity (53%-day 2), but increased the expression of i-NOS (days 5 and 7), TGF-ß (day 5) and the levels of NO (3.6 fold-day 5). CONCLUSION: The polysaccharide-rich extract of C. ferra stem barks accelerates wound healing by the control of the inflammatory phase and attenuates hypernociception via modulation of inflammatory mediators (TNF-α, IL-1ß, NO, TGF-ß).

Structural analysis of a Dioclea sclerocarpa lectin: Study on the vasorelaxant properties of Dioclea lectins.

Lectins are proteins that show a variety of biological activities. However, they share in common at least one domain capable of recognizing specific carbohydrates reversibly without changing its structure. The legume lectins family is the most studied family of plant lectins, in particular the Diocleinae subtribe, which possesses high degree of structural similarity, but variable biological activities. This variability lies in small differences that can be analyzed in studies based on structures. In particular, Dioclea sclerocarpa seed lectin (DSL) presents low ability to relax endothelialized rat aorta in comparison with other Dioclea lectins such as Dioclea violacea (DVL), Dioclea virgata (DvirL) and Dioclea rostrata (DRL). The DSL relaxation mechanism relies on nitric oxide production and carbohydrate recognition domain (CRD). This feature can be explained by structural differences, since DSL has a carbohydrate recognition domain design less favorable. In addition, the presence of a glutamate residue at position 205 proved to be a decisive factor for the low relaxant effect of Dioclea lectins.

Purification and molecular characterization of a novel mannose-specific lectin from Dioclea reflexa hook seeds with inflammatory activity.

A novel lectin present in Dioclea reflexa seeds (DrfL) was discovered and described in this study. DrfL was purified in a single step by affinity chromatography in a Sephadex G-50 column. The lectin strongly agglutinated rabbit erythrocytes and was inhibited by α-methyl-D-mannoside, D-mannose, and D-glucose. The hemagglutinating activity of DrfL is optimum at pH 5.0-7.0, stable up to 50 °C, and dependent on divalent cations. Similar to other lectins of the subtribe Diocleinae, the analysis by mass spectrometry indicated that DrfL has three chains (α, ß, and γ) with masses of 25,562, 12,874, and 12,706 Da, respectively, with no disulfide bonds or glycosylation. DrfL showed inflammatory activity in the paw edema model and exhibited low cytotoxicity against Artemia sp.

Purified polysaccharides of Geoffroea spinosa barks have anticoagulant and antithrombotic activities devoid of hemorrhagic risks.

Polysaccharides were extracted from the barks of Geoffroea spinosa, purified using anion exchange chromatography and characterized by chemical and methylation analysis, complemented by infrared and NMR spectroscopies. These polysaccharides were tested for their anticoagulant, antithrombotic and antiplatelet activities and also for their effects on bleeding. Unfractionated polysaccharide contains low levels of protein and high levels of carbohydrate (including hexuronic acid). The purified polysaccharides (fractions FII and FIII) are composed of arabinose (Ara), rhamnose (Rha), hexuronic acid, small amounts of galactose, but no sulfate ester. They have highly complex structure, which was partially characterized. NMR and methylation analysis indicate that the polysaccharides have a core of α-Rhap and branches of 5-linked α-Araf. Residues of 4-linked α-GalpA are also found in the structure. The unfractionated (TPL) and fraction FIII, but not fractions FI and FII, prolonged the activated partial thromboplastin time (aPTT). TPL, FII and FIII inhibited the platelet aggregation induced by ADP. More significantly, both unfractionated and purified fractions exhibited potent antithrombotic effect (31-60%) and the fractions did not modify the bleeding tendency. These plant polysaccharides could be alternative source of new anticoagulant, antiplatelet and antithrombotic compounds devoid of the undesirable risk of hemorrhage.

CRLI induces vascular smooth muscle relaxation and suggests a dual mechanism of eNOS activation by legume lectins via muscarinic receptors and shear stress.

Lectins are proteins able to recognize carbohydrates, without modifying their structure, via the carbohydrate-recognition domain (CRD). Here, the three-dimensional structure of the mannose-binding lectin isolated from Cymbosema roseum (CRLI) was determined with X-man molecule modeled into the carbohydrate recognition domain. CRLI relaxant activity in thoracic rat aorta was also investigated, and based on the results, a molecular docking of CRLI with heparan sulfate was performed to investigate the possible interaction with mechanoreceptors involved in vasorelaxation. CRLI (IC50=12.4 µg mL(-)(1)) elicited vasorelaxant response (96%) in endothelialized rat aorta contracted with phenylephrine. Endothelium-derived relaxant factors, extracellular calcium (Ca(2+)e) and muscarinic receptors were also evaluated as putative participants in the CRLI relaxant effect. CRLI relaxant effect was blocked by L-NAME, a nonselective inhibitor of nitric oxide synthase (NOS), and partially inhibited in a calcium-free solution (0Ca) and by atropine, but it remained unchanged in the presence of indomethacin and TEA. In summary, our data suggest interaction between CRLI and muscarinic receptors located in vascular endothelial cells leading to NOS activation triggered by a mechanism that involves Ca(2+)e along with the ability of CRLI to interact with heparan sulfate, a highly rated mechanoreceptor involved in eNOS activation.

Purification, characterization and partial sequence of a pro-inflammatory lectin from seeds of Canavalia oxyphylla Standl. & L. O. Williams.

Recent studies have shown that lectins are promising tools for use in various biotechnological processes, as well as studies of various pathological mechanisms, isolation, and characterization of glycoconjugates and understanding the mechanisms underlying pathological mechanisms conditions, including the inflammatory response. This study aimed to purify, characterize physicochemically, and predict the biological activity of Canavalia oxyphylla lectin (CoxyL) in vitro and in vivo. CoxyL was purified by a single-step affinity chromatography in Sephadex® G-50 column. Sodium dodecyl sulfate polyacrylamide gel electrophoresis showed that the pure lectin consists of a major band of 30 kDa (α-chain) and two minor components (ß-chain and γ-chain) of 16 and 13 kDa, respectively. These data were further confirmed by electrospray ionization mass spectrometry, suggesting that CoxyL is a typical ConA-like lectin. In comparison with the average molecular mass of α-chain, the partial amino acid sequence obtained corresponds to approximately 45% of the total CoxyL sequence. CoxyL presented hemagglutinating activity that was specifically inhibited by monosaccharides (D-glucose, D-mannose, and α-methyl-D-mannoside) and glycoproteins (ovalbumin and fetuin). Moreover, CoxyL was shown to be thermostable, exhibiting full hemagglutinating activity up to 60°C, and it was pH-sensitive for 1 h, exhibiting maximal activity at pH 7.0. CoxyL caused toxicity to Artemia nauplii and induced paw edema in rats. This biological activity highlights the importance of lectins as important tools to better understand the mechanisms underlying inflammatory responses.

A report of a galactan from marine alga Gelidium crinale with in vivo anti-inflammatory and antinociceptive effects.

The sulfated galactan of the red marine alga Gelidium crinale (SG-Gc) was purified by ion exchange chromatography and tested by intravenous (i.v.) route in rodent experimental models of inflammation and nociception. The anti-inflammatory activity of SG-Gc (0.01, 0.1 and 1 mg/kg) was evaluated in the model of rat paw edema induced by different inflammatory stimuli, while SG-Gc (0.1, 1 and 10 mg/kg) antinociceptive effect was assessed in models of nociception/hyperalgesia elicited by chemical (formalin test), thermal (hot plate), and mechanical (von Frey) stimuli in mice. In addition, the toxicity was evaluated after rat treatment with SG-Gc (1 mg/kg; i.v.) during 10 days, followed by analysis of the wet weight of animal's body/organs and hematological/biochemical parameters. Sulfated galactan of G. crinale inhibited the time course of dextran-induced paw edema, at all doses, showing maximal effect at 1 mg/kg (42%) and that induced by carrageenan at 0.01 (18%) and 1 mg/kg (20%), but was ineffective on the edema elicited by zymosan. At the highest dose, SG-Gc also inhibited the paw edema induced by histamine (49%), compound 48/80 (32%), and phospholipase A(2) (44%). Sulfated galactan of G. crinale inhibited both neurogenic and inflammatory phases of the formalin test, at all doses, and at 10 mg/kg, the animals flinch reaction in the von Frey test in the 1st and 3rd h by 19 and 26%, respectively. Additionally, SG-Gc treatment was well tolerated by animals. In conclusion, SG-Gc presents anti-inflammatory effect involving the inhibition of histamine and arachidonic acid metabolites and also antinociceptive activity, especially the inflammatory pain with participation of the opioid system.

Comparative study of the anti-edematogenic effects of anethole and estragole.

BACKGROUND: Anethole and estragole are monoterpene position isomers and constituents of essential oils from aromatic plants and were used in this study with the aim of analyzing their anti-inflammatory activity. METHODS: The anti-edematogenic effects of anethole and estragole were evaluated through plethysmometry in Swiss mice. RESULTS: Anethole inhibited carrageenan-induced edema at doses of 3, 10 and 30 mg/kg from 60 to 240 min after induction. However, the inhibitory effects of estragole were observed only from 60 to 120 min at the two highest doses. Anethole and estragole similarly inhibited edema elicited by substance P, bradykinin, histamine and TNF-α but were different in the inhibition of serotonin-elicited edema. In addition, only estragole inhibited sodium nitroprusside-induced edema. CONCLUSIONS: Anethole and estragole showed different profiles in the anti-inflammatory response to substance P, bradykinin, histamine, serotonin and TNF-α NO is involved only in the inhibition mechanism of estragole.

The role of endothelium in the vasorelaxant effects of the essential oil of Ocimum gratissimum in aorta and mesenteric vascular bed of rats.

This study investigated the endothelium-dependent vasorelaxant effects of the essential oil of Ocimum gratissimum (EOOG) in aortas and mesenteric vascular beds isolated from rats. EOOG (3-300 µg/mL) relaxed the tonic contractions induced by phenylephrine (0.1 µmol/L) in isolated aortas in a concentration-dependent manner in both endothelium-containing and endothelium-denuded preparations. This effect was partially reversed by L-NAME (100 µmol/L) but not by indomethacin (10 µmol/L) or TEA (5 mmol/L). In mesenteric vascular beds, bolus injections of EOOG (30, 50, 100, and 300 ng) decreased the perfusion pressure induced by noradrenaline (6 µmol/L) in endothelium-intact preparations but not in those treated with deoxycholate. L-NAME (300 µmol/L) but not TEA (1 mmol/L) or indomethacin (3 µmol/L) significantly reduced the vasodilatory response to EOOG at all of the doses tested. Our data showed that EOOG exerts a dose-dependent vasodilatory response in the resistance blood vessels of rat mesenteric vascular beds and in the capacitance blood vessel, the rat aorta. This action is completely dependent on endothelial nitric oxide (NO) release in the mesenteric vascular beds but only partially dependent on NO in the aorta. These novel effects of EOOG highlight interesting differences between resistance and capacitance blood vessels.

Antinociceptive activity of lectins from Diocleinae seeds on acetic acid-induced writhing test in mice.

Diocleinae lectins administered per oral route in mice inhibited the abdominal constrictions induced by acetic acid. The percentage of the lectins antinociception varied from 61% for Canavalia grandiflora (ConGf) to 20% for Dioclea violacea. ConGf inhibited contortions at all doses tested but not in a dose-dependent manner, involving carbohydrate recognition.

Pharmacological analysis of the neutrophil migration induced by D. rostrata lectin: involvement of cytokines and nitric oxide.

In the present study, we investigated the involvement of resident cell and inflammatory mediators in the neutrophil migration induced by chemotactic activity of a glucose/mannose-specific lectin isolated from Dioclea rostrata seeds (DrosL). Rats were injected i.p. with DrosL (125-1000 microg/cavity), and at 2-96 h thereafter the leukocyte counts in peritoneal fluid were determined. DrosL-induced a dose-dependent neutrophil migration accumulation, which reached maximal response at 24 h after injection and declines thereafter. The carbohydrate ligand nearly abolished the neutrophil influx. Pre-treatment of peritoneal cavities with thioglycolate which increases peritoneal macrophage numbers, enhanced neutrophil migration induced by DrosL by 303%. However, the reduction of peritoneal mast cell numbers by treatment of the cavities with compound 48/80 did not modify DrosL-induced neutrophil migration. The injection into peritoneal cavities of supernatants from macrophage cultures stimulated with DrosL (125, 250 and 500 microg/ml) induced neutrophil migration. In addition, DrosL treatment induced cytokines (TNF-alpha, IL-1beta and CINC-1) and NO release into the peritoneal cavity of rats. Finally, neutrophil chemotaxis assay in vitro showed that the lectin (15 and 31 microg/ml) induced neutrophil chemotaxis by even 180%. In conclusion, neutrophil migration induced by D. rostrata lectin occurs by way of the release of NO and cytokines such as IL-1beta, TNF-alpha and CINC-1.

Antinociceptive and anti-inflammatory effects of a mucin-binding agglutinin isolated from the red marine alga Hypnea cervicornis.

The agglutinin from the red marine alga Hypnea cervicornis (HCA) was tested in models of nociception and inflammation. The role of carbohydrate-binding sites and the systemic toxicity were assessed. HCA (10(-1), 1, and 10 mg/kg) administered i.v. to mice inhibited writhes induced by acetic acid and, at 10 mg/kg, inhibited the second phase of the formalin test, but did not alter the response latency in the hot-plate test. HCA (1 mg/kg) administered i.v. to rats reduced carrageenan-induced paw edema at 1, 2, and 3 h after challenge, but not edema induced by dextran. The neutrophil migration induced by both N-formyl-methionyl-leucyl-phenylalanine (fMLP) and carrageenan was inhibited by HCA at 10(-1), 1, and 10 mg/kg. The combination of HCA (1 mg/kg) and its ligand mucin reversed the lectin inhibitory effect on carrageenan-induced neutrophil migration and acetic acid-induced writhes. The i.v. treatment of rats with HCA (1 mg/kg) for 7 days did not affect body mass; liver, kidney or heart wet weight; blood leukocyte counts; urea, creatinine or serum transaminase activity; or macroscopy of the organs examined. In short, H. cervicornis agglutinin showed important antinociceptive and anti-inflammatory activity via interaction with the lectin carbohydrate-binding site.

Vatairea macrocarpa (Leguminosae) lectin activates cultured macrophages to release chemotactic mediators.

The lectin from the legume Vatairea macrocarpa is a galactose/N-acetylgalactosamine binding protein that induced cellular inflammatory response mediated by resident cells. This study investigated which inflammatory mediators would be released from lectin-activated cells. The intraperitoneal injection in rats of the supernatant from cultured macrophages, but not from mast cells, stimulated with lectin induced a time- and dose-dependent release of a neutrophil chemotactic factor, termed MNCF-VML. Pharmacological modulation with dexamethasone inhibited both the lectin-induced chemotactic activity in vivo and also the lectin-induced release of MNCF-VML into the supernatant of cultured macrophages. Cyclooxygenase and lipoxygenase metabolites are apparently not involved in the action of this factor or its release, since indomethacin or MK886 were unable to affect the lectin response. The molecular weight of MNCF-VML was found to be greater than 5 kDa, which led to the investigation of which cytokine(s) could be involved by the following approaches: (a) treatment of animals with antiserum to tumor necrosis factor alpha (TNF-alpha), interleukin (IL)-1, or IL-8 before intraperitoneal injection of lectin and (b) addition of antiserum to TNF-alpha, IL-1, or IL-8 to the supernatant of lectin-stimulated macrophages before intraperitoneal administration. Antiserum to TNF-alpha, but not IL-1 nor IL-8, inhibited the neutrophil migration induced either by lectin or MNCF-VML. Our data suggest that neutrophil migration induced by V. macrocarpa lectin occurs via the release of cytokines such as TNF-alpha by macrophages. Thus, this lectin may represent an important tool to better understand pathological situations where an excess of leukocytes at inflammatory sites causes tissue injury.

Modulation of acute inflammation by a chitin-binding lectin from Araucaria angustifolia seeds via mast cells.

The effects of a lectin (AaL) from seeds of Araucaria angustifolia were investigated in the model of rat paw edema. In vivo anti-and pro-inflammatory activities, role of sugar residues, inflammatory mediators and systemic toxicity were assessed. Intravenous injection of AaL (0.1-1 mg/kg) dose-dependently inhibited the dextran-induced increase in edema and vascular permeability, which were prevented by association of the lectin with its binding sugar N-acetyl-glucosamine (Glyc-Nac). AaL also significantly inhibited edema induced by serotonin (18%) and compound 48/80 (33%), but not edema induced by histamine. In contrast, when applied by the s.c. route, AaL evoked a paw edema that peaked 1 h later and was partially prevented by association with Glyc-Nac (59%) or by prior i.v. administration of the lectin itself (38.8%). This AaL edematogenic activity was significantly inhibited by pentoxifylline (44.4%) or dexamethasone (51%) and also by depletion of rat paw mast cells (45.6%), but not by L-N-nitro-arginine methyl ester or indomethacin, excluding involvement of nitric oxide and prostaglandins. Treatment of animals with a single anti-inflammatory dose of AaL (1 mg/kg, i.v.) for 7 days did not affect rat corporal mass, liver, kidney, spleen or stomach wet weight, blood leukocyte count, and urea, creatinine or serum transaminase activity. Systemic toxicity was apparent only at much higher doses (LD50=88.3 mg/kg) than those required for the anti-inflammatory effect. Summarizing, AaL exerts anti-and pro-edematogenic actions via interaction with its specific lectin domain. These actions may share a common pathway involving either activation or inhibition of inflammatory mediators from resident mast cells.