Gastroprotective effects of N-acylarylhydrazone derivatives on ethanol-induced gastric lesions in mice are dependent on the NO/cGMP/KATP pathway.

The gastroprotective effects of N-acylarylhydrazone derivatives on ethanol-induced gastric lesions in mice were investigated with respect to the NO/cGMP/KATP pathway. To investigate our hypothesis, the mice were intraperitoneally pretreated with glibenclamide, L-NAME, or ODQ 30 min before treatment with DMSO, LASSBio-294 (1, 2, and 4 mg/kg, p.o.), LASSBio-897 (0.5, 1, and 2 mg/kg, p.o.), or omeprazole. After 1 h, the mice received absolute ethanol (4 ml/kg) by gavage to induce gastric mucosal lesions, and the microscopic and macroscopic parameters were evaluated. GSH (non-protein sulfhydryl groups) and MDA (malondialdehyde) concentrations, hemoglobin levels, nitric oxide production, myeloperoxidase (MPO) activity, and TNF-α and IL-1ß levels were also analyzed in the stomach after absolute ethanol administration. Pretreatment with LASSBio-294 or LASSBio-897 significantly reduced the microscopic and macroscopic lesion area. The compounds restored the GSH, MDA, and hemoglobin levels and reduced MPO activity. Moreover, the compounds significantly reduced nitrate and nitrite concentrations in the stomach samples after ethanol administration. Molecular docking studies revealed that LASSBio-294 and LASSBio-897 interact with active sites of the eNOS (endothelial nitric oxide synthase) enzymes through hydrogen bonds. LASSBio-294 and LASSBio-897 also reduced TNF-α and IL-1ß levels. It was observed that a NO synthase inhibitor, an ATP-sensitive potassium channel blocker, and a guanylate cyclase inhibitor significantly reversed the gastroprotective effects of these compounds. Thus, the gastroprotective effect of LASSBio-294 and LASSBio-897 against gastric lesions is mediated through the NO/cGMP cascade, followed by blocking of the KATP channels.

Relaxant effects of the essential oil of Mentha pulegium L. in rat isolated trachea and urinary bladder.

OBJECTIVES: We evaluated the relaxant activity of the essential oil of Mentha pulegium L. (EOMP) and pulegone in rat isolated tracheal and bladder smooth muscles. METHODS: ISOMETRIC contractions of isolated tracheal and bladder strips from male Wistar rats were induced by KCl (K60; 60 mm) or acetylcholine (ACh; 10 µm). EOMP and its majory compound pulegone were incubated, after contracting agent, with the tissues in cumulating concentrations. KEY FINDINGS: EOMP (3-300 µg/ml) inhibited the contractions induced by ACh and K60 in both tissues, but was more effective against the contractions induced by K60 in trachea (IC50 = 40.47 ± 3.27 µg/ml) compared with ACh. Its relaxant action rules out ganglia and NO participation. Pulegone (10(-7) to 10(-3 ) m) inhibited the contractions induced by ACh and K60 in both tissues. EOMP concentration-dependently inhibited the contractions evoked by addition of CaCl(2) in depolarised trachea, suggesting inhibition of extracellular calcium entry. CONCLUSIONS: These findings suggests that EOMP induced relaxant responses in pre-contracted smooth muscles of rat trachea and bladder, which are likely to be mediated via inhibition of calcium entry, mainly by its major compound, pulegone. These effects are coherent with the popular use of EOMP as an antispasmodic agent.

Antispasmodic effect of Mentha piperita essential oil on tracheal smooth muscle of rats.

AIM OF THE STUDY: Mentha piperita is a plant popularly known in Brazil as "hortelã-pimenta" whose essential oil is used in folk medicine for its anti-inflammatory, antispasmodic, expectorant actions and anti-congestive. Here, it was investigated the effect of Mentha piperita essential oil (peppermint oil) in rat tracheal rings along with its mechanism of action. MATERIALS AND METHODS: Tracheal tissue from male Wistar rats (250-300 g) were used. Peppermint oil was added in cumulative concentrations [1-300 microg/ml] to the tissue basal tonus or pre-contracted by carbachol [10 microM] at 10 min intervals, incubated or not with indomethacin [10 microM], L-N-metyl-nitro-arginine [100 microM], hexamethonium [500 microM], or tetraethylammonium [5 mM]. RESULTS: Peppermint oil [100 and 300 microg/ml] inhibited the contractions induced by carbachol, which was reversed by indomethacin, L-N-metyl-nitro-arginine and hexamethonium, but not by tetraethylammonium. These data suggest the participation of prostaglandin E(2), nitric oxide and autonomic ganglions in the peppermint oil relaxant effect and may be correlated with its popular use in respiratory diseases. CONCLUSIONS: Peppermint oil exhibited antispasmodic activity on rat trachea involving prostaglandins and nitric oxide synthase.

Structural analysis of Canavalia maritima and Canavalia gladiata lectins complexed with different dimannosides: new insights into the understanding of the structure-biological activity relationship in legume lectins.

Plant lectins, especially those purified from species of the Leguminosae family, represent the best studied group of carbohydrate-binding proteins. The legume lectins from Diocleinae subtribe are highly similar proteins that present significant differences in the potency/efficacy of their biological activities. The structural studies of the interactions between lectins and sugars may clarify the origin of the distinct biological activities observed in this high similar class of proteins. In this way, this work presents a crystallographic study of the ConM and CGL (agglutinins from Canavalia maritima and Canavalia gladiata, respectively) in the following complexes: ConM/CGL:Man(alpha1-2)Man(alpha1-O)Me, ConM/CGL:Man(alpha1-3)Man(alpha1-O)Me and ConM/CGL:Man(alpha1-4)Man(alpha1-O)Me, which crystallized in different conditions and space group from the native proteins. The structures were solved by molecular replacement, presenting satisfactory values for R(factor) and R(free). Comparisons between ConM, CGL and ConA (Canavalia ensiformis lectin) binding mode with the dimannosides in subject, presented different interactions patterns, which may account for a structural explanation of the distincts biological properties observed in the lectins of Diocleinae subtribe.

New crystal forms of Diocleinae lectins in the presence of different dimannosides.

Studying the interactions between lectins and sugars is important in order to explain the differences observed in the biological activities presented by the highly similar proteins of the Diocleinae subtribe. Here, the crystallization and preliminary X-ray data of Canavalia gladiata lectin (CGL) and C. maritima lectin (CML) complexed with Man(alpha1-2)Man(alpha1)OMe, Man(alpha1-3)Man(alpha1)OMe and Man(alpha1-4)Man(alpha1)OMe in two crystal forms [the complexes with Man(alpha1-3)Man(alpha1)OMe and Man(alpha1-4)Man(alpha1)OMe crystallized in space group P3(2) and those with Man(alpha1-2)Man(alpha1)OMe crystallized in space group I222], which differed from those of the native proteins (P2(1)2(1)2 for CML and C222 for CGL), are reported. The crystal complexes of ConA-like lectins with Man(alpha1-4)Man(alpha1)OMe are reported here for the first time.

Crystallization and preliminary X-ray diffraction analysis of the lectin from Dioclea rostrata Benth seeds.

Lectins from the Diocleinae subtribe (Leguminosae) are highly similar proteins that promote various biological activities with distinctly differing potencies. The structural basis for this experimental data is not yet fully understood. Dioclea rostrata lectin was purified and crystallized by hanging-drop vapour diffusion at 293 K. The crystal belongs to the orthorhombic space group I222, with unit-cell parameters a = 61.51, b = 88.22, c = 87.76 A. Assuming the presence of one monomer per asymmetric unit, the solvent content was estimated to be about 47.9%. A complete data set was collected at 1.87 A resolution.

Native crystal structure of a nitric oxide-releasing lectin from the seeds of Canavalia maritima.

Here, we report the crystallographic study of a lectin from Canavalia maritima seeds (ConM) and its relaxant activity on vascular smooth muscle, to provide new insights into the understanding of structure/function relationships of this class of proteins. ConM was crystallized and its structure determined by standard molecular replacement techniques. The amino acid residues, previously suggested incorrectly by manual sequencing, have now been determined as I17, I53, S129, S134, G144, S164, P165, S187, V190, S169, T196, and S202. Analysis of the structure indicated a dimer in the asymmetric unit, two metal binding sites per monomer, and loops involved in the molecular oligomerization. These confer 98% similarity between ConM and other previously described lectins, derived from Canavalia ensiformis and Canavalia brasiliensis. Our functional data indicate that ConM exerts a concentration-dependent relaxant action on isolated aortic rings that probably occurs via an interaction with a specific lectin-binding site on the endothelium, resulting in a release of nitric oxide.