Antiulcer and Antioxidant Activity of a Lectin from Mucuna pruriens Seeds on Ethanol- induced Gastropathy: Involvement of Alpha-2 Adrenoceptors and Prostaglandins.

ETHNOPHARMACOLOGICAL RELEVANCE: Mucuna pruriens (Mp) belongs to Leguminosae family, it is native of tropical regions and used to treat several maladies such as urinary, neurological, and menstruation disorders, constipation, edema, fever, tuberculosis, ulcers, diabetes, arthritis, dysentery, and cardiovascular diseases. Mp seeds are rich in bioactive compounds, for instance, lectins, a heterogeneous group of proteins and glycoproteins with a potential role as therapeutic tools for several conditions, including gastric disorders. This study investigated the acute toxicity, gastroprotective, and antioxidant activities of a lectin from Mucuna pruriens seeds (MpLec) on ethanol-induced gastropathy model in mice. MATERIAL AND METHODS: Mice received MpLec (5 or 10 mg/kg; i.v.) and were observed for acute toxicity signs; in another experimental series, mice were pre-treated with MpLec (0.001; 0.01 or 0.1 mg/kg, i.v.), ranitidine (80 mg/kg, p.o.), or saline (0.3 mL/30g, i.v.) before ethanol 99.9% (0.2 mL/animal, p.o.), and euthanized 30 min after ethanol challenge. Macroscopic and microscopic gastric aspects, biochemical parameters (tissue hemoglobin levels, iron-induced lipid peroxidation, GSH content, SOD activity, and gastric mucosal PGE2) were measured. Additionally, pharmacological tools (yohimbine, indomethacin, naloxone, L-NAME) were opportunely used to clarify MpLec gastroprotective mechanisms of action. RESULTS: No toxicity signs nor death were observed at acute toxicity tests. MpLec reduced ethanol-induced gastric damage, edema, and hemorrhagic patches formation, as well as decreased lipid peroxidation, SOD activity, and increased GSH content. Yohimbine and indomethacin prevented MpLec effects, suggesting the involvement of alpha-2 adrenoceptors and prostaglandins in the MpLec-mediated effects. CONCLUSION: MpLec does not present toxicity signs and shows gastroprotective and antioxidant activities via alpha-2 adrenoceptors and prostaglandins in the ethanol-induced gastropathy model.

Antinociceptive, anti-inflammatory and toxicological evaluation of semi-synthetic molecules obtained from a benzyl-isothiocyanate isolated from Moringa oleifera Lam. in a temporomandibular joint inflammatory hypernociception model in rats.

Inflammation is a key component of many clinical conditions that affect the temporomandibular joint (TMJ) and Moringa oleifera Lam. has been used to treat inflammatory diseases. Here, we evaluated the toxicological effects on mice of a naturally-occurring isothiocyanate from M. oleifera and its seven analogue molecules. Further, the anti-nociceptive and anti-inflammatory effects on a rat model of TMJ inflammatory hypernociception were assessed. The systemic toxicological profile was determined in mice over a 14-day period: MC-1 1 µg/kg; MC-D1 1 µg/kg, MC-D3 100 µg/kg, MC-D6 1 µg/kg, MC-D7 1 µg/kg, MC-D8 1 µg/kg, MC-D9 10 µg/kg, and MC-H 1 µg/kg. The safest molecules were assayed for anti-nociceptive efficacy in the formalin (1.5%, 50 µL) and serotonin (255 mg) induced TMJ inflammatory hypernociception tests. The anti-inflammatory effect was evaluated through the vascular permeability assay using Evans blue. Further, the rota-rod test evaluated any motor impairment. Among the tested molecules, MC-D7, MC-D9, and MC-H were not toxic at the survival rate test, biochemical, and hystological analysis. They reduced the formalin-induced TMJ inflammatory hypernociception, but only MC-H decreased the serotonin-induced TMJ inflammation, suggesting an adrenergic receptor-dependent effect. They diminished the plasmatic extravasation, showing anti-inflammatory activity. At the rota-rod test, no difference was observed in comparison with control groups, reinforcing the hypothesis of anti-nociceptive effetc without motor impairment in animals. The analogues MC-D7, MC-D9, and MC-H were safe at the tested doses and efficient in reducing the formalin-induced TMJ hypernociception in rats. Our next steps include determining their mechanisms of anti-nociceptive action.

Heme oxygenase-1/biliverdin/carbon monoxide pathway downregulates hypernociception in rats by a mechanism dependent on cGMP/ATP-sensitive K+ channels.

OBJECTIVE AND DESIGN: To investigate the role of heme oxygenase-1 (HO-1), carbon monoxide (CO), and biliverdin (BVD) in the zymosan-induced TMJ arthritis in rats. MATERIALS AND METHODS: Mechanical threshold was assessed before and 4 h after TMJ arthritis induction in rats. Cell influx, myeloperoxidase activity, and histological changes were measured in the TMJ lavages and tissues. Trigeminal ganglion and periarticular tissues were used for HO-1, TNF-α, and IL-1ß mRNA time course expression and immunohistochemical analyses. Hemin (0.1, 0.3, or 1 mg kg-1), DMDC (0.025, 0.25, or 2.5 µmol kg-1), biliverdin (1, 3, or 10 mg kg-1), or ZnPP-IX (1, 3 or 9 mg kg-1) were injected (s.c.) 60 min before zymosan. ODQ (12.5 µmol kg-1; s.c.) or glibenclamide (10 mg kg-1; i.p.) was administered 1 h and 30 min prior to DMDC (2.5 µmol kg-1; s.c), respectively. RESULTS: Hemin (1 mg kg-1), DMDC (2.5 µmol kg-1), and BVD (10 mg kg-1) reduced hypernociception and leukocyte migration, which ZnPP (3 mg kg-1) enhanced. The effects of DMDC were counteracted by ODQ and glibenclamide. The HO-1, TNF-α, and IL-1ß mRNA expression and immunolabelling increased. CONCLUSIONS: HO-1/BVD/CO pathway activation provides anti-nociceptive and anti-inflammatory effects on the zymosan-induced TMJ hypernociception in rats.

Lectin from seeds of a Brazilian lima bean variety (Phaseolus lunatus L. var. cascavel) presents antioxidant, antitumour and gastroprotective activities.

Lectins are proteins able to interact specifically and reversibly with carbohydrates. They are present in all living beings, particularly in legume seeds, which have many biological functions. The aim of this study was to isolate, characterize and verify antioxidant, anti-hemolytic, antitumor and gastroprotective activities in a lectin present in seeds of Phaseolus lunatus L. var. cascavel (PLUN). The isolation of lectin was performed by size exclusion chromatography on Sephadex G-100, which was isolated from a protein capable of agglutinating only human erythrocytes type A, being this the only inhibited haemagglutination n-acetyl-d-galactosamine. Its weight was estimated by PAGE is 128kDa. The lectin is thermostable up to 80°C and is active between pH 2-11. As 8M urea was able to denature the lectin. PLUN is a glycoprotein consisting of 2% carbohydrate and has antioxidant action with ascorbic acid equivalent antioxidant capacity (µMAA/g) of 418.20, 326 and 82.9 for total antioxidant activity, ABTS radical capture and capture of DPPH radical, respectively. The lectin has antitumor activity against melanoma derived cells at doses of 100 and 50mg/ml, reducing up to 83% tumor cells, and gastroprotective action, reducing up to 63% damaged area of ​​the stomach induced by ethanol.

Αlpha-2 Adrenergic and Opioids Receptors Participation in Mice Gastroprotection of Abelmoschus esculentus Lectin.

Lectins are a heterogeneous group of proteins and glycoproteins with potential role as therapeutic and diagnostic tools to combat various diseases, besides some functions on human organism. Abelmoschus esculentus (Okra), a horticultural plant of African origin, is cultivated in northeastern Brazil, and used for different medicinal purposes. This work is aimed to elucidate the action mechanisms of Abelmoschus esculentus lectin (AEL) gastro protective effect on gastropathy induced by ethanol. Fasted mice treated with Ethanol 99.9% (0.2 ml/animal, p.o.) received previously AEL (0.01, 0.1, 1.0, 10 or 50 mg/kg, i.v.), saline (5 ml/kg; i.v.) or ranitidine (80 mg/kg, p.o.) in four experimental series, in which pharmacological tools (yohimbine, naloxone, L-NAME or indomethacin), were administered with the purpose of make clear possible molecular action mechanisms. Mice were euthanized 30 min after ethanol challenge to verify the stomach damages. Establishment of gastric oxidative stress, tissue hemoglobin (Hb) content and microscopic features (H&E) were taken in order to characterize the AEL gastro protective effect. AEL (1 mg/kg) was capable of protect mucosa against ethanol damages in presence of two (L-NAME and indomethacin) of four antagonists/inhibitors used. The AEL effect was reversed by naloxone and yohimbine, showing the involvement of opioids and Αlpha-2 adrenergic receptors on gastric protective effect of this lectin. Evaluation of microscopic features, oxidative stress, and Hb levels pointed the protective effects of AEL. This activity seems to be mediated by alpha-2 adrenergic and opioid receptors activation. Nitric oxide or prostaglandins were not involved. AEL simultaneously showed antioxidant effect that is probably implicated in its intricate defensive mechanism of action.