Polysaccharide extract of Mimosa tenuiflora stem barks stimulates acute inflammatory response via nitric oxide/Extrato polissacaridico oriundo das cascas do caule de Mimosa tenuiflora induz resposta inflamatoria aguda via oxido nitrico

Mimosa tenuiflora (Mimosaceae) or "jurema-preta" is well distributed in the northeast Brazil, being popularly used to treat skin lesions, burns and inflammation. The healing effect of the alcoholic extract prepared with its barks corroborates the popular use. This study aimed to evaluate the inflammatory response of polysaccharides extracted from M. tenuiflora barks (EP-Mt) by methanol/NaOH and ethanol precipitation. Inflammatory activity was assessed in rat models of acute inflammation (paw edema and peritonitis), by the following parameters: edema, vascular permeability, leukocyte migration, myeloperoxidase activity and pharmacological modulation of nitric oxide and prostaglandins. EP-Mt presented 3.8% yield, 41% carbohydrate and 0.34% protein. EP-Mt (0.01, 0.1, 1.0 mg [kg.sup.-1]) injected by subcutaneous route elicited paw edema that lasted from 30-420 min, with maximal effect at 1 mg [kg.sup.-1] (40x vs. saline), and was inhibited by L-NAME (52%) and dexamethasone (26%). EP-Mt (1 mg [kg.sup.-1], via intraperitoneal) stimulated leukocytes migration (2.2x), mainly neutrophils (6.5x) and MPO activity (96%). The leukocyte migration elicited by EP-Mt was inhibited by dexamethasone (39%) and L-NAME (38%). EP-Mt containing high carbohydrate content induces acute inflammation via nitric oxide, which open perspectives of application in pathological conditions of immunosuppression. Keywords: Mimosaceae, medicinal plant, carbohydrate, inflammation. Mimosa tenuiflora (Mimosaceae) ou 'jurema-preta", amplamente distribuida no nordeste brasileiro, e utilizada popularmente no tratamento de lesoes de pele, queimaduras e inflamacao. O efeito cicatrizante do extrato alcoolico de suas cascas corrobora o uso popular. Avaliou-se o efeito inflamatorio dos polissacarideos da casca de M. tenuiflora (EP-Mt), obtidos por extracao com metanol/NaOH e precipitacao com etanol. O efeito inflamatorio foi avaliado em modelos agudos em ratos (edema de pata, peritonite) por meio dos seguintes parametros: edema, permeabilidade vascular, migracao leucocitaria, atividade da mieloperoxidase e modulacao farmacologica de prostaglandinas e oxido nitrico. EP-Mt apresentou 3,8% de rendimento, 41% de carboidratos totais e 0,34% de proteina. EP-Mt (0,01, 0,1, 1,0 mg [kg.sup.-1]), administrado por via subcutanea, induziu edema de pata com duracao de 30 a 420 min e efeito maximo na dose de 1 mg [kg.sup.-1] (40x vs. salina), o qual foi inibido por L-NAME (52%) e dexametasona (26%). EP-Mt (1 mg [kg.su