Estudo da atividade antinociceptiva e anti-inflamatória do extrato etanólico, frações e de uma epicatequina isolada da casca do caule da espécie Ximenia americana L. (OLACACEAE)

Abstract

Ximenia americana L. (Oleacaceae) is a plant used in folk medicine in several countries for the treatment of inflammation and pain. This work describes the antinocipeptive, antiinflammatory and antioxidant activities of the ethanolic extract, fractions (aqueous, acetate, hexane and chloroform) and an epicatechin (XACC-I) isolated from the stem bark of X. americana L. The activity antinociceptive was tested in several models: acetic acid-induced writhing, formalin test and hot plate test. In the writhing test of the extract, fractions and XACC-1 were able to induce inhibition of the number of constrictions in: ethanol extract (98.2 %), aqueous fraction (95.5 %), hexane fraction (92.3 %), chloroform fraction (99.5 %), acetate fraction (95.0%), and XACC-I (98.5%). Still utilizing this model the dose-response curve of XACC-I with a dose of 1-300 μmol/Kg was calculated, which showed an DI50 = 38.3 μmol/Kg, CL 95 %: 10.7 - 117.8 μmol/Kg and standard drug dipyrone showed an DI50 = 29.3 μmol/kg, CL 95 %: 22.7 - 75.4 μmol/Kg. In the formalin test the ethanolic extract of the aqueous fraction in the second phase of the experiment resulted in an inhibition time of paw licking in 82.4 and 73.7 % respectively, the chloroform fraction was able to induce inhibition of only early phase of the experiment by 31.5 % to XACCI inhibited the nociceptive response in neurogenic and inflammatory phase respectively in 64.2 % and 86.8 %. The ethanol extract, all fractions and XACC-I have not been active in hot plate test, which aims to evaluate the central antinociceptive activity. The anti-inflammatory action was investigated by test of peritonitis induced by zymosan A and carrageenan. In the test of the peritonitis induced by zymosan A, the ethanolic extract, acetate and aqueous fractions, the XACC-I and the standard drug indomethacin induced inhibition of cell recruitment by 41.4 %, 38.6 %, 35.1 %, 46.0 % and 55.7 % respectively. Using the carrageenan, the ethanolic extract, fractions (acetate, aqueous, chloroform and hexane), the XACC-I and the standard drug indomethacin induced inhibition of cell recruitment in 63.5 %, 55.9 %, 69,2 %, 35.8 %, 62.1 %, 66.1 % and 72.0 % respectively. Only the ethanol extract and hexane fraction did not induce the death of any animal, the acute toxicity of XACC-I have not been evaluated. In the test of DPPH (2,2-diphenyl-1-picrylhydrazyl) the ethanolic extract, all fractions and XACC-1 showed high antioxidant activity. The ethanolic extract, acetate and aqueous fractions showed high concentration of total phenols observed using the spectrophotometric assay with Folin-Ciocalteu. These results infer that the ethanol extract, fractions and XACC-I from the stem bark of X. americana are able to modulate the antinociceptive peripheral and acute inflammatory response.