Avaliação da atividade gastroprotetora do extrato aquoso das folhas de Eugenia dysenterica DC. e Campomanesia pubescens O. Berg

Abstract

Eugenia dysenterica and Campomanesia pubescens (Myrtaceae), known in Brazil as cagaita and gabiroba , respectively, have been used by the general populace to treat some gastrointestinal disorders. Considering their folk uses and that many plants of the Myrtaceae family exhibit protective effects toward the gastric mucosa, we applied a taxonomic approach to select the E. dysenterica and Campomanesia pubescens leaf extracts to evaluate their gastroprotective effects. The abilities both extracts and carbenoxolone to protect the gastric mucosa from ethanol/HCl-induced lesions were evaluated in mice. The contributions of nitric oxide (NO), endogenous sulfhydryl (SH) groups and alterations in HCl production to the extract s gastroprotective effect were investigated. We also determined the antioxidant activity of the extract and the possible contribution of tannins to the cytoprotective effects. E. dysenterica extract, carbenoxolone, but not C. pubescens protected the gastric mucosa from ethanol/HCl-induced ulcers and the former also decreased HCl production. The blockage of SH groups by NEM, but not the inhibition of NO synthesis by L-NAME, abolished the gastroprotective action of E. dysenterica extract. Tannins are present in this extract, which was analysed by MALDI; the identified tannins by fragmentation pattern (MS/MS) are condensed, type B with the coupling until eleven flavan-3-ol units and predominantly comprised procyanidin and prodelphinidin. Partial withdraw of tannins from the extract abolished its cytoprotective actions. Finally, the extract exhibits free radical scavenger activity in vitro. Therefore, E. dysenterica, but not C. pubescens leaf extracts has gastroprotective effects that appear linked to the inhibition of HCl production, to its antioxidant activity and to endogenous SH-containing compounds. These pleotropic actions appear strictly related to the condensed tannins contained in the E. dysenterica leaf extracts.