Avaliação da atividade e do mecanismo de ação antibacteriana e antiúlcera do extrato hidroetanólico de Piper umbellatum L.

Abstract

Piper umbellatum is a plant found in the Amazon region of Brazil and widely used in folk medicine of several countries for the treatment of gastric disorders and infections. The aim of this study was to evaluate the acute toxicity, antibacterial, preventive (gastroprotective) and curative (anti-ulcer) activites of hydroethanolic extract of the leaves of Piper umbellatum (HEPu), and still know the possible mechanisms involved in these activities. The leaves of Piper umbellatum were macerated in 75% hydroethanol solution (1:3, w/v) to obtain the HEPu. The acute toxicity of HEPu against CHO-K1 cells was evaluated by cytotoxicity assay with Alamar Blue and Hippocratic test using animals. The antibacterial activity was determined by the broth microdilution method using a panel of bacteria of clinical relevance and effects of HEPu the bacterial membrane was analyzed in detail. Preliminary phytochemical analysis based on coloration/precipitation were performed according to literature procedures. The secondary metabolites were analyzed and confirmed by thin layer chromatography (TLC) , spectrophotometry and high performance liquid chromatography (HPLC). The gastroprotective activity was assessed using the models of gastric ulcer acidified ethanol (acute) and acetic acid (chronic) in rodents Additionally, we evaluated the anti-Helicobacter pylori action of the extract. The probable mechanism of action of HEPu was also evaluated by determination of gastric secretory parameters, levels of antioxidant enzymes (catalase and glutathione) and malondialdehyde in gastric tissue, and proinflammatory cytokines (IL - 1β, TNF - α, IL -17, RANTES, IFN- γ and MIP-2 ) and antiinflammatory (IL -10). Piper umbellatum did not toxic in the in vitro cytotoxicity (IC50 > 200 µg/mL) test. When administered orally at doses up to 2000 mg/kg, HEPu did not cause any signs or symptoms of toxicity in mice. A good spectrum of antibacterial activity and mechanism of this action is associated with changes in the permeability of bacterial membranes was demonstrated. Preliminary phytochemical analysis revealed the presence of flavonoids, alkaloids, terpenes and steroids in extract. The flavonoids quercetin and rutin were detected in the spectrophotometric and HPLC analyzes. The results of antiulcer studies HEPu demonstrated potent gastroprotection against acute ulceration induced by acidified ethanol and excellent curative effect of chronic ulcers induced by acetic acid. The gastroprotection against acidified ethanol is partly attributable to the antioxidative mechanisms, while the anti-ulcer action contribute mechanisms antisecretory, antiinflammatory and regenerating the gastric mucosa. No part of this last action, the anti - Helicobacter pylori activity. The results of this study showed that the HEPu has preventive and curative effects on experimental models of gastric ulcers in animals. These effects are partially dependent antioxidants, antisecretory, anti- inflammatory and regenerative properties of the mucosa, and independent of anti-Helicobacter pylori activity, with the probable substances responsible for the pharmacological activity of flavonoids quercetin and rutin. These results confirm the popular use of the leaves of Piper umbellatum in the treatment of peptic ulcers and infections.