Alternanthera brasiliana (L.) Kuntze decreases pain and inflammation in acute colitis model without hepatotoxicity

Abstract

Objectives: To investigate antinociceptive and anti-inflammatory activities of the keto-alcoholic extract of A. brasiliana leaves in a mice model of acute colitis.

Methods: The experiments were performed in Swiss mice; the keto-alcoholic extract of A. brasiliana leaves was prepared and flavonoids were quantified. The antinociceptive/analgesic activity was evaluated by the writhing test. The keto-alcoholic extract of A. brasiliana, saline and Dipyrone monohydrate were tested. Acute colitis was induced by 7.5% (v/v) acetic acid intrarectally and the animals were treated, by gavage, with keto-alcoholic extract of A. brasiliana, saline and Mesalazine. After euthanasia, intestinal segments of the mice were analyzed by macroscopic index and quantification of colonic edema. The mechanical hyperalgesia test was performed after induction of acute colitis with acetic acid and treatment of the mice using the electronic Von Frey test. Hepatotoxicity of the keto-alcoholic extract of A. brasiliana was tested by plasma dosage of the aspartate transaminase (AST) and alanine transaminase (ALT) enzymes. Data were analyzed by ANOVA followed by Tukey post-test considering P < 0.05 as significant.

Results: In vivo results indicate that mice treated with the keto-alcoholic extract of A. brasiliana leaves at 100 and 300 mg/kg (0.872 and 2.616 mg total flavonoids/kg) showed a significant decrease in the number of writhing compared to the negative control. Between the two concentrations that were shown to be effective, no significant difference was observed. The Von Frey test points that mice treated with A. brasiliana extract at 30 (0.2616 mg of total flavonoids/kg), 100 and 300 mg/kg showed greater hyperalgesia. Regarding colitis, the mice treated with keto-alcoholic extract of A. brasiliana leaves at 10, 30, 100 and 300 mg/kg showed no lesions or lower-grade lesions when compared to the untreated group. In the quantification of edema no significant difference was observed among any experimental group. Plasma AST and ALT values were within normal reference values indicating no liver damage by the extract.

Conclusion: The keto-alcoholic extract of A. brasiliana shows antinociceptive/analgesic and anti-inflammatory activity in an acute colitis model in mice without causing hepatotoxicity in the mice.