RESUMEN
CONTEXT: Alternanthera brasiliana (L.) Kuntze (Amarantaceae) is widely used in Brazilian traditional medicine as an analgesic, anti-inflammatory and antibacterial. OBJECTIVE: To investigate the potential anti-inflammatory, analgesic, anxiolytic, and locomotor effect of the infusions in preclinical models. MATERIALS AND METHODS: Anti-inflammatory activity was evaluated by a carrageenan-induced pleurisy test in Wistar rats (200 and 400 mg/kg, n = 6-7). Analgesic activity was evaluated by the number of abdominal contractions induced by 0.6% acetic acid administered to Swiss mice (25, 50, 100, 200, and 400 mg/kg, n = 10). Effects on the central nervous system (CNS) were evaluated in Wistar rats (100, 200, and 400 mg/kg, n = 10) using open field and plus maze models. RESULTS AND DISCUSSION: Possible anti-inflammatory activity was indicated by the significant reduction of 19.8% for 200 mg/kg (p < 0.05) and 23.9% for 400 mg/kg (p < 0.05) of polymorphonuclear cells in pleural exudate. Analgesic activity was suggested by the significant reduction (p < 0.01) of number of abdominal contractions for all doses under study. No anxiolytic effect was noted, but there was an increase in the number of rearings in the group of rats treated with 100 mg/kg dose (p < 0.05). CONCLUSIONS: Our findings suggest that the aqueous extract of the leaves of A. brasiliana has a potential pharmacological effect on inflammation and pain.