RESUMO
BACKGROUND: The present study covered an assessment of methanolic acetate fractions of Pistia stratiotes, commonly known as water lettuce, for analgesic, anti-inflammatory, and CNS depressant activities. METHODS: The methanol acetate fractions were extracted from Pistia stratiotes and administered to the experimental animals as 200 and 400 mg/kg doses to determine the effect on acetic acid-induced writhing and formalin-induced licking and biting, for the assessment of analgesic activity. The anti-inflammatory assay was done using the carrageenan-induced hind paw edema method, while assessment of CNS depressant activity was done using the open field and hole cross tests. The effects were compared to standard reference drugs. RESULTS: At both doses (200 and 400 mg/kg body weight), the methanolic acetate extract of P. stratiotes showed significant analgesic action (P < 0.05) against acetic acid-induced writhing. The extract was also found to give significant protection against licking and biting at both doses. The methanolic acetate extract of P. stratiotes showed a significant (P < 0.05) anti-inflammatory effect from 0 minutes up to 3 hours in the carrageenan-induced paw edema test. In the CNS depressant assay, the methanolic acetate extract showed significant (P < 0.05) depressant activity at both doses from 30 to 120 minutes in both the hole cross and open field tests. CONCLUSION: Thus we can conclude that P. stratiotes extracts have significant analgesic, anti-inflammatory, and CNS depressant activity, compared to standard compounds, in an animal model.