BACKGROUND AND OBJECTIVE: Medicinal plants as the rich source of efficient compounds are largely used worldwide especially to treat pain and inflammatory processes by the population in traditional medicine. The aim of this study was to investigate the antinociceptive effect of hydro-alcoholic extract of Biophytum sensivitum leaf on male rats.

METHODS: In this study, 42 adult male rats were divided into 7 groups: Control, groups treated with the extract (80, 100 and 300mg/kg, i.p.), Morphine (1mg/kg, i.p.), Aspirin (1mg/kg, i.p.), and Naloxone (1mg/kg, i.p.) with a dose of 300mg/kg. The analgesic effects of extract were assessed with Writhing, Tail-flick and Formalin tests.

FINDINGS: Hydro-alcoholic extract of Biophytum sensivitum leaf at dose of 300mg/kg clearly indicated the antinociceptive effect in Writhing (with 30 decrease), tail-flick (3/9 seconds increase) with p<0.01 and chronic phase of formalin (decrease of pain score from 2 to 0/6) (p<0.001) tests. The results showed that there was no significant difference between the morphine and receiving extract (300mg/kg) groups in the chronic phase of formalin. In addition, LD50 of plant extract was 3400mg/kg.

CONCLUSION: This study suggested that the hydro-alcoholic extract of Biophytum sensivitum leaf had the antinociceptive effects on both acute and chronic pains.