2.12. Acetic Acid-Induced Writhing Test

Six groups of six mice each were used for this experiment. Four different groups received fraction samples, being 100 mg·kg⁻¹ of each fraction to one group (EEB, FHX, FCL, and FEA) by oral administration. The positive control group received indomethacin at a dosage of 10 mg·kg⁻¹, and the negative control group received the normal saline solution. After 60 minutes, all mice received an intraperitoneal injection of an acetic acid solution (1%, v/v in saline solution). The abdominal writhings were counted cumulatively during 20 minutes after the injection, and the total cumulative number in this period was taken as an indicator of the nociceptive response [25].