Antinociceptive Effects of an Ethanolic Extract of Capparis erythrocarpos Isert Roots in the Mice Formalin Test

Antinociceptive effect of an ethanolic extract of Capparis erythrocarpos Isert roots (10-300 mg kg-1; p.o.) was evaluated in the mouse formalin test. Morphine (1-10 mg kg-1; i.p.) was used as positive control. The extract dose-dependently reduced pain scores in both phases of formalin-induced nociception with the 100 mg kg-1 dose significantly reducing formalin-induced pain by 47.54±5.65 and 80.01±3.77% in the first and second phases, respectively. Naloxone (an opioid antagonist) did not block the antinociceptive effect of the extract in both the neurogenic phase and the inflammatory phase; however, theophylline (an adenosine antagonist) completely blocked the effect in the neurogenic phase and significantly inhibited the effect in the inflammatory phase. These findings demonstrate that the ethanolic extract of C. erythrocarpos roots has both central and peripheral antinociceptive effect with possible involvement of adenosinergic mechanism.