Antinociceptive properties of bergenin.

Bergenin (1) is a C-glucoside of 4-O-methylgallic acid with known antiarthritic activity attributed to modulation of cytokine production. The present study was undertaken to evaluate whether 1 has antinociceptive properties in models of inflammatory pain and to investigate its possible mechanisms of action. Pretreatment with 1 (12.5-100 mg/kg, ip) produced a dose-related inhibition of acetic acid-induced writhing in mice. Furthermore, treatment with 1 (50 and 100 mg/kg) inhibited both the early and late phases in a formalin test. In addition, 1 (50 and 100 mg/kg, ip) inhibited mechanical hyperalgesia, edema, and paw production of hyperalgesic cytokines (TNF-α and IL-1β) induced by complete Freund's adjuvant. However, the local production of IL-10, an anti-inflammatory cytokine, was not altered by 1 (100 mg/kg, ip). Treatment with 1 produced a similar profile of antinociception in wild-type and IL-10-deficient mice. Mice treated with 1 did not show any motor performance alterations or apparent systemic toxicity. The results presented herein demonstrate that bergenin has consistent antinociceptive and anti-inflammatory properties, acting by the inhibition of IL-1β and TNF-α production, and suggest its potential for the control of inflammatory pain.