Physicochemical characterization and antinociceptive and anti-inflammatory activities of
atranorin (AT) extracted from Cladina kalbii Ahti in
formalin- and
capsaicin-induced
orofacial pain and anti-inflammatory tests in rodents were studied. Physicochemical characterization showed that AT has the general formula C19H18O8. Male Swiss mice were pretreated with AT (100, 200, and 400 mg/kg, i.p.),
morphine (3 mg/kg, i.p.), or vehicle (
0.9% saline with two drops of 0.2%
Tween 80) before
formalin (20 microl, 2%) or
capsaicin (20 microl, 2.5 microg) were injected into the right vibrissa. Our results showed that i.p. treatment with AT displayed marked inhibitory effects in different
orofacial pain tests in mice. AT (400 mg/kg, i.p.) was effective in reducing the nociceptive face-rubbing behavioural response in both phases of the
formalin test, which was also
naloxone-sensitive. Additionally, AT produced a significant antinociceptive effect at all doses in the
capsaicin test. Such results were unlikely to be provoked by motor abnormality, since AT-treated mice exhibited no performance alteration on the rota rod apparatus. AT exhibited significant anti-inflammatory activity in the acute model of
inflammation (leukocyte migration to the peritoneal cavity),
carrageenan- and
arachidonic acid-induced hind paw
edema in rats. Additionally, AT exhibited a dose-dependent
antioxidant activity in vitro, as assessed by total radical-trapping
antioxidant parameter and total
antioxidant reactivity assays. All these findings suggest that AT might represent an important tool for the management of
orofacial pain and/or inflammatory disorders.