Anti-inflammatory effect of licorice (Licorice common) root extract on acute carrageenan-induced inflammation in rat

There are some evidences regarding anti-allergic and anti-inflammatory effects of Licorice common in traditional medicine and its usefulness in Diabetes mellitus and Diabetes insipidus and its stimulatory effect on admeocortical gland. This medicinal plant contains glycyrrhizin, sterogenic substances, cumarins, flavonoids, sterols, choline, asparagine and glaberin. Glycyrrhizin and glaberin have analgesic and anti- inflammatory effects. In this study, we evaluated the effect of licorice root extract on acute carrageenan-induced inflammation in the rat's hind paw as compared to anti- inflammatory effect of ibuprofen. For this purpose, adult male rats were divided into eight groups. Paw edema was induced by intraplantar injection of 0.1 ml of 0.5% carrageenan solution. Different doses of licorice root extract (50, l00, 200, 300 mg/kg, i.p.) and ibuprofen (12 mg/kg, i.p.) were given ten minutes before injection of carrageenan. Assessment of edema was performed by evaluation of volume change as determined by plethysmometry and extravasations of Evans blue dye as measured by spectrophotometry and changes in paw weight in test groups as compared to the control group. The results showed that the extract exerts a significant inhibitory effect on hind paw edema (volume) in a dose-dependent manner. In this respect, the maximum inhibition (54%) was achieved at a dose of 300 mg/kg of the extract and this dose was comparable to ibuprofen at a dose of 12 mg/kg. Meanwhile, the extract administration significantly reduced Evans blue content (100, 200 and 300 mg/kg) as compared to the control group. It could be concluded that licorice root extract is able to inhibit acute inflammatory response in the rat hind paw, and these effects are comparable to ibuprofen.