Anti-inflammatory and antinociceptive effect of the ethanolic extract of Alkanna frigida and Alkanna orientalis

The species of Alkanna is used in Iranian traditional medicine for treatment of rheumatoid arthritis and other inflammatory diseases. This study was designed to evaluate the anti-inflammatory and anti-nociceptive effects of Alkanna frigida and Alkanna orientalis ethanolic extracts via carrageenan-induced paw edema test and formalin test in rat and mice, respectively. Ethanolic extracts of plants root were prepared and were intraperitoneally injected 60 min before carrageenan-induced inflammation or formalin-induced nociception at 100, 200 and 400 mg/kg. Anti-inflammatory effects of plants were monitored during 3 h after carrageenan injection and anti-nociceptive effects of them were evaluated during the first hour after formalin injection. Diclofenac a well-known anti-inflammatory and anti-nociceptive agent was used as a positive control. Our results show in contrast to Alkanna orientalis, ethanolic extract of Alkanna frigida significantly decreases the carrageenan-induced inflammation at 400 mg/kg especially 3 h after inflammation induction. Both Alkanna frigida and Alkanna orientalis ethanolic extract possess a remarkable anti-nociceptive effect at each doses (100, 200 and 400 mg/kg) in a dose dependent manner during the first hour after formalin injection. The present finding provides more evidence for potential anti-nociceptive effect of Alkanna sp. and anti-inflammation effect of Alkanna frigida. It can describe the traditional indication of them in treatment of pain and inflammatory-related diseases. These useful effects can be resulted from inhibitory interaction of plant ethanolic extract with cyclooxygenase-2 enzyme and subsequently reduction in prostaglandins production.