Anti-inflammatory and anti-nociceptive effects of the ethanolic extracts of Alkanna frigida and Alkanna orientalis.

Alkanna species are 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 the carrageenan-induced paw edema test and formalin test in rat and mouse, respectively. Ethanolic extracts of plant root were prepared and were injected intraperitoneally 60 min before carrageenan-induced inflammation or formalin-induced nociception at 100, 200 and 400 mg/kg. Anti-inflammatory effects of plants were monitored for 3 h after carrageenan injection and anti-nociceptive effects 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 that, in contrast to Alkanna orientalis, ethanolic extract of Alkanna frigida significantly decreases carrageenan-induced inflammation at 400 mg/kg, especially 3 h after inflammation induction. Both Alkanna frigida and Alkanna orientalis ethanolic extracts possess a remarkable anti-nociceptive effect at each dose (100, 200 and 400 mg/kg) in a dose-dependent manner during the first hour after formalin injection.The present findings provide more evidence for the potential anti-nociceptive effect of Alkanna sp. and the anti-inflammatory effect of Alkanna frigida. It supports their traditional indication in the treatment of pain and inflammatory-related diseases. These useful effects may result from the inhibitory interaction of the plant ethanolic extract with cyclooxygenase-2 enzyme and the subsequent reduction in prostaglandin production.