Anti-inflammatory activity of Elaeagnus angustifolia fruit extract on rat paw edema

Abstract Background: The Elaeagnus angustifolia fruit has been traditionally used in Iranian herbal medicine to treat diarrhea and rheumatoid arthritis. In the present study, the effects of E. angustifolia fruit extract on the acute and chronic phases of formalin-induced rat paw edema were examined. Methods: The acute and chronic anti-inflammatory effects of E. angustifolia fruit extract were investigated through the subcutaneous injection of 100 μL of formalin (2.5%) into a rat’s hind paw. Thirty minutes before the procedure, the experimental groups were treated intraperitoneally with hydroalcoholic fruit extracts of E. angustifolia (concentrations of 100, 300, 700, and 1000 mg/kg); sodium salicylate (SS, 400 mg/kg) and distilled water were used as positive and negative control groups, respectively. Treatment with SS and the fruit extracts were performed daily for 8 days, and the degree of edema was measured by using mercury plethysmometer and digital caliper. Results: In the acute anti-inflammatory study, the extract showed a significant anti-inflammatory effect in a dose-dependent manner. The results of 1000 mg/kg of the extract was significantly different compared with the negative control group (p<0.05) and was comparable to sodium salicylate (p<0.05). Results from the chronic study suggested that E. angustifolia extract significantly reduced paw edema and inflammation in a dose-dependent manner. The results also showed that the measurement by digital caliper and mercury plethysmometer were both reliable and might be applied interchangeably (p<0.01). Phytochemical tests indicated that the hydroalcoholic fruit extract of E. angustifolia was positive for cardiac glycosides, flavonoids, terpenoids, and saponins. Conclusions: Based on our findings, the E. angustifolia fruit extract probably has acute and chronic anti-inflammatory activities to support its applications in folk medicine.