In vitro and in vivo assessment of the anti-inflammatory activity of olive leaf extract in rats.

Inflammation is a complex and crucial process that protects the body against pathogens. Here in our study, we propose to scientifically justify the anti-inflammatory activity of olive leaf (OL). Initially, we ensured the safety of olive leaf extract (OLE) through acute oral administration of graded doses up to 4 g\kg in Wistar rats. Thus, the extract was considered generally safe. We also evaluated the ability of the extract to reduce carrageenan-induced rat paw edema. Compared to diclofenac sodium (10 mg/kg PO), OLE showed significant (P < 0.05) anti-inflammatory activity, showing the maximum inhibition percentage at the fifth hour of measurement at 42.31% and 46.99%, at doses of 200 and 400 m/kg, respectively, compared to 63.81% for the standard drug. To elucidate the potential mechanism, we measured TNF, IL-1, COX-2 and NO inside the paw tissue. Interestingly, OLE at all tested doses reduced the concentration of TNF and IL-1 to a level that was lower than that obtained by the standard drug. Additionally, OLE at the dose of 400 mg/kg reduced the levels of COX-2 and NO inside the paw tissue to a level that was statistically equivalent to the level observed in the normal control group. Finally, olive leaf extract at doses of 100, 200 and 400 mg/kg doses significantly (P < 0.05) inhibited the heat-induced hemolysis of RBCs membrane by 25.62, 57.40 and 73.88%, respectively, compared to 83.89% produced by aspirin. Consequently, we concluded that olive leaf extract has a significant anti-inflammatory activity through the reduction of TNF, IL-1, COX-2 and NO.