The effect of geographical region and harvesting date (seasonal change) on antioxidant activities (AA), total phenolic content (TPC) and total flavonoid content (TFC) of olive leaves obtained from different geographical regions of Palestine (north, middle, and south) at different maturation stages (June 2013, October 2013, and January 2014) was investigated in this study. Results revealed that both geographical region and maturation stage affect AA, TPC, and TFC of the olive leaves. Highest AA, TPC, and TFC were obtained for samples collected in June. TPC was found to be highest in north and lowest in south, while the highest AA, and TFC contents were alternating between north, middle, and south. During different maturation stages, TPC, TFC, and AA varied between 21.56 - 47.52 mg (GAE), 19.3 - 32.6 mg catechin equivalents, 318.53 – 1106.43 μmol FRAP equivalents per gram of dry olive leaves, respectively
