The olive leaves (Olea europaea L.) have long been utilized for their various beneficial effects in the folk medication due to their various active phyto-constituents such as sterols, fatty acids, phenolics and flavonoids. Therefore, the study aimed to investigate the chemical composition of lipoidal and flavonoidal extracts from Egyptian olive leaves, as well as assaying the in vitro biological activities (antioxidant, scavenging, anti-diabetic, anti-Alzheimer and anti-arthritic activities).

It was found that 43 compounds (85.36%) were identified by GC/MS in petroleum ether O. europaea extract. Among these compounds, 10 unsaturated hydrocarbons, 9 saturated hydrocarbons, 9 fatty alcohols, 9 fatty acid methyl esters and 6 phytosterols were noticed. 𝛽-Sitosterol (1.53%), stigmasterol (1.02%), Δ5-avenasterol (0.96%) and campesterol (0.84%) have the greatest values. Furthermore, UPLC- MS/MS negative ion mode technique clarified the presence of 3 phenolic acids, 4 flavonoid aglycones, 8 flavonoid monoglycosides, 3 flavonoid diglycosides and two seco-iridoids in the methanolic O. europaea extract. It is worth to mention that both petroleum ether and methanol extracts of O. europaea leaves proved remarkable biological activities (antioxidant, scavenging, anti-diabetic, anti-Alzheimer and anti-arthritic activities) with significant effect of methanol extract more than that of petroleum ether one. Our findings proved that the biological activities could be attributed to the combination of lipoidal and flavonoidal constituents. The study concluded that the methanolic O. europaea extract contains more effective phyto-constituents and exhibited higher biological efficiency than petroleum ether one.