Abstract
Polyphenols, flavonoids, and tannins of Nabali Baladi olive leaves were extracted by using four different solvents (80 % methanol, 80 % ethanol, acetone, and distilled water). The total polyphenols were in the range of 158-392 mg gallic acid equivalent (GAE.g-1 extract, the total flavonoids were 11-71 mg rutin equivalent.g-1 extract, and the total tannins were 8-18 mg GAE.g-1 extract. The highest value of extraction was obtained with 80 % methanol and the lowest one was obtained with the distilled water. The antioxidant activity of the 80% ethanol olive leaf extract (OLE) was tested using DPPH (1,1-Diphenyl-2-Picryl-Hydrazyl) free radical scavenging activity, total antioxidant activity in the linoleic acid system, and protein oxidation by measuring the carbonyl content. The free radical scavenging activity of the 40-2800 µg OLE.mL-1 ranged between 9.62-93.15 %, with IC50 at 1082.35 µg.mL-1 . Inhibition of peroxides formation in the linoleic acid system reached 76.36 % using 2400 µg OLE.mL-1 after incubation for 108 hours. Inhibition of protein oxidation was 70.80-97.33 % using 50-2400 µg OLE.mL-1 . These results indicate the capacity of the Nabali Baladi OLE against lipid and protein oxidation, as well as the formation of free radicals which were dose dependent.
