Total Phenolic Contents and Antioxidant Properties of Algerian Arbutus unedo L. Extracts

Arbutus unedo L. is a plant widely distributed in the Mediterranean basin and North Africa, frequently used in traditional folk medicine to treat diabetes and arterial hypertension. This study aims to evaluate the phenolic composition and antioxidant activity of ethyl acetate (EA.E) and n-butanolic (But.E) extracts prepared from leaves of Arbutus unedo. Total phenolic and flavonoids contents were determined spectrophotometrically. The antioxidant activity was evaluated using DPPH•, OH•, H2O2, O•-2, ß-carotene bleaching and AAPH-induced erythrocyte oxidative hemolysis assays. The phytochemical analysis showed the presence of polyphenols and flavonoids in both extracts. The high amount was observed in EA.E which exerted the stronger antioxidant effect, with IC50 values of 3.43 μg/mL, 323.45 µg/mL, 38.40 µg/mL and 11.56 µg/mL, in DPPH•, OH•, O•-2 and H2O2 tests, respectively. Both extracts inhibited β-carotene bleaching, but EA.E is always more potent (92%) than But.E (85%). Furthermore, the EA.E showed the highest protective effect on erythrocyte hemolysis induced by AAPH, with half time hemolysis (HT50) of 122.02 min at 40 µg/mL. Taken together, this study showed that Arbutus unedo leaf extracts possess strong antioxidant potential, which may be attributed to the presence of a high amount of polyphenolic constituents. So, this plant might be exploited as a potential source of natural antioxidant agents for pharmaceutical and food applications. Keywords: oxidative stress, antioxidant, phenolic compounds, Arbutus unedo