The present study reports the antioxidant properties of Arbutus unedo L. leaf and fruit extracts using
different in vitro assays including (i) reducing power, (ii) scavenging effect on DPPH free radicals, and
(iii) inhibitory effect on AAPH-induced hemolysis and lipid peroxidation in human erythrocytes. All
assays demonstrated antioxidant efficiency for A. unedo L. aqueous extracts, being consistently higher
in the leaf. EC50 values for reducing power and DPPH radical scavenging activities were, respectively,
0.318 ± 0.007 and 0.087 ± 0.007 mg/mL for leaf, and 2.894 ± 0.049 and 0.790 ± 0.016 mg/mL for fruit
extracts. Under the oxidative action of AAPH, A. unedo leaf and fruit extracts protected the erythrocyte
membrane from hemolysis (IC50 of 0.062 ± 0.002 and 0.430 ± 0.091 mg/mL, respectively) and decreased
the levels of malondialdehyde, a breakdown product of lipid peroxidation (IC50 of 0.075 ± 0.014 and
0.732 ± 0.452 mg/mL, respectively). In accordance with antioxidant activity, phenolic content was found
to be significantly higher in leaf extract. To our knowledge, this is the first time that the antioxidant activity
of A. unedo species is evaluated using human biological membranes. Overall, our results suggest that A.
unedo leaves are a promising source of natural antioxidants with potential application in diseases mediated
by free radicals.
