Determination of antioxidant activities of strawberry tree (Arbutus unedo L.) flowers and fruits at different ripening stages
Sebnem Selen Isbilir, Hakıme Hulya Orak, Hulya Yagar, Neslıhan Ekinci

Abstract. In this study, the antioxidant activities of Strawberry tree (Arbutus unedo L.) flowers at flowering period and fruits during ripening period were investigated, along with some ripening characteristics such as color, reducing sugar and acidity. Antioxidant activity characteristics were investigated using by the methods of DPPH (1,1-Diphenyl-2- -picryl-hydrazyl) scavenging activity, β-carotene bleaching, reducing power, metal chelating capacity, superoxide anion scavenging and hydrogen peroxide scavenging activity in water, ethanol and methanol extracts. The total phenolic content of flowers in water extracts was found to be 232.38 ± 7.19 mg GAE . g-1 extract, and the DPPH activity was 81.3 ± 0.49% at 50 µg·ml-1 concentration. In the ripening stages, the fully red fruits were determined higher antioxidant capacity than green and yellow fruits, except H2O2 scavenging activity which was highest in green fruit. In correlation study, the highest relationship was found between total phenolic content with reducing power (r2 = 0.987**, P < 0.01), while the lowest with H2O2 scavenging activity (r2 = 0.519*, P < 0.05).

Key words: DPPH scavenging activity, β-carotene bleaching activity, reducing power, correlations