AbstractOleaster (Elaeagnus angustifolia L.) is a plant with high medicinal value and economic and nutritional importance, which has been used in traditional medicine for a long time. Oleaster contains phenolic compounds that have the ability to prevent a wide variety of diseases. In this study antioxidant capacity, total phenolic content, and total carbohydrate content were found as 108.70 ± 0.20 μg GAE/g of oleaster extract, 28.80 ± 0.01 μg TE/g of oleaster extract, and 15.40 ± 0.01 mg D‐glucose/g of oleaster extract, respectively. The oleaster extract was analyzed using the HPLC‐DAD system. The results showed rutin, caffeic acid, protocatechuic acid, and ferulic acid. The protective abilities of rutin, caffeic acid, protocatechuic acid, ferulic acid, and oleaster extract were tested against the oxidation of DNA. The mix of phenolic compounds (inhibited about 93.29% of the damage) and oleaster extract (inhibited about 94.14% of the damage) showed better protect DNA against oxidation than phenolic compounds. The results obtained from this study are guiding for new applications involving the physicochemical properties of oleaster extract with high antioxidant properties for food applications.