تعیین فعالیت آنتی اکسیدانی عصاره های فنولی میوه یک واریته بلوط ایرانی (Q.castaneifolia var. castaneifolia)

In this study, phenolic compounds of acorns (Q.castaneifolia var castaneifolia) were extracted with water and ethanol (70%). Total phenolic content of water and ethanolic (Et) extracts were 238.85 and 142.18 mg TAE/gr dried extracts, respectively. Antioxidant activity was evaluated using three different methods: including scavenging effect on DPPH radicals, reducing power of Fe⁺³ and total antioxidant capacity. The results were compared with synthetic antioxidant, BHA and BHT. In all the methods, the antioxidant activity was concentration dependent. Ethanolic extract of Q.castaneifolia was the highest in DPPH assay (EC50=34.28 µg/ml). In the reducing power and total antioxidant capacity, BHT obtained the best results followed by ethanolic extract , BHA and water extract. Also, the protective effect of ethanolic extract in stabilizing sunflower oil was tested. Ethanolic extract of acorn at three different concentrations, i.e. 250 (Et-250), 500 (ET-500) and 1000 ppm (Et-1000) was added to sunflower oil. BHA and BHT at 100 and 200 ppm were chosed as standards along with the control. All samples were incubated in open beakers at 70°C in the dark for 12 days. The peroxide and tiobarbitoric acid values of the samples were determined at definite time intervals of 0, 2, 4, 6, 8, 10 and 12 days. Results showed that ethanolic extract at all concentration retarded the retarded the oil oxidation. Et-1000ppm and Et-500 ppm exhibited stronger antioxidant activity compared to BHT-200 and Et-250 was better than BHA-100.