Research on extraction and determination of bioactive properties of quince (Cydonia oblonga) fruit

This paper examines the quince fruit's total phenolic substance amount, its total antioxidant amount, its α-glucosidase and α-amylase inhibitory effect which plays a critical role in diabetes disease and its bioactive features like antibacterial activity. Extract is obtained through water, methanol and ethyl acetate solvents. Total phenolic substance amounts of extracts are equal to gallic acid, varying between 7 and 8.2 mg/g. The highest phenolic substance amount is observed in methanol extract. Antioxidant activity of quince extracts is determined through free radical scavenging method (DPPH). Values vary between 44.6 and 96.8 mg/mL in accordance with this method. In line with Ferric Reducing Ability of Plasma (FRAP) method, they vary between 146.2 and 1867.2 mmol/L. The highest antioxidant activity is observed in water extract. α-glucosidase inhibitory effect is calculated in terms of IC50; IC50 values are calculated as 7.44 and 1.24 µg/mL in water and methanol extracts respectively. Water extract has the strongest effect in α-glucosidase inhibition. Again, water extract has a stronger effect in α-amylase inhibition. None of quince fruit extracts show antibacterial activity. The underlying reason of the above-stated conclusion is because zone diameter cannot be measured through disc diffusion method.