Functional Properties of Fruits of Common Medlar (Mespilus germanica L.) Extract

Common medlar (Mespilus germanica L.) is a long-lived plant with hard fruits, which are harvested in the fall and stored in cold and dark places. The aim of the work was to obtain the extract from freeze-dried fruits of medlar. Then, the samples were purified on a column with Amberlite XAD-16 ion exchange resin (two fractions were obtained and tested in further steps: methanol (MF) and water (WF)). A quantitative analysis of the polyphenolic compounds and selected elements was performed. In addition, in vitro tests of antidiabetic and antioxidant activity of the extracts were carried out. The applied methodology included the determination of antidiabetic activity by diffusion method, antioxidant activity by ABTS and FRAP methods, elemental analysisby atomic spectrometry, and quantitative and qualitative determination of phenolic composition by UPLC method. The highest antioxidant activity was observed in the MF of the medlar preparation, which was 245.31 μM Trolox/g (in ABTS test). Both fractions showed positive antidiabetic effects. For WF, even a small concentration of 1 mg/mL DMSO, the percentage of α-amylase inhibition was 35%. The WF dominated in terms of the total content of phenolic compounds (mainly gallic, procatechic, chlorogenic, and ferulic acids).