Polyphenolic Profile, Antioxidant and Antidiabetic Potential of Medlar (Mespilus germanica L.), Blackthorn (Prunus spinosa L.) and Common Hawthorn (Crataegus monogyna Jacq.) Fruit Extracts from Serbia

Plant-based food represents an excellent source of different nutrients and bioactive compounds, such as phenolics, carotenoids, vitamins, etc., with proven health benefits for humans. The content of selected phytochemicals, polyphenolic profile, and biological activity (antioxidant potential and alpha-glucosidase inhibitory activity) of fruit extracts of medlar (Mespilus germanica L.), blackthorn (Prunus spinosa L.), and common hawthorn (Crataegus monogyna Jacq.), the neglected Rosaceae species originated from Serbia were studied. Targeted UHPLC/(-)HESI-MS/MS quantitative analysis of phenolic compounds revealed pinocembrin only in medlar fruit extract, and it is the first report of this flavanone in medlar fruits. Total phenolic content did not differ between extracts, whereas significant differences were observed for the contents of total flavonoids, total phenolic acids, and total gallotannins. Monomeric anthocyanins and total anthocyanins were significantly higher in blackthorn compared to medlar and hawthorn fruit extracts (p < 0.05). DPPH center dot and ABTS(center dot+) scavenging activities for examined fruits were modest compared to other natural antioxidants and BHT. The most potent inhibitory activity toward alpha-glucosidase expressed medlar and blackthorn extracts with IC50 values of 129.46 and 199.84 mu g/mL, respectively, which was higher compared to the standard drug acarbose.