Investigation on the bioactive properties of myrtle (Myrtus communis L.) berry

The bioactive properties of myrtle (Myrtus communis L.) in terms of total phenol, flavonoid content, antioxidant, inhibitory effect on diabetes-relevant enzymes, α-glycosidase and α-amylase, and antimicrobial activity were examined in this study. Four different solvents (water, methanol, ethyl acetat and hexane) were used in the extraction of bioactive compounds. The total polyphenol content of the berry extracts varied from 5.1 to 45.2 mg gallic acid equivalents/g with respect to the solvents used, while the total flavonoid content ranged between 2.3 to 11.6 mg/g in catechin equivalents. The highest total phenolics and flavonoid were found in aqueous extract. In the determination of antioxidant activity, the free radical scavenging effect (DPPH) of berry extracts ranged from EC50: 0.52 to 16.49 mg/mL, while the reducing power capacity (FRAP) of berry extracts varied from 39.5 to 173.2 mmol trolox equivalents/L. The antioxidant effect of aqueous extract was found to be the most potent in both antioxidant assays. α-glucosidase inhibition varied among extracts, from IC50: 0.7 to 44.7 μg/mL, while the α-amylase inhibition ranged from IC50: 8.7 to 44.92 μg/mL. The aqueous extract was the most effective in α-glucosidase inhibition, whereas methanolic extract was the strongest inhibitor against α-amylase. Of the myrtle berry extracts, only methanolic extract showed antimicrobial activity. The zone diameter of the methanolic extract formed in disc diffusion method was 15.5 mm for Escherichia coli and 12.5 mm for Staphylococcus aureus. The minimum inhibitory concentration (MIC) value was 9.58 mg / mL for both bacteria.