4. Conclusion
The current results showed that themethanolic extracts from blueberry leaves had the highest levels of total phenolic contents, tannins and DPPH capacity as well as the lowest RF, while the largest RF and ORAC values were found in 50% ethanol extracts. Among 9 phenolic compounds identified by HPLC, ferulic acids, quercetin and kaempferol were not detected in 95% ethanol extracts. Quercetin and kaempferol were not found in acetone extracts. The methanol extracts had no ferulic acids and kaempferol. Good correlations were found between antioxidant activities (DPPH, RP and ORAC) and active compounds (tannin and TPC) contents. All extracts (except for 95% ethanol for L.monocytogenes) were active against Gram-positive bacteria, Gram-negative bacteria and fungi in this study. The 50% ethanol extracts showed the highest inhibitory effects against S. aureus and the lowest MIC against all the bacteria. Both 95% ethanol and methanol extracts demonstrated the greatest inhibition zone and the smallest MIC for fungi. The current study indicated blueberry leaves have favorable antioxidant and antimicrobial potential and could be a good source of natural antioxidants and antimicrobials. More research in the future is required to investigate the effects of plant ripeness, extracted parameters (such as solvent concentration, temperature, time) on the functionalities of the extracts and the stability of extract methods.