Phytochemical, antioxidant, antibacterial, and α-amylase inhibitory properties of different extracts from betel leaves

Antimicrobial and antioxidant activities, phenol content, and α-amylase inhibitory effects of a local variety of betel leaves were evaluated. The effects of various solvents (methanol, ethanol, acetone, and ethyl acetate) on phenols and antioxidant activities were also studied. Methanol and ethanol (90%) extracts showed maximum phenolic contents (205.2 and 202.9 mg GAE/g, respectively). Maximum flavonoid contents were determined using 90% acetone (82.5 mg CE/g), and the highest inhibition percentage of 2,2-diphenyl-1-picrylhydrazyl radical was exhibited by 90% ethanol (percent inhibition, 94%). α-Amylase activity assay showed that α-amylase inhibitory activities were positively correlated with the total phenolic content of ethanol and methanol. Considering antimicrobial activities, we found that all of the Gram-positive bacteria and Gram-negative bacteria were inhibited by betel leaf extract except Pseudomonas aeruginosa. Our results could provide a basis of future studies on betel leaves used in food and pharmaceutical applications.