Article info.

ABSTRACT

Received 08 Jul 2019
Revised 04 May 2020

Accepted 31 Mar 2020

The present study is aimed to investigate the total polyphenol and saponin contents, antioxidant and antibacterial activities of Melastoma malabathricum leaves extracts. These fractions were carried out using n-hexane, n-hexane:ethyl acetate (ratio 1:1), ethyl acetate and methanol solvents. The crude extract (CE) exhibited the highest amount of total polyphenol content by using the Folin-Ciocalteu assay. The n-hexane fraction (F1) showed the highest total saponin content which was determined by vanillin/H₂SO₄ method. The antioxidant activity of extracts was evaluated by using three different methods including DPPH radical scavenging assay, hydrogen peroxide assay (H₂O₂) and reducing power assay (Fe³⁺). The results showed that the activity of the methanol fraction (F4) against DPPH was the strongest, the CE extract was the highest reducing power and the ethyl acetate fraction (F3) illustrated the strongest antioxidant capacity through H₂O₂ assay. Furthermore, all extracts were also tested for the antibacterial activity by agar well diffusion method at a concentration of 100 mg/mL. F4 showed the highest activity against Escherichia coli and Staphylococcus aureus, while there were no significant differences among all extracts when testing with Lactobacillus acidophilus. These findings provide important evidence that there is a correlation between the polyphenol content and antioxidant capacity and antibacterial activity. Besides, the saponin content was no contribution to antioxidant and antibacterial abilities.

Keywords

Antibacterial, antioxidant, fraction, Melastoma malabathricum, polyphenol, saponin

Cited as: Duy, H.T., Thanh, N.V., Thuy, L.N., Uyen, N.T.N and Do, N.D., 2020. Determination of total polyphenol, saponin contents, antioxidant and antibacterial activities of Melastoma malabathricum leaves by liquid-liquid extraction. Can Tho University Journal of Science. 12(1): 8-15.