Abstract

Background: The use of plants for the treatment, cure and prevention of diseases is one of the oldest medicinal practices of humanity. These plants are able to produce much diversified natural compounds (e.g. alkaloids, polyphenols, etc.) which have many pharmaceutical applications.

Objective: The aim of the present study was to evaluate the antioxidant capacity and antibacterial activity of Zizyphus lotus extracts, which has been used traditionally in folk medicine of Algeria.

Methods: The leaves of plants were submitted to extraction by water and methanol to give methanolic (Met.E) and aqueous (Aq.E). The extracts were analyzed by HPLC-TOF/MS and their antioxidant activity was determined using DPPH and ABTS free radical-scavenging test, when the antibacterial activity was determined using disc diffusion method.

Results: The quantitative analysis of polyphenols and flavonoids content showed that the Met.E had the highest amount (562.04 µg EAG/mg E and 66.34 µg EQ/mg E, respectively). The HPLC-TOF/MS analysis of Met.E reveals the presence of two major compounds, rutin and gentisic acid, when Aq.E contain rutin and quercetin-3-β-D-glucoside as a major compound. Results showed that the Met.E exhibited the highest antiradical activity against DPPH and ABTS free radical with EC50=28.19±0.51 µg/mL, and EC50=3.82±0.03 µg/mL, respectively. Moreover, the Met. E of Z. lotus presents a moderate antibacterial activity against Staphylococcus aureus, Micrococcus luteus and Bacillus subtilis, with inhibition zone ranging from 09 to 13 mm. In addition, The Met.E showed a better MIC against M. luteus and B. subtilis (MIC= 25 µg/mL).

Conclusion: Our results showed that the methanolic extract of Z. lotus reported a considerable antioxidant and antibacterial activities which may be due to their richness on polyphenols and flavonoids.

Keywords: Antioxidant, antibacterial, Z. lotus, phenolic compounds, HPLC-TOF/MS, disc diffusion method, methanolic (Met.E) extract.

Graphical Abstract