In vitro antioxidant and antibacterial activities of Citrus limon L. leaves extracts from two Algerian provenances

Abstract: An investigation was conducted to ascertain the impact of the geographical area on the biological properties of Citrus limon L., with the aim of evaluating its potential as a natural source of antioxidants and antibacterial agents. The study involved quantifying the total phenolic and flavonoid compounds in the leaves of C. limon L. collected from two Algerian regions (Chlef and Boumerdes). In vitro antioxidant activity of extract samples were assessed by radical scavenging DPPH and radical cation scavenging ABTS assays, followed by the evaluation of antibacterial activities against Staphylococcus aureus at different concentrations (200, 300 and 500 µg mL^-1) by aromatogram analyses. The results exhibited significant variation between plant provenances, with Chlef leaf sample extract being richer in total phenolic and flavonoid contents (72.51±3.05 mg QE g^-1 DM, 66.13 ± 2.25 mg GAE g ^-1 DM, respectively). In addition to its antioxidant properties, Chlef leaf extract also showed high antibacterial activity against S. aureus. Antioxidant tests showed the higher anti-free radical capacity with 86.62 ± 1.14 % and 95.87 ± 0.21 % inhibition rate values by DPPH and ABTS tests, correspondingly. A comparable scavenging capacity of Chlef leaf extract to that of Trolox activity was detected by DPPH test, with an IC₅₀ equal to 665.55 ± 4.19 µg TE mL^-1. Besides, this sample showed higher anti-free radical activity than the reference molecule by the ABTS. Furthermore, greater sensitivity of S. aureus to Chlef leaf extract was observed, with zones of inhibition superior to 10 mm. C. limon from Chlef (leaf) can be used as a source of natural antioxidants and antibacterial activity in different fields, especially medicinal applications and agri-foods.