Teneur en polyphénols et évaluation de l’activité antioxydante d’une plante médicinale

Abstract

Rhamnus alaternus L. (Imlilesse or Safir) is a medicinal plant used as an infusion for its digestive, antihypertensive, laxative, diuretic, hepatoprotective, and dermatological properties. The objective of the study was to evaluate the polyphenols and flavonoids content, and the antioxidant activity of aqueous and hydro-methanolic extracts. Polyphenols were quantified using the Folin-Ciocalteu method, flavonoids by complexation with aluminum chloride, and antioxidant activity by the DPPH and ABTS assays. The results show that the hydro-methanolic extract is richer in polyphenols than aqueous extract (182.06 ± 1.51 vs 177.59 ± 2.48 µg EAG) and flavonoids (39.86 ± 1.27 vs. 6.96 ± 0.74). It also exhibits superior antioxidant activity with lower IC₅₀ values (DPPH: 0.07 ± 0.001 vs. 0.187 ± 0.003 mg/mL; ABTS: 0.016 ± 0.001 vs. 0.388 ± 0.014 mg/mL). These results indicate a positive relationship between the richness in phenolic compounds, especially flavonoids, and the plant’s antioxidant potential.