Phenolic content and Antioxidant activities of Algerian Echium plantagineum Extracts

Abstract

This study aims to explore the phenolic composition of aqueous (Aq E) and methanolic (Met E) extracts of Algerian Echium plantagineum aerial part and evaluate their antioxidant capacity. Methods: Total phenolics, flavonoids and tannins contents were determined by spectrophotometric methods using Folin-Ciocalteu, aluminium chloride and hemoglobin precipitation assays, respectively. The antioxidant activities were evaluated using several in vitro tests including reactive oxygen species (ABTS^., OH^., O₂^. and H₂O₂) scavenging assays, ferrous ions chelating test, reducing power and anti-hemolytic assays. Results: The phytochemical study revealed a predominance of tannins, total polyphenols and flavonoids in both extracts. Aq E showed more efficiency to scavenge ABTS^., O₂^. and OH^. radicals and to chelate ferrous ions. However, Met E was more efficient (IC₅₀=193.87μg/mL) in scavenging H₂O₂ than Aq E (IC₅₀=262.46μg/mL). In the same way, Met E inhibited AAPH induced hemolysis (HT₅₀₌179.79±5.82 min) more than Aq E (HT₅₀₌161.62±5.87 min). On the other hand, both Met E and Aq E exhibited very high reducing power (IC₅₀=117μg/mL and 128μg/mL, respectively). Conclusion: This study shows that Echium plantagineum extracts possess strong antioxidant activity, which is probably due to their phenolic composition. Therefore, this plant can constitute a promising source of natural antioxidants.