Anti-oxidant activity of globe artichoke (Cynara scolymus)

Abstract

Cynara scolymus is rich in phytochemicals and bioactive compounds, that have attracted considerable scientific attention for their roles in disease prevention and health. In the present study, the aqueous (Aq.E) and ethanolic (Et.E) extracts of Cynara scolymus are obtained. The total contents of polyphenols and flavonoids were quantified using Folin-Ciocalteu and aluminum chloride (AlCl3) methods, respectively. Results showed that Et.E contains more polyphenols (27.82 ± 1.0 µg GAE/mg of dried extract) than Aq.E (13.28 ± 0.83 µg GAE/mg of dried extract). Similarly, the Et.E yielded higher flavonoid content (2.34 µg QE/mg of dried extract) than the Aq.E (1.37 µg QE/mg of dried extract). The antioxidant activity was evaluated, using the DPPH, H2O2 radical scavenging assays, the reducing power assay, and the AAPH-induced hemolysis assays. Results showed that both Et.E and Aq.E exerted a potent DPPH• scavenging effect. Indeed at 500 µg/mL, Et.E and Aq.E demonstrated 91.48% and 67.53% of DPPH• scavenging effect. At 400 µg/mL, both Et.E and Aq.E exerted a moderate scavenging effect against H2O2, with 56.50% and 30%, respectively. On other hand, the Et.E demonstrated a significant high reducing capacity with an effective concentration (EC50) = 154.11 ± 3.55 µg/mL compared to the Aq.E, which showed an EC50 = 423.52 ± 1.02 µg/mL. Furthermore, both extracts exerteda protective effect against AAPH-induced erythrocyte hemolysis. Indeed at 25 µg/mL, both Et.E and Aq.E protected erythrocyte hemolysis during all the time of experience, with high HT50 value (approximately 180 minutes), compared to the control. This protective effect was better than that obtained with ascorbic acid, used as standard. However at the highest concentration (50 µg/mL), Et.E maintained its maximum protective effect, while the activity of Aq.E decreases slightly. Despite this decrease the effect still significant. Taken to gather, Cynara scolymus bracts exhibits a good antioxidant effects, which may be due to the presence polyphenols and flavonoids. So, the globe artichoke by-products can be considered as promising source for natural antioxidants and it can recommend their use as food supplements and preservative agents.