Etude phytochimique et recherche d’activité antioxydante des extraits enrichis en polyphénols des feuilles d’Inula viscosa

Abstract

Abstract Sticky fleabane (Inula viscosa), of the asteraceae family, is considered to be one of the most frequent and most used medicinal plants in traditional medicine in the region of the Mediterranean basin (Algeria, Morocco, etc.). It is popularly known as Magramane. This work concerns the study of phytochemical tests, dosage of phenolic compounds and evaluation of antioxidant activity, in vitro, by scavenging of the free radical DPPH. , by scavenging of the cation radical ABTS.+ and iron-reducing power FRAP tests, of crude watermethanol extract, its organic ethyl acetate fraction and the residual aqueous phase, prepared by infusion followed by maceration of the leaves of Inula viscosa. The results of phytochemical screening revealed the presence of tannins, flavonoids, free quinines, terpenoids and alkaloids, and the absence of saponins and anthraquinones. The dosage of phenolic compounds has shown the presence of flavonoids and polyphenols in all extracts studied with varying amounts from one extract to another. The highest contents of polyphenols and flavonoids were recorded by the ethyl acetate fraction (518 ± 47 μg EAG/ mg E and 491,9 ± 104,2 μg EC / mg E, respectively). The study of the anti-radical activity by the DPPH test and the ABTS test, showed that the extracts of this plant has an important anti-radical activity with IC50 of the order of 0,25±0,015 mg/ml for the inhibition of DPPH. and in the order of 0,16±0,012 mg/ml for the inhibition of ABTS˙+ . Better iron-reducing power (FRAP) was recorded by the residual aqueous phase with an EC50 of about 0,248 ±0,006 mg/ml. This activity remains largely lower compared to ascorbic acid (EC50 = 0,002 mg/ml). Key words: Inula viscosa, DPPH, ABTS, FRAP, phytochemical screening, Phenolic compounds, Antioxidant activity