Identification and antioxidant activity of Ammi visnaga L. polyphenols from the Middle Atlas in Morocco

In this work, we are interested in both the study of the phenolic compounds and the evaluation of the antioxidant properties of the extracts of Ammi visnaga L. collected from the Middle Atlas in Morocco. Phytochemical screening was carried out to highlight the qualitative composition of the secondary metabolites contained in this plant. Also, the extraction of total polyphenols was carried out by maceration using hydromethanolic and hydroacetonic mixtures. Then, the fractionation of the crude extracts was conducted by liquid-liquid extraction using successively two organic solvents with different polarities: ethyl acetate and n-butanol. The polyphenols contents were spectrophotometrically estimated using the Folin-Ciocalteau method. It showed that the ethyl acetate fraction is more abundant in phenolic compounds than the other fractions. The qualitative analysis was performed by high-pressure liquid chromatography with U.V. and electrospray ionization coupled to mass spectrometry (HPLC/UV-ESI-MS), which confirmed the richness of this species in polyphenols and particularly in flavonoids, especially by the identification of kaempferol, rhamnetin, biochanin A, ammiol. These molecules belong to flavones, flavonols, and furochromones, which are also identified both in the form of genin and of heteroside. The antioxidant activity of the different fractions was evaluated by diphenyl-picryl-hydrazyl (DPPH●). The IC50 is equal to 12.87 μg / mL for the ethyl acetate fraction, against 8.8 μg / mL for ascorbic acid and 10.8 μg / mL for BHA which are used as reference compounds.