Chemical constituents and biological activities of the aerial part of Stipagrostis ciliata (Desf.) De Winter, a perennial grass in North Africa

ABSTRACT

The main objective of this research work was to investigate active constituents and potential biological activities of Stipagrostis ciliata aerial parts, which may re-explore this plant as an important medicinal plant rather than being used only forage for animals. The results indicated that the total phenolic contents of the methanol, hexane and acetate leaf extract vary from 34.45 and 263.16 mg gallic acid equivalent (EAG)/g of extract. The highest concentrations of phenolics were found in the methanol extract. The results were suggestive that methanol extract is very rich in antioxidant compounds. The highest antioxidant activity was obtained in methanol extract. Stipagrostis ciliata ethyl acetate extract has an IC₅₀ from 0.3 μg/mL. The antibacterial activity of S. ciliata extracts against six bacterial strains showed varying degrees of inhibition on the tested strains. The methanol extract was found to be the most potent (8 to 20.41 mm) against most tested strains and Escherichia coli was the most vulnerable bacteria with a MIC value of 15 µgmL⁻¹. The Liquid Chromatography Electrospray Ionization Tandem Mass Spectrometric (LC-ESI-MS/MS) analyses of methanol and ethyl acetate fractions allowed the identification of six phenolic acids and six flavonoids. The present study shows that S. ciliata could be regarded as a promising plant source of bioactive phenolic compounds with good antioxidant and antibacterial activities.

Keywords
Antibacterial activity; antioxidant activity; flavonoids phenolic acids