Isolation of powerful antioxidants from the medicinal halophyte Limoniastrum guyonianum

► Investigation of the antioxidant activity of the medicinal halophyte Limoniastrum guyonianum. ► Fractionation of the ethyl acetate partition by centrifugal partition chromatography. ► Isolation of the three highly active flavonoids using different antioxidant systems. The antioxidant capacities of the crude extract, aqueous and ethyl acetate partitions of Limoniastrum guyonianum Boiss. (Zita) were investigated in this study. The ethyl acetate phase exhibited a significant antioxidant activity as judged by total antioxidant activity, DPPH test and reducing power. Fractionation of this extract by centrifugal partition chromatography (CPC) using quaternary Arizona solvent systems composed of n-heptane/ethyl acetate/methanol/water led to ten fractions. The antioxidant capacities of these fractions were assessed using the same previous tests. Fraction 8 showed the highest antioxidant capacity (1291.1mg GAE/g DR), the power ability to quench DPPH radical (IC50=2μg/ml) and to reduce Fe3+ (EC50=65μg/ml). From this fraction, three powerful flavonoids were isolated (1–3): gallocatechin (1), epigallocatechin (2) and epigallocatechin-3-O-gallate (3). These findings suggest that the antioxidative property of L. guynianum is may be related to the presence of these flavonoids, which can be used in various industrial fields.