Verbascum sinaiticum: A Rich Source of Antioxidant Phenylethanoid Glycosides

Background: The genus Verbascum is well documented for its antioxidant potential but Verbascum sinaiticum is comparatively less studied plant. The current study was carried out to search for antioxidant nutraceuticals from this species. Objective: To explore the antioxidant potential of Verbascum sinaiticum and to identify its active constituents. Method: The methanolic extract of air-dried aerial part of the Verbascum sinaiticum was partitioned with hexane, chloroform and ethyl acetate. The water-soluble part of ethyl acetate afforded six phenylethanoid glycosides by repeated chromatography over Sephadex LH-20, silica gel and ODS columns. Antioxidant activity of solvent extracts and isolated constituents were evaluated by DPPH, ABTS and FRAP assays. Results: Six phenylethanoid glycosides was isolated and characterized as Verbascoside, Eukovoside, Martynoside, Jionoside D, Campneoside I and Campneoside II, from the most active fraction. Conclusion: Verbascum sinaiticum demonstrated prospective antioxidant activity. The watersoluble part of EtOAc (WSEAE) was found the most active extract whereas Verbascoside was identified as the most potent constituent. All isolated compounds exhibited significant antioxidant activity whereas their synergistic effect was found prominent in the parent fraction.