Antioxidant properties of aqueous extracts of Selaginella willdenowii

Abstract

Selaginella willdenowii is a plant used as traditional medicine and vegetable in some Asian countries. Unlike other medicinally important Selaginella species, little is known about the pharmacological properties of S. willdenowii. This study was therefore conducted to evaluate the antioxidant properties of aqueous extracts of leaves and stems of S. willdenowii, both fresh and dried prepared with or without heat treatment. Total phenolic and flavonoid contents of the leaf extracts were consistently higher compared with stem extracts. Total phenolic and flavonoid contents of hot water extracts of fresh leaves were up to 4.4-fold and 10.7-fold higher, respectively, when compared with all other extracts. Radical scavenging and ferric reducing activities of the leaf extracts were also consistently higher compared with stem extracts. Trolox equivalent antioxidant capacity (TEAC) and ferric reducing antioxidant power (FRAP) of hot water extracts of fresh leaves were up to 5.5-fold and 5.3-fold higher, respectively, when compared with all other extracts. Correlation analysis revealed that total phenolic content is likely a key determinant of the radical scavenging and ferric reducing abilities in the leaf extracts. Overall, our findings affirm the value of S. willdenowii as a medicinal herb as well as a source of dietary antioxidant. Key words: Ferric reducing antioxidant power, flavonoids, free radical scavenging activities,phenolics, Selaginella willdenowii, trolox equivalent antioxidant capacity.