Antioxidant potentials of the partitioned and vacuum liquid chromatographic fractions of Zea mays silk extract

Abstract

The aim of the study was to investigate the phytochemical and antioxidant activities of the fractions of methanol extract of Corn silk. The methanol extract of Corn silk obtained by cold maceration was subjected to solvent fractionated with organic solvents such as n-hexane, chloroform, ethyl acetate, and water. The fractions were subjected to DPPH and FRAP antioxidant assays at concentrations between 25-400 mg/mL. The active ethyl acetate fraction was subjected to vacuum liquid chromatographic fractionation accompanied by thin layer chromatographic analysis of the resulting ten (10) fractions, which were bulked into four sub-fractions, and were subjected to phytochemical screening and antioxidant assays (12.50-100 mg/mL). Phytochemical screening of the fractions showed variation in the presence of phytochemical groups based on solvent polarities. The ethyl acetate fraction, among the other fractions, showed the highest phenolic (83.20 ± 1.01 %) and flavonoid (69.49 ± 2.31%) contents as well as DPPH and FRAP scavenging activity of 91.30±1.94 and 71.05±4.01 % respectively, at the maximum concentration of 400 mg/mL. The vacuum liquid purification of the ethyl acetate fraction further increased the phenolic and flavonoid contents as well as the antioxidant activities. Among the sub-fractions, fractions 6 – 9 recorded highest phenolic (89.64 ±3.10 mg GAE/g), flavonoid (72.11±1.10 mg QUE/g) contents, as well as the highest DPPH (91.34±3.21 %) and FRAP (79.26±1.98 %) radical scavenging activities at 100 mg/mL. The ethyl acetate fraction of the Corn silk may be a potential natural antioxidant source for nutritional and pharmaceutical applications.