Antioxidant activity of phenolic extracts from kenaf (Hibiscus Cannabinus) seedcake

Abstract

The antioxidant activities of kenaf seedcake methanolic extract (CME) and fractions obtained from it using ethyl acetate (EAF), hexane (HF) and water (WF) were investigated. Total phenolic contents were 64.5, 36.1, 31.3 and 14.6 mg gallic acid equivalent/g dry weight in EAF, CME, WF, and HF, respectively. Kenaf seedcake extract/fractions showed inhibitory activity of β-carotene bleaching and corn oil oxidation. Also, the extract/fractions were scavenged for the 1,1-diphenyl-2-picrylhydrazyl radical. The EAF extract showed the highest DPPH radical scavenging activity followed by the CME, WF and HF extracts. Therefore, the rich phenolic fractions of kenaf seedcake may represent a potential source of natural antioxidants. The predominant phenolic compounds identified by HPLC-DAD in CME and HF extracts were gallic, (1)-catechin, chlorogenic, hydroxybenzoic, syringic, and vanillin.