Comprehensive evaluation of the antioxidant capacity of Perilla frutescens leaves extract and isolation of free radical scavengers using step-wise HSCCC guided by DPPH-HPLC

Abstract

To comprehensively examine the antioxidant capacity of Perilla frutescens leaves extract, eight assays including hydroxyl radical, hydrogen peroxide, ferrous ion-chelating, total antioxidant capacity, nitric oxide, 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid), 2,2′-diphenyl-1-picrylhydrazyl, and ferrous reducing antioxidant assays were employed. The results indicated that the ethyl acetate–soluble fraction of P. frutescens leaves extract displayed the highest antioxidant activities. The antioxidant constituents from ethyl acetate–soluble fraction of P. frutescens leaves extract were screened by 2,2′-diphenyl-1-picrylhydrazyl high-performance liquid chromatography, and 11 compounds were identified after isolation using step-wise high-speed countercurrent chromatography. Protocatechuic acid, chlorogenic acid, caffeic acid, rosmarinic acid, luteolin, methyl-rosmarinic acid, apigenin, and 4′,5,7-trimethoxyflavone are the major antioxidant constituents in ethyl acetate–soluble fraction of P. frutescens leaves extract.