Identification of phenolic compounds in polyphenols-rich extract of Malaysian cocoa powder using the HPLC-UV-ESI-MS/MS and probing their antioxidant properties

摘要

The antioxidant components of cocoa powder, which is rich in polyphenols, were isolated using column chromatography and high performance liquid chromatography. Polyphenolic compounds were then characterized by high-performance liquid chromatography/Ultraviolet and electronspray ionization-tandem mass spectrometry (HPLC-UV-/ESI-MS-MS). As a result, five phenolic compounds were detected. In this study we also investigated scavenging or the total antioxidant capacity (%) of cocoa polyphenol (CP) fractionated from cocoa powder extract. 114.0 mg/g of gallic acid-equivalent phenolics and 94.3 mg/g catechin-equivalent flavonoids were quantified in this extract. Their free radical-scavenging activity was assessed by 1, 1-diphenyl-2-picrylhydrazyl radical (DPPH) assay, beta-carotene bleaching test, and xanthine oxidase inhibitory activity (OX). Total antioxidant capacity (TAC) was further assessed against the myoglobin-induced oxidation of 6-hydroxy-2, 5, 7, 8-tetramethylchroman-2-carboxylic acid (ABTS) and expressed as Trolox equivalent. A high correlation between TAC and phenolic contents indicated that phenolic compounds from cocoa were a major contributor of antioxidant activity (0.967 <= r <= 1.00). CP extract had significantly (P < 0.05) potential antioxidant activities with various concentrations. These results suggest that Polyphenols-rich cocoa extract possess prominent medical properties and can be exploited as natural drug to treat free radical associated diseases.