Łukasz Cieśla1, Iwona Kowalska, Wiesław Oleszek, Anna Stochmal. 1. Department of Biochemistry and Crop Quality, Institute of Soil Science and Plant Cultivation-State Research Institute, 8 Czartoryskich Street, 24-100 Puławy, Poland. lukecarpenter@poczta.onet.pl
Abstract
INTRODUCTION: The structure of polyphenolic compounds influences their anti-oxidant potential. Finding a simple, rapid and reliable analytical method to study the structure-activity relationships for numerous samples is challenging. OBJECTIVE: To develop a simple thin-layer chromatography-2,2-diphenyl-1-picrylhdrazyl (TLC-DPPH˙) protocol with image processing to study the influence of the structure of polyphenols on observed direct anti-oxidant properties. METHODOLOGY: First, compounds exhibiting free radical scavenging activities were chosen from among the isolated compounds with the application of a rapid TLC dot-blot test. The active ones were further chromatographed on silica gel plates using the mobile phase: acetonitrile:water:chloroform:formic acid (60:15:10:5, v/v/v/v). Subsequently the plates were stained with DPPH˙ methanolic solution. An improved image processing protocol was used to quantitatively measure the polyphenols' activity. RESULTS: The application of a properly optimised chromatographic system enabled separation of the investigated compounds from dimethyl sulphoxide (DMSO) that influences the results of an anti-oxidant test. New solutions enabling better data processing are proposed. It has been discovered that acylation of flavonoid glycosides with hydroxycinnamic acids increases their direct anti-oxidant properties. Some of the analysed glycosides acylated with ferulic acid molecule were found to be the most potent free radical scavengers from among those analysed. The amount of sugar moieties as well as their type also influenced the observed activity. CONCLUSION: A simple, rapid and reliable TLC-DPPH˙ test with image processing has been developed enabling comparison of free radical scavenging activity of plant polyphenols. The influence of different structural features on the observed activity was measured successfully.
INTRODUCTION: The structure of polyphenolic compounds influences their anti-oxidant potential. Finding a simple, rapid and reliable analytical method to study the structure-activity relationships for numerous samples is challenging. OBJECTIVE: To develop a simple thin-layer chromatography-2,2-diphenyl-1-picrylhdrazyl (TLC-DPPH˙) protocol with image processing to study the influence of the structure of polyphenols on observed direct anti-oxidant properties. METHODOLOGY: First, compounds exhibiting free radical scavenging activities were chosen from among the isolated compounds with the application of a rapid TLC dot-blot test. The active ones were further chromatographed on silica gel plates using the mobile phase: acetonitrile:water:chloroform:formic acid (60:15:10:5, v/v/v/v). Subsequently the plates were stained with DPPH˙ methanolic solution. An improved image processing protocol was used to quantitatively measure the polyphenols' activity. RESULTS: The application of a properly optimised chromatographic system enabled separation of the investigated compounds from dimethyl sulphoxide (DMSO) that influences the results of an anti-oxidant test. New solutions enabling better data processing are proposed. It has been discovered that acylation of flavonoid glycosides with hydroxycinnamic acids increases their direct anti-oxidant properties. Some of the analysed glycosides acylated with ferulic acid molecule were found to be the most potent free radical scavengers from among those analysed. The amount of sugar moieties as well as their type also influenced the observed activity. CONCLUSION: A simple, rapid and reliable TLC-DPPH˙ test with image processing has been developed enabling comparison of free radical scavenging activity of plant polyphenols. The influence of different structural features on the observed activity was measured successfully.
Authors: Si Chen; Xiang Li; Xin Liu; Ning Wang; Qi An; Xi Mei Ye; Zi Tong Zhao; Meng Zhao; Yi Han; Ke Hui Ouyang; Wen Jun Wang Journal: Oxid Med Cell Longev Date: 2020-02-10 Impact factor: 6.543