Approach to develop a standardized TLC-DPPH• test for assessing free radical scavenging properties of selected phenolic compounds

TLC-DPPH center dot test belongs to a group of frequently performed assays aimed at detection of compounds with desired activity (effect directed analysis). Despite its popularity a standard procedure has not been elaborated so far causing difficulties in comparing results obtained in different laboratories. Thus the aim of the presented research was an approach to develop a standardized procedure for assessing free radical scavenging properties of plant polyphenols. It was observed that specifically positive adsorbent (silica gel) strengthened the observed result of radical-antioxidant reaction, while polar bonded stationary phase CN-silica weakened it. Based on the observed results it was concluded that the TLC-DPPH center dot assay should be preferably performed on the surface of non-specific adsorbents (e.g.: RP-18) with the use of n-hexane for DPPH center dot dissolution. It is also proposed to document the results every 5 min after staining, as they change in time. (C) 2012 Elsevier B.V. All rights reserved.