Free radical-scavenging activity of phenolics by reversed-phase TLC

: Yrjonen T, Li PW, Summanen J, Hopia A, Vuorela H

Publisher: AMER OIL CHEMISTS SOC A O C S PRESS

: USA

: 2003

Journal of the American Oil Chemists' Society

: JOURNAL OF THE AMERICAN OIL CHEMISTS SOCIETY

: J AM OIL CHEM SOC

: 80

: 1

: 9

: 14

: 6

: 0003-021X

DOI: https://doi.org/10.1007/s11746-003-0642-z

A method was developed to measure the radical-scavenging activity of compounds separated by reversed-phase TLC (RP-TLC) using phenolic acids as model analytes. TLC separation was followed by dipping the plate in a 0.04% (wt/vol) solution of 1,1-diphenyl-2-picrylhydrazyl (DPPH) in methanol. The compounds possessing radical-scavenging activity were detected as bright yellow bands against a purple background. A video documentation system based on a CCD video camera was used for the detection and quantification of the activity. The developed RP-TLC-DPPH method was compared to the widely used spectrophotometric DPPH assay. The results obtained by the two methods correlated well, apart from syringic acid, ascorbic acid, and n-propyl gallate, which proved to be outliers in the regression analyses. The correlation coefficient, after excluding outliers, was r(2) = 0.923. The RP-TLC-DPPH method was applied for the measurement of free radical-scavenging activity of rapeseed meal fractions. A total of 10 separated zones with free radical-scavenging activity were detected, with R-f values ranging from 0.04 to 0.85. The results show that the method can be used for the effective fractionation and analysis of potential antioxidative compounds in natural extracts.

1,1-diphenyl-2-picrylhydrazyl, free radical scavenging activity, phenolic compounds, reversed-phase thinlayer chromatography