Investigation of antiradical activity of plant material by thin-layer chromatography with image processing

A novel, easy, and cheap technique for preliminary quantitative evaluation of antiradical activity, based on HPTLC, has been proposed. This method combines chromatographic separation of polar compounds, present in plant extracts, with data analysis by means of image processing software. Bleaching of the purple DPPH colour, caused by substances with antiradical activity, was observed and recorded using a photo camera. ImageJ, a free and open source image processing program was used for quantitative measurements. For evaluation of assay efficiency, the antiradical activity of rose flower extracts (from Rosa rugosa Thunb.) was expressed as Standard Activity Coefficients (SACs), which are relative measures of the activity to the four well known antioxidants; i.e., quercetin, gallic acid, protocatechuic acid, and Trolox. The method uses small amounts of free radical and is easily applicable – only a digital camera with freely available open source software is required.