The use of TLC-DPPH* test with image processing to study direct antioxidant activity of phenolic acid fractions of selected Lamiaceae family species.

TLC coupled with 2,2-diphenyl-1-picrylhydrazyl staining was used to analyze phenolic acid fractions of selected Salvia and Thymus species. Documented videoscans were processed by means of an image processing program. This is the first time that free phenolic acids fractions, as well as fractions containing phenolic acids derived from basic and acidic hydrolysis, have been analyzed and compared for selected sage and thyme species. The analyzed samples along with caffeic acid (CA; standard) were chromatographed on silica gel plates with toluene-ethyl acetate-formic acid (60 + 40 + 1, v/v/v) mobile phase. The extracts were investigated with respect to the activity of CA. It was found that CA was most abundant in the fractions derived from basic hydrolysis. This compound was not detected in any of the fractions obtained after acidic hydrolysis. S. officinalis and S. triloba have similar free radical scavenging activity fingerprints obtained for all the analyzed fractions.