HPTLC determination of flavonoids and phenolic acids in some Croatian Stachys taxa

Stachys is a large genus belonging to the family Lamiaceae. In common with many other representatives of this family, the aerial parts of plants belonging to this genus have been used in folk medicine and phytotherapy for many years. The aim of this work was to determine the amounts of biologically active compounds (flavonoids and phenolic acids) present in seven Croatian Stachys taxa (S. alpina, S. officinalis, S. palustris, S. recta subsp. recta, S. recta subsp. subcrenata, S. salviifolia, and S. sylvatica). This was achieved by establishing an appropriate extraction procedure and by analyzing the samples by HPTLC with densitometric evaluation. Plant extracts and standard solutions of flavonoids and phenolic acids were applied to silica gel 60 F-254 HPTLC plates as 10 mm bands. Plates were developed in vertical glass chambers previously saturated with the mobile phase, ethyl acetate-acetic acid-formic acid-water, 100 + 11 + 11 + 26 (v/v). After drying and spraying with NP/PEG reagent, the bands were visualized under short and long-wavelength UV light. By use of standard solutions, RF values and fluorescence colors of the investigated compounds were determined. Concentrations of the standard solutions were adjusted to the amounts in the samples and again chromatographed with Stachys samples. The Camag Reprostar 3 Videosystem was used for quantitative evaluation. The compound occurring in most of the samples investigated was found to be chlorogenic acid (it was not present in S. recta subsp. recta only); isoquercitrin, luteolin 7-O glucoside, rutin, and quercitrin were present in several of the samples. Although S. recta subsp. recta did not contain chlorogenic acid, it was found to be richest in the flavonoids whose presence was determined.