TLC ANALYSIS TO DETERMINE THE SEASONAL DEPENDENCE OF THE LEVEL OF 20-HYDROXYECDYSONE IN THE LEAVES OF SERRATULA-TINCTORIA (L)

A quantitative method has been developed for determination of the 20-h ydroxyecdysone content of Serratula tinctoria (L.), Thin-layer chromat ography on silica was performed in two consecutive steps; the first wa s with chloroform - ethanol and the separation was completed with chlo roform - methanol - benzene. Plant samples of different phenophases we re collected in 1994, ecdysteroids were extracted, and, after a clean- up procedure, the 20-hydroxyecdysone content was determined by TLC - d ensitometry.