Analytical/preparative thin layer chromatography
The extracts and reference standards were applied on 60F254
silica gel TLC plates (Merck, Germany) with a Linomat III
autosampler (Camag, Switzerland). The plates were eluted in
saturated tanks (mobile phases are described in the legends to
figures), observed under UV 254 nm and sprayed with Dragendorff’s
reagent. When stated, the plates were treated by ammonia
vapors in a closed tank for 15 min prior to revelation with
Dragendorff’s reagent.