Chromatographic
analysis was performed on 20 × 10 cm silica gel 60 F254 plates
(Merck KGaA, Darmstadt, Germany) pre-washed with methanol and
activated at 100 °C for 30 min. The solvent system for separation was
chloroform/methanol/ddH2O (55/37/8, v/v/v). Briefly, 10 μL of standard
or sample was applied as 8 mm bands under a flow of nitrogen using a
HPTLC autosampler (ATS4, CAMAG AG, Muttenz, Switzerland).