Determination of compounds in plant extract by HPLC
The method was adopted from one used and validated previously to determine similar compounds [11]. The aqueous extract was
dissolved in 50 % MeOH to give two solutions at 50 and 250 mg/mL. The three compounds 1, 2 and 4 were dissolved separately
in MeOH (50 mg/mL) and diluted to give solutions of 4.17, 8.33
and 16.67 mg/mL. The solutions were examined by HPLC: column: Lichrosorb RP-18 (Merck) (250 ” 4.6 mm I.D., 5 mm); mobile
phase: linear gradient MeOH : 0.5 % HOAc, 1 : 4 to 4 : 1, over 20
min; flow rate: 0.8 mL/min; detection: 266 nm (Waters 440 detector); injection: 20 mL. Calibration curves were drawn for the
three compounds so that their concentrations in the extract
could be determined.