Forsythiae Fructus obtained from an herbal market in Seoul, Korea, was extracted three times with hot MeOH (3 hours) and then evaporated at 40°C under reduced pressure to dryness. The MeOH extract was then resuspended in distilled water and successively partitioned with CHCl
3, EtOAc, and n-BuOH. The BuOH fraction was then loaded onto a silica gel column and eluted with MeOH-CHCl
3 mixtures (1:5 to 1:1). The result was white amorphous powders, which were identified as authentic samples using spectrometric data of nuclear magnetic resonance (
1H-NMR), mass spectrometry (MS).
1H-NMR (300 MHz), DMSO-d
6 : δ 6.97(1H, d,
J = 8.3, H-5), 6.82 (1H, d,
J = 8.0, H-5'), 6.77 (1H, d,
J = 1.7, H-2), 6.65 (1H, dd,
J = 8.3, 1.7, H-6), 6.65 (1H, s, H-2'), 6.59 (1H, dd,
J = 8.0, 1.8, H-6'), 4.83 (1H, d,
J = 7.3, H-1''), 4.00 (2H, m, H-9'), 3.70 (3H, s, OCH
3), 3.69 (6H, s, OCH
3), 2.76 (2H, m, H-7'), 2.54 (4H, m, H-7, 8, 8'). Positive FABMS (
m/z): 557 (M + Na
+), 372 (M + gluco), 154, 136. The white amorphous powder compound analyzed by NMR and MS was identified to arctiin (Figure
1A).