The scaly bulbs of Lilium longiflorum (Liliaceae) are used as a food
ingredient and a traditional medicine
in East Asia. A preliminary study revealed that treatment with 100
μg/mL of the ethyl acetate fraction of this plant material inhibited
dipeptidyl peptidase IV (DPP-IV) to 58.99%. Phytochemical studies
were conducted to identify the active ingredient, and five compounds,
namely, 1 (2.9 mg, 75.8% purity at 320 nm), 2 (12.2 mg, 97.9% purity at 320 nm), 3 (3.1 mg, 66.5%
purity at 320 nm), 4 (6.8 mg, 96.9% purity at 320 nm),
and 5 (6.2 mg, 90.2% purity at 320 nm) were purified
from 200 mg of the ethyl acetate fraction of L. longiflorum via centrifugal partition chromatography (CPC) with a two-phase
solvent system composed of chloroform/methanol/isopropanol/water (5:2:2:4,
v/v/v/v) in an ascending mode. Their structures were identified as
1-O-p-coumaroyl-2-O-β-glucopyranosylglycerol (regaloside D, 1), 3,6′-O-diferuloylsucrose (2), 1-O-p-coumaroyl-2-O-β-glucopyranosyl-3-O-acetylglycerol (regaloside B, 3), 1-O-p-coumaroylglycerol (4),
and 4-O-acetyl-3,6′-O-diferuloylsucrose
(5), respectively, by 1H and 13C NMR and MS analysis. Compounds 2 and 5 exhibited DPP-IV inhibitory activities with IC50 values
of 46.19 and 63.26 μM, respectively. Compounds 1, 3, and 4 did not show activities, indicating
that biphenylpropanoids linked via the sugar moiety are more effective
than phenylpropanoids with glycerol or glyceryl glucoside. This is
the first report of simultaneous separation of five phenylpropanoids
from L. longiflorum by CPC and evaluation
of their DPP-IV inhibitory activities.
