Purification of Phenylpropanoids from the Scaly Bulbs of by CPC and Determination of Their DPP-IV Inhibitory Potentials.

The scaly bulbs of (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, (2.9 mg, 75.8% purity at 320 nm), (12.2 mg, 97.9% purity at 320 nm), (3.1 mg, 66.5% purity at 320 nm), (6.8 mg, 96.9% purity at 320 nm), and (6.2 mg, 90.2% purity at 320 nm) were purified from 200 mg of the ethyl acetate fraction of 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---coumaroyl-2--β-glucopyranosylglycerol (regaloside D, ), 3,6'--diferuloylsucrose (), 1---coumaroyl-2--β-glucopyranosyl-3--acetylglycerol (regaloside B, ), 1---coumaroylglycerol (), and 4--acetyl-3,6'--diferuloylsucrose (), respectively, by H and C NMR and MS analysis. Compounds and exhibited DPP-IV inhibitory activities with IC values of 46.19 and 63.26 μM, respectively. Compounds , , and 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 by CPC and evaluation of their DPP-IV inhibitory activities.