Isolation and profiling of coumarin glycosides from the anti-hyperuricemic ethanol extract of mulberry (Morus alba L.) twigs (Chin.Ph.)

In Traditional Chinese Medicine (TCM) dried twig of Morus alba L. are extensively used as an antiasthmatic and antirheumatic agent. In order to identify constituents contributing to this activity, the raw drug was extracted twice with 60% ethanol under reflux for 2h. The resulting extract was evaporated to dryness under reduced pressure and subjected to column chromatography (ODS, gradient H₂O/MeOH (20:1, 10:1, 5:1, 1:1, 0:1, v/v)). The fraction eluted with 20% MeOH was subjected to HPLC/UV analysis, and then was analyzed by LC/ESI-MS (Xtimate XB-C18 column (5 µm, 4.6 × 250 mm); acetonitrile, water, methanol gradient; 1 ml/min; 25 °C; DAD 324nm). On the basis of the fragmentation behaviour of known coumarin glycosides isolated, one new compound, 6-hydroxyl-7-O-glucopyrano-xylopyranosyl coumarin (1), along with one known compound, 6,7-di-O-glucopyra-nosylaesculetin, were detected and identified. In addition to the mass spectral data, we also report NMR data for the two compounds which allowed the completion of their structural elucidation. Furthermore, the known constituents of Mori ramulus (Chin.Ph.) umbelliferone-7-β-D-apiofuranosyl-(1-> 6)-β-D-glucopyranoside, 7-[[6-O-(6-deoxy-α-L-mannopyranosyl)-β-D-glucopyranosyl]oxy]-2 H-1-benzopyran-2-one, Xeroboside, Scopolin, and 7-[(6-O-D-apio-β-D-furanosyl-β-D-glucopyranosyl)oxy]-5-hydroxy-2 H-1-benzopyran-2-one were rediscovered.

Fig. 1: 6-hydroxyl-7-O-glucopyrano-xylopyranosyl coumarin (1)

Keywords: Morus alba L., anti-hyperuricemic activity, coumarin glycosides.