α-Glucosidase inhibitory constituents from Chrozophora plicata

Five new secondary metabolites have been isolated from Chrozophora plicata including an acacetin derivative (1), three pyrrole alkaloids plicatanins A-C (2-4, resp.) and the bilactone plicatanone (5). Together with these compounds, the known compounds, beta-sitosterol (6), methyl p-coumarate (7), 4-hydroxyphenylacetic acid (8), succinic acid (9), speranberculatine A (10), beta-sitosterol-3-O-beta-D-glucopyranoside (11) and apigenin-5-O-beta-D-glucopyranoside (12) have also been isolated. The structures of isolates 1-12 were established by 1D (H-1, C-13) and 2D NMR (HMQC, HMBC, COSY) spectroscopy and mass spectrometry (EIMS, HREIMS, FABMS, HRFABMS). The structure of plicatanin A (3) was further confirmed through single crystal X-ray technique. Compounds 1-12 were evaluated for their inhibitory activity against the enzyme yeast a-glucosidase. The compound 4 was found to be most potent with IC50 value 27.8 mu M. (C) 2013 Phytochemical Society of Europe. Published by Elsevier B.V. All rights reserved.