Diastereomeric stilbene glucoside dimers from the bark of Norway spruce (Picea abies)

As part of a long-term study of the chemical defenses of Norway spruce (Picea abies) against herbivores and pathogens, a phytochemical survey of the phenolics in the bark was carried out. Eight stilbene glucoside dimers, designated as piceasides A-H (1a-4b), were isolated as four 1:1 mixtures of inseparable diastereomers. Their structures were determined by extensive spectroscopic means including 1D ((1)H and (13)C) and 2D NMR ((1)H-(1)H COSY, HSQC, HMBC, ROESY) spectra, and were supported by enzymatic hydrolysis and computational analysis. (c) 2007 Elsevier Ltd. All rights reserved.