Two diastereomeric 3-oxo-α-ionol β-d-glucosides from raspberry fruit

From a methanolic extract of raspberry fruit two 3′-O-β-d-glucopyranosides of diastereomeric 4-(3′-hydroxy-1′-butenyl)-3,5,5-trimethyl-2-cyclohexen-1-one (3-oxo-α-ionol) were isolated by adsorption chromatography on XAD-2 followed by LC on Sephadex LH-20, MPLC on RP-18, and flash chromatography on silica gel as well as by HPLC on diol and RP-18 phases. Their structures were determined by 1H and 13C NMR spectroscopy. The absolute configurations of the diastereomeric aglycones were established as (6R,9R) and (6R,9S), respectively, by CD correlation as well as 1H NMR analysis of their corresponding (R)-(−)-α-phenylpropionic acid esters.