(6S)-Hydroxy-3-oxo-alpha-ionol glucosides from Capparis spinosa fruits.

Two new (6S)-hydroxy-3-oxo-alpha-ionol glucosides, together with corchoionoside C ((6S,9S)-roseoside) and a prenyl glucoside, were isolated from mature fruits of Capparis spinosa. The structures were established on the basis of spectroscopic, chiroptic and chemical evidence. In addition, the 13C-resonance of C-9 was found to be of particular diagnostic value in assigning the absolute configuration at that center in ionol glycosides. The alpha-ionol derivatives are metabolites of (+)-(S)-abscisic acid.