Absolute configuration of epi-rhododendrin and (–)-rhododendrol [=(–)-betuligenol] and X-ray crystal and molecular structure of rhododendrin [= betuloside], a hepatoprotective constituent of Taxus baccata

Abstract

Rhododendrin (= betuloside) has been isolated from the leaves of Taxus baccata L. From its X-ray diffraction studies, the absolute configuration at the chiral centre in the aglucone portion has been found to be R. These results establish the stereochemical assignments to different samples of this glucoside isolated from different plants. Our sample of rhododendrin exhibited hepatoprotective activity against two hepatotoxins in rats.