Rhododendrol glycosides and phenyl glucoside esters from inner bark of Betula pubescens

Abstract

A chemical investigation of the inner bark of Betula pubescens has led to the isolation of rhododendrin, epirhododendrin, apiosylrhododendrin and apiosylepirhododendrin. This is the first observation of both (+)- and (−)-rhododendrol glycosides in the same species. Also, the new compounds 3,4,5-trimethoxyphenyl-6- O-vanilloyl-β- d-glucopyranoside and 3,4,5-trimethoxyphenyl-6- O-syringoyl-β- d-glucopyranoside, and the known 4- O-β- d-glucoside of p-hydroxybenzoic acid, as well as (+)-catechin, catechin 7- O-β- d-xylopyranoside and B1 and B3 procyanidins were found.