The isolation and structure identification of four Lignan’s stereoisomers from Uncaria sinensis (Oliv. ) Havil.

Abstract

The study of the chemical constituents from Uncaria sinensis (oliv.) Havil. has resulted in the isolation and identification of four stereosturcture of lignans, which were identified as: (2R,3R,4S)-lyoniresinol-3α-O-β-D-glucopyranoside (1); (2S,3S,4R)-lyoniresinol-3α-O-β-D-glucopyranoside (2); (2S,3R,4S)-lyoniresinol-3α-O-β-D-glucopyranoside (3); (2R,3S,4R)-lyoniresinol-3α-O-β-D-glucopyranoside (4). All these four compounds were obtained from theUncaria genus for the first time. The compounds were individually identified by one-dimensional (1D), two-dimensional (2D) nuclear magnetic resonance (NMR) and mass spectrometry (MS) spectral analyses and comparisons with reported data, and their absolute stereosturcture were identified by the helicity rule of exciton coupled circular dichroism for the first time. The study also constitutes a method of the identification of absolute stereosturcture by the helicity rule of exciton coupled circular dichroism for the first time. Key words: Uncaria sinensis (oliv.) Havil., Rubiaceae, natural products, lignans, the helicity rule.