A pair of taxifolin-3-<i>O</i>-arabinofuranoside isomers from <i>Juglans regia</i> L.

<p>Diaphragma juglandis Fructus has been known for its effect on tonifying kidney in traditional Uighur medicine. During our ongoing studies on the discovery of biologically active compounds from folk medicine, a pair of flavanonol glycoside isomers named (2<i>S</i>,3<i>S</i>)-taxifolin-3-<i>O</i>-α-d-arabinofuranoside (<b>1</b>) and (2<i>S</i>,3<i>S</i>)-taxifolin-3-<i>O</i>-α-l-arabinofuranoside (<b>2</b>) were isolated, among them, <b>1</b> was a new compound. It is the first report of taxifolin-3-<i>O</i>-arabinofuranosides in both α-d and α-l configuration forms in genus <i>Juglans</i>. Their structures were determined on the basis of spectroscopic analysis and chemical evidence, in combination with circular dichroism.</p