A pair of taxifolin-3-O-arabinofuranoside isomers from Juglans regia L.

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 (2S,3S)-taxifolin-3-O-α-d-arabinofuranoside (1) and (2S,3S)-taxifolin-3-O-α-l-arabinofuranoside (2) were isolated, among them, 1 was a new compound. It is the first report of taxifolin-3-O-arabinofuranosides in both α-d and α-l configuration forms in genus Juglans. Their structures were determined on the basis of spectroscopic analysis and chemical evidence, in combination with circular dichroism.