Isolation and characterization of xanthine oxidase inhibitory constituents of Pyrenacantha staudtii

Six compounds have been isolated from the leaves of Pyrenacantha staudtii, two of which are new compounds.  The new compounds have been characterized as kaempherol 3-O-β-rhamnopyranosyl (1®6)- β-D-glucopyranoside (1) and 4-β-glucopyranosyl-(2-furyl)-5-methy-l,2-glucopyranoside phenylmethanone (2).  The known compounds are 3-pyridinecarboxylic acid (3), β-sitosterol (4), sitosterol 3-O-β-glucopyranoside (5) and taraxerol (6).  Their structures were determined by spectroscopic and chemical evidences.  The two new compounds together with 3-pyridinecarboxylic acid showed significant in vitro xanthine oxidase inhibitory activity.  To the best of our knowledge, this is the first report of these compounds from this plant.