Direct determination of polydatin and its metabolite in rat excrement samples by high-performance liquid chromatography.

Simultaneous determination of polydatin and its metabolite in excrement samples using high-performance liquid chromatography (HPLC) with UV detection was accomplished. After extracted them by C18 solid phase extraction, the samples were separated on a reversed-phase column. Detection wave-lengths were set at 306 nm. The separation was carried out with a gradient elution. The mobile phase was acetonitrile-water (containing 0.1% formic acid) at a flow rate of 1.0 ml.min(-1). The identities of the peaks were accomplished by comparing retention times, UV and mass data with reference compounds under the same conditions. The standard curve was rectilinear in the range of 0.803-642.6 microg x ml(-1) (r=1.0000) for polydatin, 0.407-325.8 microg x ml(-1) (r=1.0000) for resveratrol. The recoveries of the markers listed above were 102.2% and 97.3%, respectively. The verified method can be used to determine the contents of two compounds in samples of stomach, small intestine, caecum, and large intestine (including excrement) of rats fed with polydatin. The analytical results demonstrated that the metabolism of polydatin is mainly processed in the intestines; polydatin can be transformed into resveratrol by de-sugaring process.