Tissue distribution and excretion of resveratrol in rat after oral administration of Polygonum cuspidatum extract (PCE)

Abstract

Polygonum cuspidatum extract as a traditional Chinese medicine is extracted from the dried rhizome and root of Polygonum cuspidatum Sieb.et Zucc. Resveratrol is one of its active components. Studies were performed in rats to define the tissue distribution and excretion of resveratrol in urine and bile, and to characterize (if possible) any metabolites of resveratrol observed in tissues after ig 20mg/kg Polygonum cuspidatum extract. For tissue distribution studies, tissues (300 mg) were homogenized and centrifuged with methanol, and metabolites found in selected tissue extract were identified by LC/MS/MS. For urinary and biliary excretion experiments, urine and bile samples were cleaned up by using solid-phase extraction (SPE) with polyamide cartridges. All the concentrations of resveratrol in these biological samples were determined by HPLC with UV detection. After a single oral dose of 20mg/kg PCE in rats, resveratrol was mainly distributed in stomach, duodenum, liver and kidney with detectable metabolites resveratrol monoglucuronide and resveratrol monosulfate. The majority of the resveratrol was excreted as metabolites, only 0.59% and 0.027% of the dosage were excreted in urine and bile respectively as unchanged drug within 24h.