ABSTRACT
OBJECTIVE: To study the in vivo metabolism of granatum tannins by liquid chromatography-mass spectrometry and clarify their metabolic pathways. METHODS: The rat urine samples were collected after intragastric administration of tannins preparation of Punica granatum L. husk. The analysis was performed on a Venusil MP-C18 column with gradient elution system of acetonitrile and water containing 0.1% formic acid. Using electrospray ionization (ESI) in negative ion mode with scanning range from m/z 100 to 1000, the metabolites were identified by comparing the MS spectra and MS data with the literatures. RESULTS: Seven metabolites were detected in the rat urine, among which six were identified according to their second mass spectra to be U-1 (urolithin B), U-2 (urolithin A methyl ether), U-3 (urolithin A), U-4 (urolithin A glucuronide), U-5 (ellagic acid) and U-6 (urolithin C). CONCLUSION: Tannins in Punica granatum L. husk are metabolized after oral administration mainly through hydrolysis, glucuronidation gly-cosidation, decomposition and methylation reaction to generate a series of derivatives of urolithin. These results preliminarily indicate the metabolic pathway and material basis of the pharmacological activity of tannins in Punica granatum L. husk in rats.