Pharmacokinetics, excretion of 8-cetylberberine and its main metabolites in rat urine

Abstract

Berberine (BBR) is a bioactive plant ingredient derived from the roots and bark of Berberis aristata and Coptis chinensis and has a wide variety of pharmacological effects. 8-cetylberberine (8-BBR-C16) is the berberine (BBR) derivative reconstructed from adding octadecyl at C-8 of BBR to enhance its activity. This study presents a reliable method for the determination of BBR and 8-BBR-C16 in rat plasma, urine and feces. BBR and 8-BBR-C16 were determined by HPLC-UV after liquid-liquid extraction for plasma samples, and solid-phase extraction for urinary and fecal samples. The method was linear over the concentration range of 10-300 ng·ml−1 for the plasma samples, 25-2000 ng·ml−1 for the urinary samples, and 100-2000 ng·g−1 for the fecal samples. Furthermore, a metabolic investigation on urine was performed by LC/MS/MS analysis to identify the structures of 8-BBR-C16 metabolites by full scan and product ion scan. Adult Sprague-Dawley rats were divided into two groups. In the control group, rats received 80 mg·kg−1 BBR, and in the drug-treated group, rats received 80 mg·kg−1 8-BBR-C16. The results indicate that there were significant differences in the pharmacokinetic parameters and in the accumulated excretion levels between the control group and the drug-treated group. The Cmax and AUC0-t of 8-BBR-C16 were 2.8 and 12.9 times higher than those of BBR, and the relative bioavailability of BBR to 8-BBR-C16 was 7.7%. The total excretion amount through the urine and feces of 8-BBR-C16 was 76.9%, but that of BBR was only 20.5%. Additionally, 8-BBR-C16 was metabolized in rat urine with phase I demethylation and phase II glucuronidation or sulfation.