Effects of flavonoids derived from Taxus yunnanensis on p-glycoprotein and cytochrome P450 3A4

The intestinal uptake of paclitaxel is hampered by trans-membrane efflux transporters such as P-glycoprotein (P-gp), and paclitaxel is mainly metabolized by cytochrome P450 3A4 (CYP3A4) presented in the liver. Our previous results demonstrated that flavonoids extracted from Taxus yunnanensis could improve the oral absorption of paclitaxel. The current study was purposed to investigate the effects of the flavonoid extracts on P-gp and CYP3A4 in vitro. The expression and activity of P-gp were detected by western blotting and intracellular rhodamine 123 accumulation assay in Caco-2 cells treated with the flavonoids extract. The expression of CYP3A4 was investigated by western blotting in mouse primary hepatocytes and the activity of CYP3A4 was detected by LC-MS/MS method using rat liver microsomes. Our results showed that the flavonoid extracts from T. yunnanensis could inhibit P-gp activity and concurrently decrease the expression and activity of CYP3A4. In conclusion, activity of P-gp and CYP3A4 could be inhibited by flavonoids extracted from T. yunnanensis which might be potential candidates for development of oral formulation of paclitaxel. (C) 2013 Shenyang Pharmaceutical University. Production and hosting by Elsevier B.V. All rights reserved.