In Vitro Assessment of Cytochrome P450 2C19 Potential of Naoxintong

The effects of Buchang Naoxintong Capsules (BNCs) on S-mephenytoin 4'-hydroxylation activities in human liver microsomes in vitro were assessed. Human liver microsome was prepared by different ultracentrifugation. Human liver microsome incubation experiment was carried out to assay BNC on S-mephenytoin 4'-hydroxylation activities. The 4'-hydroxylation of S-mephenytoin, a representative substrate toward CYP2C19, was increased by phenytoin sodium (positive control). After the incubation, the metabolites of the substrates (4'-OH-mephenytoin) were determined by HPLC. Results showed that both phenytoin sodium and BNC showed obvious increase effect on CYP2C19. The enzymatic reaction of BNC was observed with concentrations ranging from 5 μg/mL to 250 μg/mL. Compared to blank, the increase effect of BNC showed significant difference from the beginning of concentration of 150 μg/mL (P < 0.001). The conclusion was that BNC showed obvious increase effect on the catalytic activities of drug-metabolising CYP2C19 enzyme.