Inhibitory effects of polyphyllin VII on cytochrome P450 2C19, 2D6, 2E1, and 3A4 in human liver microsomes

Polyphyllin VII is a major active component extracted from the traditional Chinese medicinal plant Paris polyphylla. It exhibits antitumor and anti-inflammatory activities, positioning it as a promising drug candidate. Nevertheless, its potential to induce drug-drug interactions remains unknown.

The effects of polyphyllin VII on eight key cytochrome P450 (CYP450) isoenzymes were assessed using human liver microsomes, providing insights to inform its drug development and clinical use.

Using specific probe substrates, the effects of polyphyllin VII on CYP1A2, 2A6, 2C9, 2D6, 2C19, 2C8, 2E1, and 3A4 were evaluated in human liver microsomes. The inhibition patterns were characterized through Lineweaver-Burk plots to determine the corresponding kinetic parameters.

Polyphyllin VII suppressed the activity of CYP2C19, 2D6, 2E1, and 3A4. The inhibition of CYP2C19, 2D6, 2E1, and 3A4 by polyphyllin VII was concentration-dependent, with IC₅₀ values of 21.41 ± 2.59, 18.88 ± 2.20, 9.83 ± 1.85, and 12.54 ± 1.93 μM, respectively. Polyphyllin VII was a competitive inhibitor of CYP2C19, 2D6, and 2E1, and a noncompetitive inhibitor of CYP3A4, with K_i values of 10.70, 9.52, 5.28, and 6.39 μM, respectively. Additionally, the inhibitory effect of polyphyllin VII on CYP3A4 was time-dependent, with K_I and K_inact values of 5.60 μM and 0.038 min^-1.

This study highlights the inhibitory characteristics of polyphyllin VII on the activity of CYP2C19, 2D6, 2E1, and 3A4. Although these findings require further in vivo studies and clinical validation, polyphyllin VII has the potential to interact with other drugs metabolized by CYP2C19, 2D6, 2E1, and 3A4.