In Vitro Investigation on the Effect of Dendrobine on the Activity of Cytochrome P450 Enzymes

Dendrobine is the major active ingredient of Dendrobium nobile, Dendrobium chrysotoxum , and Dendrobium fimbriatum , all of which are used in traditional Chinese medicine owing to their antitumor and anti-inflammation activities. Hence, investigation on the interaction of dendrobine with cytochrome P450 enzymes could provide a reference for the clinical application of Dendrobium . The effects of dendrobine on cytochrome P450 enzymes activities were investigated in the presence of 0, 2.5, 5, 10, 25, 50, and 100 mu M dendrobine in pooled human liver microsomes. The specific inhibitors were employed as the positive control and the blank groups were set as the negative control. The Lineweaver-Burk plots were plotted to characterize the specific inhibition model and obtain the kinetic parameters. The study reveals that dendrobine significantly inhibited the activity of CYP3A4, 2C19, and 2D6 with IC (50) values of 12.72, 10.84, and 15.47 mu M, respectively. Moreover, the inhibition of CYP3A4 was found to be noncompetitive ( Ki = 6.41 mu M) and time dependent ( KI = 2.541 mu M (-1) , K (inact) = 0.0452 min (-1) ), while the inhibition of CYP2C19 and 2D6 was found to be competitive with the Ki values of 5.22 and 7.78 mu M, respectively, and showed no time-dependent trends. The in vitro inhibitory effect of dendrobine implies the potential drug-drug interaction between dendrobine and CYP3A4-, 2C9-, and 2D6-metabolized drugs. Nonetheless, these findings need further in vivo validation.