Heterotropic Activation of Cytochrome P450 3A4 by Perillyl Alcohol

Background/Objectives: Perillyl alcohol (POH), a monoterpene natural product derived from the essential oils of plants such as perilla (Perilla frutescens), is currently in phase I and II clinical trials as a chemotherapeutic agent. In this study, we investigated the effect of POH on cytochrome P450 (CYP) activity for evaluating POH-drug interaction potential. Methods: The investigation was conducted using pooled human liver microsomes (HLMs), recombinant CYP3A4 (rCYP3A4) enzymes, and human pluripotent stem cell-derived hepatic organoids (hHOs) employing liquid chromatography-tandem mass spectrometry. Results: POH inhibited the activities of CYP2A6 and CYP2B6 with Ki of 6.35 and 3.78 mu M, respectively, whereas it stimulated CYP3A4 activity in pooled HLMs incubated with midazolam (MDZ). In a direct CYP inhibition assay using HLMs, activities of CYP2C9, CYP2C19, and CYP2E1 were also inhibited by POH, with IC50 values greater than 50 mu M, but those of CYP1A2, CYP2C8, CYP2D6, and CYP3A4 (testosterone) were not significantly inhibited. In pooled HLMs, the Vmax/Km value of 1 '-hydroxy MDZ, but not that of 4-hydroxy MDZ, was increased 2.7-fold by 100 mu M POH compared with that in the absence of POH. Moreover, stimulation of MDZ 1 '-hydroxylation by CYP3A4 was observed in hHOs and rCYP3A4 with cytochrome b5 but not rCYP3A4 without cytochrome b5. Furthermore, activation of CYP3A4-mediated metabolism by POH was observed in HLMs incubated with fimasartan but not atorvastatin, buspirone, donepezil, nifedipine, or tadalafil, suggesting a substrate-dependent activation of CYP3A4 by POH. Conclusions: POH inhibits CYP2A6 and CYP2B6, but it activates CYP3A4. These findings underscore the need for further evaluation of the interactions of clinical drugs with POH.