Ginseng is one of the most commonly used herbal medicines and health foods. Korean red ginseng (KRG; Panax ginseng C.A. Meyer) extract is known to have potential therapeutic activities, such as anti-viral effects, the amelioration of food allergies, anti-oxidant effects, and obesity reduction. Nevertheless, no reports have been issued the modulatory effects of KRG extract on the activity of cytochrome P450 (CYP). In the present study, we investigated the modulatory effect of KRG extract in vitro and in vivo by using pooled human liver microsomes and male ICR mice. When human liver microsomes were incubated with KRG extract at 0.01-10 mg/ml, CYP1A2, 2B6, 2C19, 2D6, and 3A were not significantly inhibited by KRG extract, although CYP2B6 was slightly inhibited. Mice were orally administered KRG extract at 50, 250, or 500 mg/kg daily for 3, 7, or 14 days. However, the activities of CYPs in mouse livers were not significantly different from those of vehicle-treated controls. In conclusion, no significant ginseng-drug interaction was observed. KRG extract did not significantly modulate the activities of CYPs in vitro or in vivo.

Osthenol is a furanocoumarin with anti-tumor, anti-inflammatory, and anti-viral activity. It is present in various citrus juices and fruits; however, its inhibitory effects on cytochrome P450 (CYP) enzyme activity, in the context of herb-drug interaction (HDI) prediction, have not been previously studied. In this study, osthenol was chemically synthesized in order to identify potential HDIs. Its inhibitory effect on eight CYP isoforms and the underlying mechanism of inhibition were investigated by using cocktail assays and liquid chromatography-tandem mass spectrometry in pooled human liver microsomes. The inhibitory effect of osthenol on CYP2C8-catalyzed paclitaxel hydroxylation was selective and dose-dependent, but not time-dependent. The IC 50 value was 2.8 μM. Additionally, osthenol displayed mixed mode inhibition with a relatively low Ki value of 0.96 μM, which is indicative of the potential for HDIs with co-administered CYP2C8 substrates. To the best of our knowledge, this is the first report of selective inhibition of CYP2C8 by osthenol.

: High-resolution quadrupole-Orbitrap mass spectrometry (HRMS), with high-resolution (> 10,000 at full-width at half-maximum) and accurate mass (< 5 ppm deviation) capabilities, plays an important role in the structural elucidation of drug metabolites in the pharmaceutical industry. ML106, a derivative of imidazobenzimidazole, decreased melanin content and tyrosinase activity in a dose-dependent manner. Here, we investigated the phase 1 metabolic pathway of ML106 using HRMS in human liver microsomes (HLMs) and recombinant cDNA-expressed cytochrome P450 (CYP). After the incubation of ML106 with pooled HLMs and recombinant cDNA-expressed CYP in the presence of NADPH, five phase 1 metabolites, including three mono-hydroxylated metabolites (M1-3) and two di-hydroxylated metabolites (M4 and M5), were investigated. The metabolite structures were postulated by the elucidation of protonated mass spectra using HRMS. The CYP isoforms related to the hydroxylation of ML106 were studied after incubation with recombinant cDNA-expressed CYP. Here, we identified the phase 1 metabolic pathway of ML106 induced by CYP in HLMs.

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