Strong and Selective Inhibitory Effects of the Biflavonoid Selamariscina A against CYP2C8 and CYP2C9 Enzyme Activities in Human Liver Microsomes

Abstract

Like flavonoids, biflavonoids, dimeric flavonoids, and polyphenolic plant secondary metabolites have antioxidant, antibacterial, antiviral, anti-inflammatory, and anti-cancer properties. However, there is limited data on their effects on cytochrome P450 (P450) and uridine 5′-diphosphoglucuronosyl transferase (UGT) enzyme activities. In this study we evaluate the inhibitory potential of five biflavonoids against nine P450 activities (P450s1A2, 2A6, 2B6, 2C8, 2C9, 2C19, 2D6, 2E1, and 3A) in human liver microsomes (HLMs) using cocktail incubation and liquid chromatography-tandem mass spectrometry (LC–MS/MS). The most strongly inhibited P450 activity was CYP2C8-mediated amodiaquine N-dealkylation with IC50 ranges of 0.019~0.123 μM. In addition, the biflavonoids—selamariscina A, amentoflavone, robustaflavone, cupressuflavone, and taiwaniaflavone—noncompetitively inhibited CYP2C8 activity with respective Ki values of 0.018, 0.083, 0.084, 0.103, and 0.142 μM. As selamariscina A showed the strongest effects, we then evaluated it against six UGT isoforms, where it showed weaker inhibition (UGTs1A1, 1A3, 1A4, 1A6, 1A9, and 2B7, IC50 > 1.7 μM). Returning to the P450 activities, selamariscina A inhibited CYP2C9-mediated diclofenac hydroxylation and tolbutamide hydroxylation with respective Ki values of 0.032 and 0.065 μM in a competitive and noncompetitive manner. However, it only weakly inhibited CYP1A2, CYP2B6, and CYP3A with respective Ki values of 3.1, 7.9, and 4.5 μM. We conclude that selamariscina A has selective and strong inhibitory effects on the CYP2C8 and CYP2C9 isoforms. This information might be useful in predicting herb-drug interaction potential between biflavonoids and co-administered drugs mainly metabolized by CYP2C8 and CYP2C9. In addition, selamariscina A might be used as a strong CYP2C8 and CYP2C9 inhibitor in P450 reaction-phenotyping studies to identify drug-metabolizing enzymes responsible for the metabolism of new chemicals.

Comprehensive Investigation of Stereoselective Food Drug Interaction Potential of Resveratrol on Nine P450 and Six UGT Isoforms in Human Liver Microsomes

“…IC 50 values were determined by nonlinear regression analysis using WinNonlin (Pharsight, Mountain View, CA, USA). We used WinNonlin to estimate the apparent kinetic parameters of inhibitory activity ( K i ) and the type of inhibitory activity by several criteria, including visual inspection of Lineweaver–Burk double reciprocal plots, Dixon plots, and secondary plots of Lineweaver–Burk plots versus RVT concentrations in each inhibitory model [ 35 , 36 ].…”

“…An in vivo FDI via the inhibition of a drug-metabolizing enzyme might occur if the ratio of the maximum plasma concentration (C max )/K i exceeded 1.0 [35,62]. After oral administration of RVT (5 g, single dose) to healthy subjects, the plasma C max value of RVT was approximately 2.36 µM [63].…”

Development of Non-Ethoxypropanoic Acid Type Cryptochrome Inhibitors with Circadian Molecular Clock-Enhancing Activity by Bioisosteric Replacement

“…The inhibitory effects of KS15 and compound 5d on the metabolism of five cytochrome P450 (P450) probe substrates were evaluated using previous methods with slight modifications [ 19 , 20 ]. The following P450 probe substrates were used: phenacetin (100 μM) for CYP1A2, tolbutamide (100 μM) for CYP2C9, omeprazole (20 μM) for CYP2C19, dextromethorphan (5 μM) for CYP2D6, and midazolam (5 μM) for CYP3A.…”

In Vitro Metabolism Study of Seongsanamide A in Human Liver Microsomes Using Non-Targeted Metabolomics and Feature-Based Molecular Networking

“…The inhibitory potency of seongsanamide A was evaluated by a previously described method with slight modifications in the pooled HLMs [ 26 , 27 ]. The microsomal incubation was conducted using two cocktail sets containing P450-specific probe substrates; A: phenacetin (CYP1A2), bupropion (CYP2B6), amodiaquine (CYP2C8), tolbutamide (CYP2C9), omeprazole (CYP2C19), and dextromethorphan (CYP2D6); B: coumarin (CYP2A6), chlorzoxazone (CYP2E1), and midazolam (CYP3A).…”