Quinidine

Lysionotin (≥98%) and testosterone (≥98%) were obtained from the National Institute for the Control of Pharmaceutical and Biological Products (Beijing, China). The chemical structure of lysionotin is shown in Figure 1. d-Glucose-6-phosphate, glucose-6-phosphate dehydrogenase, corticosterone (≥98%), NADP⁺, phenacetin (≥98%), acetaminophen (≥98%), 4-hydroxymephenytoin (≥98%), 7-hydroxyCoumarin (≥98%), 4′-hydroxydiclofenac (≥98%), sulfaphenazole (≥98%), quinidine (≥98%), tranylcypromine (≥98%), chlorzoxazone (≥98%), 6-hydroxychlorzoxazone (≥98%), paclitaxel (≥98%), 6β-hydroxytestosterone (≥98%), clomethiazole (≥98%), and furafylline (≥98%) were obtained from Sigma Chemical Co. Montelukast (≥98%) was obtained from Beijing Aleznova Pharmaceutical (Beijing, China). Coumarin (≥98%), diclofenac (≥98%), dextromethorphan (≥98%), and ketoconazole (≥98%) were purchased from ICN Biomedicals. Pooled HLMs were purchased from BD Biosciences Discovery Labware. All other reagents and solvents were of analytical reagent grade.

The luminescent CYP3A4 P450-Glo™ and CYP2D6 P450-Glo™ assays and protocols were provided by Promega (Madison, WI, USA) (Cali et al. 2006 (link)). The reference drugs ketoconazole (KE) and quinidine (QD) were obtained from Sigma-Aldrich (St. Louis, USA). The enzymatic reactions were performed in white polystyrene, flat-bottom Nunc™ MicroWell™ 96-Well Microplates (Thermo Scientific, Waltham, MA USA). The luminescence signal was measured with a microplate reader in luminescence mode (EnSpire, PerkinElmer, Waltham, MA USA). The IC₅₀ values of KE and QD were determined and calculated as we described previously (Sadek et al. 2016 (link)). The final concentrations of EMD 386088 were similar for both CYP3A4 and CYP2D6 assays from 0.025 to 25 μM.

Xanthotoxol (purity > 98%) was purchased from Sichuan Weikeqi Biotechnology Co. Ltd. (Sichuan, China). Paclitaxel, 1-aminobenzotriazole (ABT), phenacetin, sulfaphenazole, chlorzoxazone, quinidine, clomethiazole, furafylline, 8-methoxypsoralen, coumarin, diclofenac, quercetin, dextromethorphan, ketoconazole, testosterone, S-mephenytoin, omeprazole, glucose-6-phosphate dehydrogenase, NADP⁺, and D-glucose-6-phosphate were obtained from Sigma-Aldrich (St. Louis, MO, USA). All other reagents were the highest purity commercially available or HPLC grade.

The following compounds were obtained from Sigma-Aldrich (Stockholm, Sweden): atenolol, carbamazepine (Cbz), loperamide, propranolol, rhodamine 123 (Rho123), quinidine, and verapamil. Cyclosporin A (CsA; Sandimmun, 50 mg/mL, Novartis, Tärby, Sweden) was purchased from the drug store, Apoteket AB (Lund, Sweden). All other chemicals were analytical reagent grade and were purchased from Sigma-Aldrich.

PAs (europine (CAS# 570-19-4; assay 100%), riddelliine (CAS# 23,246-96-0; assay ≥ 98%) and lasiocarpine (CAS# 303-34-4; assay 100%) were obtained from PhytoLab (Vestenbergsgreuth, Bayern, Germany); Cyclophosphamide (CAS# 6055–19-2; assay ≥ 97%) was from Alfa Aesar (Karlsruhe, Germany). Gel Green Nucleic Acid stain was obtained from Biotium (Darmstadt, Germany). Fluorescein diacetate (FDA; CAS# 596-09-8) was from Invitrogen (Germany). Dimethylsulfoximide (DMSO; ≥ 99.8%), bisBenzimide H33258 (CAS# 23,491–45-4; assay ≥ 98%), diazabicyclo-octane (DABCO), ketoconazole (CAS# 65,277-42-1; assay ≥ 98%), quinidine (CAS# 56-54-2; assay ≥ 97%), verapamil (CAS# 152-11-4; assay ≥ 99%), nelfinavir (CAS# 159,989-65-8; assay ≥ 98%), benzbromarone (CAS# 3562-84-3; assay ≥ 95%), vincristine (CAS# 2068-78-2; assay ≥ 97%), cytochalasin B (CAS# 14,930-96-2), ethidium bromide (CAS# 1239-45-8; assay ≥ 95%) and sodium fluorescein (CAS# 518-47-8; assay ≥ 95%) were from Sigma-Aldrich (Steinheim, Germany). Calcein-acetoxymethyl ester (Calcein-AM; CAS# 148,504-34-1; assay ≥ 95%) was from Cayman Chemical Company (Germany). Cell culture media and reagents were all from Sigma-Aldrich (Steinheim, Germany), except foetal bovine serum, which was from Biochrom (Berlin, Germany).

Sepin-1 (2,2-dimethyl-5-nitro-2H-benzimidazole-1,3-dioxide) with >97% purity was purchased from ChemBridge (San Diego, CA, United States). Phenacetin, efavirenz, paclitaxel, (S)-mephenytoin, quercetin, α-naphthoflavone, ticlopidine, ketoconazole, sulfaphenazole, and dextromethorphan were purchased from Cayman Chemical (Ann Arbor, MI, United States). Reduced GSH, diclofenac sodium, quinidine, midazolam solution, formic acid, and NADPH were obtained from Sigma-Aldrich (St. Louis, MO, United States). HLM, MLM, and RLM, and the recombinant human CYP450s (EasyCYP Bactosomes) were purchased from XenoTech (Lenexa, KS, United States). All the solvents for LC and MS were of the highest grade commercially available.