Rat liver microsomes

5-O-Desmethyldonepezil, 6-O-desmethyldonepezil, hydroxydonepezil, 3-hydroxydonepezil, donepezil N-oxide, and desbenzyldonepezil were supplied by Toronto Research Chemicals (Figure 1, Toronto, ON, Canada). Donepezil hydrochloride was purchased from Tokyo Chemical Industry (Tokyo, Japan). Potassium cyanide (KCN) and reduced L-glutathione (GSH) were obtained from Sigma-Aldrich (St. Louis, MO, USA). Nicotinamide adenine dinucleotide phosphate reduced form (β-NADPH) was purchased from Oriental Yeast (Tokyo, Japan). Human liver microsomes (HLM (cytochrome P450, 0.411 nmol/mg protein; cytochrome b₅, 0.449 nmol/mg protein; and NADPH-cytochrome c reductase, 182 ± 11 nmol/mg protein/min), catalog No. H2630), mouse liver microsomes (MLM (cytochrome P450, 0.939 nmol/mg protein; cytochrome b₅, 0.414 nmol/mg protein; and NADPH-cytochrome c reductase, 138 ± 4 nmol/mg protein/min), catalog No. M1000), and rat liver microsomes (RLM (cytochrome P450, 0.646 nmol/mg protein; cytochrome b₅, 0.484 nmol/mg protein; and NADPH-cytochrome c reductase, 124 ± 8 nmol/mg protein/min), catalog No. R1000) were acquired from XenoTech (Lenexa, KS, USA). All solvents for liquid chromatography-MS were obtained from Fisher Scientific Co. (Pittsburgh, PA, USA) with the highest grade commercially available.

Reference standards of PCB and PCBG (purity both ≥98% by HPLC at 280 nm, identified by ¹H-NMR, ¹³C-NMR) were prepared in the Laboratory of Chemistry of Chinese Medicinal Materials of Capital Medical University (Beijing, China). Genistein (Internal standard, IS) was provided by Shenyang Pharmaceutical University (Shenyang, China). HPLC grade acetonitrile and methanol were obtained from TEDIA Company (Fairfield, OH, USA). Cryopreserved hepatocytes from Spague-Dawley (SD) rats and rat liver microsomes were purchased from XenoTech LLC (Lenexa, KS, USA). β-Nicotinamide adenine dinucleotide 2′-phosphate reduced tetrasodium salt (NADPH) and dimethyl sulfoxide (DMSO, BioReagent, ≥99.7%) were purchased from Sigma-Aldrich Co. (St. Louis, MO, USA). Dulbecco’s Modified Eagle Medium (DMEM) and fetal bovine serum (FBS) were purchased from Invitrogen (Grand Island, NY, USA). All other chemicals were of analytical grade. Distilled water was prepared by a Milli-Q water purification system from Millipore (Molsheim, France).