Assay Method Information

Assay Name:  Inhibition Assay
Description:  The CYP2D6 inhibition assays were conducted using Human Liver Microsomes purchased from Invitrogen and designed to screen potential inhibitors of Cytochrome P450 in physiological condition. Initially the following reagents/mixtures were prepared: (i) Assay buffer: 0.1 M Phosphate buffer pH 7.4 (ii) Cofactor: 15 mM stock was prepared in assay buffer. Final concentration in assay 1.5 mM (iii) Substrate 50 mM DMSO stock was prepared for Bufuralol. From this, a 10 mM sub-stock was prepared in MeCN. Further, a working stock solution of 50 μM was prepared in assay buffer. Final concentration in assay 5 μM (iv) Enzyme: 20 mg/mL stock was provided by the manufacturer. Final concentration in assay is 0.25 mg/mL. At the start of the experiment, various concentrations of compound (7 different concs.) or positive control (Quinidine at a single concentration) were prepared in assay buffer. For 1004 of final reaction system, 1.254 of HLM (20 mg/ml), 504 of 2× stock of test compound/reference compound (from each concentration) was added. Subsequently, 104 of substrate (Bufuralol 50 μM) and 104 of Cofactor (NADPH; 15 mM) were added. The volume was increased to 1004 by adding assay buffer. The reaction was then incubated for 10 min at 37° C. After completion of the incubation period, the reaction was terminated by addition of 2004 of chilled MeOH containing internal standard (Propranolol). The samples were than centrifuged and supernatants were analyzed using LCMS/MS. The data normalization was performed with respect to internal standard and % inhibition was calculated with respect to DMSO control.
Affinity data for this assay
 

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