| Assay Method Information | |
| | Inhibition Assay |
| Description: | The CYP3A4 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 testosterone. From this a 10 mM sub-stock was prepared in MeCN. Further, a working stock solution of 700 μM was prepared in assay buffer. Final concentration in assay 70 μM (iv) Enzyme: 20 mg/mL stock was provided by manufacturer. Final concentration in assay was 0.5 mg/mL. At the start of the experiment, various concentrations of compound (7 different concs.) or positive control (Ketoconazole at a single concentration) were prepared in assay buffer. For 100 μL of final reaction system, 2.5 μL of HLM (20 mg/ml), 50 μL of test compound/reference compound from each concentration was added. Subsequently, 10 μL of substrate (testosterone 700 μM) and 10 μL of Cofactor (NADPH; 15 mM) were added. The volume was increased to 100 μL by adding assay buffer. DMSO concentration was kept as 0.5% uniform across all the reactions. The reaction was then allowed to incubate for 45 min at 37° C. After completion of the incubation period, the reaction was terminated by addition of 200 μL of chilled MeCN containing internal standard (Dexamethasone). The samples were than centrifuged and supernatants were analyzed using LCMS/MS. |
| Affinity data for this assay | |
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