Query String: LABETALOL
Normodyne 2-hydroxy-5-{1-hydroxy-2-[(4-phenylbutan-2-yl)amino]ethyl}benzamide Labetolol BDBM25758 Albetol labetalol
- CYP450 Enzyme Inhibition Test Experimental Method: 4-hydroxydiclofenac (the substrate for CYP450 and 2C9 enzymes) and different doses of compounds were added into human liver microsome (Xenotech, LLC), then NADPH (Reduce dcoenzyme II, Chem-impex international, Inc.) was added, mixed, and then incubated in 37° C. water bath, at the terminal time, the stop solution (200 ng/mL tolbutamide and 200 ng/mL labetalol dissolved in acetonitrile) was added to stop the reaction, methanol or ethanol was used to precipitate proteins, the concentration of the metabolites of substrates was determined by using LC-MS/MS to obtain the IC50 values of compounds on CYP450 and 2C9 enzyme.
- Inhibition Assay Master solutions were prepared containing human liver microsomes (Gibco, 0.2 mg/mL) and MgCl2 (5 mM) in potassium phosphate buffer (10 mM). To aliquots (169 μL) of the microsome solution was added test compound in acetonitrile (1 μL) and DMSO (1 μL) to provide final test compound concentrations of 0, 0.005, 0.05, 0.25, 1, 5, 10, and 25 μM.NADPH (10 mM) in ultra-pure water (20 μL) was added, and this mixture was incubated at 37° C. for 30 minutes. The enzyme reaction then was initiated by the addition of enzyme substrate (dextromethorphan) dissolved in 1 μL of acetonitrile and 9 μL of ultra-pure water. The final substrate concentration was 10 μM.After 20 minutes, the incubation mixture was diluted with 3 volumes of cold methanol containing imipramine (200 nM), labetalol (200 nM), and ketoprofen (2 μM) as internal standards. Samples were centrifuged at 16,000 g for 10 minutes, then an aliquot of the supernatant (200 μL) was removed and a
- CYP1A2 Inhibition Assay CYP1A2 Inhibition in Human Liver Microsomes. Pooled human liver microsomes were incubated with individual CYP, CYP1A2, isozyme-specific marker substrate (Phenacetin) in the presence of test compound at various concentrations (0.05, 0.15, 0.5, 1.5, 5, 15, 50 uM). The specific marker metabolites are measured with LC/MS/MS. The remaining enzymatic activities and inhibitory potency IC50 are determined. Procedure: Microsomes are removed out of the −80° C. freezer to thaw on ice and 20 μL of the substrates solution added to the corresponding wells. Then 20 μL PB was added to blank wells and 2 μL of the test compounds and positive control working solution added to the corresponding wells. 2 μL of solvent was added to No Inhibitor wells and Blank wells. Then 158 μL of the HLM working solution was added to all wells of the incubation plate. The plate was pre-warmed for about 10 min using a 37° C. water bath. Then 20 μL of the NADPH cofactor solution was added to all incubation wells, mixed and incubated for 10 minutes at 37° C. water bath. The reaction is terminated by adding 400 μL cold stop solution (200 ng/mL Tolbutamide and 200 ng/mL Labetalol in ACN). The samples were centrifuged at 4000 rpm for 20 minutes to precipitate protein. Finally 200 μL of the supernatant was transferred to 100 μL HPLC water, shaken for 10 min and analyzed by LC/MS/MS.
- Cytochrome P450 Isoenzyme Inhibitory Activity Test The inhibitory activities of test compound against different isoforms of human cytochrome P450 isoenzymes were determined. Experimental Operation. The test compound, standard inhibitor (100×final concentration) and mixed substrate working solution were prepared; the microsome frozen in −80° C. refrigerator was taken out and thawed. 2 μL of the compound to be tested and standard inhibitor solution were added to the corresponding wells, and at the same time, 2 μL of the corresponding solvent was added to the non-inhibitor control wells (NIC) and the blank control wells; secondly, 20 μL of mixed substrate solution was added to the corresponding wells except the blank wells (20 μL of Pb was added to the blank wells); human liver microsome solution was prepared (the solution was put back in the refrigerator immediately after using and marking the date), and then 158 μL of human liver microsome solution was added to all wells; the sample plate was put in a 37° C. water bath for pre-incubation, and then a coenzyme factor (NADPH) solution was prepared; after 10 minutes, 20 μL of NADPH solution was added to all wells, the sample plate was shaken well, and incubated in a 37° C. water bath for 10 minutes; at the corresponding time point, 400 μL of cold acetonitrile solution (internal standard is 200 ng/mL tolbutamide and labetalol) was added to terminate the reaction; after the plates were evenly mixed, the mixture was centrifuged at 4000 rpm for 20 minutes to precipitate protein; 200 μL of supernatant was added into 100 μL of water, shaken well and detected by LC/MS/MS.
- Inhibition Against Cytochrome P450 Isoenzymes Table 9: The inhibition of the test compound against different subtypes of the human cytochrome P450 isoenzyme was determined. The test compound, a standard inhibitor (100×final concentration) and a mixed substrate working solution were prepared; the microsomes frozen in a refrigerator at −80° C. were taken out and thawed. 2 μL of a solution of the test compound and the standard inhibitor was added to corresponding wells, and 2 μL of a corresponding solvent was added to a non-inhibitor control (NIC) well and a blank control (Blank) well; then, 20 μL of a solution of mixed substrate was added to corresponding wells except for the Blank well (adding 20 μL of PB to the Blank well); a human liver microsome solution (labeled with the date after use and immediately putting back to a refrigerator) was prepared and then added to all wells at 158 μL per well; the sample plate was put into a 37° C. water bath for pre-incubation, and then a coenzyme factor (NADPH) solution was prepared; after 10 min, the NADPH solution was added to all the wells at 20 μL per well, and the sample plate was shaken to mix well and then incubated in a 37° C. water bath for 10 min; at corresponding time points, 400 μL of cold acetonitrile solution (internal standard: 200 ng/mL tolbutamide and labetalol) was added to stop the reaction; after being mixed well, the mixture in the sample plate was centrifuged at 4,000 rpm for 20 min, and proteins were precipitated; 200 μL of supernatant was collected and added into 100 μL of water, and the mixture was mixed well and then analyzed by LC/MS/MS.
- Des1 Activity Assays Jurkat clone E6-1 cells were grown and then seeded at 106 cells/mL in a 96-well plate (400 μL in each well. The cells were administered 100 μL of cell culture media containing 50-μM NBD-C6-dihydroceramide (Des1 substrate), affording a final concentration of substrate of 10 μM. The cells were incubated with substrate at 4° C. for 30 minutes. Following the incubation at 4° C., the cell suspension was centrifuged at 1200 rpm for 3 minutes, and the cell pellet is resuspended in 400 μL of fresh media containing various concentrations of either fenretinide (known Des1 inhibitor control compound) or test article. The final concentrations of control compound and test compounds were tested in a range from 0-10 μM. The cells and compounds were incubated at 37° C. for 3 hours. Following the 3-hour incubation, the plate was centrifuged at 2500 g for 3 minutes at 4° C., followed by collection and transfer of 200 μL of the supernatant to a new 96-well plate with 300 μL of methanol an containing appropriate internal standards for liquid chromatography/tandem mass spectroscopy (LC/MS/MS) analysis (internal standard: 500 nM labetalol and 100 nM alprazolam). The samples were vortexed for 2 minutes followed by centrifugation at 3,220 g for 20 minutes. Following centrifugation, 200 μL of the supernatant was transferred to a new 96-well plate for LC-MS/MS analysis to determine the amount of NBD-C6-ceramide (Des1 product) produced. The assay was typically performed in duplicate. A reduction of at least 30% compared to vehicle control (0 μM test article) is indicative of an active compound, and a reduction of 75% compared to vehicle control is preferred.