Aequorin Functional Assay: Changes in intracellular calcium levels are a recognized indicator of G protein-coupled receptor activity. The efficacy of compounds of the invention to inhibit NKA-mediated NK-3 receptor activation was assessed by an in vitro Aequorin functional assay. Chinese Hamster Ovary recombinant cells expressing the human NK3 receptor and a construct that encodes the photoprotein apoaequorin were used for this assay. In the presence of the cofactor coelenterazine, apoaequorin emits a measurable luminescence that is proportional to the amount of intracellular (cytoplasmic) free calcium. Antagonist Testing: the antagonist activity of compounds of the invention is measured following pre-incubation (3 minutes) of the compound with the cells, followed by addition of the reference agonist (NKA) at a final concentration equivalent to the EC80 (3 nM) and recording of emitted light (FDSS 6000 Hamamatsu) over the subsequent 90-second period. The intensity of the emitted light is integrated using the reader software. Compound antagonist activity is measured based on the inhibition of the luminescence response to the addition of Neurokinin A. Inhibition curves are obtained for compounds of the invention and the concentrations of compounds which inhibit 50% of reference agonist response (IC50) were determined (see results in table 5 below). The IC50 values shown in table 5 indicate that compounds of the invention are potent NK-3 antagonist compounds.
Binding Competition Assay: The ability of compounds of the invention to inhibit the binding of the NK-3 receptor selective antagonist 3H-SB222200 was assessed by an in vitro radioligand binding assay. Membranes were prepared from Chinese hamster ovary recombinant cells stably expressing the human NK3 receptor. The membranes were incubated with 5 nM 3H-SB222200(ARC) in a HEPES 25 mM/NaCl 0.1M/CaCl2 1 mM/MgCl2 5 Mm/BSA 0.5%/Saponin 10 μg/ml buffer at pH 7.4 and various concentrations of compounds of the invention. The amount of 3H-SB222200 bound to the receptor was determined after filtration by the quantification of membrane associated radioactivity using the TopCount-NXT reader (Packard).
Binding Assay: The affinity of compounds of the invention for the NK1 receptor was evaluated in CHO recombinant cells which express the human NK1 receptor. Membrane suspensions were prepared from these cells. The following radioligand: [3H] substance P (PerkinElmer Cat#NET111520) was used in this assay. Binding assays were performed in a 50 mM Tris/5 mM MnCl2/150 mM NaCl/0.1% BSA at pH 7.4. Binding assays consisted of 25 μl of membrane suspension (approximately 5 μg of protein/well in a 96 well plate), 50 μl of compound or reference ligand (Substance P) at increasing concentrations (diluted in assay buffer) and 2 nM [3H] substance P. The plate was incubated 60 min at 25° C. in a water bath and then filtered over GF/C filters (Perkin Elmer, 6005174, presoaked in 0.5% PEI for 2 h at room temperature) with a Filtration unit (Perkin Elmer). The radioactivity retained on the filters was measured by using the TopCount-NXT reader (Packard).
Binding Assay: The affinity of compounds of the invention for the NK2 receptor was evaluated in CHO recombinant cells which express the human NK2 receptor. Membrane suspensions were prepared from these cells. The following radioligand [125I]-Neurokinin A (PerkinElmer Cat#NEX252) was used in this assay. Binding assays were performed in a 25 mM HEPES/1 mM CaCl2/5 mM MgCl2/0.5% BSA/10 μg/ml saponin, at pH 7.4. Binding assays consisted of 25 μl of membrane suspension (approximately 3.75 μg of protein/well in a 96 well plate), 50 μl of compound or reference ligand (Neurokinin A) at increasing concentrations (diluted in assay buffer) and 0.1 nM [125I]-Neurokinin A. The plate was incubated 60 min at 25° C. in a water bath and then filtered over GF/C filters (Perkin Elmer, 6005174, presoaked in assay buffer without saponine for 2 h at room temperature) with a Filtration unit (Perkin Elmer). The radioactivity retained on the filters was measured by using the TopCount-NXT reader (Packard).
Inhibition Assay: The hERG inhibition study aims at quantifying the in vitro effects of compounds of the invention on the potassium-selective IKf current generated in normoxic conditions in stably transfected HEK 293 cells with the human ether-a-go-go-related gene (hERG).Whole-cell currents (acquisition by manual patch-clamp) elicited during a voltage pulse were recorded in baseline conditions and following application of tested compounds (5 minutes of exposure). The concentrations of tested compounds (0.3 uM; 3 uM; 10 uM; 30 uM) reflect a range believed to exceed the concentrations at expected efficacy doses in preclinical models.The pulses protocol applied is described as follow: the holding potential (every 3 seconds) was stepped from -80 mV to a maximum value of +40 mV, starting with -40 mV, in eight increments of +10 mV, for a period of 1 second. The membrane potential was then returned to -55 mV, after each of these incremented steps, for 1 second and finally repolarized to -80 mV for 1 second. The current density recorded were normalized against the baseline conditions and corrected for solvent effect and time-dependent current run-down using experimental design in test compound free conditions. Inhibition curves were obtained for compounds and the concentrations which decreased 50% of the current density determined in the baseline conditions (IC50) were determined. All compounds for which the IC50 value is above 10 uM are not considered to be potent inhibitors of the hERG channel whereas compounds with IC50 values below 1 uM are considered potent hERG channel inhibitors.