## Endpoint to Predict
- Endpoint scope: assay
- Measurement type: IC50
- Label type: continuous
- Binary semantics: pchembl
- Assay description: HTS cell-based calcium flux assay: NMDA receptors are ion channels that are highly permeable to Ca2+ ions, rendering it possible to monitor NMDA receptor function using cell-based calcium flux assay. In this assay, co-agonists glutamate and glycine are added to cells heterologously expressing human GluN1/GluN2B NMDA receptors to initiate cellular Ca2+ influx. The time course of the changes in intracellular calcium is measured using a fluorescent dye and a FLIPR (Fluorometric Imaging Plate Reader) device.Twenty four hours before measurements, the expression of the NMDA receptors in the stable cell line is induced with Tet-On inducible system in the presence of a non-selective NMDA receptor blocker. On the day of the experiment, cell culture media is carefully washed and the cells are loaded with Calcium 5 Dye Kit (Molecular Devices) in dye loading buffer containing 137 mM NaCl, 4 mM KCl, 2 mM CaCl2, 0.5 mM MgCl2 (standard assay) or 1.5 mM MgCl2 (HTS assay), 10 mM HEPES and 5 mM D-glucose; pH 7.4. After 1 h incubation at the room temperature, the dye is washed away with the assay buffer (137 mM NaCl (standard assay) or 150 mM (HTS assay), 4 mM KCl (standard assay) or 3 mM (HTS assay), 2 mM CaCl2, 0.01 mM EDTA, 10 mM HEPES and 5 mM D-glucose; pH 7.4) In the FLIPR TETRA reader, various concentrations of the test compounds are added to the cells for 5 min while fluorescence is monitored to detect potential agonist activity. Next, co-agonists, glutamate and glycine are added for another 5 minutes. The concentration of glutamate corresponding to EC40 (HTS assay) is used to maximize the assay's signal window and ability to detect NMDA receptor antagonists and negative allosteric modulators. A saturating concentration (10 μM) of glycine is also present in the assay. A non-selective NMDA receptor antagonist, (+)MK-801 is used as a positive control for antagonist activity. The fluorescent signal in the presence of test compounds is quantified and normalized to the signal defined by the appropriate control wells.
- Assay organism: Homo sapiens
- Target name: Glutamate receptor ionotropic, NMDA 2B
- Target type: SINGLE PROTEIN
- Target organism: Homo sapiens

## Reference Molecule A
- Canonical SMILES: COCCNC(=O)Cn1c(=O)[nH]c2ncc(-c3ccc(OC)cc3)cc21
- Properties:
- ChEMBL ID: CHEMBL5888092
- Molecular weight: 356.38
- Heavy atoms: 26
- Hydrogen bond donors: 2
- Hydrogen bond acceptors: 5
- TPSA: 98.24
- LogP: 1.16
- Rotatable bonds: 7
- Ring count: 3
- Aromatic rings: 3
- Formal charge: 0
- Fraction Csp3: 0.28
- QED: 0.62

## Known Reference Result on This Endpoint
- Molecule A clean result: median pChEMBL = 6.13
- This result is provided as context for predicting Molecule B on the same endpoint.

## Reference Molecule A Other ChEMBL Evidence
- type IC50; relation =; value 747; units nM; pChEMBL 6.13; comment 889208

## Query Molecule B
- Canonical SMILES: COc1ccc(-c2cnc3[nH]c(=O)n(CC4CC4)c3c2)cc1C
- Properties:
- ChEMBL ID: CHEMBL6059346
- Molecular weight: 309.37
- Heavy atoms: 23
- Hydrogen bond donors: 1
- Hydrogen bond acceptors: 3
- TPSA: 59.91
- LogP: 3.12
- Rotatable bonds: 4
- Ring count: 4
- Aromatic rings: 3
- Formal charge: 0
- Fraction Csp3: 0.33
- QED: 0.81

## Molecule Similarity
- Weighted Tanimoto: 0.48

Answer: 5.38