## Endpoint to Predict
- Endpoint scope: assay
- Measurement type: IC50
- Label type: continuous
- Binary semantics: pchembl
- Assay description: FLIPR Ca2+ Flux Assay: The following table shows representative data for the compounds of the Examples as orexin receptor antagonists as determined by the FLIPR Ca2+ Flux Assay (Okumura et al., Biochem. Biophys. Res. Comm., 2001, 280:976-981). Chinese hamster ovary (CHO) cells expressing the human orexin-1 receptor (hOX1R) or the human orexin-2 receptor (hOX2R) were grown in Iscove's modified DMEM containing 2 mM L-glutamine, 0.5 g/ml G418, 1% hypoxanthine-thymidine supplement, 100 U/ml penicillin, 100 μg/ml streptomycin and 10% heat-inactivated fetal calf serum (FCS). The cells were seeded at 20,000 cells/well into Becton-Dickinson black 384-well clear bottom sterile plates coated with poly-D-lysine. All reagents were from GIBCO-Invitrogen Corp. The seeded plates were incubated overnight at 37° C. and 5% CO2. Ala-6,12 human orexin-A, used as the agonist, was prepared as a 1 mM stock solution in 1% bovine serum albumin (BSA) and diluted in assay buffer (HBSS containing 20 mM HEPES, 0.1% BSA and 2.5 mM probenecid, pH7.4) for use in the assay at a final concentration of 70 pM. Test compounds were prepared as 10 mM stock solution in DMSO, then diluted in 384-well plates, first in DMSO, then assay buffer.On the day of the assay, cells were washed 3× with 100 μl assay buffer and then incubated for 60 minutes (37° C., 5% CO2) in 60 μl assay buffer containing 1 μM Fluo-4AM ester, 0.02% pluronic acid, and 1% BSA. The dye loading solution was then aspirated and cells were washed 3× with 100 μl assay buffer. 30 μl of that same buffer was left in each well. Within the Fluorescent Imaging Plate Reader (FLIPR, Molecular Devices), test compounds were added to the plate in a volume of 25 μl, incubated for 5 minutes, and then 25 μl of agonist was added. Fluorescence was measured for each well at 1 second intervals for 5 minutes, and the height of each fluorescence peak was compared to the height of the fluorescence peak induced by 70 pM of Ala-6,12 orexin-A with buffer in place of test compound.
- Assay organism: Homo sapiens
- Target name: Orexin receptor type 2
- Target type: SINGLE PROTEIN
- Target organism: Homo sapiens

## Reference Molecule A
- Canonical SMILES: C[C@@H]1CC[C@@H](Oc2ccc3c(c2)[C@H](O)CC3)CN1C(=O)c1ccccc1-n1nccn1
- Properties:
- ChEMBL ID: CHEMBL5832492
- Molecular weight: 418.5
- Heavy atoms: 31
- Hydrogen bond donors: 1
- Hydrogen bond acceptors: 5
- TPSA: 80.48
- LogP: 3.32
- Rotatable bonds: 4
- Ring count: 5
- Aromatic rings: 3
- Formal charge: 0
- Fraction Csp3: 0.38
- QED: 0.7

## Known Reference Result on This Endpoint
- Molecule A clean result: median pChEMBL = 7.72
- This result is provided as context for predicting Molecule B on the same endpoint.

## Reference Molecule A Other ChEMBL Evidence
- type IC50; relation =; value 19; units nM; pChEMBL 7.72; comment 647989

## Query Molecule B
- Canonical SMILES: C[C@@H]1CC[C@@H](Oc2cccc3c2CC[C@H]3O)CN1C(=O)c1ccccc1-n1nccn1
- Properties:
- ChEMBL ID: CHEMBL6060002
- Molecular weight: 418.5
- Heavy atoms: 31
- Hydrogen bond donors: 1
- Hydrogen bond acceptors: 5
- TPSA: 80.48
- LogP: 3.32
- Rotatable bonds: 4
- Ring count: 5
- Aromatic rings: 3
- Formal charge: 0
- Fraction Csp3: 0.38
- QED: 0.7

## Molecule Similarity
- Weighted Tanimoto: 0.73

Answer: 6.62