## Endpoint to Predict
- Endpoint scope: assay
- Measurement type: IC50
- Label type: continuous
- Binary semantics: pchembl
- Assay description: In Vitro Assay: Chinese hamster ovary (CHO) cells expressing the human orexin-1 receptor and the human orexin-2 receptor, respectively, are grown in culture medium (Ham F-12 with L-Glutamine) containing 300 μg/mL G418, 100 U/mL penicillin, 100 μg/mL streptomycin and 10% heat inactivated fetal calf serum (FCS). The cells are seeded at 20'000 cells/well into 384-well black clear bottom sterile plates (Greiner). The seeded plates are incubated overnight at 37 °C. in 5% CO2. Human orexin-A as an agonist is prepared as 1 mM stock solution in MeOH:water (1:1), diluted in HBSS containing 0.1% bovine serum albumin (BSA), NaHCO3: 0.38 g/l and 20 mM HEPES for use in the assay at a final concentration of 3 nM. Antagonists are prepared as 10 mM stock solution in DMSO, then diluted in 384-well plates using DMSO followed by a transfer of the dilutions into in HBSS containing 0.1% bovine serum albumin (BSA), NaHCO3: 0.38 g/l and 20 mM HEPES. On the day of the assay, 50 μl of staining buffer (HBSS containing 1% FCS, 20 mM HEPES, NaHCO3: 0.38 g/l, 5 mM probenecid (Sigma) and 3 μM of the fluorescent calcium indicator fluo-4 AM (1 mM stock solution in DMSO, containing 10% pluronic) is added to each well. The 384-well cell-plates are incubated for 50 min at 37 °C. in 5% CO2 followed by equilibration at RT for 30 min before measurement. Within the Fluorescent Imaging Plate Reader (FLIPR Tetra, Molecular Devices), antagonists are added to the plate in a volume of 10 μl/well, incubated for 120 min and finally 10 μl/well of agonist is added. Fluorescence is measured for each well at 1 second intervals, and the height of each fluorescence peak is compared to the height of the fluorescence peak induced by 3 nM orexin-A with vehicle in place of antagonist.
- Assay organism: Homo sapiens
- Target name: Orexin receptor type 2
- Target type: SINGLE PROTEIN
- Target organism: Homo sapiens

## Reference Molecule A
- Canonical SMILES: COc1ccc2ccn(CCn3cc(NC(=O)c4ncoc4-c4cccc(C)c4)cn3)c2n1
- Properties:
- ChEMBL ID: CHEMBL3939125
- Molecule type: Small molecule
- Molecular weight: 442.48
- Heavy atoms: 33
- Hydrogen bond donors: 1
- Hydrogen bond acceptors: 6
- TPSA: 100
- LogP: 4.16
- Rotatable bonds: 7
- Ring count: 5
- Aromatic rings: 5
- Formal charge: 0
- Fraction Csp3: 0.17
- QED: 0.41

## Known Reference Result on This Endpoint
- Molecule A clean result: median pChEMBL = 8.4
- This result is provided as context for predicting Molecule B on the same endpoint.

## Reference Molecule A Other ChEMBL Evidence
- type IC50; relation =; value 4; units nM; pChEMBL 8.4; comment 387512

## Query Molecule B
- Canonical SMILES: COc1cccc2[nH]cc(CCn3cc(NC(=O)c4ncoc4-c4cccc(C)c4)cn3)c12
- Properties:
- ChEMBL ID: CHEMBL3928882
- Molecule type: Small molecule
- Molecular weight: 441.49
- Heavy atoms: 33
- Hydrogen bond donors: 2
- Hydrogen bond acceptors: 5
- TPSA: 97.97
- LogP: 4.83
- Rotatable bonds: 7
- Ring count: 5
- Aromatic rings: 5
- Formal charge: 0
- Fraction Csp3: 0.16
- QED: 0.38

## Molecule Similarity
- Weighted Tanimoto: 0.58

Answer: 6.96