## Endpoint to Predict
- Endpoint scope: assay
- Measurement type: IC50
- Label type: continuous
- Binary semantics: pchembl
- Assay description: Humna P2X3 Binding Assay: Stably expressing cell line (C6BU-1 cell transfected with human P2X3 receptor gene (GenBank accession number Y07683) was used. The cells were seeded in a 384-well PDL-coated microtiter plate at a concentration of 3000 cells/well and cultured in the medium (8.3% fetal bovine serum, 8.3% horse serum, and 1% antibiotic and antifungal in DMEM) for one day at 37° C. under 5% carbon dioxide atmosphere. The medium was replaced with 4 μM Fluo-3-AM solution (20 mM HEPES, 137 mM NaCl, 2.7 mM KCl, 0.9 mM MgCl2, 5 mM CaCl2, 5.6 mM D-glucose, 2.5 mM probenecid, 0.5% BSA, and 0.04% Pluronic F-127, pH 7.5) and incubated at 37° C. under 5% dioxide carbon atmosphere for one hour. The plate was washed with washing buffer (20 mM HEPES, 137 mM NaCl, 2.7 mM KCl, 0.9 mM MgCl2, 5 mM CaCl2, 5.6 mM D-glucose, 2.5 mM probenecid, pH7.5), and each well was added with 20 μL of the washing buffer. The plate was placed in High-Throughput Screening System FLIPR 384 (Molecular Device Co.). Measurement of fluorescence intensity by FLIPR 384 was started, and 20 μL of DMSO solutions containing different concentrations of the test compound as prepared by dilution with dilution buffer (20 mM HEPES, 137 mM NaCl, 2.7 mM KCl, 0.9 mM MgCl2, 5 mM CaCl2, 5.6 mM D-glucose, 2.5 mM probenecid, 0.1% Pluronic F-127, pH7.5) were dispensed to each well through the built-in automatic dispenser. Five minutes after, 150 nM ATP solution (25 μL) prepared by dilution with the dilution buffer was dispensed through the built-in automatic dispenser, and the measurement of fluorescence intensity was continued for 4 min. For each well, the specific maximum fluorescence intensity was calculated as the ratio of the maximum fluorescence intensity after addition of the ATP solution to the fluorescence intensity at the starting of the measurement. The 50% inhibitory concentration (IC50) was calculated under the assumption that the specific maximum fluorescence intensity without test compound is 0% inhibition and that the specific maximum fluorescence intensity when the dilution buffer was added in place of ATP solution is 100% inhibition, to evaluate the inhibitory activity of the test compound. The specific maximum fluorescence intensity and IC50 were calculated using Spotfire (Science & Technology Systems, Inc.)
- Assay organism: Homo sapiens
- Target name: P2X purinoceptor 3
- Target type: SINGLE PROTEIN
- Target organism: Homo sapiens

## Reference Molecule A
- Canonical SMILES: COC(=O)[C@@H](C)Cn1c(=O)[nH]/c(=N\c2ccc(Oc3ccc(C(F)(F)F)nn3)cc2)n(Cc2ccc(Cl)cc2)c1=O
- Properties:
- ChEMBL ID: CHEMBL6005750
- Molecular weight: 590.95
- Heavy atoms: 41
- Hydrogen bond donors: 1
- Hydrogen bond acceptors: 8
- TPSA: 133.46
- LogP: 3.68
- Rotatable bonds: 8
- Ring count: 4
- Aromatic rings: 4
- Formal charge: 0
- Fraction Csp3: 0.23
- QED: 0.31

## Known Reference Result on This Endpoint
- Molecule A clean result: median pChEMBL = 8.15
- This result is provided as context for predicting Molecule B on the same endpoint.

## Reference Molecule A Other ChEMBL Evidence
- type IC50; relation =; value 7; units nM; pChEMBL 8.15; comment 513730

## Query Molecule B
- Canonical SMILES: COC(=O)[C@@H](C)Cn1c(=O)[nH]/c(=N\c2ccc(Oc3ccc(CO)nc3)cc2)n(Cc2ccc(Cl)cc2)c1=O
- Properties:
- ChEMBL ID: CHEMBL5745635
- Molecular weight: 551.99
- Heavy atoms: 39
- Hydrogen bond donors: 2
- Hydrogen bond acceptors: 8
- TPSA: 140.8
- LogP: 2.76
- Rotatable bonds: 9
- Ring count: 4
- Aromatic rings: 4
- Formal charge: 0
- Fraction Csp3: 0.22
- QED: 0.3

## Molecule Similarity
- Weighted Tanimoto: 0.67

Answer: 8.3