Figure 7.

Examples of ligand overlap within histamine receptor subtypes (H₁R/H₃R/H₄R) as observed in the ChEMBL database (Gaulton et al., 2012) and the VU-MedChem fragment library (de Graaf et al., 2013). Compounds with annotated affinities (K_i/IC₅₀) and a confidence factor of 8 or higher for H₁R, H₃R or H₄R were retrieved from the ChEMBL database and considered as ligands for a receptor if the affinity for that receptor was ≤10 μM. The median affinity was used when multiple values were reported. Two-dimensional structures of some subtype selective as well as subtype unselective histamine ligands are presented.