Evaluating the activities of compounds is essential for developing novel therapeutic strategies. Radioligand binding assays remain the main technique to investigate binding affinities, thus quantifying, e.g. compound-receptor interactions. However, fluorescent ligand-binding assays (homogenous time-resolved fluorescence, HTRF) are an emerging alternative. While general assay conditions like salt concentration, pH range, co-factors, incubation time, and receptor concentration are mostly pre-determined in commercially available assays, co-solvents, e.g. DMSO or PEG and solubility enhancer concentrations are customizable. While co-solvents are used to increase solubility of lipophilic compounds, most receptor binding assays are cell-based and solvents may interfere with membrane integrity, thus limiting the assay’s applicability. However, solubility enhancing substances, e.g. cyclodextrins (CDs), have been shown to overcome limiting issues in FDA-approved formulations. Via the generation of inclusion complexes (ICs) compound solubility and plasma concentration are improved while solvent cytotoxicity is decreased simultaneously. Interestingly, CDs have not been investigated in vitro considering the simultaneous increase of solubility while not interfering with compound-receptor interactions. The dopamine receptor family, a major GPCR family, represents an interesting candidate for the investigation of ICs regarding such receptor interaction. This project aims at comparing dopamine D<sub>2</sub> receptor ligands formulated with and without CDs, and subsequently quantifying their binding affinity utilizing a HTRF receptor-ligand binding assay. In this case study it could be shown, that CDs didn’t interfere with receptor binding or exhibit cytotoxic effects, thus rendering CD-based ICs applicable for in vitro testing. Overcoming solubility issues of newly designed compounds via IC formulation is a promising strategy to significantly increase the applicability of HTRF-based cell-based compound-receptor binding assays.

Investigating the effect of β-cyclodextrin on dopamine D<sub>2</sub> receptor ligand binding

ACS Fall 2021

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.

Investigating the effect of β-cyclodextrin on dopamine D2 receptor ligand binding

Investigating the effect of β-cyclodextrin on dopamine D₂ receptor ligand binding