Abstract (eng)
Positron emission tomography (PET) is a nuclear medicine imaging technique and a modern non-invasive diagnosis tool for different diseases. In PET, a biologically active molecule which can target a function, metabolic process or endogenous macromolecule and which is tagged by a positron-emitting isotope, is tracked in vivo. In this work, we aimed to develop a novel targeting molecule for visualization of beta-2 adrenergic receptors in human body with PET. In the first phase of the work, we identified a lead structure of beta-2 adrenergic ligands from a literature search and designed a group of potent analogues of the structure. Six compounds, the racemic mixtures of (1-(3-((9H-carbazol-4-yl)oxy)-2-hydroxypropyl)piperidin-4-yl)(4-fluorophenyl)methanone (VIEBAR11), N-(1-(3-((9H-carbazol-4-yl)oxy)-2-hydroxypropyl)piperidin-4-yl)-4-fluorobenz¬amide (VIEBAR52), N-(1-(3-((9H-carbazol-4-yl)oxy)-2-hydroxypropyl)piperidin-4-yl)-4-methoxybenzamide (VIEBAR53) and their (S)-enantiomers were synthesized in decent yields. Receptor binding affinity (Ki) towards the target protein (β2) as well as β2/β1 and β2/β3 selectivity ratios were determined using a competitive radioligand binding assay. All compounds displayed high affinity and good selectivity for the beta-2 adrenergic receptor as Ki values were in the low nanomolar range (0.3 nM – 1.4 nM). Hence, radiolabeling of the respective candidates and further preclinical evaluations can be conducted in the near future.