Pharmaceutica Analytica Acta

Abstract

Characterization of New Atherosclerosis Imaging Ligands with Aminomethylpyridinyl-Tetraazacyclododecane Group Using Liquid Chromatography and Tandem Mass Spectrometry

Weihsi Chen*, Chienchung Hsia, Siaosyun Guan and Chengliang Peng

Macrophage expression C-X-C motif chemokine receptor 4 (CXCR4) plays important role in inflammation and induces atherosclerosis. Two novel similar small molecular CXCR4 antagonists with aminomethylpyridinyl and macrocyclic tetraazadodecanyl groups, known as APD and APO, were designed and synthesized and then used as radio-imaging agents (after chelating with radio isotope of gallium ion) for atherosclerosis diagnosis using an ApoE^-/- mouse model. By PET/CT scanning, the imaging performance of ⁶⁸Ga-APD on atherosclerotic animal model surpasses over ⁶⁸Ga-APO. The structures of the complexes of the ligands with gallium, impurities in APD and metabolites of APD in serum were analyzed using High-Performance Liquid Chromatography (HPLC) and tandem mass spectrometry. The HPLC method based on a C-18 column (25 cm × 4.6 mm and 5 µm) and mobile phase made of programed gradient aqueous acetonitrile spiked with 0.05% trifluoroacetic acid at a flow rate of 0.8 mL min^-1. According to tandem mass spectra and fragmented patterns, both complexes of APD and APO with Ga³⁺ undergo ligand chelation with a metal ion, releasing two protons from the tetraazacyclododecane of APD and the acetyl acid of APO, respectively. The impurities in APD ligand are its partially degraded products with MW values of 256, 349 and 411. Three metabolites of APD in serum were identified after incubation for up to 2 h. The metabolic reaction of APD results in the degradation and release of tetraazacyclododecane, oxidative deamination, and hydroxylation products. The results of the characterization of APD-like ligands used for vascular disease diagnosis base on radio imaging and biostability are satisfactory.

Published Date: 2024-01-05; Received Date: 2023-12-06