Ga complexes of 8-hydroxyquinoline-2-carboxylic acid: Chemical speciation and biological activity

• Published in: Journal of inorganic biochemistry Vol. 260; p. 112670
• Main Authors: Ryza, Izabela, Granata, Claudia, Ribeiro, Nadia, Nalewajko-Sieliwoniuk, Edyta, Kießling, Andreas, Hryniewicka, Marta, Plass, Winfried, Godlewska-Żyłkiewicz, Beata, Cabo Verde, Sandra, Milea, Demetrio, Gama, Sofia
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.11.2024
• Subjects: Anti-inflammatory action; Ga3+ complexes; Human microbiota; Ionizing radiation; Stability constants; Ionizing radiation; Stability constants; Human microbiota; Ga3+ complexes; Anti-inflammatory action; Ga(3+) complexes
• ISSN: 0162-0134; 1873-3344; 1873-3344
• DOI: 10.1016/j.jinorgbio.2024.112670

The binding ability of 8-hydroxyquinoline-2-carboxylic acid (8-HQA) towards Ga3+ has been investigated by ISEH+ (Ion Selective Electrode, glass electrode) potentiometric and UV/Vis spectrophotometric titrations in KCl(aq) at I = 0.2 mol dm−3 and at T = 298.15 K. Further experiments were also performed adopting both the metal (with Fe3+ as competing cation) and ligand-competition approaches (with EDTA as competing ligand). Results gave evidence of the formation of the [Ga(8-HQA)]+, [Ga(8-HQA)(OH)], [Ga(8-HQA)(OH)2]− and [Ga(8-HQA)2]− species, the latter being so far the most stable, as also confirmed by ESI-MS analysis. Experiments were also designed to determine the stability constants of the [Ga(EDTA)]− and [Ga(EDTA)(OH)]2− in the above conditions. Due to the relevance of Ga3+ hydrolysis in aqueous systems, literature data on this topic were collected and critically analyzed, providing equations for the calculation of mononuclear Ga3+ hydrolysis constants at T = 298.15 K, in different ionic media, in the ionic strength range 0 < I / mol dm−3 ≤ 1.0. The synthesis and characterization (by ElectroSpray Ionization – Mass Spectrometry (ESI-MS), Attenuated Total Reflectance - Fourier-Transform Infrared Spectroscopy (ATR-FTIR) and ThermoGravimetric Analysis (TGA)) of Ga3+/8-HQA complexes were also performed, identifying [Ga(8-HQA)2]− as the main isolated species, even in the solid state. Finally, the potential effects of 8-HQA and Ga3+/8-HQA complex towards human microbiota exposed to ionizing radiation were evaluated (namely Actinomyces viscosus, Streptococcus mutans, Streptococcus sobrinus, Pseudomonas putida, Pseudomonas fluorescens and Escherichia coli), as well as their anti-proliferative and anti-inflammatory properties. A radioprotective effect of Ga3+/8-HQA complex was observed on Actinomyces viscosus, while showing a potential radiosensitizing effect against Streptococcus mutans and Streptococcus sobrinus. No cytotoxicity on RAW264.7 murine macrophage cells was observed, neither for the free ligand or Ga3+/8-HQA complex. Nevertheless, Ga3+/8-HQA complex highlighted potential anti-inflammatory properties. The chemical speciation of 8-hydroxyquinoline-2-carboxylic acid (8-HQA) / Ga3+ system was studied in aqueous solution. Solid state complexes were also obtained and characterized. Their effect on microbiota radiosensitivity and their anti-inflammatory action were also evaluated. [Display omitted] •The chemical speciation of Ga3+/8-HQA system was studied.•Stability constants of Ga3+/EDTA and Ga3+ hydrolysis constants were reported.•[Ga(8-HQA)2]− is the main species formed, both in aqueous solution and solid state.•Ga3+/8-HQA complex shows radioprotective effect towards A. viscosus.•Ga3+/8-HQA complex shows radiosensitizing effect towards Streptococcus spp..•Ga3+/8-HQA complex shows anti-inflammatory potential.