Ru(II)-arene azole complexes as anti-amyloid-β agents.

With the recent clinical success of anti-amyloid-β (Aβ) monoclonal antibodies, there is a renewed interest in agents which target the Aβ peptide of Alzheimer's disease (AD). Metal complexes are particularly well-suited for this development, given their structural versatility and ability to form stabile interactions with soluble Aβ. In this report, a small series of ruthenium-arene complexes were evaluated for their respective ability to modulate both the aggregation and cytotoxicity of Aβ. First, the stability of the complexes was evaluated in a variety of aqueous media where the complexes demonstrated exceptional stability. Next, the ability to coordinate and modulate the Aβ peptide was evaluated using several spectroscopic methods, including thioflavin T (ThT) fluorescence, dynamic light scattering (DLS), and transmission electron microscopy (TEM). Overall, the complex RuBO consistently gave the greatest inhibitory action towards Aβ aggregation, which correlated with its ability to coordinate to Aβ in solution. Furthermore, RuBO also had the lowest affinity for serum albumin, which is a key consideration for a neurotherapeutic, as this protein does not cross the blood brain barrier. Lastly, RuBO also displayed promising neuroprotective properties, as it had the greatest inhibition of Aβ-inducted cytotoxicity.