A Dual-Pronged Approach: A Ruthenium(III) Complex That Modulates Amyloid-ß Aggregation and Disrupts Its Formed Aggregates.

Alzheimer's disease (AD) is a devastating neurological disorder for which soluble oligomers of the peptide amyloid-ß (Aß) are now recognized as the neurotoxic species. Metal-based therapeutics are uniquely suited to target Aß, with ruthenium-based (Ru) complexes emerging as propitious candidates. Recently, azole-based Ru(III) complexes were observed to modulate the aggregation of Aß in solution, where the inclusion of a primary amine proximal to the ligand coordination site improved the activity of the complexes. To advance these structure-activity relationships, a series of oxazole-based Ru complexes were prepared and evaluated for their ability to modulate Aß aggregation. From these studies, a lead candidate, Oc, emerged that had superior activity relative to its azole predecessors in modulating the aggregation of soluble Aß and diminishing its cytotoxicity. Further evaluation of Oc demonstrated its ability to disrupt formed Aß aggregates, resulting in smaller amorphous species. Because altering both sides of the aggregation equilibrium for Aß has not been previously suggested for metal-based complexes for AD, this work represents an exciting new avenue for improved therapeutic success.

Importance of Hydrogen Bonding: Structure-Activity Relationships of Ruthenium(III) Complexes with Pyridine-Based Ligands for Alzheimer's Disease Therapy.

Alzheimer's disease (AD) is the most common form of dementia, where one of the pathological hallmarks of AD is extracellular protein deposits, the primary component of which is the peptide amyloid-ß (Aß). Recently, the soluble form of Aß has been recognized as the primary neurotoxic species, making it an important target for therapeutic development. Metal-based drugs are promising candidates to target Aß, as the interactions with the peptide can be tuned by ligand design. In the current study, 11 ruthenium complexes containing pyridine-based ligands were prepared, where the functional groups at the para position on the coordinated pyridine ligand were varied to determine structure-activity relationships. Overall, the complexes with terminal primary amines had the greatest impact on modulating the aggregation of Aß and diminishing its cytotoxicity. These results identify the importance of specific intermolecular interactions and are critical in the advancement of metal-based drugs for AD therapy.