A Rigid Supramolecular Solution to a Flexible Problem: A Multifunctional Calix[4]arene-Based Strategy to Prevent α‑Synuclein Toxicity

The pathological aggregation of α-synuclein (syn) is a hallmark of Parkinson’s disease (PD) and related synucleinopathies. In the present study, we report a supramolecular strategy to reduce syn aggregation and its associated cellular toxicity using a panel of rationally designed anionic calix[4]arenes. Among them, CLXP1, a tetraphosphonato derivative with a rigid, preorganized cavity, emerged as a potent inhibitor of syn aggregation in a validated yeast model of PD based on syn overexpression. CLXP1 significantly improved cell viability by reducing the formation of toxic intracellular inclusions of syn, and restoring multiple dysregulated molecular pathways, while preserving mitochondrial morphology, redox and lipid homeostasis, and enhancing autophagic clearance. NMR analyses revealed that CLXP1 interacts with key residues of the N-terminal domain of syn, critically involved in membrane anchoring and oligomerization, supporting a model in which this interaction stabilizes the α-helical, membrane-bound conformation of syn, thereby preventing its progression toward toxic oligomeric species. These findings highlight the potential of supramolecular host–guest chemistry to selectively target intrinsically disordered proteins and provide a promising scaffold for the development of new modulators of protein aggregation.