Structural and functional insights into the selective inhibition of mutant tau aggregation by purpurin and oleocanthal in frontotemporal dementia

Tau aggregation driven by microtubule-associated protein tau (MAPT) mutations is central to frontotemporal dementia pathology, yet no disease-modifying therapies effectively target mutant tau. Here, we identify purpurin (PUR) and oleocanthal (OLC) as selective inhibitors of mutant tau aggregation using peptide models spanning the R2R3 interface. Biophysical and cellular assays demonstrated that both compounds more effectively inhibit the aggregation of mutant tau peptides compared to wild-type, with PUR preferentially targeting V287I and N279K variants, and OLC showing broader inhibitory activity. Surface plasmon resonance and docking analyses revealed more stable interactions and lower binding free energies with mutant tau, consistent with their enhanced inhibitory effects. Computational studies using monomeric and fibrillar tau structures supported the mutation-specific binding profiles of PUR and OLC. Atomic force microscopy and confocal imaging confirmed reduced fibril formation, while post-transduction treatment assays showed that both compounds significantly suppressed intracellular tau propagation. Additionally, OLC reduced tau phosphorylation and oligomerization in SY5Y-TauP301L-EGFP cells expressing mutant tau. These findings highlight the potential of PUR and OLC as structurally distinct, mutation-targeted inhibitors of tau aggregation and propagation, providing a rationale for their further development as candidate therapeutics for frontotemporal dementia.