YIAD-0501 directly dissociates aggregates of full-length and N-terminal pyroglutamate-modified forms of Aβ

Recent approvals of amyloid-β (Aβ) antibody drugs have established amyloid clearance as a viable therapeutic approach in Alzheimer’s disease (AD). However, despite substantial amyloid reduction, their cognitive benefits remain modest, potentially reflecting incomplete targeting of the structurally diverse pathogenic Aβ assemblies that drive AD progression. Given this molecular heterogeneity, a therapeutic strategy capable of targeting multiple toxic Aβ forms is required to achieve broader efficacy. To address this need, we investigated YIAD-0501, a small-molecule candidate designed to simultaneously engage multiple pathogenic Aβ species, including oligomeric and fibrillar forms of Aβ (1–42) and pyroglutamate Aβ(pE3–42). A series of 6H-furo3,2-fpyrrolo1,2-d1,4diazepine derivatives was synthesized and screened by Thioflavin T fluorescence and A11 dot blot assays to identify compounds active against diverse pathogenic Aβ assemblies. The lead compound, YIAD-0501, was further characterized by transmission electron microscopy, circular dichroism, microscale thermophoresis, molecular docking, and amyloid plate mapping to define its Aβ interaction and structural effects. For in vivo evaluation, YIAD-0501 (10 mg/kg, daily for 4 weeks) was administered to 6-month-old male 5XFAD mice, followed by Y-maze testing for spatial working memory and contextual fear conditioning for hippocampal-dependent memory. Biochemical analyses, including immunoblotting, immunohistochemistry, and ELISA, were subsequently conducted to quantify Aβ plaque burden, soluble Aβ levels, and gliosis. YIAD-0501 effectively reduced both oligomeric and fibrillar assemblies of Aβ (1–42) and Aβ(pE3–42) in vitro. Molecular docking and amyloid mapping analyses indicated interactions between YIAD-0501 and both the C-terminal hydrophobic region and the KLVFFA aggregation core of Aβ, consistent with the observed reduction in β-sheet content and direct binding. In 5XFAD mice, YIAD-0501 treatment decreased amyloid plaque burden, soluble Aβ levels, and neuroinflammation in the hippocampus, accompanied by improvements in spatial working and hippocampal-dependent memory. Collectively, our findings identify YIAD-0501 as a small-molecule candidate that reduces multiple pathogenic Aβ assemblies and ameliorates hippocampal pathology and memory deficits in the 5XFAD mouse model. These findings highlight a chemically driven, multi-target mode of Aβ clearance, representing a strategy for broader intervention across the heterogeneous pathogenic landscape of AD.