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

Abstract

Background Recent approvals of amyloid-beta (A beta) 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 A beta assemblies that drive AD progression. Given this molecular heterogeneity, a therapeutic strategy capable of targeting multiple toxic A beta 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 A beta species, including oligomeric and fibrillar forms of A beta (1-42) and pyroglutamate A beta(pE3-42). Methods A series of 6H-furo[3,2-f]pyrrolo[1,2-d][1,4]diazepine derivatives was synthesized and screened by Thioflavin T fluorescence and A11 dot blot assays to identify compounds active against diverse pathogenic A beta 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 A beta 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 A beta plaque burden, soluble A beta levels, and gliosis. Results YIAD-0501 effectively reduced both oligomeric and fibrillar assemblies of A beta (1-42) and A beta(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 A beta, consistent with the observed reduction in beta-sheet content and direct binding. In 5XFAD mice, YIAD-0501 treatment decreased amyloid plaque burden, soluble A beta levels, and neuroinflammation in the hippocampus, accompanied by improvements in spatial working and hippocampal-dependent memory. Conclusions Collectively, our findings identify YIAD-0501 as a small-molecule candidate that reduces multiple pathogenic A beta assemblies and ameliorates hippocampal pathology and memory deficits in the 5XFAD mouse model. These findings highlight a chemically driven, multi-target mode of A beta clearance, representing a strategy for broader intervention across the heterogeneous pathogenic landscape of AD.