Alzheimer's disease (AD) is characterized by progressive cognitive decline, amyloid plaque accumulation, synaptic dysfunction, and neuroinflammation. This study reports the therapeutic potential of (S)-4-amino-5,5-difluoro-N'-methyl-N'-phenylpentanehydrazide hydrochloride (RA-058HM), a novel compound, in ameliorating these pathological features of AD in the 5xFAD mouse model. RA-058HM was administered orally for 8 weeks, and its multi-target effects - including relief from neuroinflammation, normalization of synaptic transmission, reduction of amyloidogenesis (plaque and soluble oligomers, as well as BACE1 levels), and rescue of cognitive function-were evaluated. To our knowledge, RA-058HM is the first compound to demonstrate simultaneous modulation of these key pathways in the 5xFAD model, highlighting its potential as a comprehensive disease-modifying therapy for AD. Behavioural tests revealed marked improvements in spatial and recognition memory in RA-058HM-treated 5xFAD mice, suggesting a reversal of cognitive deficits. At the molecular level, RA-058HM treatment reduced amyloidogenesis, as evidenced by decreased levels of amyloid precursor protein (APP) and β-secretase (BACE1) in the hippocampus, accompanied by reduced plaque formation, as detected by Thioflavin-S staining. Furthermore, synaptic transmission was restored to near-normal levels in RA-058HM-treated neurons, indicating that RA-058HM effectively rescues synaptic deficits without altering synaptic protein levels of PSD95 and synaptophysin. In addition, treatment of RA-058HM downregulated hippocampal levels of the NLRP3 inflammasome, TNF-α, and GFAP, suggesting a decrease in neuroinflammatory signaling and a modulation of glial activity. Restoration of mitochondrial motility in hippocampal neurons further suggests that RA-058HM may improve cellular energy dynamics. Collectively, these findings indicate that RA-058HM has multifaceted effects on AD pathology, targeting amyloid accumulation, synaptic transmission, neuroinflammation, and mitochondrial function. This study highlights RA-058HM as a promising candidate for AD therapy and underscores the potential of multi-targeted approaches in addressing the complex mechanisms underlying AD progression.
