Naphthoquinone derivative TPN inhibits Aβ aggregation and improves cognition in scopolamine-induced AD mice

The accumulation of amyloid-β (Aβ) plaques is a central pathological hallmark of Alzheimer's disease (AD), contributing significantly to neuronal dysfunction and cognitive decline. Current therapeutic strategies often target single pathways, leading to limited efficacy. There is a critical need for multitarget-directed ligands that can address the complex pathology of AD, including Aβ aggregation, neuroinflammation, oxidative stress, and neurotransmitter deficits. This study explores a novel naphthoquinone derivative, TPN, as a potential candidate to fill this therapeutic gap.

Researchers synthesized and evaluated naphthoquinone derivatives for their Aβ aggregation inhibitory activity. The most potent compound, TPN (2-(4-(2,3,4-trimethoxybenzyl)piperazin-1-yl)naphthalene-1,4-dione), was then tested in scopolamine (SCO)-induced cognitive impairment mice. In vitro assays included Aβ aggregation inhibition, monoamine oxidase (MAO)-A, MAO-B, acetylcholinesterase, and butyrylcholinesterase inhibition at 10 μM. Molecular dynamics simulations assessed TPN's interaction with Aβ42. In vivo, TPN-treated mice underwent behavioral tests for cognitive function, followed by analysis of Aβ-related protein expression, inflammatory markers, oxidative stress, apoptosis, and metabolite profiling in serum, cortex, and hippocampus. Curcumin served as a reference compound for Aβ inhibition, and donepezil for metabolite profiling comparison.

TPN demonstrated superior Aβ aggregation inhibitory activity with an IC50 = 0.14 μM, making it over 10-fold more potent than the reference compound curcumin (IC50 = 1.63 μM). At 10 μM, TPN effectively inhibited MAO-A, MAO-B, acetylcholinesterase, and butyrylcholinesterase, suggesting a multitarget mechanism. Molecular dynamics simulations revealed prolonged and stable interactions between TPN and Aβ42. TPN was also confirmed to be permeable through the blood-brain barrier and non-toxic to MDCK and SH-SY5Y cells. > Cognitive impairment was significantly improved by TPN treatment in behavioral tests in scopolamine-induced mice. Furthermore, TPN attenuated Aβ-related protein expression, reduced inflammatory responses, mitigated oxidative stress-related changes, and decreased apoptosis-related alterations. Histological analysis showed TPN preserved hippocampal pyramidal neurons and their typical morphology. Metabolite profiling indicated that TPN modulated a narrower set of pathways, primarily related to amino acid and kynurenine metabolism, in contrast to donepezil's broader effects.