Alzheimer’s Disease (AD) is characterized by a progressive cholinergic neurotransmission imbalance, with a decrease of acetylcholinesterase (AChE) activity followed by a significant increase of butyrylcholinesterase (BChE) in the later AD stages. BChE activity is also crucial for the development of Aβ plaques, the main hallmarks of this pathology. Moreover, systemic copper dyshomeostasis alters neurotransmission leading to AD. In the search for structures targeting both events, a set of novel 6-benzamide purine nucleosides was synthesized, differing in glycone configuration and N⁷/N⁹ linkage to the purine. Their AChE/BChE inhibitory activity and metal ion chelating properties were evaluated. Selectivity for human BChE inhibition required N⁹-linked 6-deoxy-α-d-mannosylpurine structure, while all three tested β-d-derivatives appeared as non-selective inhibitors. The N⁹-linked l-nucleosides were cholinesterase inhibitors except the one embodying either the acetylated sugar or the N-benzyl-protected nucleobase. These findings highlight that sugar-enriched molecular entities can tune bioactivity and selectivity against cholinesterases. In addition, selective copper chelating properties over zinc, aluminum, and iron were found for the benzyl and acetyl-protected 6-deoxy-α-l-mannosyl N^9-linked purine nucleosides. Computational studies highlight molecular conformations and the chelating molecular site. The first dual target compounds were disclosed with the perspective of generating drug candidates by improving water solubility.

Alzheimer’s disease (AD) is a neurodegenerative disease characterized by multiple factors, such as the progressive decline in the levels of the neurotransmitter acetylcholine, and the deregulation of the homeostasis of bio-metals, such as copper, zinc and iron. Acetylcholine is hydrolyzed by acetylcholinesterase and butyrylcholinesterase and the current therapeutic strategies are based on the treatment of AD patients with these enzymes’ inhibitors. Although these strategies are focused on symptomatic relief of the disease, recent studies have shown that the long-term use of these drugs may lead to disease-modifying benefits. The deregulation of the bio-metals’ homeostasis has been related to oxidative stress and to the induction of Ab aggregation and tau hyperphosphorylation and aggregation. Since AD is a multifactorial disease, discovering a multi-target drug could be an interesting challenge, leading to a disease-modifying therapy. In this context, mannosylpurines synthesized by our group have already shown potent butyrylcholinesterase (BChE) inhibition. Aiming at the discovery of multitarget drug candidates, we have synthesized a new series of mannosyl and rhamnosylpurines and evaluated copper chelation and cholinesterase inhibition. The results obtained will be presented and discussed.