Targeting neuroinflammation by activation of the sigma-1 receptor (S1R) and inhibition of butyrylcholinesterase (hBChE) leads to highly potent anti-amnesic compounds in an Alzheimer's disease mouse model.

Alzheimer's disease (AD) is a neurodegenerative disorder for which no effective preventative or curative treatment has yet been identified. Due to the multifactorial nature and complex pathophysiology of the disease, we developed a multi-target ligand that both inhibits human butyrylcholinesterase (hBChE), a key enzyme linked to β-amyloid plaque formation, and activates the sigma-1 receptor (S1R), which modulates neuroinflammatory and protective pathways. To this end, a series of isoindolines were designed and synthesized, and their biological activities were evaluated. The most promising compound, 7c, exhibited significant dual activity, achieving nanomolar IC50 values against hBChE and potent S1R activation. Subsequent in vivo studies in an Aβ25-35 mouse model revealed a remarkable improvement in cognitive deficits in both short- and long-term memory at an effective dose of 0.01 mg/kg in WT Swiss-OF1 mice. This dose is 10-fold lower compared to single-target compounds 7a and 7b of this isoindoline series. The lack of neuroprotective effects in BChE knock-out (KO) mice confirmed the involvement of BChE inhibition in the pharmacological effects of compound 7c in WT mice. Further combinatorial studies employing a two-drug combination demonstrated synergy in the neuroprotective effect of addressing the two targets.