In vitro and in vivo Biological Evaluation of Newly Tacrine-Selegiline Hybrids as Multi-Target Inhibitors of Cholinesterases and Monoamine Oxidases for Alzheimer’s Disease

Abstract

Purpose

Alzheimer’s disease (AD) is the most common neurodegenerative disease, and its multifactorial nature increases the difficulty of medical research. To explore an effective treatment for AD, a series of novel tacrine-selegiline hybrids with ChEs and MAOs inhibitory activities were designed and synthesized as multifunctional drugs.

Methods

All designed compounds were evaluated in vitro for their inhibition of cholinesterases (AChE/BuChE) and monoamine oxidases (MAO-A/B) along with their blood-brain barrier permeability. Then, further biological activities of the optimizing compound 7d were determined, including molecular model analysis, in vitro cytotoxicity, acute toxicity studies in vivo, and pharmacokinetic and pharmacodynamic property studies in vivo.

Results

Most synthesized compounds demonstrated potent inhibitory activity against ChEs/MAOs. Particularly, compound 7d exhibited good and well-balanced activity against ChEs (hAChE: IC₅₀ = 1.57 μM, hBuChE: IC₅₀ = 0.43 μM) and MAOs (hMAO-A: IC₅₀ = 2.30 μM, hMAO-B: IC₅₀ = 4.75 μM). Molecular modeling analysis demonstrated that 7d could interact simultaneously with both the catalytic active site (CAS) and peripheral anionic site (PAS) of AChE in a mixed-type manner and also exhibits binding affinity towards BuChE and MAO-B. Additionally, 7d displayed excellent permeability of the blood-brain barrier, and under the experimental conditions, it elicited low or no toxicity toward PC12 and BV-2 cells. Furthermore, 7d was not acutely toxic in mice at doses up to 2500 mg/kg and could improve the cognitive function of mice with scopolamine-induced memory impairment. Lastly, 7d possessed well pharmacokinetic characteristics.

Conclusion

In light of these results, it is clear that 7d could potentially serve as a promising multi-functional drug for the treatment of AD.

Graphical Abstract

Keywords:

• Alzheimer’s disease
• cholinesterase
• monoamine oxidase
• multi-target
• designed

Supporting Information

The ¹H NMR and HRMS spectra of intermediates 3a-e, 4a-4e, as well as the ¹H NMR, ¹³C NMR, HRMS spectra and HPLC analysis of the target compounds 6a-o, 7a-l, were available as Supporting Information.

Ethical Approval

All animal work was carried out in accordance with the institutional guidelines for animal care and use and was approved by the Ethical Committee at Guangxi Medical University Cancer Hospital (Approval LW2023114, date 10/01/2023).

Acknowledgments

This work is supported by the Guangxi Science Fund for Distinguished Young Scholars (Grant No. 2022GXNSFFA035030), the Special Funds for Science and Technology Development under the Guidance of the Central Government (Grant No. ZY20198020), the National Natural Science Foundation of China (Grant Nos. 31970371, 31600265), the Open Project Program of Guangxi Key Laboratory of Brain and Cognitive Neuroscience (Guilin Medical University, GKLBCN-202301-02), the Guangxi Medical University Training Program for Distinguished Young Scholars, the Guangxi Postdoctoral Research Fund.

Author Contributions

All authors made a significant contribution to the work reported, whether that is in the conceptualization, study design, execution, acquisition of data, analysis and interpretation, or in all these areas; took part in drafting, revising or critically reviewing the article; gave final approval of the version to be published; have agreed on the journal to which the article has been submitted; and agree to be accountable for all aspects of the work.

Disclosure

The authors report no conflicts of interest in this work.