Development of novel salicylic acid–donepezil–rivastigmine hybrids as multifunctional agents for the treatment of Alzheimer’s disease

Figures & data

Figure 1. Design of salicylic acid–donepezil–rivastigmine hybrids.

Scheme 1. Synthesis of 5a–5h. Conditions: (i) EDCI, HOBT, THF, and room temperature. (ii) N,N-disubstituted carbamoyl chlorides (4a–4e), CH₃CN, 65 °C.

Table 1. The inhibitory capacity of AChE/BuChE by 5a–5h, rivastigmine and donepezil.

Comp.	Position of OCONR1R2	NR1R2	IC50 ± SD^a (μM)		SI^d
			eeAChE^b	eqBuChE^c
5a	4		7.8 ± 0.36	0.53 ± 0.01	14.7
5b	4		6.3 ± 0.41	2.6 ± 1.8	2.4
5c	4		7.1 ± 0.23	10.8 ± 0.56	0.66
5d	4		22.3 ± 1.8	8.7 ± 0.93	2.6
5e	4		18.3 ± 0.87	13.1 ± 0.72	1.4
5f	5		5.2 ± 0.35	16.3 ± 0.86	0.32
5g	5		4.9 ± 0.68	13.5 ± 0.52	0.36
5h	5		8.2 ± 0.67	16.7 ± 1.2	0.49
1a			16.3 ± 0.17%^e	25.8 ± 0.93%^e	–
1b			20.6 ± 1.2%^e	18.2 ± 0.67%^e	–
Donepezil			0.018 ± 0.002	7.6 ± 0.68	0.003
Rivastigmine			11.3 ± 0.08	4.9 ± 0.02	2.3

^a IC₅₀ was indicated as the mean ± SD.

^b eeAChE = electric eel AChE.

^c eqBChE = equine serum BuChE.

^d SI = IC₅₀ (AChE)/IC₅₀ (BuChE).

^e Inhibition percent rate at 25 μM.

Figure 2. (A) BuChE recovery capability after preincubation of compound 5a was diluted to 0.1 × IC₅₀. (B) The recovery capability of BuChE inhibition by rivastigmine, donepezil, and 5a was diluted to 0.1 × IC₅₀ by monitoring with time for 240 min. The results were indicated as the mean ± SEM.

Figure 3. (A) 5a (green stick) interacted with the binding residues of huBuChE (PDB code: 4tpk). (B) 2D interaction of 5a (green stick) with huBuChE.

Figure 4. The cell viability was determined using CCK-8 assay. The results were indicated as the mean ± SD.

Figure 5. (A) Effects of compounds 5a and donepezil on the production of IL-6; (B) effects of compound 5a and donepezil on the production of IL-1β; (C) effects of compound 5a and donepezil on NO release. The results were expressed as the mean ± SD. *p < 0.05, **p < 0.01 vs. model group; ^##p < 0.01 vs. control.

Figure 6. (A) The cytotoxicity of 5a. (B) Neuroprotective effects of compounds 5a and donepezil on Aβ_25-35-induced PC12 cell injury by CCK-8 assay. Data were listed as the mean ± SD. *p < 0.05, **p < 0.01 vs. Aβ_25-35-induced group; ^##p < 0.01 vs. control group.

Figure 7. Stabilities of 5a in artificial gastrointestinal fluids (n = 3).

Figure 8. (A) Rat microsomes stability of 5a (n = 3); (B) plasma stability of 5a (n = 3).

Figure 9. The in vivo effects of compound 5a and donepezil on scopolamine-induced cognitive dysfunction in mice. The results were indicated as the mean ± SD. **p < 0.01 vs. scopolamine-induced group; ^##p < 0.01 vs. normal group.