Prospective Application of Two New Pyridine-Based Zinc (II) Amide Carboxylate in Management of Alzheimer’s Disease: Synthesis, Characterization, Computational and in vitro Approaches

Figures & data

Scheme 1 Schematic representation of the synthesis of NaL⁷ and NaL⁸ and its zinc (II) complexes along with numbering pattern for NMR spectroscopy.

Table 1 In vitro AChE Inhibitory Values of New Compounds AAZ7 and AAZ8

Concentrations (µg/mL)	AAZ7% Inhibition (Mean±SEM)	AAZ8% Inhibition (Mean±SEM)	Galantamine % Inhibition (Mean±SEM)
1,000	72.65±1.02	89.32±0.65***	96.32±0.75
500	71.97±0.25	87.65±0.87	94.51±0.46
250	69.34±0.48***	86.35±0.45	193.42±0.84
125	68.65±0.63	85.52±0.14***	92.19±0.43
62.5	66.12±0.84***	83.14±0.74	90.56±0.87
31.25	65.32±1.31	82.97±0.98***	89.87±1.64
15.62	63.17±0.58	80.45±0.67***	87.62±0.47
IC50 (µg/mL)	215	14	<0.1
IC50 (μm)	317	25	0.147

Notes: Values are stated as % inhibition (mean SEM of n 3) and IC₅₀values. The detected calculations might be significantly different as compared to a positive control (Galantamine) p ‹ 0.001***.

Abbreviations: SEM, standard error Mean; IC₅₀, inhibitory concentration in 50% of the population.

Figure 1 Graph pad profile of AAZ7 and AAZ8 as AChE inhibitors.

Table 2 In vitro BChE Inhibitory Values of New Compounds AAZ7 and AAZ8

Concentrations (µg/mL)	AAZ7% Inhibition (Mean±SEM)	AAZ8% Inhibition (Mean±SEM)	Galantamine % Inhibition (Mean±SEM)
1,000	81.01±0.14	85.17±0.87***	90.10±0.73
500	79.47±0.58	84.13±0.45***	88.63±0.51
250	78.13±0.95***	83.54±0.74	86.25±0.75
125	76.25±0.31	81.64±1.04***	85.34±0.67
62.5	75.64±0.42***	80.72±0.58	84.97±0.14
31.25	74.95±0.13***	79.31±0.67	83.91±0.24
15.62	72.42±0.27	77.93±0.78***	82.76±0.44
IC50(µg/mL)	31	18	<0.1
IC50 (μm)	45	26.5	0.132

Notes: Values are stated as % inhibition (mean SEM of n 3) and IC₅₀ values. The detected calculations might be significantly different as compared to positive control (Galanthamine), p ‹ 0.001***.

Abbreviations: SEM, standard error mean; IC₅₀, the concentration required to inhibit 50% of the population.

Figure 2 Graph pad profile of AAZ7 and AAZ8 as BChE inhibitors.

Table 3 In vitro DPPH Free Radical Scavenging Activity of New Compounds AAZ7 andAAZ8

Concentrations (µg/mL)	AAZ7% Inhibition (Mean±SEM)	AAZ8% Inhibition (Mean±SEM)	Ascorbic Acid % Inhibition (Mean± SEM)
1000	74.16±0.77***	83.97±0.12	95.63±0.12
500	71.65±0.14	81.69±0.45***	93.65±0.54
250	68.25±0.64	79.54±0.63***	91.54±0.37
125	66.34±0.17	77.85±0.39***	87.25±0.48
62.5	65.02±1.0 ***	75.68±0.97	84.44±0.15
31.25	63.78±0.51	73.47±0.26***	82.74±0.23
15.62	61.64±0.78***	69.87±0.59	77.28±0.79
IC50(µg/mL)	53	17	<0.1
IC50 (μm)	78	29	0.173

Notes: Values are stated as % inhibition (mean SEM of n 3) and IC₅₀ values. The detected calculations might be significantly different as compared to a positive control (Ascorbic acid), p ‹ 0.001***.

Abbreviations: SEM, standard error mean; IC₅₀, inhibitory concentration in half of population.

Figure 3 Graph pad profile of AAZ7 and AAZ8 as DPPH free radical scavengers.

Table 4 In vitro ABTS Free Radical Scavenging Activity of Newly Synthesized AAZ7 and AAZ8

Concentrations (µg/mL)	AAZ7% Inhibition (Mean±SEM)	AAZ8% Inhibition (Mean±SEM)	Ascorbic Acid % Inhibition (Mean± SEM)
1,000	80.45±1.02	81.35±0.35	92.36±0.65
500	75.36±0.69	79.27±0.64***	88.25±0.87
250	71.85±0.57***	78.36±0.58	85.34±0.47
125	68.27±0.24	77.45±0.87***	84.68±0.56
62.5	65.24±0.38***	73.62±0.29	81.75±0.85
31.25	64.95±0.74	70.28±0.36***	79.29±0.91
15.62	63.21±0.16***	65.39±0.89	77.65±0.32
IC50(µg/mL)	110	29	<0.1
IC50 (μm)	190	41	0.129

Notes: Values are stated as % inhibition (mean SEM of n 3) and IC₅₀ values. The detected calculations might significantly different as compared to a positive control (Ascorbic acid), p ‹ 0.001***.

Abbreviations: SEM, standard error mean; IC₅₀, inhibitory concentration in half of population.

Figure 4 Graph pad profile of AAZ7 and AAZ8 as ABTS free radical scavengers.

Figure 5 Docking model of AAZ7 interacting with acetylcholinesterase AChE enzyme. (A) Structure of synthesized compound AAZ7 (brown) at a specific site inside protein cartoon model (white). (B) Three dimensional display of AAZ7 (brown) with amino acid residue (blue) at the binding site with bond distance shown. (C) Two-dimensional visualization of AAZ7 at the enzyme binding site with bonding patterns and bond distance shown.

Figure 6 Docking model of AAZ7 interacting with butyrylcholinesterase BChE enzyme. (A) Structure of synthesized compound AAZ7 (red) at a specific site inside protein cartoon model (white). (B) Three- dimensional display of AAZ7 (red) with amino acid residue (green) at the binding site with bond distance shown. (C) Two-dimensional visualization of AAZ7 at the enzyme binding site with bonding patterns and bond distance shown.

Figure 7 Docking model of AAZ8 interacting with acetylcholinesterase AChE enzyme. (A) Structure of synthesized compound AAZ8 (blue) at a specific site inside protein cartoon model (yellow).(B) Three- dimensional display of AAZ7 (blue) with amino acid residue (light blue) at the binding site with bond distance shown. (C) Two-dimensional visualization of AAZ7 at the enzyme binding site with bonding patterns and bond distance shown.

Figure 8 Docking model of AAZ8 interacting with butyrylcholinesterase BChE enzyme. (A) Structure of synthesized compound AAZ8 (green) at a specific site inside protein cartoon model (purple). (B) Three- dimensional display of AAZ8 (green) with amino acid residue (purple) at the binding site with bond distance shown. (C) Two-dimensional visualization of AAZ8 at the enzyme binding site with bonding patterns and bond distance shown.

Figure 9 Results of molecular dynamics simulations of AAZ7 docked complex with BChE. (A) NMA mobility, (B) eigenvalues, (C) variance (red color represents individual variance in comparison with green color representing cumulative variance), (D) covariance map correlated in red color, uncorrelated in white color and blue color giving correlated, (E) elastic region as more grey area represents more hard regions.

Figure 10 Results of molecular dynamics simulations of AAZ8 docked complex with AChE. (A) NMA mobility, (B) eigenvalues, (C) variance (red color represents individual variance in comparison with green color representing cumulative variance), (D) covariance map correlated in red color, uncorrelated in white color and blue color giving correlated, (E) elastic region as more grey area represents more hard regions.