Introduction

Alzheimer’s disease (AD) is characterized as a progressive neurodegenerative disorder that leads to severe behavioral and mental health issues. It is estimated that Alzheimer’s disease accounts for over 80% of dementia cases in the elderly population worldwide [1, 2]. AD is associated with impaired cholinergic functions in the basal forebrain and cortex [3, 4]. Within cholinergic transmission, acetylcholinesterase (AChE) is a key enzyme that hydrolyzes the neurotransmitter acetylcholine (ACh), thus terminating cholinergic signals in the nervous system. Additionally, butyrylcholinesterase (BChE) assists AChE in the regulation of ACh levels [5, 6].

Chitosan, composed of N-acetyl glucosamine units and known as β-(1–4)-linked-D-glucosamine, is a plentiful natural polysaccharide found abundantly in nature. It can be extracted from chitin using a straightforward deacetylation process [7, 8]. Chitosan has remarkable applications in fields such as medicinal chemistry, agriculture, biomedical, chemistry, agriculture and food due to its non-toxicity, biocompatibility and biodegradability [9,10,11,12,13]. Chitosan has limited solubility in most organic solvents and is completely insoluble in neutral and alkaline environments due to its rigid and compact crystal structure and intramolecular hydrogen bonding [14, 15]. To address these limitations, the presence of hydroxyl and amino groups throughout the molecular structure of chitosan enables its chemical modification. This modification facilitates the adjustment of the physico-chemical properties of chitosan, making it suitable for various applications [16, 17].

Quinolones, belonging to the class of N-heterocyclic compounds, hold a significant position in modern drug design and development studies as one of the crucial pharmacophore groups. They are not only synthetic compounds but also occur naturally in certain compounds found in nature [18, 19]. The quinolone-based moiety in the structure of many chemotherapeutic drugs has a broad spectrum of biological activity and is therefore important in medicinal chemistry [20,21,22,23,24,25,26,27]. The intense research efforts of medicinal chemists and pharmacologists are driven by the very reason to explore, design, develop and investigate the diverse pharmacological properties of these agents, reflecting their importance in the field [18, 19].

In derivatization studies from the amino group of chitosan, some derivatives of chitosan-Schiff base were synthesized through the formation of imine bonds (–N=C–). Although quinolone-grafted chitosan derivatives are less common, some compounds have been synthesized and investigated of their biological activities [28,29,30,31,32]. For example, Cheng et al. developed norfloxacin-grafted chitosan antimicrobial sponge and conducted wound healing examinations [33]. In another study, antimicrobial activity studies were carried out by forming a chitosan-ofloxacin complex with electrostatic interaction instead of chemical bonding [34]. By using chitosan as a base matrix and creating a chitosan sponge, norfloxacin, a fluoroquinolone class drug, was loaded into this system and wound healing/burn dressing studies were performed [35].

In the present study, quinolone-grafted chitosan derivatives were synthesized by a chemical cross-linking method using 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS) as crosslinking agents. The synthesized compounds were subjected to characterization using various techniques, including UV–vis spectroscopy, Fourier-transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM) imaging, and elemental analysis. Furthermore, the synthesized compounds were evaluated for acetylcholinesterase and butyrylcholinesterase activity and antioxidant capacity.

Experimental

Materials and methods

Chitosan (CS) with the following specifications: 75–85% deacetylated and medium molecular weight of 190–310 kDa based on viscosity, was purchased from Sigma Aldrich (Germany). Analytical-grade reagents, including EDC, NHS and other necessary materials, were used without further purification. For solubility tests, the ratio of product mass (mg) to solvent volume (mL) was maintained at 1:2. FTIR spectra were recorded using a ThermoFisher Scientific Nicolet IS50 FTIR spectrometer. TGA analysis of the compounds was conducted using a PerkinElmer TGA-8000 Thermogravimetric Analyzer (TGA 800). Elemental analysis (C, H, and N) of the synthesized compounds was carried out by Leco/Truespec Micro. The surface morphology of the compounds was examined using a JEOL JCM-7000 NeoscopeTM at 5 kV.

Synthesis of chitosan-quinolone derivatives, CsMON and CsMOC

The quinolone derivatives (MON and MOC) were synthesized according to procedure previously reported by our group [13]. Chitosan-quinolone derivatives were synthesized according to Scheme 1. The compound MON or MOC (0.2 g) was dissolved in 20 mL 1% glacial acetic acid solution, and to which 0.1 g EDC and 0.1 g NHS were added. The mixture was stirred for activation at room temperature for 1 h. Chitosan was then dissolved in 20 mL 1% glacial acetic acid solution until completely dissolved and transparent (molar ratio of quinolone derivative to chitosan 1:1). The chitosan solution was transferred slowly to the above activated-quinolone mixture. The resulting mixture was then stirred at rt for 24 h. Following the completion of the reaction, the dialyzing process were applied to the resultant solution for removing unreacted quinolone derivative and isourea (dialysis membrane MWCO 3.5 kDa, Merck) against water for 3 days. Subsequently, the solution was frozen and lyophilized to obtain quinolone-grated chitosan conjugates.

Scheme 1
scheme 1

Synthetic pathway for synthesizing quinolone-grafted chitosan derivatives

Full size image

Quantum chemistry calculations

Theoretical calculations employing the Density Functional Theory (DFT) method were conducted to gain insight into the molecular geometry and electronic properties of the synthesized derivatives. All computations were executed using Gaussian 09 software [36], employing the B3LYP functional [37, 38] in conjunction with the 6-311G(d,p) basis set. The reliability of this method has been established through prior investigations [39]. The absence of imaginary frequencies was checked to confirm the ground states.

Antioxidant activity

DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging activity: CsMON or CsMOC (DMSO:AcOH 10:1 (v/v) solution) was added to a methanolic solution of DPPH (2.0 mL) and 5 mL of methanol. The mixture was incubated for 30 min at room temperature in the dark and was measured at 520 nm as described by Blois [40]. The activity was given IC50 values.

CUPRAC (cupric ion reducing antioxidant capacity): 100 μL of each compound solution (DMSO:AcOH 10:1 (v/v)) was mixed with 900 μL bi-distilled water, 1 mL acetate buffer solution (1 mmol/L, pH: 7.0), 1 mL CuCl2 (10 mmol/L) and 1 mL 7.5 mmol/L neocuproine to a final volume of 4 mL. The reaction mixture was then incubated in the dark for 30 min at room temperature, and the absorbance of the reaction mixture was measured at 450 nm against a water blank [41]. Trolox was used as the standard calibration curves, and the results were expressed as mmol Trolox equivalent per g.

FRAP (the ferric reducing ability of plasma): A mixture of 3 mL of FRAP reagent-300 mM pH 3.6 acetate, a 10 mM TPTZ, and 20 mM FeCl3) in a ratio of 10:1:1-was combined with 100 μL of the sample in (DMSO:AcOH 10:1 (v/v) solution. The results were compared against a standard FeSO4.7H2O, tested under the same conditions, and expressed as the μM FeSO4.7H2O equivalent antioxidant power. The mixture was incubated for 30 min at 37 °C and measured at 593 nm [42]. The values were expressed as mmol of Trolox/g.

Acetylcholinesterase and butyrylcholinesterase activity

A modified version of the Ryan and Elman method was used for enzyme inhibition analysis. First, 50 μL of chitosan quinolone derivatives at a concentration of 50 μM were mixed with 50 μL of the corresponding enzyme solution (0.3 U/mL for AChE and 0.15 U/mL for BChE) [43]. The mixture of compounds and enzyme was incubated for 15 min. For AChE inhibition analysis, after the incubation period, butyrylthiocholine chloride (0.2 mM) and acetylthiocholine iodide (0.71 mM) were added to the mixture. Then 50 μL of 5,5′-dithio-bis(2-nitrobenzoic acid) (DTNB) solution (0.5 mM) was added together with 500 μL phosphate buffer (pH 8) to maintain the pH. The resulting solution was thoroughly mixed and incubated at 37 °C for 30 min. Hydrolysis of the substrate resulted in the formation of a yellow colour. The intensity of the yellow colour was measured using a spectrophotometric method with absorbance measurements at 400 nm for AChE. For BChE inhibition analysis, the same procedure was followed except that spectrophotometric measurements were carried out at 412 nm to determine the intensity of the yellow colour. Each assay was performed in triplicate and the averages were used for calculations. Donepezil was chosen as the reference drug for comparison.

Docking study

Docking studies were conducted to elucidate the binding modes of the synthesized derivatives within the active site of AChE and BChE. The molecular geometries obtained from DFT calculations of the compounds were used for the docking study, while the coordinates of human AChE and BChE were obtained from the Protein Data Bank (PDB) under the identification codes 7E3H [44] and 4BDS [45], respectively. These protein structures were stripped of ligands, water molecules, heteroatoms, and co-crystallized solvents. Subsequently, AutoDockTools (v. 1.5.6) [46] was employed to introduce partial charges and hydrogens to both the protein and the ligands. The search space for docking was defined as a 25 Å cube with grid points spaced at 1 Å intervals, centred on active site of the enzyme. AutoDock Vina (v. 1.1.2) was employed for the docking studies [47], with most parameters left at their default settings, except for num_modes, which was set to 20. Visualization of the results was accomplished using BIOVIA Discovery Studio (https://3dsbiovia.com/). The accuracy of the docking procedure was verified by comparing the crystallographic and theoretical data of the native ligands, resulting in a root mean square deviation (RMSD) of < 0.498 Å [48] (Figure S1).

Results and discussion

Synthesis of the quinolone-grafted chitosan derivatives is achieved by scalable technique by modification of chitosan through amide formation using coupling reagents as NHS and EDC. The reaction was carried out with a grafting ratio of 1:1. At the end of the reaction, unreacted quinolone derivatives, formed isourea, and excess acetic acid were removed by dialysis. As shown in Scheme 1, two different chitosan-quinolone derivatives were obtained.

Characterization

The solubility investigation of the obtained compounds in various solvents was tested. In particular, the compounds were found to be insoluble in many polar and non-polar solvents such as acetone, diethyl ether, dichloromethane, benzene and tetrahydrofuran as well as the general organic solvents listed in the table. Further, the compounds were found to be partially soluble and swell form in DMSO, CF3COOH (1%), and CH3COOH (1%). However, it was designated that dimethylsulfoxide/trifluoroacetic acid (DMSO/TFA (10:1) v/v) and (DMSO/CH3COOH (10:1) v/v) solvent system dissolved the compounds (Table 1).

Table 1 Solubility of synthesized compounds
Full size table

Figure 1 displays the FTIR analysis of the both quinolones and quinolone-conjugated chitosan derivatives. The stretching vibration peaks corresponding to the ketocarbonyl and carboxyl groups in the previously synthesized quinolone derivatives were observed in the range of 1722.25–1673.15 cm−1 for MON and 1722.91–1677.38 cm−1 for MOC, respectively. The stretching vibration peaks attributed to -OH and -NH2 groups in the chitosan structure were seen as a broad peak at 3359 cm−1. Furthermore, the absorption bands of the symmetric and asymmetric sp3 alkyl groups in the structure gave stretching vibrations in the range of 2922–2869 cm−1. Characteristic absorption peaks of amide I, amide II, and amide III at 1645.92 cm−1, 1584.51 cm−1, and 1419.02 cm−1 originating from the acetamide group were assigned to –C=O, –N–H, and –C–N vibrations, respectively. As a result of the reaction of chitosan and its quinolone derivatives, the absorption bands of the amino and hydroxyl groups in the chitosan structure were redshifted and was observed at 3345.78 cm−1 and 3271.47 cm−1, respectively [33]. On the other hand, there were minor, though not very specific, changes in the stretching vibration peak of the ketocarbonyl group at the C-4 position of the quinolone. However, reductions in peak intensities were also found, possibly due to the degree of substitution in the reaction between chitosan and the quinolone compound. The amide peaks (I, II, and III) shifted separately to 1627 cm−1, 1526 cm−1, and 1404 cm−1 (for CsMON), and 1628 cm−1, 1525 cm−1, and 1403 cm−1 (for CsMOC), also indicating that the reaction between the amino group in chitosan and the carboxyl group in quinolone derivative was successfully realized.

Fig. 1
figure 1

FTIR spectra of synthesized compounds

Full size image

Table 2 presents the results of the elemental analysis data and the yield of the synthesized chitosan derivatives. Additionally, the elemental analysis was conducted to calculate the degree of substitution (DS) of chitosan using Eq. (1) [29]. It was concluded that slight deviations from the assumed value were realized for the 100% degree of substitution (DS). The presence of sulfur composition and the increase of nitrogen content in both synthesized compounds showed that the successful grafting of quinolone derivatives onto the chitosan chain.

$$ DS = \frac{{a(C/N)_{x} - (C/N)_{y} }}{n} $$
(1)
Table 2 Reaction yield and elemental analysis results
Full size table

The UV–Vis spectra of Cs and Cs-quinolone derivatives were illustrated in Fig. 2. Cs exhibited an absorption peak at 281 nm. On the other hand, the strong UV absorption peaks seen at 273 nm and 271 nm for the compounds CsMON and CsMOC, respectively, confirm the successful achievement of the Cs-quinolone chemical cross-linking reaction.

Fig. 2
figure 2

The UV–Vis spectra of Cs, CsMON, and CsMOC

Full size image

The evaluation of the thermal properties of chitosan and corresponding quinolone-grafted chitosan derivatives was carried out, and the TGA thermograms were shown in Fig. 3. As shown in Fig. 3, the chitosan decomposed in three steps. The first is a mass loss approximately 9% observed at 50–110 °C, due to loss of physically adsorbed water or weak hydrogen bonded by hydroxyl and amine groups in the structure. The second degradation step between 230 °C and 560 °C was the one in which the maximum mass loss (57%) occurred, which is attributed to a loss of volatile compounds due to depolymerization of chitosan. The mass loss of about 18% at 600 °C to 1000 °C and the remaining 19% of the decomposition indicated that the pure chitosan did not decompose completely. The last step determined is probably due to the thermal degradation of the cross-linked molecules formed, which can occur due to the breakdown of the amino group in Cs [49].

Fig. 3
figure 3

TGA results of the Cs and Cs-quinolone derivatives

Full size image

The compound CSMOC exhibited a three-step degradation as in chitosan, whereas the compound CsMON had a two-step degradation. The first step indicated mass loss as a result of removal of adsorbed water. The lower mass loss in the Cs-quinolone derivatives (this ratio is approximately 1.6% in CsMON and 4% in CsMOC) due to water removal can also be attributed to the newly formed amide bond. The second and main decomposition step was designated at 196–380 °C with a mass loss of 55.6% for CsMOC, and 182–450 °C with a mass loss of 73.5% for CsMON. These mass losses are assigned to dehydration, removal of the phenyl, quinolone, piperazine and oxadiazole rings attached to the chitosan backbone, and possible depolymerization of Cs. A weight loss of 14% was observed for the compound CsMOC at around 540 °C in the last step. The residual weight remaining after this step was found to be 25% for CsMON and 27% for CsMOC. This residual weight can be attributed to the degradation of the cross-linking structure that was formed during the destruction of the remaining unreacted amino groups of Cs.

The morphological structures of quinolone-grafted derivatives were analyzed by scanning electron microscopy. The SEM images of Cs, CsMON, and CsMOC are shown in Fig. 4, and the structural morphology changes between Cs and its derivatives were determined. When the SEM images of the structures of quinolone-grafted chitosan were examined, it was found that they had both more polymorphic pores and a rougher surface, whereas chitosan alone has a non-porous and smoother surface. The binding of quinolone derivatives to chitosan by amidation reaction and the differentiation of glucosamine units caused these results.

Fig. 4
figure 4

SEM images of (A); Chitosan, (B); CsMON, (C); CsMOC

Full size image

Quantum chemistry calculations

The molecular geometries of the quinolones MOC and MON were established through quantum chemistry calculations performed at the B3LYP/6-311G(d,p) theoretical level. The most stable molecular configurations are illustrated in Figure S2. Additionally, the frontier molecular orbitals (FMO) of both derivatives were determined using the same theoretical approach and are presented in Fig. 5. The FMO consists of two main types of orbitals: HOMO (highest occupied molecular orbital) and LUMO (lowest unoccupied molecular orbital), which play a crucial role in the reactivity of molecule [50]. HOMO represents the most energetically favorable molecular orbital occupied by at least one electron and governs chemical reactivity with electrophilic species. In contrast, LUMO represents the lowest energy vacant orbital and determine the ability of the molecule to accept electrons and its potential to react with electron-rich species. Figure 5 shows that both molecules have a similar orbital profile. The HOMO is exclusively localized within the quinolone moiety, while the LUMO is distributed on the opposite side of the molecule, specifically on the benzene ring. This electronic distribution underscores the mechanism of electronic transfer within the molecule.

Fig. 5
figure 5

The frontier molecular orbitals (A) and ESP (B) of MOC and MON obtained at B3LYP/6-311G(d,p) level of theory

Full size image

On the other hand, the HOMO and LUMO energies suggest that the molecules possess a relatively low energy gap (3.66 and 3.68 eV), indicative of their high reactivity. Furthermore, the HOMO energy of both molecules (− 5.43 eV) is comparable to that of commonly recognized antioxidant standards such as Butylated hydroxytoluene (− 5.94 eV) and Trolox (− 5.39 eV), implying potential antioxidant activity [51, 52]. This could explain the significant antioxidant activity of CsMON and CsMOC observed experimentally.

The electronic distribution around the molecules was also assessed by calculating the electrostatic potential (ESP), as illustrated in Fig. 5. ESP is as a valuable method for characterizing the reactivity of a molecule, especially for reactions driven by electrostatic attraction. Notably, the most electron-rich regions appear relatively concentrated, primarily located on the acid and carbonyl groups, whereas the electron-poor regions are less concentrated, and distributed over several hydrogen atoms within the molecules. This analysis provides valuable insights into the electrophilic and nucleophilic regions of these compounds.

Biological activity

Antioxidant activity

The antioxidant capacity of the free Cs and quinolone-grafted-Cs derivatives was determined by three different assays, FRAP, CUPRAC, and DPPH. Considering the results, it was found that free Cs showed less activity than other synthesized compounds, as expected. The compound CsMOC exhibited approximately threefold better activity than Cs with a value of 2281.65 ± 42.21 μmol TE/g for CUPRAC assay. The CsMON and CsMOC demonstrated similar activity results for FRAP assay with the value of 3567.22 ± 48.48 μmol TE/g and 3011.05 ± 14.67 μmol TE/g, respectively (Table 3). DPPH radical scavenging results were expresed as the SC50 value (µg/mL), and Trolox was used as a standard. It was observed that although both synthesized compounds demonstrated no better activity than Trolox (0.04 ± 0.01), they showed threefold (0.71 ± 0.07) and fourfold (0.57 ± 0.03) better activity than the free Cs (2.21 ± 0.02), respectively (Table 3). Quinolone derivatives, compounds MON and MOC exhibited better antioxidant activity than chitosan itself, but a lower activity than those grafted with chitosan. For example, the compound MON.

Table 3 Antioxidant activity results of the compounds
Full size table

In vitro acetylcholinesterase and butyrylcholinesterase activity

Chitosan and its synthesized derivatives were investigated for their inhibitory activity against acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) enzymes, using Donepezil as a reference drug. In general, both chitosan (Cs) and the compounds CsMON and CsMOC exhibited higher inhibitory activity against AChE than BChE. Among them, CsMOC demonstrated the most potent inhibitory potential against AChE, with an IC50 value of 0.22 ± 0.04 μg/mL, while CsMON showed moderate activity with an IC50 value of 0.88 ± 0.05 μg/mL. It was observed that Cs had the lowest inhibitory activity against AChE.

However, contrasting results were observed when BChE activity was analyzed. In this case, CsMOC displayed even lower inhibitory potential compared to Cs, with an IC50 value of 4.88 ± 0.12 μg/mL. On the other hand, CsMON exhibited almost the same level of inhibitory activity as Donepezil (Table 4).

Table 4 AChE and BChE activity of compounds
Full size table

Overall, covalent binding of quinolone derivatives to the chitosan skeleton resulted in an increase in both AChE/BChE and antioxidant activities. This showed us that chitosan itself has a certain biological activity, and we concluded that both the amide bond formed as a result of the reaction of quinolone derivatives with chitosan and the heterocyclic structures in these molecules act by increasing the interaction (binding) with amino acids in the active site of the enzyme. This is even better understood when molecular docking results are also analyzed. For example, piperazine, oxadiazole and quinolone, which are three important heterocyclic rings in quinolone derivatives, are thought to interact with different amino acid residues and therefore these groups are thought to play an important role in enzyme inhibition in derivatives formed with chitosan.

Docking investigations

As demonstrated above, the CsMON and CsMOC derivatives exhibit greater overall activity in inhibiting cholinesterase enzymes compared to free Cs. This suggests that the quinolone derivatives, MOC and MON, may contribute, at least in part, to the inhibitory activity of the Cs derivatives. To validate this hypothesis, we conducted a molecular docking study for MOC and MON to assess their affinity for both enzymes, AChE and BChE.

Molecular docking was carried out using the Autodock Vina software with human AChE (PDB ID: 7E3H) and human BChE (PDB ID: 4BDS) enzymes. The docking protocol was first validated by docking the native ligands Donepezil and Tacrine. The results demonstrated RMSD values of less than 0.498 Å (see Figure S1), confirming the accuracy of the procedure. Additionally, docking was performed for Donepezil with both AChE and BChE for comparison.

The outcomes from the molecular docking are presented in Table 5 and Figs. 6, 7, and 8. Table 5 reveals that MOC and MON exhibit a strong binding affinity for AChE, with energy values comparable to or lower than that of Donepezil (− 9.50 and − 10.33 vs. − 9.92 kcal/mol). Similarly, for BChE, both compounds displayed a high binding affinity for the enzyme, with energy values lower than that of Donepezil (− 6.91 and − 7.02 vs. − 5.53 kcal/mol).

Table 5 Binding energies in kcal/mol of MOC, MON and the native ligands into the active site of AChE and BChE
Full size table
Fig. 6
figure 6

The localization of docked native ligands, MON and MOC in the BChE (A) and AChE (B) enzymes

Full size image
Fig. 7
figure 7

The binding mode of native ligand Donepezil (A), MON (B), and MOC (C) at the catalytic site of the human AChE enzyme

Full size image
Fig. 8
figure 8

The binding mode of Donepezil (A), MON (B), and MOC (C) at the catalytic site of the human BChE enzyme

Full size image

Looking at Fig. 6, it becomes evident that MOC and MON occupy the same region as the native ligand in the active sites of both AChE and BChE enzymes. Donepezil, as depicted in Fig. 7, forms hydrogen bond-like interactions with SER293, TYR34, and TYR72, and favorable interactions with TYR337, TRP86, and ASP47. These amino acids are all located within the active sites of the enzymes, explaining the potent inhibitory activity of Donepezil. Similarly, the analysis of MOC and MON interactions reveals that they share several amino acids with Donepezil, including TYR341, TRP86, HIS447, TYR337, and TYR341. In terms of bond types, MOC forms 3 hydrogen bonds, one hydrogen-carbon bond, one halogen bond, and 5 hydrophobic bonds, whereas MON forms 3 hydrogen-carbon bonds, one halogen bond, and 5 hydrophobic bonds. This may explain the higher inhibitory activity of MOC compared to MON.

It is also apparent that the two molecules, MOC and MON, also share some amino acids with Donepezil for BChE (Fig. 8). MOC interacts favorably with PHE37, TYR332, GLY283, and THR284, all of which are involved in the complex with Donepezil. In contrast, MON has only a single interaction with TYR332. TYR332 is a key element of the catalytic site of BChE located in the PAS, which may explain the potential anti-BChE activity of these molecules.

Conclusion

In this study, two quinolone derivatives were successfully obtained by chemical crosslinking method. The structures of the synthesized products were analyzed and confirmed via different spectroscopic, spectrophotometric, thermogravimetric methods such as FTIR, UV–Vis, TGA, SEM, and elemental analysis. In addition, their molecular geometry and electronic properties were examined using DFT calculations. The antioxidant capacity, acetylcholinesterase and butyrylcholinesterase activity of quinolone-grafted chitosan were investigated throughout compared with chitosan alone. In all three antioxidant activity studies (CUPRAC, FRAP, and DPPH), the synthesized derivatives exhibited approximately threefold better activity than chitosan. Furthermore, the compounds showed significant activity against two enzymes that play a critical role in Alzheimer’s disease. In particular, CsMON showed almost the same activity as the standard drug donepezil against the butyrylcholinesterase enzyme. Molecular docking studies also revealed good affinity towards the active site of AChE and BChE for the two quinolones MOC and MON. It was concluded that these novel polymeric compounds could be utilized as antioxidants in both medical and food applications. The compound CsMON may also be a promising drug candidate for the treatment of Alzheimer’s disease.