Synthesis, Antibacterial, and Antioxidant Activities of Thiazolyl-Pyrazoline Schiff Base Hybrids: A Combined Experimental and Computational Study

iazole-pyrazoline Schi base hybrids have a broad range of pharmacological potential with an ability to control the activity of numerous metabolic enzymes. In this work, a greener and more ecient approach has been developed to synthesize a novel series of thiazole-pyrazoline Schi base hybrids using ZnO nanoparticle-assisted protocol in good to excellent yields (78.3–96.9%) and examined their antibacterial activity against Gram-positive and Gram-negative bacteria, as well as their antioxidant activity. Compound 24 (IZD 18.67± 0.58) displayed better activity against P. aeruginosa compared with amoxicillin (IZD 14.33± 2.52) at 250 μg/mL, whereas compounds 22 and 24 (IZD 13.33± 0.58mm and 17.00± 1.00mm, respectively) showed better activity against E. coli compared with amoxicillin (IZD 14.67± 0.58mm) at 500 μg/mL.e remaining compounds showed moderate to weak activity against the tested bacterial strains. Compound 21 displayed signicant inhibition of DPPH (IC50 4.63 μg/mL) compared with ascorbic acid (IC50 3.21 μg/mL). Compound 21 displayed 80.01± 0.07% inhibition of peroxide formation, suggesting its potential in preventing the formation of lipid peroxides.e results of the ADMETstudy showed that all synthesized compounds obeyed Lipinski’s rule of ve. In silico pharmacokinetic study demonstrated that compound 24 had superior intestinal absorption compared with amoxicillin. In silico molecular docking analysis revealed a binding anity of −9.9 Kcal/mol for compound 24 against PqsA compared with amoxicillin (−7.3 Kcal/mol), whereas compounds 22 and 24 displayed higher binding anity (−8.5 and −7.9 Kcal/mol, respectively) with DNA gyrase B compared with amoxicillin (-7.1 Kcal/mol), in good agreement with in vitro antibacterial activity against P. aeruginosa and E. coli. In silico toxicity study showed that all synthesized compounds had LD50 (mg/kg) values ranging from 800 to 1,000 putting them in ProTox-II class 4. e in vitro antibacterial activity and molecular docking analysis showed that compound 24 is a promising antibacterial therapeutic agent against P. aeruginosa and E. coli and compound 22 is a promising antibacterial agent against E. coli, whereas compound 21 is found to be a potential natural antioxidant agent. Moreover, the green synthesis approach using ZnO nanoparticle as catalyst was found to be a very ecient method to synthesize biologically active thiazole-pyrazoline Schi base hybrids compared with the conventional method.


Introduction
Antimicrobial resistance (AMR) poses a major threat to human health around the world [1]. In recent years, attention has been given to the development of treatments that generate oxidative stress as part of their antibacterial mechanism of action [2]. erefore, there is an imperative need to search for antimicrobials with antioxidant and antibacterial properties to counter the problems of bacterial resistance. A molecular hybridization is a valuable approach for the design and development of new biological molecules in which two or more active pharmacophoric units are combined to form a new hybrid molecule with increased potency [3,4].
For many decades, thiazole and pyrazoline scaffolds have been studied extensively and found to possess a wide range of chemical reactivity and pharmacological activities [5,6]. ese five-membered heterocyclic compounds have been proven to possess antibacterial activity and the ability to delocalize free radicals and produce stable DPPH fragments [7]. In addition to antibacterial activity, thiazole derivatives exhibit antimicrobial [8], antiviral [9], antidiabetic [10], anticonvulsant [11], antioxidant [12], anti-HIV [13], antiinflammatory [14], Alzheimer's disease [15], and antitumor activities [16]. Previous studies revealed that 3,5-diaryl-4,5dihydro-1H-pyrazole derivatives, which are members of the 2-pyrazoline class, have been extensively investigated using a variety of structural manipulations and it has been discovered that the steric and electronic properties of the various substituents at the N-1, C-3, and C-5 positions, as well as the chirality aspects of these molecules, have a critical influence on activity [17]. e N-N bond link of the pyrazoline ring is thought to be important in their biological activity [18]. Zinc oxide nanoparticle is gaining popularity as a heterogeneous catalyst for a variety of organic transformations due to their low cost, nontoxicity, waste reduction, and recycling properties [19]. e impressive catalytic ability of ZnO nanoparticles associated with morphology-tuned specific microstructures, ability of electron transportation, and their high stability when combined with the intrinsic Lewis acid of the zinc ion motivated us to consider this catalyst.
In the present work, we hereby present ZnO nanoparticle-assisted synthesis of nine novel thiazolyl-pyrazoline Schiff base hybrids, in vitro antibacterial and antioxidant activity along with molecular docking studies, in silico ADMET prediction, drug-likeness, and pharmacokinetic and toxicity properties.

Materials and Methods
All starting chemicals and materials used were analytical grades. Merck (Germany), Sigma-Aldrich Sigma Chemical, Co. (USA), and Loba Chemie, Pvt Ltd. (India) provided preliminary chemicals and reagents, which were purchased from commercial vendors and used immediately without additional purification unless otherwise noted. Column chromatography was performed using (Merck) silica gel (particle size 60-120 mm) with n-hexane, ethyl acetate, and dichloromethane as mobile phase. ZnO nanoparticles were obtained from the Department of Applied Chemistry, Material Chemistry Research Team of ASTU, which is characterized by UV-vis and FT-IR spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM), photoluminescence (PL), and thermogravimetric analysis (TGA) techniques [20]. Amoxicillin and L-ascorbic acid (99%) were employed as standards, both obtained from Ethiopian Pharmaceutical Manufacturing Factory (EPHARM).
Melting points were determined on a Gallenkamp MFB-595 apparatus, uncorrected. UV spectra were obtained using a double-beam UV-visible spectrophotometer (Model 2201, India). e 1 H-NMR and 13 C-NMR spectra were recorded at 400 and 100 MHz, respectively, on a Bruker Avance III 400 Nanospectrometer using tetramethylsilane (TMS) as an internal standard. e chemical shifts are expressed in δ (ppm) and reported as s (singlet), d (doublet), t (triplet), q (quartet), m (multiplet), dd (doublet of doublets), and brs (broad singlet), respectively. Analytical TLC analysis was performed on pre-coated aluminum plate silica gel 60 F 254 (Merck, Darmstadt, Germany). Detection was carried out under UV light (254 and 365 nm). Column chromatographic separations were carried out on silica gel (60-120 mesh, Merck). SwissADME and AutoDock Vina 4.2.6 version software packages were used to undertake in silico ADMET and molecular docking simulation investigations, respectively. [3][4][5]. To an equimolar amount of p-nitro acetophenone (1, 0.06 mol) and the corresponding aldehyde derivatives (2, 0.06 mol) in 5-10 mL of ethanol, 60% (w/v) NaOH was added dropwise (3 mL) and stirred for 30 min (Scheme 1 and SI Appendix A Figure S1) [21]. e resulting solid products (5-7) were stirred in an ice bath for 30 min and then at RT until the precipitate was formed within 3 h. e reaction progress was monitored by TLC with an eluent of n-hexane: ethyl acetate (9 : 1). e precipitate was filtered off and washed thoroughly with cold distilled water and cold methanol (2 × 20 mL). e products (5-7) were recrystallized from absolute ethanol to yield a yellow precipitate of chalcone derivatives. (10)(11)(12).

Synthesis of 2-Amino-4-(substituted-phenyl)-1, 3-thiazole Derivatives
e thiazole moiety was synthesized by utilizing Hantzsch's modified approach (Scheme 2), which involved a solvent-free reaction of substituted acetophenone (6-8) derivatives with thiourea (9) and iodine under thermal conditions resulting in 2-amino-4-aryl thiazole derivatives (10-12, SI Appendix A, Figure S2) [22]. iourea (40 mmol, 2 molar equiv.) was mixed with iodine beads (20 mmol, 1 molar equiv.) in a mortar, and the mixture was homogenized with a pestle. e solids were scratched off into a 250 mL round-bottom flask with a magnetic stirring bar and charged with the corresponding acetophenone (20 mmol, 1 molar equiv.). e flask was heated in an oil bath under an air-cooled condenser at 100°C with stirring. e reaction progress was monitored using TLC in n-hexane and ethyl acetate (4 : 1). After 3 hours, the mixture was cooled and it solidified again. A saturated aqueous solution of sodium thiosulfate (Na 2 S 2 O 3 .5H 2 O, 5%) was added with concomitant mechanical disruption of the solid matrix in a sufficient amount to reduce the remaining iodine. e product as a suspension was filtered off and carefully washed with 20 mL of diethyl ether to remove the residues of unreacted acetophenone. e crude product was dissolved in hot water, filtered, and the hot filtrate was adjusted to pH � 9 by aqueous NaHCO 3 . After cooling, the precipitated product was collected and recrystallized using ethanol. (13)(14)(15). Chalcones 13-15 (0.04 mol), 9.72 mL hydrazine hydrate (80%, 0.2 mol), and ethanol (15 mL) mixture were heated under reflux for 10 minutes until the chalcone was entirely consumed [23]. e progress of the reaction was monitored using TLC in n-hexane and ethyl acetate (9 : 1) as the mobile phase. When the reaction was completed, the warm reaction mixture was poured into icecold water (50 mL), and the precipitate was filtered and rinsed with water and ethanol using suction filtration. e solid produced was recrystallized with ethanol to yield N-formyl pyrazoline derivatives in high purity with good yields (SI Appendix A Figure S3). 4,5-Dihydro-3-(4-nitrophenyl)-5-phenylpyrazole-1-carbaldehyde (13 Journal of Chemistry thiazole derivatives, 10-12 (3 mmol eqiv.), in ZnO nanoparticles (43 mg, 0.2 mmol, 20 mol %) as a catalyst in methanol (20 mL) under reflux for 3 h. e progress of the reaction was monitored using TLC at an appropriate time interval using n-hexane: ethyl acetate (7 : 3). At the end of the reaction, the solution was slowly evaporated, and the precipitate was filtered, washed with ethanol, and dried under a vacuum. Finally, the resulting solid was recrystallized from ethanol to provide a microcrystalline solid product (Scheme 3 and SI Appendix A Figure S4). (18E)-N-((4,5-dihydro-3-(4-nitrophenyl)-5-phenylpyrazol-1-yl)methylene)-4-phenylthiazol-2-amine (16   e antibacterial susceptibility of each bacterial strain to all synthesized compounds was assessed using the Clinical and Laboratory Standards Institute (CLSI) procedures using agar disc diffusion assay. e inhibition zone technique shows the ability of a compound or drug to prevent microbial growth [24].

Synthesis of 3, 5-Diphenyl-4,5-dihydro-1H-pyrazol-1carbaldehydes
e Adama Public Health Research and Referral Laboratory Center provided four strains of pathogenic microorganisms of two Gram-positive bacteria, including the MRSA strain of Staphylococcus aureus (ATCC 25923) and Streptococcus pyogenes (ATCC 27853), and two Gram-negative bacteria, Escherichia coli (ATCC 25922) and Pseudomonas aeruginosa (ATCC 27853). Colony morphology and Gram staining, as well as routine biochemical assays, were used to identify and authenticate the bacterial strains, according to Bergey's Manual of Determinative Bacteriology [25]. e antibacterial activity was assessed at 250 and 500 μg/mL concentrations by measuring the zone of inhibition against the test organisms and comparing it with amoxicillin as the reference antibiotic. Amoxicillin (25 and 50 mg/mL) was the standard drug used as a positive control, and DMSO was used as a negative control. e experiments were repeated three times, and the average clear zone (inhibition zone) around each compound was measured in millimeters (mm) [26].

DPPH Free Radical Scavenging
Assay. By bleaching the purple color of a methanolic solution of DPPH, the ability of the related compounds to transfer hydrogen atoms or electrons was measured. e 2,2-diphenyl-1-picrylhydrazyl (DPPH) approach was used to examine the in vitro radical scavenging activity of the synthesized compounds with minor adjustments [27]. To a solution of 1 ml of 0.004% methanolic solution of diphenyl picrylhydrazyl (DPPH), 4 ml of various sample concentrations was added. After 60 minutes in the dark, the absorbance was measured against a blank at 517 nm using a double-beam UV-vis spectrophotometer. e blank reading solution was methanol, while the standard solution was ascorbic acid, which was calculated by the following equation:

In Vitro Lipid Peroxidation Inhibition Assay.
Lipid peroxidation proceeds in the form of a self-sustaining chain reaction and is very harmful. e formation of lipid-free radicals and lipid peroxide radicals in the cell membranes is considered an important feature of the cell damage caused by reactive oxygen species [28]. Ascorbic acid was used as a positive control. e percentage of lipid peroxidation inhibition was calculated from the following equation: where A sample � absorbance of the sample and A control � absorbance of control. e percentage of lipid peroxidation inhibition was plotted against the synthetic compound concentration to determine the concentration required to achieve 50% inhibition of phospholipid oxidation (IC 50 ) in linoleic acid; ascorbic acid was used as a positive control.

In Silico Computational Studies
(1) ADMET, Drug-Likeness, and Toxicity Prediction. e prediction of the in silico ADMET parameters before the experimental studies is one of the most important aspects of drug discovery and development processes. ADMET studies play a critical role in helping to optimize the pharmacokinetic and pharmacodynamic properties of new drugs [29].
is prediction is based on an already established concept by the Lipinski rule of five [30] and the Veber rule [31]. Properties of the compounds were estimated using ADME descriptors by using SwissADME (https://www.swissadme.ch/), Molinspiration (https:// www.molinspiration.com/), and PreADMET (https:// preadmet.webservice.bmdrc.org/) online servers. Structures of compounds were submitted to SwissADME tools and converted to their canonical simplified molecularinput line-entry system (SMILEs), to estimate in silico pharmacokinetic parameters and other molecular properties based on the reported method [32]. e organ toxicity profiles and toxicological endpoints of the ligands and toxicity class were predicted using ProTox-II Web server explorer (https://tox-new.charite.de/).

Molecular Docking Study.
A molecular docking study was performed to investigate the binding mode between the synthesized compounds against target enzymes. ChemDraw program (Chem Create 16.0) was used to draw chemical structures of compounds with suitable 2D orientation, and ChemDraw Ultra 8.0 was employed to minimize the energy of ligands and standard drugs. e protein preparation and docking simulation were then carried out using the energyminimized ligand molecules as input to AutoDock Vina 4.2.6 [33]. e DNA gyrase B (PDB ID: 6f86), the N-terminal domain of PqsA in complex with 6-fluoroanthraniloyl-AMP (PDB ID:5oe3), Pyruvate Kinase in complex with bis-indole alkaloid (PDB ID:3t07), LuxS of S. pyogenes (Uniprot id: P0C0C7), and Human peroxiredoxin 5 (PDB ID: 1HD2) crystal structures were downloaded from the Protein Data Bank (https://www.rcsb.org) to investigate the binding interaction of the synthesized compounds with the active site of protein targets using the following grid box parameters (PDB ID: 6f86) [ [34]. e best-docked conformation between ligand and protein was searched using the docking algorithm with AutoDock Vina. During the docking process, a maximum of nine conformers were considered for each ligand. Meanwhile, the Discovery Studio Visualizer 2021 and PyMOL (version 2.4) were used to investigate the possible interactions and ligand orientations between the target receptor and ligands by identifying conformations to optimize the docking function [35].

Results and Discussion
A series of novel thiazolyl-pyrazoline Schiff base hybrids were synthesized and characterized using spectroscopic methods with good to excellent yields (78.3-96.9%). Shorter reaction times were achieved for the ZnO nanoparticlecatalyzed approach compared with the conventional glacial acetic acid-catalyzed reactions under reflux conditions. Physical properties and NMR spectral data of the synthesized compounds are presented in supporting information (SI Appendix B Figures 19-45).

Recyclability Study of the Catalyst.
A good catalyst for scale-up applications should have high activity and stability. After the reaction was completed, the catalyst was filtered, washed with dichloromethane and methanol, and dried at 100°C for 5 hr before being used in the next cycle with no apparent loss of activity, making this technique cost-effective and environmentally benign (SI Appendix A, Table S3) [36].
e catalyst ZnO NPs were found to have good catalytic activity for six consecutive runs with no appreciable catalytic activity loss and delivered a modest decrease in reaction yield ( Figure 1). ZnO nanoparticle catalysis provides a shorter time and a higher product yield compared with typical acid catalysts [37,38]. (3)(4)(5). Chalcone scaffolds were synthesized at room temperature by combining p-nitro acetophenone with various substituted aryl aldehydes via a basic catalyzed Claisen-Schmidt condensation reaction (Scheme 1 and SI Appendix A Figure S1). e aryl ring substitution pattern was carefully chosen to provide a variety of electronic environments that would affect the target molecules' antibacterial and antioxidant activity patterns. In the 1 H _ NMR spectrum of compounds (3)(4)(5), H-β and H-α protons of α, β-conjugated system of chalcone appeared as a broad doublet in between δ 7.75 _ 7.73 and δ 7.32 _ 7.39, respectively, with a coupling constant of 3 J � 15.6 Hz, which agrees with a trans-configuration. For compound 3, AAXX' spin system aromatic protons for ring A and monosubstituted ring B are evident at δ7.43 _ 7.95. For compound 4, two sets of AAXX′ spin system aromatic protons are observed between δ 7.23 _ 7.46 and δ 7.52-7.96. For compound 5, AAXX′ spin system aromatic protons for ring A and disubstituted ring B are evident at δ7.70 _ 7.88 and δ8.00 _ 8.04, respectively. In the 13 C-NMR spectrum of compounds (3)(4)(5), the C-β and C-α signals appeared at δ138.4 and 120.1, respectively, while the carbonyl group appeared between δ 167 and 189.9.

3.3.1.
Structure-Activity Relationships (SARs). Structure-activity-based mechanism of antimicrobial action is critical for the design and improvement of novel antimicrobial and antioxidant agents. e results demonstrate that compound 17, with a p-NO 2 substituent on the aromatic ring of thiazole moiety, resulted in a decreasing pattern in antibacterial activity against all strains compared with compound 16, which has a hydrogen atom at para position of the aromatic ring of thiazole moiety. Compound 18, with a p-OH substituent on the aromatic ring of thiazole moiety, resulted in an increase in antibacterial activity towards S. aureus at 250 µg/mL and S. pyogenes at 250 and 500 µg/mL compared with compound 16. Compound 20, with a p-NO 2 substituent on the aromatic ring of thiazole moiety, resulted in an increase in antibacterial activity towards S. aureus at 500 µg/mL and S. pyogenes at 250 µg/mL compared with compound 19, which has hydrogen at the para position of the aromatic ring of thiazole moiety. Compound 21, with a p-OH substituent on the aromatic ring of thiazole moiety, resulted in an increase in antibacterial activity towards S. aureus and S. pyogenes at 500 µg/mL compared with compound 19, which has hydrogen at the para position of the aromatic ring of thiazole moiety, whereas compound 23, with a p-NO 2 substituent on the aromatic ring of thiazole moiety, resulted in an increasing antibacterial activity trend towards S. aureus and S. pyogenes at 500 µg/mL compared with compound 22. On the other hand, compound 21, with a p-OH substituent on the aromatic ring of thiazole moiety, resulted in an increase in antibacterial activity towards S. pyogenes, E. coli, and P. aeruginosa at 500 µg/mL compared with compound 19, which has hydrogen at the para position of the aromatic ring of thiazole moiety. In addition, the presence of p-Br and p-OH group pyrazoline moiety bearing with substituted-phenyl rings might be the most relevant cause for enhancing the antibacterial activities. e results suggest that the antibacterial activity of the investigated compounds was influenced by the physicochemical properties of the type and position of substituent on the aromatic rings of thiazole and pyrazoline moieties.

DPPH Free Radical Scavenging and Lipid Peroxidation
Inhibition.
e antioxidant activity of compounds 16-24 was determined by the DPPH assay. From the results obtained ( antioxidant activity (IC 50 � 4.63 μg/mL) compared with the positive control, ascorbic acid (IC 50 � 3.21 μg/mL) (Figure 3). e rest of the compounds showed moderate to weak activity. Most of the synthesized compounds (except 17 and 22) showed greater than 80% of DPPH radical scavenging activity at a concentration of 200 μg/mL (Figure 4). e presence of electron-donating hydroxyl functionality at an ortho position of thiazole phenyl groups could be the most possible reason, which might stabilize the radicals for their strong electron-donating nature [41]. Compounds 21 and 24 inhibited peroxide formation by 80.01 ± 0.07% and 79.44 ± 0.05%, respectively, demonstrating their potential in preventing lipid peroxide formation as presented (Table 2). us, the results showed that the studied thiazole-pyrazoline-based Schiff base hybrids remove the free radicals, especially the lipid peroxide radicals, by giving them their hydrogen atom and thus inhibiting the lipid peroxidation reaction.

In Silico ADMET Prediction.
SwissADME is a Webbased tool that provides important information about druglikeness and pharmacokinetic properties of bioactive molecules [42,43]. In this perspective, the theoretical agreement of synthesized compounds to Lipinski's rule of five and Veber's rule [30,31,44], as well as the pharmacokinetic and toxicity parameters, was estimated using ADMET descriptors by a SwissADME [31] and PreADMET [45] online servers. e percent absorption (%Abs) of the synthesized compounds was computed using the formula % Abs � 109-0.345TPSA [46]. e filter that combines Lipinski's "rule of five" refers physicochemical properties of a molecule to become a drug (i.e., MW ≤ 500 Daltons, iLog P ≤ 5, H-bond donors ≤5, and H-bond acceptors ≤10) [44] and Veber's parameters (TPSA ≤140Å 2 and rotatable bonds ≤10) [30]. ProTox-II Web server exploration was used to forecast the ligands' organ toxicity profiles and toxicological endpoints, as well as their LD 50 [46,47]. e results showed that all of the compounds obeyed Lipinski's rule of five (Table 3), with only minor deviations for 19-21 and 23, and thus, they have the potentials to be developed as orally bioavailable drugs. All synthesized compounds have a higher bioavailability score of 0.55 and were suitable for oral administration, indicating drug-like qualities [48]. eir HBD values are <3, indicating that they are highly soluble in cellular membranes, with HBA values ranging from 5 to 8.     Journal of Chemistry e iLogP values for all compounds are <5, notably for 20 and 22-24 indicating the compounds have good lipophilicity characteristics, which may protect them against ROS degradation. TPSA ranged from 86.68 to 152.73Å 2 , while the consensus log Po/w (indicator of lipophilicity) was observed in an optimal range from 2.06 to 3.64. Compounds that satisfy the parameters of TPSA ≤140Å 2 are expected to have adequate solubility, oral bioavailability, and cell permeability [49]. All compounds (16-24) exhibited better percent absorption (% Abs) than amoxicillin suggesting good oral bioavailability.
In silico pharmacokinetic characteristic results (Table 4) revealed that compounds 16-24 had superior intestinal absorption to amoxicillin, ranging from 90.80 to 99.82% absorption with HIA values near 100%. In vitro, Caco2 and MDCK cells have moderate to high permeability, notably 18, 22, and 24, and especially 19 and 24, which are better than amoxicillin (0.39), respectively. Skin permeability (SP, Log Kp ) was found to be somewhat below the permitted range of −5.42 to −6.59 cm/sec, and a substance with a low negative Log Kp value has higher absorption into human skin. e results indicate that the synthesized compounds are showing good absorption properties to cross the gut wall by passive diffusion mechanism to reach the target. All of the compounds were poorly absorbed into the CNS in vivo, showing that they have a decreased ability to cross the CNS, with a total clearance value of 24 (0.07), which is comparable to amoxicillin (0.06). All of the substances have a high PPB%, with values of more than 90%, suggesting that they are strongly bound. e results revealed that compounds 18 (99.75) and 24 (97.31) had high PPB values, indicating longer half-lives than amoxicillin (23.35) [50]. Furthermore, glycoprotein (P-gp) inhibition measurements are utilized to forecast the target drugs' excretion properties. P-gp and cytochrome P450 (CYP) are known to aid in the protective efflux (biotransformation) of biological membranes (GI tract or brain) from xenobiotics to protect tissues [51]. e compounds' metabolic properties were predicted by the behavior of cytochrome P450 and their isoform enzymes. In this investigation, compounds 16-24 showed no inhibitory activity against CYP2C19, CYP2C9, CYP2C6, or CYP3A4, except 3b and 3c, which showed inhibitory activity against CYP2D9. In our study, none of the synthesized compounds inhibited P-gp substrates, except 16 and 19. Toxicity data must be connected with in vitro safety investigations before being examined in relevant laboratory animal models [52]. In addition, all compounds were predicted for their computational toxicity risks, such as the AMES test (for mutagenicity prediction), tumorigenicity carcino-mouse/rat (for carcinogenicity prediction), and skin irritancy hERG inhibition (for checking cardiac toxicity), and cytotoxicity effect (Table 5). Based on toxicity profiles, all compounds (16)(17)(18)(19)(20)(21)(22)(23)(24) and amoxicillin showed mutagenic behavior in the AMES test. All compounds, except for 17, 20, 23, 24, and amoxicillin, exhibited no possible carcinogenic effect in mice and no potential carcinogenic effect in rats. All of the compounds exhibited a low risk of being cardiotoxic or cytotoxic, as well as being safer than standard drugs. All of the synthesized compounds tested had predicted LD 50 (mg/ kg) values ranging from 800 to 1,000 putting them in ProTox-II class 4, indicating that they could be harmful if swallowed (300LD 50 ≤ 2000) [53]. e bioavailability radar plots of the tested compounds (16)(17)(18)(19)(20)(21)(22)(23)(24) indicated that all of the compounds were completely within the pink area, indicating that they have drug-like qualities with an improved bioavailability profile (SI Appendix C Figure S7) [54]. Even though the chemical violates type Fsp3˂0.25, unsaturation score (INSATU), it is verifiable that it does not violate any of Lipinski and Veber's standards, satisfying the qualifications within the ideal spectrum that combines drug-likeness criteria. Using wLogP and TPSA, the BOILED-Egg server predicts this pharmacokinetics [55]. As a result, pharmacokinetics were evaluated using the BOILED-Egg model, which appeared in the white ellipse (HIA) justifying their high probability of being passively absorbed by the gastrointestinal tract, with red points for 18, 21, and 24 (non-    substrate of P-gp) and blue points for 16 and 19 (substrate of P-gp), respectively (SI Appendix C Figure S8). ey were predicted to be no P-gp substrate, despite their promising intestinal absorption and bioavailability, and they cannot pass through the blood-brain barrier (BBB), demonstrating they are not able to cross the blood-brain barrier to the brain when it attaches to certain receptors.

Conclusion and Future Outlooks
In this study, we reported the conventional and green synthesis of nine thiazolyl-pyrazoline Schiff base hybrids together with their ADMET profile predictions and molecular docking study as antibacterial and antioxidant agents. e structures of the synthesized compounds were determined using combined spectroscopic techniques (UV -Vis, 1 H-NMR, and 13 C − NMR). e results of antibacterial screening indicate that compound 24 (IZD � 18.67 ± 0.58 mm) was more potent than amoxicillin (IZD � 14.33 ± 2.52 mm) against P. aeruginosa at 250 μg/mL, whereas compounds 22 and 24 (IZD � 13.33 ± 0.58 mm and 17.00 ± 1.00 mm, respectively) showed better activity compared with amoxicillin (IZD � 14.67 ± 0.58 mm) at 500 μg/ mL against E. coli.
e remaining compounds showed moderate to weak activity against the tested bacterial strains. Compound 21 displayed significant inhibition of DPPH (IC 50 � 4.63 μg/mL) compared with ascorbic acid (IC 50 � 3.21 μg/mL). Compound 21 displayed 80.01 ± 0.07% inhibition of peroxide formation, suggesting its potential in preventing the formation of lipid peroxides. e results of the ADMET study showed that all synthesized compounds obeyed Lipinski's rule of five. In silico pharmacokinetic study demonstrated that compound 24 had superior intestinal absorption compared with amoxicillin.
Compounds 22 and 24 displayed binding affinities of -10.7 and -9.9 Kcal/mol, respectively, against PqsA compared with amoxicillin (−7.3 Kcal/mol) in agreement with the observed in vitro antibacterial activity against P. aeruginosa. Compound 21 displayed a binding affinity of −5.1 Kcal/mol and −7.8 Kcal/mol with LuxS and human peroxiredoxin 5, respectively, compared with amoxicillin and ascorbic acid (−5.5 and-5.2 Kcal/mol, respectively). Compounds 22 and 24 displayed higher binding affinity (−8.5 and -7.9 Kcal/mol, respectively) with DNA gyrase B compared with amoxicillin (−7.1 Kcal/mol). In silico toxicity study showed that all synthesized compounds had LD 50 (mg/ kg) values ranging from 800 to 1,000 putting them in ProTox-II class 4. e in vitro antibacterial activity and molecular docking analysis showed that compound 24 is a promising antibacterial therapeutic agent against P. aeruginosa and E. coli, whereas compound 22 is a promising antibacterial agent against E. coli. Compound 21 is found to be a promising antioxidant agent. Moreover, the green synthesis approach using ZnO nanoparticles as catalysts was found to be a very efficient method to synthesize biologically active thiazole-pyrazoline Schiff base hybrids compared with the conventional method. Future attempts should be carried out to synthesize a series of related thiazole-based Schiff base hybrids for comprehensive structureactivity relationship and in vivo studies to develop lead antioxidant and antibacterial drugs.

Data Availability
e data used to support the findings of this study are included within the manuscript and supplementary information.

Conflicts of Interest
e authors declare that they have no conflicts of interest regarding the publication of this study.