In Silico, SwissADME, and DFT Studies of Newly Synthesized Oxindole Derivatives Followed by Antioxidant Studies

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Introduction
Oxindoles are endogenous aromatic organic compounds that are present in some plant natural products as well as in the tissues and bodily fuids of mammals.Tey have a bicyclic structure and are aromatic heterocyclic organic compounds.Te unsubstituted oxindole nucleus is characterized as an ofwhite crystalline powder with a defned melting point range of 124-126 °C [1,2].Te fusion of a nitrogen-containing fvemembered ring with a six-membered benzene ring results in the formation of an oxindole molecule.Te structure of an oxindole is similar to that of an indoline, with the exception that one of the fve members' 2-positions is occupied by a carbonyl [3].According to the literature, oxindole has been used to treat infammation, cancer, gastric ulcers, infections, and other medical conditions [4].Te diverse pharmacological profle of oxindole has inspired both industry and academia to create novel synthetic derivatives with a wide range of biological activities.Te development of synthetic oxindole derivatives has played a crucial role in the creation of sunitinib, a commercialized anticancer drug used to treat metastatic renal cell cancer and gastrointestinal stromal tumors [5].Alkaloids in the form of the frst known oxindole derivative have been naturally extracted from the bark of the tropical climber plant cat's claw (Uncaria tomentosa).
Te compound "oxindole" and its derivatives, in both keto-enol tautomeric forms, are referred to as "1,3-dihydro-2H-indole-2-one(s)" by the IUPAC (International Union of Pure and Applied Chemistry) due to their structural composition, which is composed of a fused sixmembered benzene ring and a fve-membered pyrrole ring, along with a carbonyl group located at the C-2 position.In this context, lactam-lactim interconversion used as a tool for the synthesis of complex molecules in organic chemistry is an important kind of tautomerism that denotes the shifting of hydrogen between the nitrogen atom and the oxygen atom in such heterocyclic bicyclic rings.Tus, the nomenclature of oxindole is considered as 2-indolinone being one of the indole derivatives [6], and the characteristic peak of oxindole in the mass spectrum has appeared at m/z 133 (100%).Te tautomeric form of oxindole is typically represented as the lactam (I′) of o-aminophenyl acetic acid.Te other forms are enol form (I‴), which has H of CH 2 group tautomerase, and lactim form (I″), which has H of N tautomerism [1].
As known well, "reactive oxygen species" (ROS) and "reactive nitrogen species" (RNS) are the two main types of free radicals that can be produced via internal (mitochondria, the endoplasmic reticulum, phagocytic cells, etc.) and external sources (pollution, smoke, alcohol, etc.).Both ROS and RNS, when levels of ROS and RNS are kept in balance in the body, can play important roles in normal cellular signaling and immune system function, but they can also cause damage to cells and tissues by reacting with and damaging cellular components such as lipids, proteins, and DNA.
However, if there occurs imbalance in the level of both ROS and RNS, they can cause the development of diseases such as cancer, cardiovascular disease, and neurodegenerative diseases [6].
Te oxindole molecule inhibited oxidative stress-related cell death, especially ferroptosis and oxytosis caused by glutamate and erastin, respectively [7].For the discovery of a new therapeutic class, the oxindole derivatives may be evaluated as viable candidates [8].Until now, computational methods and applications were implemented very satisfactorily in molecular systems from organic [9] to complex molecules [10] to explore the intrinsic feature of the systems underlying the key reactivity trend.
In this connection, the current article deals with the synthesis of a couple of oxindoles derivatives, which were characterized using various spectroscopic techniques as compounds C-1 and C-2.Te synthesized compounds were evaluated for the physicochemical properties, and pharmacokinetic profle through SwissADME.Similarly, the computations of this study has been employed by the B3LYP/6-311++G * * level for the elucidation of the possible reactivity attitude and sites of the synthesized compounds.Moreover, the compounds were also subjected to various in vitro free radical scavenging tests.

Synthesis of Compounds.
Synthesis of the selected compounds was carried out via refuxing 6-chlorooxindole with 2,3-dichlorobenzaldehydes and 2,6-dichlorobenzaldehydes in ethanol and piperidine as a catalyst quantity, respectively (Scheme 1).Te reaction mixture was refuxed for 3.5 and 3 hours.After the completion of reactions as determined by TLC analysis, the materials were cooled and concentrated at reduced pressure that led to solid 3-oxindole derivatives C-1 and C-2.Te products were washed with equal volumes of a mixture of hexane-ethyl acetate (25 mL) and dried to aford desired compounds [11]. 1 H NMR, 13 C NMR, and HR ESI mass spectroscopy were used for the determination of their structures.Rf values, isolated yields of the pure-produced compounds, and the compounds' physical characteristics were all documented individually.

Characterization.
Rf values, isolated yields of the pureproduced compounds, and the compounds' physical characteristics were all documented individually.Mass spectroscopy and nuclear magnetic resonance ( 1 H and 13 C NMR) were utilized to determine the structures of the produced compounds.[M+H] + calcd for 323.970, found 323.978.Specifc details can be found in the supplementary materials (FS-24 and FS-24 mass spectra).

Studies on Pharmacokinetics.
Te idea of drug-like chemical species is widely utilized in drug discovery and candidate selection.Compounds that possess pharmacokinetic properties suitable for persisting throughout humanphase clinical trials are considered to belong to drug-like chemical species [12].Te SwissADME database [13,14] was employed to evaluate the physicochemical properties, pharmacokinetic profle, drug similarity, and medicinal chemistry of the compounds, including their lipophilicity and water solubility [15].Te 2D structures from the 2 Journal of Chemistry database were converted into a string-based search format, allowing for efcient screening and analysis of potential drug candidates (Table 1).

DFT Computational Study.
Te G09W [12] and GaussView 6.0.16 [13,15] packages were used for all computations and visualizations of the optimized molecule geometries and FMO graphs, respectively.All computational eforts of the compounds were made at the B3LYP [14]/6-311++G * * level [16].Te second-order perturbative energy analysis [17] was conducted by the NBO code [18] implemented in the G09W package.Te energy lowering for a specifc interaction depending on the qi ⟶ "bonding orbital occupancy," εi and εj ⟶ "bonding and antibonding orbital energies" (diagonal elements), and Fij ⟶ the ofdiagonal NBO Fock matrix element is defned as follows: Te I ionization energy" and A "electron afnity" are approximated [19] via the HOMO and LUMO energies.

Journal of Chemistry
Te electron and hole density distributions (EDD and HDD) are estimated by using the molecular orbital (MO) wave function (Φ) and the confguration coefcient (w), which represent the transition of an electron from an occupied MO (i) to a virtual MO (j), as shown in the following equations: Total electron density is quantifed by the following equation: where G(r) and V(r) are Lagrangian kinetic energy and potential energy densities at critical points, respectively.

Antioxidant Studies
2.4.1.DPPH Scavenging Assay.Te potential of test compounds to neutralize free radicals was scrutinize using 1,1diphenyl-2-picrylhydrazyl (DPPH) radicals [24].Briefy, fve dilutions of each synthesized compound including 62.5, 125, 250, 500, and 1000 µl were prepared.It was followed by the addition of 0.1 ml of each dilution to methanol diluted 4 × 10 −3 % solution of DPPH [2].Te positive control was ascorbic acid.Calculating scavenging activity as a percentage, the following equation is derived: where A 0 is the absorbance of the control and A 1 is the absorbance of the compound sample.Every experiment was run in triplicate, and median inhibitory doses (IC 50 ) values were calculated by using SPSS.
Here, the antioxidant activity is represented by the scavenge potential on ABTS + radical cation, causing down shift in absorbance at 734 nm, provides the basis for the action.Te radical solutions (7 mM) and K 2 S 2 O 4 (2.45 mM) were made and added.At room temperature, the resulting mixture was kept in the dark (12-16 h), formed a dark-colored solution carrying ABTS + .Te phosphate bufer (0.01 M, pH 7.4) was used to dilute the ABTS + radical cation solution in order to achieve an absorbance value of 0.70 at 734 nm at the time of activity.Te compounds' ability to scavenge radicals was tested by mixing 3.0 mL of the ABTS solution with 3 μL of each sample dilution (62.5, 125, 250, 500, and 1000 μL) of the compounds.Following the one-minute mixing of the solutions, the decrease in absorbance was recorded for six minutes using spectrophotometry.Te positive control was ascorbic acid.Te assay was carried thrice, and a formula was used to compute the % inhibition: Table 1: IUPAC name and chemical structures of the studied oxindoles (C-1 and C-2).

Journal of Chemistry
Te percent inhibition and IC 50 values were determined to present the efects [24].IC 50 was calculated using SPSS, and results were interpreted.

Statistical Analysis.
Statistical analysis was performed by using SPSS.Every experiment was run in triplicate, and median inhibitory doses (IC 50 ) values were calculated using SPSS.P < 0.05 was considered as the level of signifcance.

Evaluation of Physicochemical Characteristics.
Both the compounds C-1 and C-2 (Figure 1), comply with Lipinski's rule.Tis suggests that their molecular makeup is similar to that of oral medicines (Table 2).All oxindole derivatives are within the established ranges of ≤500, ≤5, ≤140 A 2 , and ≤10, respectively, for molecular weight (MW), the number of hydrogen bond donors (nHBD), topological polar surface area (TPSA), logP, and the number of hydrogen bond acceptors (nHBAs).For the oxindole derivatives C-1 and C-2, the F. Csp3 values are the same as 0.00 s (Table 2).Both oxindole derivatives feature 1,1 rotatable bond, which is similar.Te molar refractivity was discovered to be the same as 87.17.

Lipophilicity and Water Solubility.
Te partition of the oxindole derivatives C-1 and C-2 preferred into the water compartment, is shown by their log Po/w values, which ranged from 4.33 to 4.34.Both the compounds C-1 and C-2 are predicted as moderately soluble.For the C-1 and C-2 compounds, Log S is aqueous solubility and has the same value of −5.12, which is less than the specifed range of −4 to 0.5 log mol/L, as indicated (Table 3).

Characteristics of Pharmacokinetics.
Pharmacokinetics is crucial to obtain the intended pharmacological outcome of a drug.Tis suggests that every compound's pharmacokinetic characteristic has the potential to impact a drug's pharmacological profle.High GI absorption was found for both substances C-1 and C-2 derivatives according to the SwissADME database.Figures 2 and 3 indicate the boiledegg graphs for C-1 and C-2, respectively.Both the oxindole derivatives C-1 and C-2 demonstrated strong GI absorption, indicating that they are suitable for intestinal absorption.Both the C-1 and C-2 derivatives of oxindole can pass the blood-brain barrier.Compounds C-1 and C-2 are not substrates for P-glycoprotein (Table 4).
In the case of drug metabolism, C-1 and C-2 were discovered to be CYP1A2, CYP2C19, and CYP2C9 inhibitors.CYP2D6 and CYP3A4 are unafected by compounds C-1 and C-2.Te bioavailability score for C-1 and C-2 oxindole derivatives is 0.55, which is similar.5, the fve druglikeness approaches (Lipinski, Muegge, Ghose, Veber, and Egan) are not violated by the compounds C-1 and C-2.

Medicinal Chemistry.
Te oxindole derivatives (C-1 and C-2) have no PAINS alert, without α-screen artifacts and frequent hitters, and with reasonable reactivity.Brenkstructural-alert indicated a couple of reactive groups in these selected oxindole derivatives with Michael acceptor and stilbene.Compounds C-1 and C-2 have MW < 350, so they have lead likeness capability.Oxindole derivatives had scores of 2.52 and 2.55 in the SwissADME database, which are indicative of simple step reactions in synthesis.

DFT Computations. Te optimized geometries and
FMOs amplitudes of compounds C-1 and C-2 are presented in Figure 4. Table 6 presents the computed thermochemical quantities and reactivity parameters of the compounds.
In terms of the stability of the molecules, it could be seen from Table 6 that the position of the second chlorine atom substituted on the benzene ring afected the molecular stability.Namely, the chlorine substitution on the 3-position of benzene made the compound C-1 more stable than the C-2 with chlorine substitution on the 6-position of the benzene ring.Te ΔE, ΔH, and ΔG quantities (in au) of C-1 were calculated as −2087.061203,−2087.043669,and −2087.108101,respectively, while these quantities of C-2 were found to be −2087.060467,−2087.042719,and −2087.107219.Also, the position of the second chlorine on the structure afected the thermal energies; the ΔE thermal (kcal/mol) order of the compounds was determined as C-1 (130.145)> C-2 (129.694).Te entropy of the compounds was predicted as C-1 (135.608)< C-2 (135.751), which implied that the C-2 molecule would be slightly more disordered than the C-1 molecule.Also, the DM and α values of C-1 were calculated, at 1.099939 D and 261.327036, as greater than those of the C-2.
From Figure 4, the presence of chlorine at the 6-position for C-2 shifted the HOMO electron density towards the indoline ring, while HOMO for C-1 was expanded over almost the entire benzene surface.On the other hand, Journal of Chemistry LUMO for C-1 was located on both chlorines positioned at 2-and 3-, while for C-2, it was not expanded on the 6positioned chlorine.For both compounds, the surround of the oxygen atom was pointed out to the electron-rich region that was signed by red color (V < 0).As expected, the secondary amine hydrogen belonging to the indoline part of the compound was overlaid by blue (V > 0), which represented the electron-poor region.Te chlorine of both compounds was covered by a very light blue close to green which indicated they could have presented a neutral attitude.Journal of Chemistry But they would have been able to change the charge density on the oxygen and benzene ring via inductive efect.

Natural Bond Orbital Study.
Te results of the NBO analysis have been very informative to enlighten the possible electronic movements in the molecular systems from the organic-based to complex systems [25,26] and thus consideration of the intrinsic reason underlying the possible reactivity potency of the systems.In this context, the possible electronic interactions taking place in the compounds were determined and summarized in Table 7.

Analysis of Electron Excitation Using Electron and Hole
Density Distribution.By comparing the ground state MO with the photoexcited states, we can see the diferences in the electron density distribution maps (Figure 5).Tese maps displayed the spatial distribution of the electrons and gaps in the molecule, expressing details about the energy level of the excited state, the location and type of excited electrons, and the extent of electron delocalization.

Topology Analysis.
To investigate the intramolecular interactions within these targeted derivatives, topological analysis of the atoms in each compound was implemented (Figure 6).Bond critical path (BCP), which manifests as blue isosurface in the atoms in molecule (AIM) assessment, assures the occurrence of bonds between the atoms.Executed BCP for 2,3 and 2,6-dichloro indolinone is illustrated in Figure 6.In Figure 6, the blue dot in molecules revealed the presence of H-interaction at C-Cl• • •C�C.Te total electron density p(r) and Laplacian ∇ 2 p(r) values characterize bond constitution.Figure 6 proposes the occurrence of weak hydrogen bonding as blue dot between the O of the indolinone ring and phenyl rings.Te isosurfaces appear between C�C• • •C 6 H 4 for both compounds, which is indicative of noncovalent hydrogen bond dynamic.

Free Radical Scavenging Action in DPPH.
We observed the free radical scavenging activity of the prepared compounds (C-1 and C-2) in terms of DPPH.

Discussion
Te primary goal of every research project is to discover novel and more potent compounds without compromising the safety issue.Te present study evaluated the pharmacokinetic studies via SwissADME and stability through DFT studies of the newly synthesized compounds followed by antioxidant potential through in vitro assays.
Oxindoles are endogenous aromatic chemical molecules that are present in various natural products from plants as well as in the body fuids and tissue of mammals.Tey have a bicyclic structure and are aromatic heterocyclic organic molecules [3].Te name "oxindole" and its derivatives are defned as "1,3-dihydro-2H-indole-2-one(s)" because of the structure of the compound, which consists of a sixmembered benzene ring combined with a fve-membered pyrrole ring while C-2 position have a carbonyl group.Even though it is a familiar term, oxindole, is frequently used instead of its more scientifc nomenclature, 2-indolinone [15,27].
According to the traditional literature, oxindole has been used to treat infammatory conditions such as arthritis, gastric ulcers, cancer, and infections [4].Industry and academics have been attracted by its varied pharmacological profle to create novel synthetic oxindole derivatives with a range of biological functions.Sunitinib, a commercialized anticancer drug used to treat renal and gastrointestinal cancers, was made possible by the synthesis of synthetic oxindole derivatives [5].Due to potential efects of indolidan and adibendan on cardiovascular system, they have also been used to treat congestive heart failure [28].Spirooxindole derived compounds have been linked to a widespread biological actions, such as anticancer and antioxidant [29], anti-Alzheimer [30], kinase inhibitory activity [31], β3 adrenergic receptor agonist [32], antibacterial [33], neuroprotective [34], spermicidal [35], and analgesic activity [36].
Te study aimed to synthesize two derivatives of 6chlorooxindole, referred to as C-1 and C-2, by refuxing 6-chlorooxindole with 2,3-dichlorobenzaldehydes and 2,6dichlorobenzaldehydes in ethanol with the addition of a catalytic amount of piperidine.Te structures of C-1 and C-2 were characterized and confrmed by using 1 H NMR, 13 C NMR, and HR ESI mass spectroscopy.
Lipinski's rule of fve is required for practical drug creation, according to the results of the pharmacokinetic investigation of the oxindole derivative compounds C-1 and C-2.Any medication molecule that breaks even one of the requirements could have poor absorption or low permeability [37,38].Te fraction of sp 3 hybridized Cs in entire number of carbon atoms is defned as F.Csp3.It displays the complexity of the molecular spatial structure and represents the carbon saturation.F.Csp3 should be ≥ 0.42 because 84% of commercially available medicines meet this requirement [39].Te sp 3 content must be increased, but only to a certain extent, as a higher F.Csp3 score is not a confrmation of high quality and may make chemical production more complex [40].Natural goods are therefore a potential source of therapeutics because synthetic products often have a smaller percentage of F.Csp3 than do natural compounds [41].As known well, the number of rotatable bonds greater than 10 tends to be more fexible and have higher entropy, making them more difcult to be absorbed by the body [42].Although the count of the "rotatable bond flter" has not directly related to the rate of clearance in vivo, its mechanism of action is still unknown.Tis flter is justifed, however, by the potential of in vitro screening due to the potency of ligand afnity drops at a rate of, on average, 0.5 kcal for every two rotatable bonds [43].Both the H-bond-acceptor and the donor is still within range and thus H-bond acceptors, donors, and rotatable bonds are less frequent in oral medicines [44].Tese three factors promote the oral mode of delivery as being adaptable, practical, and easy one.
As known well, a specifc molecular system with a TPSA more than 140 Å2 would result in low absorption with fractional absorption less than 10%, whereas a TPSA of 60 Å2 would lead to strong absorption with fractional absorption greater than 90% [45].Accordingly, the oxindoles (C-1 and C-2) could be potent agents to have better absorption as refected by TPSA of 29.10 Å2 .
Te consensus Log P o/w known as the octanol/water partition coefcient is the average of the Log P o/w calculated via the approaches of iLOGP, XLOGP3, WLOGP, MLOGP, and SILICOS-IT.Based on polarity, molecule size, and hydrogen bonding, a higher Log P o/w number suggests greater lipophilicity.In this work, Log P o/w values of C-1 and C-2 are predicted as 4.33, which refects optimal lipophilicity.Te Log P o/w values demonstrate optimal lipophilicity (optimal: 0 < Log P < 3) [46].Log S is the aqueous solubility of both compounds C-1 and C-2 which showed poor solubility in water.Te SwissADME database showed that both compounds C-1 and C-2 had high GI absorption [45].
Te C-1 and C-2 oxindole derivatives are expected to pass the blood-brain barrier.Te chemicals (C-1 and C-2) that are oxindole derivatives are not p-glycoprotein substrates.Tis might not link them to interactions with various endogenous or exogenous substances, particularly medications.It is anticipated that the oxindole derivatives chemicals (C-1 and C-2) will not interact with P-glycoprotein, which may not have an impact on the pharmacological profle of other medications [47].Te majority of medications are metabolized by CYP3A4 which is one of the most critical isoforms of the CYP P450 and endogenous substances are projected to not afect CYP3A4, indicating a reduced frequency of interactions.Oxindole derivatives (C-1 and C-2) are projected to behave similarly, with no impact on CYP2D6.Te compounds C-1 and C-2 would be involved in drug design because of their pharmacokinetic characteristics in terms of their potencies for CYP1A2, CYP2C19, and CYP2C9 inhibitions.Here, the bioavailability scores implied a sufcient plasma concentration.Te bioavailability and permeability are the keys in new drug discovery.As a result, a medication candidate is awarded a probability-based score if F > 10% in vivo [48].Te drug similarity parameters are anticipated to be followed by the oxindole derivatives compounds (C-1 and C-2).Also, in the boiled-egg charts, the white area refects intestinal absorption in humans, whereas the yellowish area shows CNS penetration.If a medicine is absorbed via a method other than the oral route, it would be seen in the gray region of the chart [14].
Te oxindoles (C-1 and C-2) could present good GI absorption and would be suitable for intestinal absorption.Te oxindole derivatives (C-1 and C-2) are expected to pass the blood-brain barrier, which indicates that they are not completely free of CNS toxicity.Te fact that neither of the oxindole derivatives (C-1 and C-2) is a P-glycoprotein substrate implies favorably that they might not afect the pharmacological profle of other medicines.Te oxindole derivatives (C-1 and C-2) are not included in the list of " α-screen artifacts," "frequent hitters," and "reactive compounds" since they have "zero" PAINS (Pan Assay interference compounds) warning.During HTS, PAINS have an uncontrollable tendency to produce false positive fndings.Although the process is unclear, they are connected to protein reactivity and noncovalent interactions [49].As known well, SwissADME tools generate structural limits for the possible usage, or structural violation, in smart drug design in terms of pharmacokinetics via using the 105 fragments presented by Brenk et al.Tus, it could have revealed an issue-causing fragment present in a particular molecule [50].Two groups have been detected by this structural alert such as stillbene group and Michael acceptor group in oxindole derivatives, which might be reactive and reduce the potential side efects [51].Yet, this can be linked to already accessible preclinical investigations that have been done.Te ability of a molecule to act as a "lead" in the drug development process is represented by the lead likeness parameter.Due to their molecular weights being <350, C-1 and C-2 are capable of lead likeness.Tese pharmacophores can be further changed to produce superior pharmacological outcomes on the basis of SAR.Te chemicals (C-1 and C-2) that are oxindole derivatives have been produced in a laboratory.Te SwissADME database's assessment of its synthetic accessibility, however, is consistent with the reality.Te oxindole derivatives compounds (C-1 and C-2) were given scores of 2.52 and 2.55 by the SwissADME database, indicating simple step processes for synthesis.Te challenging synthetic methods are for compounds with scores of 10 [44].
Te distribution of electrons and holes forms the foundation of the idea of multimolecular orbital excitation density in the receptors and their corresponding receptor anions.Tis concept reveals the characteristics of the excited state for the 2,3-and 2,6-dichloro indolinone derivatives.Te electron and hole density distribution can also help us understand the electronic structure and properties of these molecules, as well as to the way that molecules recognize and bind in receptor-ligand.Te excited state can be modeled by the excitation of an electron from an occupied to a virtual molecular orbital (MO).For both compounds 2,3-and 2,6dichloro indolinone that were the subject of the investigation, the EDD map in Figure 5 shows a thicker surface at 6-chloroindolinone, indicating a higher electron density in the entire chloroindolinone ring for C-1 and C-2.HDD map for C-1 and C-2 shows a denser isosurface capped over ethylidenepyrrolidinone core, which denotes a larger hole density.
Te covalent, noncovalent, and electrostatic interactions are among the various forms of interactions that have an impact on compounds C-1 and C-2.Analysis using reduced density gradient (RDG) can identify and display noncovalent interactions (NCIs), employing a fuctuation of

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gradient isosurfaces proportionate to the interaction intensity.Te sign (λ 2 ) ρ values designates the bonding variety, where great negative quantities signify hydrogen bonding (blue dot), great positive quantities signify repulsive interactions (blue isosurface), and quantities near zero signify weak Van der Waals interactions (green isosurface) [50].Simultaneously, the green isosurface indicated the presence of repulsive interaction present between pyrrolidine and phenyl rings for C1 and C2.Te green color depicted the presence of weak Van der Waals interactions between Cl atom and C�C for C-2 compound.From these results, it is concluded that the manifestation of noncovalent interactions in the investigated compounds enhanced their stability in the biological media.Te BCP associated with C�C• • •Cl in (2) and C• • •Cl in (1) corroborates the incidence of intramolecular interaction, which stabilizes the molecular structure.Te strong interaction which is represented as blue dots was formed between carbonyl of indoline and C3 for benzene ring in both compounds, and other noncovalent interaction formed in 2,3-and 2,6-dichloro indolinone.Ring critical path (RCP) formed in three rings which appeared in the center for the surface of these rings.

Conclusion
In the current study, 6-chlorooxindole compounds C-1 and C-2 were prepared by refuxing 6-chlorooxindole with 2,3dichlorobenzaldehydes and 2,6-dichlorobenzaldehydes in ethanol in the presence of a catalytic amount of piperidine, respectively.C-1 and C-2 showed greater GI absorption with good lipid solubility and pharmacokinetic properties.ΔE (L-H) values revealed that C-1 could likely prefer the intramolecular interactions rather than the intermolecular interactions, and vice versa for C-2.Also, Δε back-donat.(eV) values indicated that C-2 (−0.478) would have gained stability more than C-1 (−0.417) via back donation.Te NBO analysis disclosed that the n-π * and π-π * interactions would contribute to the stabilization of both compounds.In DPPH and ABTS assay, the compounds C-1 and C-2 both functioned as efective antioxidants.To sum up, the results obtained from in silico experiments followed by in vitro assays suggested signifcant therapeutic potential of these compounds.

Figure 1 :
Figure 1: Te radar charts of compounds C-1 and C-2 depending on the physicochemical properties.

Figure 6 :
Figure 6: Interaction region indicator surfaces of C-1 and C-2 based on QTAIM analysis.B: BCP, R: RCP.Blue dot represents (S) strong interaction, and noncovalent interaction (N) and isosurface represent (w) weak interaction.

Table 2 :
Te physicochemical property of oxindole (C-1 and C-2) derivatives calculated with the SwissADME database.

Table 3 :
Te characteristics of lipophilicity and water solubility of oxindoles (C-1 and C-2).

Table 4 :
Te bioavailability scores and pharmacokinetics of oxindole (C1 and C2) derivatives calculated with SwissADME database.

Table 6 :
Te thermochemical and quantum chemical values of the compounds at the B3LYP/6-311++G * * level.max (eV) 2.793 2.341 Δε back-donat.(eV) −0.417 −0.478 Table 8 displays the signifcant IC 50 values for both substances.In the DPPH activity, ascorbic acid was used as a reference medication with an IC 50 value of 293.10 M. Both the compounds caused signifcant scavenging efect against DPPH at various test concentrations ranging from 62.5 to 1000 μM.Te maximum inhibition for compound 1 was 91% at 1000 μM with IC 50 of 37.390 μM.Compound 2 illustrated maximum inhibition of 86% at 1000 μM and IC 50 of 34.676 μM.

Table 8 :
Free Radical Scavenging Activity in ABTS.Te results of the tested compounds, C-1 and C-2, in ABTS assay at various concentrations are displayed in Table9.Overall, both the compounds exhibited signifcant scavenging activity.Compound 1 produced concentration-dependent inhibition with maximum efects of 88% at 1000 μM, and the IC 50 value was calculated as 25.381 μM.Similarly, compound 2 showed 85% of maximum inhibition at highest test concentration at 1000 μM with IC 50 value calculated as 33.706 μM.Te standard (gallic acid) had IC 50 value of 307.30 μM in the ABTS test.

Table 9 :
Results of compounds (C-1 and C-2) for ABTS scavenging activity.Inhibition percentages (%) and IC 50 values (mean ± SEM of n � 3) are used to present the results.