Design, Construction, and Characterization of a New Regioisomer and Diastereomer Material Based on the Spirooxindole Scaffold Incorporating a Sulphone Function

A novel alpha-amylase inhibitor-based spirooxindole-pyrrolidine-clubbed thiochromene-pyrzaole pharmacophores: Unveiling the [3+2] cycloaddition reaction by molecular electron density theory

A novel spirooxindole-pyrrolidine clubbed thiochromene and pyrazole motifs were synthesized by [3+2] cycloaddition (32CA) reactions in one step process starting from the ethylene-based thiochromene and pyrazole scaffolds with the secondary amino-acids and substituted isatins in high yield. The 32CA reaction of AY 10 with ethylene derivative 6 has also been studied with Molecular Electron Density Theory. The high nucleophilic character of AY 10, N = 4.39 eV, allows explaining that the most favorable TS-on is 13.9 kcal mol-1 below the separated reagent. This 32CA, which takes place through a non-concerted one-step mechanism, presents a total ortho regio- and endo stereoselectivity, which is controlled by the formation of two intramolecular H… O hydrogen bonds. The design of spirooxindole-pyrrolidines engrafted thiochromene and pyrazole was tested for alpha-amylase inhibition and show a high efficacy in nanoscale range of reactivity. The key interaction between the most active hybrids and the receptor was studied by molecular docking. The physiochemical properties of the designed spirooxindole-pyrrolidines were carried out by in silico ADMET prediction. The newly synthesized most potent hybrid could be considered as a lead compound for drug discovery development for type 2 diabetes mellitus (T2DM).

Design, Synthesis and In Vitro Evaluation of Spirooxindole-Based Phenylsulfonyl Moiety as a Candidate Anti-SAR-CoV-2 and MERS-CoV-2 with the Implementation of Combination Studies

The search for an effective anti-viral to inhibit COVID-19 is a challenge for the specialized scientific research community. This work investigated the anti-coronavirus activity for spirooxindole-based phenylsulfone cycloadducts in a single and combination protocols. The newly designed anti-SARS-CoV-2 therapeutics spirooxindoles synthesized by [3 + 2] cycloaddition reactions represent an efficient approach. One-pot multicomponent reactions between phenyl vinyl sulfone, substituted isatins, and amines afforded highly stereoselective anti-SARS-CoV-2 therapeutics spirooxindoles with three stereogenic centers. Herein, the newly synthesized spirooxindoles were assessed individually against the highly pathogenic human coronaviruses and proved to be highly potent and safer. Interestingly, the synergistic effect by combining the potent, tested spirooxindoles resulted in an improved antiviral activity as well as better host-cell safety. Compounds 4i and 4d represented the most potent activity against MERS-CoV with IC₅₀ values of 11 and 23 µM, respectively. Both compounds 4c and 4e showed equipotent activity with the best IC₅₀ against SARS-CoV-2 with values of 17 and 18 µM, respectively, then compounds 4d and 4k with IC₅₀ values of 24 and 27 µM, respectively. Then, our attention oriented to perform a combination protocol as anti-SARS-CoV-2 for the best compounds with a different binding mode and accompanied with different pharmacophores. Combination of compound 4k with 4c and combination of compounds 4k with 4i proved to be more active and safer. Compounds 4k with 4i displayed IC₅₀ = 3.275 µM and half maximal cytotoxic-concentration CC₅₀ = 11832 µM. MD simulation of the most potential compounds as well as in silico ADMET properties were investigated. This study highlights the potential drug-like properties of spirooxindoles as a cocktail anti-coronavirus protocol.

A Molecular Electron Density Theory Study of the [3+2] Cycloaddition Reaction of an Azomethine Ylide with an Electrophilic Ethylene Linked to Triazole and Ferrocene Units

The [3+2] cycloaddition (32CA) reaction of an azomethine ylide (AY) with an electrophilic ethylene linked to triazole and ferrocene units has been studied within the Molecular Electron Density Theory (MEDT) at the ωB97X-D/6-311G(d,p) level. The topology of the electron localization function (ELF) of this AY allows classifying it as a pseudo(mono)radical species characterized by the presence of two monosynaptic basins, integrating a total of 0.76 e, at the C1 carbon. While the ferrocene ethylene has a strong electrophilic character, the AY is a supernucleophile, suggesting that the corresponding 32CA reaction has a high polar character and a low activation energy. The most favorable ortho/endo reaction path presents an activation enthalpy of 8.7 kcal·mol^-1, with the 32CA reaction being exergonic by -42.1 kcal·mol^-1. This reaction presents a total endo stereoselectivity and a total ortho regioselectivity. Analysis of the global electron density transfer (GEDT) at the most favorable TS-on (0.23 e) accounts for the high polar character of this 32CA reaction, classified as forward electron density flux (FEDF). The formation of two intermolecular hydrogen bonds between the two interacting frameworks at the most favorable TS-on accounts for the unexpected ortho regioselectivity experimentally observed.

A Molecular Electron Density Theory Study of the [3+2] Cycloaddition Reaction of Pseudo(mono)radical Azomethine Ylides with Phenyl Vinyl Sulphone

The [3+2] cycloaddition (32CA) reaction of an azomethine ylide (AY), derived from isatin and L-proline, with phenyl vinyl sulphone has been studied within Molecular Electron Density Theory (MEDT) at the ωB97X-D/6-311G(d,p) level. ELF topological analysis of AY classifies it as a pseudo(mono)radical species with two monosynaptic basins at the C1 carbon, integrating a total of 0.76 e. While vinyl sulphone has a strong electrophilic character, AY is a supernucleophile, suggesting a high polar character and low activation energy for the reaction. The nucleophilic Parr functions indicate that the pseudoradical C1 carbon is the most nucleophilic center. The 32CA reaction presents an activation Gibbs free energy of 13.1 kcal·mol−1 and is exergonic by −26.8 kcal·mol−1. This reaction presents high endo stereoselectivity and high meta regioselectivity. Analysis of the global electron density transfer (GEDT) at the most favorable meta/endo TS, 0.31 e, accounts for the high polar character of this 32CA reaction, classified by forward electron density flux (FEDF). A Bonding Evolution Theory (BET) study along the most favorable meta/endo reaction path characterizes this 32CA reaction, taking place through a non-concerted two-stage one-step mechanism, as a pseudo(mono)radical-type 32CA reaction, in agreement with the ELF analysis of the AY.

Construction of Spirooxindole Analogues Engrafted with Indole and Pyrazole Scaffolds as Acetylcholinesterase Inhibitors

Twenty-five new hits of spirooxindole analogs 8a-y engrafted with indole and pyrazole scaffolds were designed and constructed via a [3+2]cycloaddition (32CA) reaction starting from three components: new chalcone-based indole and pyrazole scaffolds 5a-d, substituted isatins 6a-c, and secondary amines 7a-d. The potency of the compounds were assessed in modulating cholinesterase (AChE) activity using Ellman's method. Compounds 8i and 8y showed the strongest acetylcholine esterase inhibition (AChEI) with IC50 values of 24.1 and 27.8 μM, respectively. Molecular docking was used to study their interaction with the active site of hAChE.

Stereoselective Synthesis of the Di-Spirooxindole Analogs Based Oxindole and Cyclohexanone Moieties as Potential Anticancer Agents

A new series of di-spirooxindole analogs, engrafted with oxindole and cyclohexanone moieties, were synthesized. Initially, azomethine ylides were generated via reaction of the substituted isatins 3a-f (isatin, 3a, 6-chloroisatin, 3b, 5-fluoroisatin, 3c, 5-nitroisatin, 3d, 5-methoxyisatin, 3e, and 5-methylisatin, 3f, and (2S)-octahydro-1H-indole-2-carboxylic acid 2, in situ azomethine ylides reacted with the cyclohexanone based-chalcone 1a-f to afford the target di-spirooxindole compounds 4a-n. This one-pot method provided diverse structurally complex molecules, with biologically relevant spirocycles in a good yields. All synthesized di-spirooxindole analogs, engrafted with oxindole and cyclohexanone moieties, were evaluated for their anticancer activity against four cancer cell lines, including prostate PC3, cervical HeLa, and breast (MCF-7, and MDA-MB231) cancer cell lines. The cytotoxicity of these di-spirooxindole analogs was also examined against human fibroblast BJ cell lines, and they appeared to be non-cytotoxic. Compound 4b was identified as the most active member of this series against prostate cancer cell line PC3 (IC50 = 3.7 ± 1.0 µM). The cyclohexanone engrafted di-spirooxindole analogs 4a and 4l (IC50 = 7.1 ± 0.2, and 7.2 ± 0.5 µM, respectively) were active against HeLa cancer cells, whereas NO2 substituted isatin ring and meta-fluoro-substituted (2E,6E)-2,6-dibenzylidenecyclohexanone containing 4i (IC50 = 7.63 ± 0.08 µM) appeared to be a promising agent against the triple negative breast cancer MDA-MB231 cell line. To explore the plausible mechanism of anticancer activity of di-spirooxindole analogs, molecular docking studies were investigated which suggested that spirooxindole analogs potentially inhibit the activity of MDM2.

Regio- and Stereoselective Synthesis of a New Series of Spirooxindole Pyrrolidine Grafted Thiochromene Scaffolds as Potential Anticancer Agents

A series of new spiro-heterocycles engrafted spirooxindole/pyrrolidine/thiochromene scaffolds was synthesized by the three-component 1,3-dipolar cycloaddition reactions in a fully controlled regio- and stereo-selective fashion. Condensation of several substituted isatin derivatives with L-proline generated the azomethine ylides which subsequently reacted with chalcones based thiochromene scaffold, and finally afforded the target spiro-compounds. This simple protocol furnished a structurally complex, biologically relevant spiro-heterocycles in good yields through a one-pot process. All synthesized chalcone-based thiochromene, along with the spirooxindole/pyrrolidine/thiochromene scaffolds, were tested for their anticancer activity against four cancer cell lines (PC3, HeLa, MCF-7, and MDA-MB231). Toxicity of these compounds was also evaluated against human fibroblast BJ cell line, and they appeared to be not cytotoxic. For the prostate cancer (PC3) cell line, the most active hybrid, among synthesized series, was compound (7f, IC50 = 8.7 ± 0.7 µM). The most potent spirooxindole/pyrrolidine/thiochromene hybrid against cervical (HeLa) cancer cells was compound (7k, IC50 = 8.4 ± 0.5 µM) having chlorine and p-trifluoromethyl substituents attached to phenyl rings. Finally, against the MCF-7 and MDA-MB231 breast cancer cell lines, compound (7d) was the most active member of this series (IC50 = 7.36 ± 0.37, and 9.44 ± 0.32 µM, respectively).

Synthesis of a New Class of Spirooxindole-Benzo[b]Thiophene-Based Molecules as Acetylcholinesterase Inhibitors

A series of new oxindole-based spiro-heterocycles bearing the benzo[b]thiophene motif were synthesized via a 1,3-dipolar cycloaddition reaction and their acetylcholinesterase (AChE) inhibitory activity was evaluated. All the synthesized compounds exhibited moderate inhibitory activities against AChE, while IIc was found to be the most active analog with an IC50 value of 20,840 µM·L-1. Its molecular structure was a 5-chloro-substituted oxindole bearing benzo[b]thiophene and octahydroindole moieties. Based on molecular docking studies, IIc was strongly bound to the catalytic and peripheral anionic sites of the protein through hydrophilic, hydrophobic, and π-stacking interactions with Asp74, Trp86, Tyr124, Ser125, Glu202, Ser203, Trp236, Trp286, Phe297, Tyr337, and Tyr341. These interactions also indicated that the multiplicity of the IIc aromatic core significantly favored its activity.