Regioselective synthesis, stereochemical structure, spectroscopic characterization and geometry optimization of dispiro[3H-indole-3,2′-pyrrolidine-3′,3″-piperidines]

The Therapeutic Potential of Spirooxindoles in Cancer: A Focus on p53-MDM2 Modulation

The p53, often referred to as the "guardian of the genome", is a well-established tumor-suppressor protein that plays a critical role in regulating the cell cycle, DNA repair, differentiation, and apoptosis, with its activity primarily modulated by the MDM2 protein (murine double minute 2, also known as HDM2 in humans). Disrupting the protein-protein interaction between p53 and MDM2 represents a promising therapeutic strategy for developing anticancer agents. Recent studies have shown that several spirooxindole-containing compounds exhibit significant antitumor properties, primarily by inhibiting the p53-MDM2 interaction. This review provides an overview of structure-based spirooxindoles that could have therapeutic potential. It highlights findings from the past decade concerning their antiproliferative properties and implications for interfering with the p53-MDM2 interaction. The discussion includes various analogs of spirooxindoles as promising candidates for optimizing leads in drug discovery programs aimed at developing novel and clinically effective agents.

Design, Synthesis, and Antitumor Activity of Novel Dispiro[oxindole-cyclohexanone]-pyrrolidines

BACKGROUND

Spirooxindoles are privileged scaffolds in medicinal chemistry and were identified through Wang's pioneering work as inhibitors of MDM2-p53 interactions.

OBJECTIVE

To design and synthesize 2,6-diarylidenecyclohexanones and dispiro[oxindole-cyclohexanone]-pyrrolidines of potential antitumor effect.

METHOD

Dispiro[oxindole-cyclohexanone]-pyrrolidines 6a-h were synthesized in a regioselective manner via 1,3-dipolar cycloaddition reaction of 2,6-diarylidenecyclohexanones 3a-h, isatin, and sarcocine. Compounds 6a-h were alkylated to give (7-10) a,b. All compounds were evaluated in vitro for their antitumor activity and cytotoxic selectivity against breast cancer cell lines (MCF-7, and MDA-MB-231), breast fibrosis cell line (MCF10a) and placental cancer cell line (JEG-3). Molecular modeling inside the MDM2 binding site was performed using AutoDock4.2.

RESULTS

Synthesized compounds showed antitumor activity comparable to tamoxifen, and compounds 3a,b,f,g, and 9a,b showed selective cytotoxicity against tumor cells but reduced toxicity toward MCF-10a cells. Molecular modelling shows that both classes of synthesized compounds are predicted to fit the deep hydrophobic cleft on the surface of MDM2 and mimic the interactions between p53 and MDM2.

CONCLUSION

The synthesized compounds have antitumor activity against MCF-7, MDA-MB-231, and JEG-3. Few compounds showed a selective cytotoxic effect and may have the potential to inhibit MDM2 and stimulate p53. Future medicinal chemistry optimization and mechanistic study will be conducted to enhance the inhibition effect of identified compounds and elucidate their mechanism of action.

Synthesis and molecular modeling studies of cholinesterase inhibitor dispiro[indoline-3,2'-pyrrolidine-3',3''-pyrrolidines]

A set of dispiro[indoline-3,2′-pyrrolidine-3′,3′′-pyrrolidines] 8a–l was regioselectively synthesized utilizing multi-component azomethine cycloaddition reaction of 3-(arylmethylidene)pyrrolidine-2,5-diones 5a–e, isatins 6a–c and sarcosine 7. Single crystal X-ray studies of 8c add conclusive support for the structure. Compounds 8e and 8g reveal cholinesterase inhibitory properties with promising efficacy against both AChE and BChE and were found to be more selective towards AChE than BChE as indicted by the selectivity index like Donepezil (a clinically used cholinesterase inhibitory drug). Molecular modeling studies assist in understanding the bio-observations and identifying the responsible parameters behind biological properties.

Dispiro[indoline-3,2′-pyrrolidine-3′,3′′-pyrrolidines] were regioselectively synthesized revealing cholinesterase (AChE, BChE) inhibitory properties.

Structure and absolute configuration of some 5-chloro-2-methoxy-N-phenylbenzamide derivatives

The absolute configuration of 5-chloro-2-methoxy-N-phenylbenzamide single crystal [compound (1)] and the effect of introducing -[CH₂]_n-, n=1,2 group adjacent to the amide group [compounds (2) and (3)], were studied. Furthermore, the replacement of the methoxy group with a hydroxy group [compound (4)] was defined. Proton and carbon-13 NMR spectrometer were used to record the structural information of the prepared compounds. X-ray single crystal diffractometer were used to elucidate the 3D structural configurations. Intensity data for the studied compounds were collected at room temperature. The X-ray data prove that compound (1) is almost planar, with maximum r.m.s. deviations of 0.210(3)Å corresponds to C13. This planarity starts to disturb by adding -[CH₂]_n-, n=1,2 groups between the NH group and the phenyl ring in compounds (2) and (3), respectively. By replacing the OCH₃ group by an OH group in compound (4), the plane of the chlorophenyl moiety is nearly perpendicular to that of the phenyl ring. Such new structural configurations were further illustrated by the infrared, and ultraviolet-visible spectroscopy measurements in the frequency range 400-4000cm^-1 and 190-1100nm, respectively. Spectroscopic analyses were verified with the help of molecular modeling using density functional theory. The estimated total dipole moment for the prepared compounds reflects its ability to interact with its surrounding molecules. The higher dipole moment for a given structures is combined with the higher reactivity for potential use in medicinal applications.

Synthesis, X-ray powder diffraction and DFT-D studies of indole-based compounds

Four indole-based compounds have been synthesized and their crystal structures determined using high-resolution synchrotron powder X-ray diffraction. In vacuo density function theory (DFT) optimization has been used in building initial molecular models for structure solution with the help of the Cambridge structure database. All four compounds were found to crystallize in the monoclinic space group P21/c. Dispersion-corrected DFT (DFT-D) has been used for experimental crystal structure validation with acceptable agreement found between the DFT-optimized and final refined structures. Three of the compounds exhibit bronchodilation properties with potency comparable to the theophylline (standard reference).

Synthesis and 2D-QSAR Study of Active Benzofuran-Based Vasodilators

A new series of 2-alkyloxy-pyridine-3-carbonitrile-benzofuran hybrids (4a–x) was synthesized. All the new derivatives were examined via the standard technique for their vasodilation activity. Some of the investigated compounds exhibited a remarkable activity, with compounds 4w, 4e, 4r, 4s, 4f and 4g believed to be the most active hits in this study with IC₅₀ values 0.223, 0.253, 0.254, 0.268, 0.267 and 0.275 mM, respectively, compared with amiodarone hydrochloride, the reference standard used (IC50 = 0.300 mM). CODESSA PRO was employed to obtain a statistically significant 2-Dimensional Quantitative Structure Activity Relationship (2D-QSAR) model describing the bioactivity of the newly synthesized analogs (N = 24, n = 4, R² = 0.816, R²_cvOO = 0.731, R²_cvMO = 0.772, F = 21.103, s² = 6.191 × 10⁻⁸).

Molecular structure studies of novel bronchodilatory-active 4-azafluorenes

Two 5H-indeno[1,2-b]pyridines, 7a and 7b, were synthesized and characterized by X-ray crystallography. In the molecular packing, molecules of 7a are linked into chains by C–H···N hydrogen bond which, in turn, are connected by H···π, N···π, Cl···π and π···π interactions. In the crystal structure of 7b, molecules are connected by C–H···N and C–H···Cl interactions as well as a set of N···π and Cl···π interactions. The molecular structures were studied by theory using AM1, PM3 and DFT. The basic difference between the theoretical and experimental structures was found in the relative orientation of dichlorophenyl ring attached to the indenopyridine residue, which was revealed to be aligned in nearly opposite orientations. This observation is attributed to the bulky chlorine atom(s) of the phenyl ring that prevent free rotation around the sigma bond attaching this ring with the heterocyclic system. DFT was used to determine the molecular electrostatic potential revealing the nitrile nitrogen to be the most nucleophilic site. A low HOMO-LUMO energy gap indicates high reactivity of 7a and 7b. The synthesized azafluorenes show more potent bronchodilation properties than the standard reference compound (theophylline).

Rational design, synthesis and 2D-QSAR studies of antiproliferative tropane-based compounds

Novel tropane-based compounds were synthesized exhibiting antiproliferative properties against HepG2 and MCF7 carcinoma cell lines.

Synthesis and molecular modeling studies of indole-based antitumor agents

Potent antitumor active (HeLa, cervical carcinoma cell line) indole-based compounds were synthesized via azomethine ylide 1,3-dipolar cycloaddition with 3,5-arylidene-4-piperidones.

Synthesis, X-ray powder diffraction and DFT calculations of vasorelaxant active 3-(arylmethylidene)pyrrolidine-2,5-diones

Two 3-(arylmethylidene)pyrrolidine-2,5-diones, 12a and 12b, were synthesized and characterized by powder X-ray diffraction utilizing a high-resolution synchrotron X-ray powder technique as well as DFT calculations.

Synthesis, and QSAR analysis of anti-oncological active spiro-alkaloids

QSAR study describes the anti-neoplastic spiro-alkaloids with relevant molecular descriptors using CODESSA III software. The dispiro[3H-indole-3,2'-pyrrolidine-3',3"-piperidines] 24-48 were synthesized via [3 + 2]-cycloaddition reaction of azomethine ylides, (generated in situ via decarboxylative condensation of isatins 21-23 with sarcosine) and 3E,5E-1-alkyl-3,5-bis(arylmethylidene)-4-piperidones 10-20. Some of the synthesized analogues exhibited promising antitumor properties against HELA (cervical), HEPG2 (liver), T-47D, MCF7 (breast), and HCT116 (colon) human tumor cell lines, demonstrating activity close to or even better than the standard Doxorubicin, based on in vitro Sulfo-Rhodamine-B bio-assay.

Novel antibacterial active quinolone-fluoroquinolone conjugates and 2D-QSAR studies

Novel, quinolone-fluoroquinolone conjugates 10a-f, 11a-f, 13a-f and 14a-f with amino acid linkers were synthesized in good yields utilizing benzotriazole chemistry. Antibacterial bioassay showed the synthesized bis-conjugates exhibit anti-bacterial properties comparable with the parent drugs.

Regioselective synthesis and theoretical studies of an anti-neoplastic fluoro-substituted dispiro-oxindole

An anti-neoplastic fluoro-substituted dispiro-oxindole is described along with theoretical studies and single crystal X-ray analysis.

Rational design, synthesis, and 2D-QSAR study of anti-oncological alkaloids against hepatoma and cervical carcinoma

A series of novel substituted dispiro-oxindole were synthesized and screened for anti-cancer properties. The anti-cancer data were validated by QSAR studies.

Synthesis and DFT studies of an antitumor active spiro-oxindole

DFT studies of an anti-proliferative active spiro-oxindole against diverse tumor cell lines were reported.

Rational design, synthesis and molecular modeling studies of novel anti-oncological alkaloids against melanoma

Anti-oncological active spiro-alkaloids were synthesized exhibiting promising antitumor properties against melanoma cell lines. Molecular modeling studies describe the observed properties.