Novel spirooxindole based benzimidazole scaffold: In vitro, nanoformulation and in vivo studies on anticancer and antimetastatic activity of breast adenocarcinoma

Advancements in targeting tumor suppressor genes (p53 and BRCA 1/2) in breast cancer therapy

Globally, among numerous cancer subtypes, breast cancer (BC) is one of the most prevalent forms of cancer affecting the female population. A female's family history significantly increases her risk of developing breast cancer. BC is caused by aberrant breast cells that proliferate and develop into tumors. It is estimated that 5-10% of breast carcinomas are inherited and involve genetic mutations that ensure the survival and prognosis of breast cancer cells. The most common genetic variations are responsible for hereditary breast cancer but are not limited to p53, BRCA1, and BRCA2. BRCA1 and BRCA2 are involved in genomic recombination, cell cycle monitoring, programmed cell death, and transcriptional regulation. When BRCA1 and 2 genetic variations are present in breast carcinoma, p53 irregularities become more prevalent. Both BRCA1/2 and p53 genes are involved in cell cycle monitoring. The present article discusses the current status of breast cancer research, spotlighting the tumor suppressor genes (BRCA1/2 and p53) along with structural activity relationship studies, FDA-approved drugs, and several therapy modalities for treating BC. Breast cancer drugs, accessible today in the market, have different side effects including anemia, pneumonitis, nausea, lethargy, and vomiting. Thus, the development of novel p53 and BRCA1/2 inhibitors with minimal possible side effects is crucial. We have covered compounds that have been examined subsequently (2020 onwards) in this overview which may be utilized as lead compounds. Further, we have covered mechanistic pathways to showcase the critical druggable targets and clinical and post-clinical drugs targeting them for their utility in BC.

Development of indole hybrids for potential lung cancer treatment - part II

Lung cancer has become the most prevalent cancer for the past three decades, and the 5-years survival rate of lung cancer is only ~20% nowadays. Chemotherapy is the mainstay of lung cancer therapy, especially for non-small cell lung cancer. However, drug resistance represents a principal cause of therapeutic failure in non-small cell lung cancer leading to therapeutic insensitivity, tumor recurrence, and disease progression. Indole hybrids have the potential to conquer drug resistance, enhance efficacy, reduce adverse events, and improve pharmacokinetic properties due to their capacity to inhibit multiple targets simultaneously. Moreover, indole hybrids osimertinib, mobocertinib, cediranib, and vizimpro are currently applied in clinics for lung cancer therapy, demonstrating that indole hybrids are valuable scaffolds in the treatment and eradication of lung cancer. This review provides a comprehensive overview of the evolving landscape of indole hybrids with the in vitro and in vivo efficacy against lung cancer, and the structure-activity relationships as well as mechanisms of action are also discussed, covering articles published from 2021 onward.

Diastereoselective Cascade Double Michael Addition to Access Bridged Coumarins, Oxindoles and Spirooxindoles: A Sustainable Strategy for Synthesis of Anticancer Molecules

An efficient and concise synthesis of highly functionalized bridged coumarins has been developed through a diastereoselective double Michael addition reaction of p-quinols with various 4-hydroxy coumarins under catalyst-free conditions in H2O-DMSO (8 : 2). The method has been applied to oxindoles for the synthesis of a variety of bridged-oxindoles and bridged-spiroxindoles in presence of a DABCO base using H2O-EtOH (8 : 2) as solvent medium. The strategy is simple, highly atom economical as there is no by-product and environmentally benign (E-factor=0.1-0.9). The synthesized compounds were screened against triple-negative breast cancers and found that bridged coumarin (3 a) and oxindole (5 d) compounds exhibit potent anti-cancer activity at 6.6 and 8.8 μM (IC50) concentrations respectively. Further analysis revealed that 3 a and 5 d caused elevated early and total apoptosis by arresting the MDA-MB-468 cells in G2/M phase of the cell cycle. Overall, our results demonstrate that bridged coumarin (3 a) and oxindole (5 d) compounds-based approach attenuates the cancer progression and may pave a path for the translational outcome.

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.

Novel Spirooxindole–Benzofuran Scaffold: Potential Inhibition Against Hepatocellular Carcinoma by Targeting MDM2‐p53 Interaction

We synthesized a novel compound library featuring a spirooxindole core structure combined with various heterocycles, including benzofuran, benzothiophene, and thiophene scaffolds. Evaluation using MTT assays against HepG2, 4T1, and MDA‐MB‐231 cells revealed the most potent candidate, spirooxindole hybrid 5c, with an IC50 of 5 ± 0.6 µM against HepG2, inducing G2/M phase cell cycle arrest, inhibition of the wound healing, and induction of ROS. Selected spirooxindole conjugates exhibited significant inhibitory potential against MDM2, with KD values ranging from 0.0531 to 16.8 µM. Notably, the salt of spirooxindole analogue 5q demonstrated the highest inhibitory activity at KD = 53.1 nM. Molecular docking studies revealed excellent accommodation of the designed compounds within the MDM2 receptor. All compounds displayed favorable ADME profiles, suggesting their potential as lead compounds for further optimization.

Utilizing MEDT analysis of [3 + 2] cycloaddition reaction: x-ray crystallography of spirooxindole linked with thiophene/furan heterocycles and triazole framework

Hybridization of spirooxindole with different pharmacophores such as triazole and heterocycle such as thiophene and furan moiety was achieved by the [3 + 2] cycloaddition (32CA) reaction approach. Structural investigations of the compounds 4a and 4b were performed using X-ray single crystal structure determinations and Hirshfeld analysis. Both compounds crystallized in monoclinic crystal system. The space group is P21/c for 4a and P21/n for 4b. The crystal parameters are a = 10.2619(3) Å, b = 13.6776(3) Å, c = 10.9318(3), β = 116.640(4)° for the former while a = 13.0012(1) Å, b = 14.9692(1) Å, c = 14.1178(1) Å, β = 97.101(1)° for the latter. In both compounds, the aryl group and the triazole moieties are twisted from one another. The twist angle is 84.75˚for 4a while 86.64˚ for 4b. Based on Hirshfeld calculations, the Cl…H, O…H, N…H and C…H non-covalent interactions in 4a while the O…H interactions in 4b are the most important. The molecular mechanism of the key 32CA reaction between the in situ generated azomethine ylides and the corresponding chalcones has been studied within the Molecular Electron Density Theory (MEDT). The MEDT study reveals that the low activation energies and high experimental selectivity are the result of the supernucleophilic character of the ylides and the strong electrophilicity of the chalcones, which favour the process through a high polar character. This high polar character accounts for the total endo selectivity experimentally found.

Activation of p53 signaling and regression of breast and prostate carcinoma cells by spirooxindole-benzimidazole small molecules

This study discusses the synthesis and use of a new library of spirooxindole-benzimidazole compounds as inhibitors of the signal transducer and activator of p53, a protein involved in regulating cell growth and cancer prevention. The text includes the scientific details of the [3 + 2] cycloaddition (32CA) reaction between azomethine ylide 7a and ethylene 3a within the framework of Molecular Electron Density Theory. The mechanism of the 32CA reaction proceeds through a two-stage one-step process, with emphasis on the highly asynchronous transition state structure. The anti-cancer properties of the synthesized compounds, particularly 6a and 6d, were evaluated. The inhibitory effects of these compounds on the growth of tumor cells (MDA-MB 231 and PC-3) were quantified using IC50 values. This study highlights activation of the p53 pathway by compounds 6a and 6d, leading to upregulation of p53 expression and downregulation of cyclin D and NF-κB in treated cells. Additionally, we explored the binding affinity of spirooxindole analogs, particularly compound 6d, to MDM2, a protein involved in regulation of p53. The binding mode and position of compound 6d were compared with those of a co-crystallized standard ligand, suggesting its potential as a lead compound for further preclinical research.

New spiro-indeno[1,2-b]quinoxalines clubbed with benzimidazole scaffold as CDK2 inhibitors for halting non-small cell lung cancer; stereoselective synthesis, molecular dynamics and structural insights

Despite the crucial role of CDK2 in tumorigenesis, few inhibitors reached clinical trials for managing lung cancer, the leading cause of cancer death. Herein, we report combinatorial stereoselective synthesis of rationally designed spiroindeno[1,2-b]quinoxaline-based CDK2 inhibitors for NSCLC therapy. The design relied on merging pharmacophoric motifs and biomimetic scaffold hopping into this privileged skeleton via cost-effective one-pot multicomponent [3 + 2] cycloaddition reaction. Absolute configuration was assigned by single crystal x-ray diffraction analysis and reaction mechanism was studied by Molecular Electron Density Theory. Initial MTT screening of the series against A549 cells and normal lung fibroblasts Wi-38 elected 6b as the study hit regarding potency (IC50 = 54 nM) and safety (SI = 6.64). In vitro CDK2 inhibition assay revealed that 6b (IC50 = 177 nM) was comparable to roscovitine (IC50 = 141 nM). Docking and molecular dynamic simulations suggested that 6b was stabilised into CDK2 cavity by hydrophobic interactions with key aminoacids.

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).

Synthesis and Characterization of New Spirooxindoles Including Triazole and Benzimidazole Pharmacophores via [3+2] Cycloaddition Reaction: An MEDT Study of the Mechanism and Selectivity

A new series of spirooxindoles based on benzimidazole, triazole, and isatin moieties were synthesized via a [3+2] cycloaddition reaction protocol in one step. The single X-ray crystal structure of the intermediate triazole-benzimidazole 4 was solved. The new chemical structures of these spirooxindole molecules have been achieved for the first time. The final synthesized chemical architecture has differently characterized electronic effects. An MEDT study of the key 32CA reaction between in situ generated azomethine ylide (AY) and chalcones explained the low reaction rates and the total selectivities observed. The supernucleophilic character of AY and the strong electrophilicity of chalcones favor these reactions through a highly polar two-stage one-step mechanism in which bond formation at the β-conjugated carbon of the chalcones is more advanced. The present combined experimental and theoretical study reports the synthesis of new spirooxindoles with potential biological activities and fully characterizes the molecular mechanisms for their formation through the key 32CA reaction step.

Rational Design, Synthesis, Separation, and Characterization of New Spiroxindoles Combined with Benzimidazole Scaffold as an MDM2 Inhibitor

Rational design for a new spiroxindoles, combined with a benzimidazole scaffold to identify a new murine double minute two (MDM2) inhibitor was synthesized and characterized. The desired spiroxindoles were achieved via a [3+2] cycloaddition reaction approach which afforded the cycloadducts with four asymmetric centers separated in an excellent regioselective and diastereoselective compound. The separated spiroxindoles were subjected to a set of biochemical assays including an NCI cell panel assay, MTT assay, and MDM2 binding analysis by a microscale thermophoresis assay. The anticancer reactivity for the tested compounds showed IC50 (µM) in the range between 3.797–6.879 µM, and compound 7d with IC50 = 3.797 ± 0.205 µM was the most active candidate between the series. The results showed promising results that identified that compound 7a could be inhibited the MDM2 with KD = 2.38 μm. Compound 7a developed a network of interactions with the MDM2 receptor studied in silico by molecular docking.

p53 as a potential target for treatment of cancer: A perspective on recent advancements in small molecules with structural insights and SAR studies

Cancer represents one of the world's biggest hazardous diseases. p53 is the uttermost researched tumour suppressor protein. It is commonly considered the "guardian of the genome," performing a critical function in genetic stability maintenance through controlling the cell cycle, programmed cell death, DNA repair, aging, and angiogenesis. The abnormalities in p53 lead to genetic instability and plays a significant role in carcinogenesis. The role of p53 in tumour suppression is emphasized in addition by the observation that primary silencing with this protein occurred in more than 50% of cancers. MDM2, p53, and the p53-MDM2 connections are well-known targets for the prevention and treatment of cancer. Moreover, in tumors with wild-type p53, their efficacy is decreased due to MDM2 enlargement or by the gradual decrease of MDM2 blocker ARF. As a result, improving p53 activity in cancerous cells provides a promising anticancer strategy. Various techniques are now being investigated, and addressing the p53-MDM2 interaction had also evolved as a potentially feasible strategy for contending with tumors. Both p53 and MDM2, interact via an autoregulation response signal: p53 activity induces MDM2 transcription, which in response interacts with p53's N-terminal transactivation domain, inhibiting its transcriptional activity. This article provides information on the current scenario of anti-tumor activities, with a particular emphasis on structure-activity relationship characteristics (SAR) against the p53-MDM2 to treat cancer. The primary purpose of this review is to cover recent advancements in the creation and testing of anticancer drugs that target the p53-MDM2 structure. This review contains different heterocyclic moieties which show significant results toward cancer. A mechanistic route is shown here, demonstrating both normal and malignant conditions via several stressed factors. Several compounds entered clinical trials as p53-MDM2 inhibitors for the treatment of cancer.

[3 + 2] Cycloadditions in Asymmetric Synthesis of Spirooxindole Hybrids Linked to Triazole and Ferrocene Units: X-ray Crystal Structure and MEDT Study of the Reaction Mechanism

Derivatization of spirooxindole having triazole and ferrocene units was achieved by the [3 + 2] cycloaddition (32CA) reaction approach. Reacting the respective azomethine ylide (AY) intermediate generated in situ with the ethylene derivative produced novel asymmetric cycloadducts with four contiguous asymmetric carbons in an overall high chemical yield with excellent regioselectivity and diastereoselectivity. X-Ray single-crystal structure analyses revealed, with no doubt, the success of the synthesis of the target compounds. The 32CA reaction of AY 5b with ferrocene ethylene 1 has been studied within MEDT. This 32CA reaction proceeds via a two-stage one-step mechanism involving a high asynchronous transition state structure, resulting from the nucleophilic attack of AY 5b on the β-conjugated position of ferrocene ethylene 1. The supernucleophilic character of AY 5b and the strong electrophilic character of ferrocene ethylene 1 account for the high polar character of this 32CA reaction. Further, Hirshfeld analyses were used to describe the molecular packing of compounds 4b, 4e, 4h and 4i.