Design and optimization of (3-aryl-1 H -indazol-6-yl)spiro[cyclopropane-1,3′-indolin]-2′-ones as potent PLK4 inhibitors with oral antitumor efficacy

Therapeutic potential of targeting polo-like kinase 4

Polo-like kinase 4 (PLK4), a highly conserved serine/threonine kinase, masterfully regulates centriole duplication in a spatiotemporal manner to ensure the fidelity of centrosome duplication and proper mitosis. Abnormal expression of PLK4 contributes to genomic instability and associates with a poor prognosis in cancer. Inhibition of PLK4 is demonstrated to exhibit significant efficacy against various types of human cancers, further highlighting its potential as a promising therapeutic target for cancer treatment. As such, numerous small-molecule inhibitors with distinct chemical scaffolds targeting PLK4 have been extensively investigated for the treatment of different human cancers, with several undergoing clinical evaluation (e.g., CFI-400945). Here, we review the structure, distribution, and biological functions of PLK4, encapsulate its intricate regulatory mechanisms of expression, and highlighting its multifaceted roles in cancer development and metastasis. Moreover, the recent advancements of PLK4 inhibitors in patent or literature are summarized, and their therapeutic potential as monotherapies or combination therapies with other anticancer agents are also discussed.

Contribution of Knoevenagel Condensation Products towards Development of Anticancer Agents: An Updated Review

Knoevenagel condensation is an entrenched, prevailing, prominent arsenal following greener principles in the generation of α, β-unsaturated ketones/carboxylic acids by involving carbonyl functionalities and active methylenes. This reaction has proved to be a major driving force in many multicomponent reactions indicating the prolific utility towards the development of biologically fascinating molecules. This eminent reaction was acclimatised on different pharmacophoric aldehydes (benzimidazole, β-carboline, phenanthrene, indole, imidazothiadiazole, pyrazole etc.) and active methylenes (oxindole, barbituric acid, Meldrum's acid, thiazolidinedione etc.) to generate the library of chemical compounds. Their potential was also explicit to understand the significance of functionalities involved, which thereby evoke further developments in drug discovery. Furthermore, most of these reaction products exhibited remarkable anticancer activity in nanomolar to micromolar ranges by targeting different cancer targets like DNA, microtubules, Topo-I/II, and kinases (PIM, PARP, NMP, p300/CBP) etc. This review underscores the efficiency of the Knoevenagel condensation explored in the past six-year to generate molecules of pharmacological interest, predominantly towards cancer. The present review also provides the aspects of structure-activity relationships, mode of action and docking study with possible interaction with the target protein.

Current progress, challenges and future prospects of indazoles as protein kinase inhibitors for the treatment of cancer

The indazole core is an interesting pharmacophore due to its applications in medicinal chemistry. In the past few years, this moiety has been used for the synthesis of kinase inhibitors. Many researchers have demonstrated the use of indazole derivatives as specific kinase inhibitors, including tyrosine kinase and serine/threonine kinases. A number of anticancer drugs with an indazole core are commercially available, e.g. axitinib, linifanib, niraparib, and pazopanib. Indazole derivatives are applied for the targeted treatment of lung, breast, colon, and prostate cancers. In this review, we compile the current development of indazole derivatives as kinase inhibitors and their application as anticancer agents in the past five years.

The Anticancer Activity of Indazole Compounds: A Mini Review

The incidence and mortality of cancer continue to grow since the current medical treatments often fail to produce a complete and durable tumor response and ultimately give rise to therapy resistance and tumor relapse. Heterocycles with potential therapeutic values are of great pharmacological importance, and among them, indazole moiety is a privileged structure in medicinal chemistry. Indazole compounds possess potential anticancer activity, and indazole-based agents such as, axitinib, lonidamine and pazopanib have already been employed for cancer therapy, demonstrating indazole compounds as useful templates for the development of novel anticancer agents. The aim of this review is to present the main aspects of exploring anticancer properties, such as the structural modifications, the structure-activity relationship and mechanisms of action, making an effort to highlight the importance and therapeutic potential of the indazole compounds in the present anticancer agents.

Visible-Light-Mediated Cyclopropanation Reactions of 3-Diazooxindoles with Arenes

The cyclopropanation reaction of 3-diazooxindoles with arenes was first accomplished using visible-light irradiation. A series of spiro[norcaradiene-7,3'-indolin]-2'-ones were synthesized for the first time in high yields and with excellent diastereoselectivities. The synthetic usefulness of this catalyst-free photochemical methodology is illustrated by the further controllable rearrangement and epoxidation reactions.

Recent progress in agents targeting polo-like kinases: Promising therapeutic strategies

Polo-like kinases (PLKs) play important roles in regulating multiple aspects of cell cycle and cell proliferation. In many cancer types, PLK family members are often dysregulated, which can lead to uncontrolled cell proliferation and aberrant cell division and has been shown to associate with poor prognosis of cancers. The key roles of PLK kinases in cancers lead to an enhanced interest in them as promising targets for anticancer drug development. In consideration of PLK inhibitors and some other anticancer agents, such as BRD4, EEF2K and Aurora inhibitors, exert synergy effects in cancer cells, dual-targeting of PLK and other cancer-related targets is regarded as an rational and potent strategy to enhance the effectiveness of single-targeting therapy for cancer treatment. This review introduces the PLK family members at first and then focuses on the recent advances of single-target PLK inhibitors and summarizes the corresponding SARs of them. Moreover, we discuss the synergisms between PLK and other anti-tumor targets, and sum up the current dual-target agents based on them.

Structural insights of oxindole based kinase inhibitors as anticancer agents: Recent advances

Small-molecule kinase inhibitors are being continuously explored as new anticancer therapeutics. Kinases are the phosphorylating enzymes which regulate numerous cellular functions such as proliferation, differentiation, migration, metabolism, and angiogenesis by activating several signalling pathways. Kinases have also been frequently found to be deregulated and overexpressed in cancerous tissues. Therefore, modulating the kinase activity by employing small molecules has emerged as a strategic approach for cancer treatment. On the other hand, oxindole motifs have surfaced as privileged scaffolds with significant multi-kinase inhibitory activity. The present review summarises recent advances in the development of oxindole based kinase inhibitors. The role of distinguished structural frameworks of oxindoles, such as 3-alkenyl oxindoles, spirooxindoles, 3-iminooxindoles and similar hydrazone derivatives have been described based on their kinase inhibition potential. Furthermore, the design strategies, mechanism of actions, structure activity relationships (SARs) and their mode of interaction with target protein have been critically highlighted.

Anticancer potential of spirocompounds in medicinal chemistry: A pentennial expedition

Spirocompounds constitute an important class of organic frameworks enveloping numerous pharmacological activities, among them, the promising anticancer potential of spirocompounds have enthused medicinal chemists to explore new spiro derivatives with significantly improved pharmacodynamic and pharmacokinetic profile along with their mechanism of action. The current review intends to provide a sketch of the anticancer activity of various spirocompounds like spirooxindole, spiroisoxazole, spiroindole etc, from the past five years unfolding various aspects of pharmacological activities and their structure-activity relationships (SARs). This literature analysis may provide future direction for the efficient design of novel spiromolecules with enhanced safety and efficacy.

Highly diastereoselective spiro-cyclopropanation of 2-arylidene-1,3-indanediones and dimethylsulfonium ylides

High diastereoselectivity, mild conditions and excellent functional group compatibility.

The Azoles in Pharmacochemistry: Perspectives on the Synthesis of New Compounds and Chemoinformatic Contributions

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Due to their versatile biological activity, Azoles are widely studied in pharmacochemistry. It is possible to use them in many applications and in studies aimed at discovering antiparasitic, antineoplastic, antiviral, antimicrobial compounds; and in the production of materials for treatment of varied pathologies. Based on their biological activity, our review presents several studies that involve this class of organic compounds. A bibliographic survey of this type can effectively contribute to pharmaceutical sciences, stimulating the discovery of new compounds, and structural improvements to biological profiles of interest. In this review, articles are discussed involving the synthesis of new compounds and chemoinformatic contributions. Current applications of azoles in both the pharmaceutical and agri-business sectors are well known, yet as this research highlights, azole compounds can also bring important contributions to the fight against many diseases. Among the heterocyclics, azoles are increasingly studied by research groups around the world for application against tuberculosis, HIV, fungal and bacterial infections; and against parasites such as leishmaniasis and trypanosomiasis. Our hope is that this work will help arouse the interest of research groups planning to develop new bioactives to fight against these and other diseases.

Synthesis and Activity Evaluation of Nasopharyngeal Carcinoma Inhibitors Based on 6-(Pyrimidin-4-yl)-1H-indazole

Human nasopharyngeal carcinoma is a common head and neck malignancy with high incidence in Southeast Asia and Southern China. It is necessary to develop safe, effective and inexpensive anticancer agents to improve the therapeutics of patients with nasopharyngeal carcinoma. A series of small molecular compounds based on 6-(pyrimidin-4-yl)-1H-indazole were synthesized and evaluated for antiproliferative activities against human nasopharyngeal carcinoma cell lines SUNE1. Compounds 6b, 6c, 6e and 6l showed potent antiproliferative activities similar to positive control drug cisplatin in vitro with lower nephrotoxicity than it. N-[4-(1H-Indazol-6-yl)pyrimidin-2-yl]benzene-1,3-diamine (6l) was selected for further study. It was found that 6l induced mitochondria-mediated apoptosis and G₂ /M phase arrest in SUNE1 cells. Furthermore, compound 6l at 10 mg/kg can suppress the growth of an implanted SUNE1 xenograft with a TGI% (tumor growth inhibition) value of 50 % and did not cause serious side effects in BALB/c nude mice. This study suggests that 6-(pyrimidin-4-yl)-1H-indazole derivatives are a series of small molecule compounds with anti-nasopharyngeal carcinoma activities.

Synthesis and X-ray study of dispiro 8-nitroquinolone analogues and their cytotoxic properties against human cervical cancer HeLa cells

A series of unique dispiro analogues containing an oxindole pyrrolidine 8-nitroquinolone hybrid has been obtained through a one-pot three-component 1,3-dipolar cycloaddition of azomethine ylides generated in situ from the condensation of isatins and benzylamine with (E)-3-arylidene-2,3-dihydro-8-nitro-4-quinolones. The structures of the newly synthesized compounds were characterized by using different spectroscopic techniques and by X-ray diffraction studies of their regio- and stereochemistry. All the synthesized compounds were screened for in vitro cytotoxic activity against the human cervical cancer cell line HeLa. The compounds have exhibited potent inhibition against human cervical cancer cells and insignificant toxicity to normal cells. The compounds 6d, 6a, 6h, 6b, and 6e induced apoptosis of HeLa cells, through ROS influx. The expression levels of proteins involved in the mitochondrion-related pathways were detected, and Western blot analysis showed that apoptosis occurred via activation of caspase-3.

Recent Advances in the Development of Indazole-based Anticancer Agents

Cancer is one of the leading causes of human mortality globally; therefore, intensive efforts have been made to seek new active drugs with improved anticancer efficacy. Indazole-containing derivatives are endowed with a broad range of biological properties, including anti-inflammatory, antimicrobial, anti-HIV, antihypertensive, and anticancer activities. In recent years, the development of anticancer drugs has given rise to a wide range of indazole derivatives, some of which exhibit outstanding activity against various tumor types. The aim of this review is to outline recent developments concerning the anticancer activity of indazole derivatives, as well as to summarize the design strategies and structure-activity relationships of these compounds.

Highly stereoselective spirocyclopropanation of various diazooxindoles with olefins catalyzed using Ru(ii)-complex

Optically active spirocyclopropyloxindole derivatives were efficiently synthesized from diazooxindoles and olefins in the presence of a Ru(ii)-Pheox catalyst. Among a series of Ru(ii)-Pheox catalysts, Ru(ii)-Pheox 6e was determined to be the best catalyst for spirocyclopropanation reactions of diazooxindoles with various olefins in high yields (up to 98%) with high diastereoselectivities (up to trans:cis = >99:1<) and enantioselectivities (up to 99% ee). Furthermore, as the first catalytic asymmetric synthesis, anti-HIV active candidate 4a and a bioactive compound of AMPK modulator 4c were easily synthesized from the corresponding diazooxindoles 1i and 1b, respectively, in high yields with high enantioselectivities (4a: 82% yield, 95% ee, 4b: 99% yield, 93% ee).

Optically active spirocyclopropyloxindole derivatives were efficiently synthesized from diazooxindoles and olefins in the presence of a Ru(ii)-Pheox catalyst.

Anti-addition of Dimethylsulfoxonium Methylide to Acyclic α,β-Unsaturated Ketones and Its Application in Formal Synthesis of an Eicosanoid

Cyclopropanation using dimethylsulfoxonium methylide (Corey-Chaykovsky reaction) was examined with a series of linear α,β-unsaturated ketones, and the results showed that the major trajectory for the addition of the sulfur ylide to the enones is anti, related to the γ-substituent. The stereochemical assignment for the generated cyclopropanes was achieved by X-ray crystallography or comparing with the reported spectroscopic data. We found that the diastereoselectivity was influenced by several factors, including the protecting groups, solvents, and temperatures, and good anti/syn ratios (>10:1) were often obtained using the tert-butyldimethylsilyl and tert-butyldiphenylsilyl-protected substrates. The method was applied to a formal synthesis of a natural eicosanoid with good efficiency.

Organoiodine reagent-promoted intermolecular oxidative amination: synthesis of cyclopropyl spirooxindoles

An organoiodine-promoted intramolecular direct oxidative C(sp²)–N cross-coupling reaction was developed for the preparation of cyclopropyl spirooxindoles from readily available secondary cyclopropyl carboxamides.

Synthesis and biological evaluation of (E)-4-(3-arylvinyl-1H-indazol-6-yl)pyrimidin-2-amine derivatives as PLK4 inhibitors for the treatment of breast cancer

SAR explorations identified (E)-4-(3-arylvinyl-1H-indazol-6-yl)pyrimidin-2-amine derivative14ias a potential PLK4 inhibitor with significant anti-breast cancer activityin vitroandin vivo.