Synthesis and biological evaluation of pyrazole linked benzothiazole-β-naphthol derivatives as topoisomerase I inhibitors with DNA binding ability

Recent advances in the transformation reactions of the Betti base derivatives

Betti bases are the products resulting from the one-pot multicomponent reaction involving 1-naphthol/2-naphthol, aliphatic/aromatic aldehydes, and secondary amines. This chemical process is commonly referred to as the Betti reaction. The significance of Betti bases in medicinal chemistry has grown substantially due to their diverse array of pharmacological applications. Furthermore, their synthetic utility is considerable, given their use as catalysts and ligands in asymmetric synthesis. Moreover, Mannich products, incorporating diverse functional groups such as -OH and -NH, find application in a range of organic reactions. This utilization enables the synthesis of novel C-C bond linkages and diverse heterocycles, including biologically active naphthoxazines, which hold biological applications such as antibacterial, antifungal and anticancer. The focus of this review article is on the application of aminonaphthol derivatives in transformation reactions and the synthesis of organic compounds, with particular emphasis on heterocycles.

Benzothiazole-based apoptosis inducers: A comprehensive overview and future prospective

Cancer has become a major concern in healthcare globally, and over time, incidences and prevalence of cancer are increasing. To counter this, a lot of anticancer drugs are approved and are in clinical use, playing a pivotal role in its treatment. Due to drug resistance and adverse effects, a continuous demand for novel, potent, and safe candidates to treat cancer is always there. Over the last few decades, various heterocyclic ring-based derivatives have been explored and reported in the literature. In this regard, benzothiazole scaffold-based compound emerged as the versatile ring for developing novel and safe anticancer candidates. In this article, we have reported various benzothiazole heterocyclic ring-based derivatives demonstrating potent antiproliferative activity by induction of apoptosis via an intrinsic pathway in a dose-dependent manner. These compounds also displayed inhibition of different enzymes, for example, Aurora kinase, epidermal growth factor receptor, vascular endothelial growth factor receptor, phosphoinositide kinases, DNA topoisomerase, and tubulin polymerases. This study focused on a comprehensive overview of antiproliferative activity, structure-activity relationship, apoptosis induction activity, and enzyme inhibition by benzothiazole-based compounds.

Nanoparticles of a Pyrazolo-Pyridazine Derivative as Potential EGFR and CDK-2 Inhibitors: Design, Structure Determination, Anticancer Evaluation and In Silico Studies

The strategic planning of this study is based upon using the nanoformulation method to prepare nanoparticles 4-SLNs and 4-LPHNPs of the previously prepared 4,5-diphenyl-1H-pyrazolo[3,4-c]pyridazin-3-amine (4) after confirming its structure with single crystal X-ray analysis. These nanoparticles exhibited promising cytotoxic activity against HepG-2, HCT-116 and MCF-7 cancer cell lines in comparison with the reference doxorubicin and the original derivative 4. Moreover, their inhibitory assessment against EGFR and CDK-2/cyclin A2 displayed improved and more favorable impact than the parent 4 and the references. Detection of their influence upon cancer biomarkers revealed upregulation of Bax, p53 and caspase-3 levels and downregulation of Bcl-2 levels. The docking simulation demonstrated that the presence of the pyrazolo[3,4-c]pyridazin-3-amine scaffold is amenable to enclosure and binding well within EGFR and CDK-2 receptors through different hydrophilic interactions. The pharmacokinetic and physicochemical properties of target 4 were also assessed with ADME investigation, and the outcome indicated good drug-like characteristics.

Synthesis, Computational, and Anticancer In Vitro Investigations of Aminobenzylnaphthols Derived from 2-Naphtol, Benzaldehydes, and α-Aminoacids via the Betti Reaction

Multicomponent reactions have emerged as an important approach for the synthesis of diverse and complicated chemical compounds. They have various advantages over two-component reactions, including the convenience of one-pot procedures and the ability to modify the structure of agents. Here, we employed in vitro and in silico studies to explore the anticancer potential of novel aminobenzylnaphthols derived from the Betti reaction (MMZ compounds). MTT assay was used to explore the cytotoxic activity of the compounds in pancreatic (BxPC-3 cells) and colorectal (HT-29) cancer cell lines or normal human lung fibroblasts (WI-38 cells). Proapoptotic properties of two derivatives MMZ-45AA and MMZ-140C were explored using AO/EB and annexin V-FITC/PI staining. In silico studies including ADMET profiling, molecular target prediction, docking, and dynamics were employed. The compounds exhibited cytotoxic properties and showed proapoptotic properties in respective IC50 concentrations. As indicated by in silico investigations, anticancer activity of MMZs can be attributed to the inhibition of ADORA1, CDK2, and TRIM24. Furthermore, compounds exhibited favorable ADMET properties. MMZs constitute an interesting scaffold for the potential development of new anticancer agents.

Prospects of Topoisomerase Inhibitors as Promising Anti-Cancer Agents

Topoisomerases are very important enzymes that regulate DNA topology and are vital for biological actions like DNA replication, transcription, and repair. The emergence and spread of cancer has been intimately associated with topoisomerase dysregulation. Topoisomerase inhibitors have consequently become potential anti-cancer medications because of their ability to obstruct the normal function of these enzymes, which leads to DNA damage and subsequently causes cell death. This review emphasizes the importance of topoisomerase inhibitors as marketed, clinical and preclinical anti-cancer medications. In the present review, various types of topoisomerase inhibitors and their mechanisms of action have been discussed. Topoisomerase I inhibitors, which include irinotecan and topotecan, are agents that interact with the DNA-topoisomerase I complex and avert resealing of the DNA. The accretion of DNA breaks leads to the inhibition of DNA replication and cell death. On the other hand, topoisomerase II inhibitors like etoposide and teniposide, function by cleaving the DNA-topoisomerase II complex thereby effectively impeding the release of double-strand DNA breaks. Moreover, the recent advances in exploring the therapeutic efficacy, toxicity, and MDR (multidrug resistance) issues of new topoisomerase inhibitors have been reviewed in the present review.

Synthesis, anticancer activity and molecular modeling study of novel substituted triazole linked tetrafluoronaphthalene hybrid derivatives

To create some novel anticancer molecules, a library of novel series of various triazoles linked to the hydroxyl group of 5,6,7,8-tetrafluoronaphthalen-1-ol (3) was designed and synthesized via CuAAC reaction 'Click Chemistry' of tetrafluoronaphthalene based terminal alkyne with substituted organic azides. The structural characterizations of the targeted Click products 9-18 were confirmed by FTIR, 1H NMR, 19F NMR, 13C NMR and HRMS spectroscopy. Synthesized compounds were tested in two triple negative breast cancer (TNBC) cell lines to understand their anticancer potentials. According to our findings, compounds 14 and 13 showed high cytotoxicity in BT549 cells at 20 μM and 30 μM, respectively. Moreover, these compounds blocked the migration of BT549 cells. In the MDA-MB-231 cell line, compound 18 exhibited high cytotoxicity and can block cell migration for 24 h. Molecular docking study with synthesized novel compounds was performed by Glide/SP method against SphK1 drug target. Furthermore, molecular dynamics (MD) simulation was carried out for the compounds 12-14 and 18. The compounds 13 and 14 may be potential inhibitor candidates in place of a reference inhibitor. A pharmacophore model was generated with the most potent compound 14, and the approved drugs were screened using the modules of Discovery Studio to find similar drugs. Consequently, this comprehensive study encompassing design, synthesis, in vitro and in silico analyses were correlated with the structure-activity relationship between compounds. The findings have the potential to unveil promising drug candidates for future studies.Communicated by Ramaswamy H. Sarma.

Recent Advances in the Development of Pyrazole Derivatives as Anticancer Agents

Pyrazole derivatives, as a class of heterocyclic compounds, possess unique chemical structures that confer them with a broad spectrum of pharmacological activities. They have been extensively explored for designing potent and selective anticancer agents. In recent years, numerous pyrazole derivatives have been synthesized and evaluated for their anticancer potential against various cancer cell lines. Structure-activity relationship studies have shown that appropriate substitution on different positions of the pyrazole ring can significantly enhance anticancer efficacy and tumor selectivity. It is noteworthy that many pyrazole derivatives have demonstrated multiple mechanisms of anticancer action by interacting with various targets including tubulin, EGFR, CDK, BTK, and DNA. Therefore, this review summarizes the current understanding on the structural features of pyrazole derivatives and their structure-activity relationships with different targets, aiming to facilitate the development of potential pyrazole-based anticancer drugs. We focus on the latest research advances in anticancer activities of pyrazole compounds reported from 2018 to present.

Current development of pyrazole-azole hybrids with anticancer potential

Chemotherapy is a critical treatment modality for cancer patients, but multidrug resistance remains one of the major challenges in cancer therapy, creating an urgent need for the development of novel potent chemical entities. Azoles, particularly pyrazole, could interact with different biological targets and exhibit diverse biological properties including anticancer activity. Many clinically used anticancer agents own an azole moiety, demonstrating that azoles are privileged and pivotal templates in the discovery of novel anticancer chemotherapeutics. The present article is an attempt to highlight the recent advances in pyrazole-azole hybrids with anticancer potential and discuss the structure-activity relationships, covering articles published from 2018 to present, to facilitate the rational design of more effective anticancer candidates.

Synthesis of novel mono- and bis-pyrazolylthiazole derivatives as anti-liver cancer agents through EGFR/HER2 target inhibition

3-Bromoacetyl-4-(2-naphthoyl)-1-phenyl-1H-pyrazole (6) was synthesized from 2-acetylnaphthalene and was used as a new key building block for constructing the title targets. Thus, the reaction of 6 with the thiosemicarbazones 7a-d and 9-11 afforded the corresponding simple naphthoyl-(3-pyrazolyl)thiazole hybrids 8a-d and 12 ~ 14. The symmetric bis-(2-naphthoyl-pyrazol-3-yl)thiazol-2-yl)hydrazono)methyl)phenoxy)alkanes 18a-c and 21a-c were similarly synthesized from reaction of 6 with the appropriate bis-thiosemicarbazones 17a-c and 19a-c, respectively. The synthesized two series of simple and symmetrical bis-molecular hybrid merging naphthalene, thiazole, and pyrazole were evaluated for their cytotoxicity. Compounds 18b,c and 21a showed the most potent cytotoxicity (IC₅₀ = 0.97-3.57 µM) compared to Lapatinib (IC₅₀ = 7.45 µM). Additionally, they were safe (non-cytotoxic) against the THLE2 cells with higher IC₅₀ values. Compounds 18c exhibited promising EGFR and HER-2 inhibitory activities with IC₅₀ = 4.98 and 9.85 nM, respectively, compared to Lapatinib (IC₅₀ = 6.1 and 17.2 nM). Apoptosis investigation revealed that 18c significantly activated apoptotic cell death in HepG2 cells, increasing the death rate by 63.6-fold and arresting cell proliferation at the S-phase. Compound 18c upregulated P53 by 8.6-fold, Bax by 8.9-fold, caspase-3,8,9 by 9, 2.3, and 7.6-fold, while it inhibited the Bcl-2 expression by 0.34-fold. Thereby, compound 18c exhibited promising cytotoxicity against EGFR/HER2 inhibition against liver cancer.

2-Aminobenzothiazoles in anticancer drug design and discovery

Cancer is one of the major causes of mortality and morbidity worldwide. Substantial research efforts have been made to develop new chemical entities with improved anticancer efficacy. 2-Aminobenzothiazole is an important class of heterocycles containing one sulfur and two nitrogen atoms, which is associated with a broad spectrum of medical and pharmacological activities, including antitumor, antibacterial, antimalarial, anti-inflammatory, and antiviral activities. In recent years, an extraordinary collection of potent and low-toxicity 2-aminobenzothiazole compounds have been discovered as new anticancer agents. Herein, we provide a comprehensive review of this class of compounds based on their activities against tumor-related proteins, including tyrosine kinases (CSF1R, EGFR, VEGFR-2, FAK, and MET), serine/threonine kinases (Aurora, CDK, CK, RAF, and DYRK2), PI3K kinase, BCL-XL, HSP90, mutant p53 protein, DNA topoisomerase, HDAC, NSD1, LSD1, FTO, mPGES-1, SCD, hCA IX/XII, and CXCR. In addition, the anticancer potentials of 2-aminobenzothiazole-derived chelators and metal complexes are also described here. Moreover, the design strategies, mechanism of actions, structure-activity relationships (SAR) and more advanced stages of pre-clinical development of 2-aminobenzothiazoles as new anticancer agents are extensively reviewed in this article. Finally, the examples that 2-aminobenzothiazoles showcase an advantage over other heterocyclic systems are also highlighted.

Interaction of the platinum complex of tyrosine-β-cyclodextrin with G-quadruplex DNA

The telomeric quadruplex structures formed by the guanine-rich sequences of DNA have emerged as targets for small molecules designed and synthesized to stabilize the G-quadruplexes. This report presents a newly synthesized tyrosine-tethered cyclodextrin derivative and its platinum complex. Their structures are characterized using IR, NMR, and mass spectral techniques. The binding interactions of the platinum complex with CT-DNA and the kit22, myc22, and telo24 G-quadruplexes are investigated employing absorption and fluorescence spectral titrations. The binding constant or KSV values of the interaction with the G-quadruplexes are more significant than those with the duplex DNA by order of 10. It presents the compound as a G-quadruplex-selective binder. Further, the well-known G-quadruplex binding molecule Berberine is encapsulated in the Tyr- β-CD through a host: guest association. The structure of the host: guest complex is investigated employing 2D ROESY spectroscopy. In addition, the study on the binding interaction of the complex to the DNA targets is also carried out. The mode and strength of interaction of the free and the Berberine-loaded Tyr-β-CD to the duplex and the quadruplexes are reported.

Recent updates on thienopyrimidine derivatives as anticancer agents

Thienopyrimidine derivatives hold a unique place between fused pyrimidine compounds. They are important and widely represented in medicinal chemistry as they are structural analogs of purines. Thienopyrimidine derivatives have various biological activities. The current review discusses different synthetic methods for the preparation of heterocyclic thienopyrimidine derivatives. It also highlights the most recent research on the anticancer effects of thienopyrimidines through the inhibition of various enzymes and pathways, which was published within the last 9 years.

Graphical Abstract

Novel pyrazole-based COX-2 inhibitors as potential anticancer agents: Design, synthesis, cytotoxic effect against resistant cancer cells, cell cycle arrest, apoptosis induction and dual EGFR/Topo-1 inhibition

Novel differently substituted pyrazole derivatives were designed, synthesized and evaluated for their anticancer activity. All compounds selectively inhibited COX-2 enzyme (IC₅₀ = 0.043-0.56 μM). Compounds 11, 12 and 15 showed superior potency (IC₅₀ = 0.043-0.049 μM) and screened for their antiproliferative effect against MCF-7 and HT-29 cancer cell lines using doxorubicin and 5-FU as reference drugs. Compounds 11, 12 and 15 showed good potency against MCF-7 (IC₅₀ = 2.85-23.99 μM) and HT-29 (IC₅₀ = 2.12-69.37 μM) cell lines. Also, compounds 11, 12 and 15 displayed (IC₅₀ = 56.61-115.75 μM) against non-cancerous WI-38 cells compared to doxorubicin (IC₅₀ = 13.32 μM). Compound 11 showed superior cytotoxicity against both MCF-7 (IC₅₀ = 2.85) and HT-29 (IC₅₀ = 2.12 μM) and was more potent than 5-FU (HT-29: IC₅₀ = 8.77 μM). Besides, it displayed IC₅₀ of 115.75 μM against normal WI-38 cells regarding it as a safe cytotoxic agent. In addition, compound 11 displayed IC₅₀ values of 63.44 μM and 98.60 μM against resistant HT-29 and resistant MCF-7 cancer cell lines sequentially. The most potent compound arrested cell cycle at G1/S phase in HT-29 treated cells displaying accumulation of cells in G0 phase and increase in percentage of cells in both early and late apoptotic stages. Apoptotic induction ability was confirmed via up-regulation of BAX, down-regulation of Bcl-2 and activation of caspase-3/9 protein levels. Compound 11 inhibited both EGFR (IC₅₀ = 0.083 μM) and Topo-1 (IC₅₀ = 0.020 μM) enzymes. Also, compound 11 decreased both total and phosphorylated EGFR concentration in HT-29 cells. Finally, molecular docking study showed good binding interactions between novel compounds and target receptors.

Recent advances in the green synthesis of Betti bases and their applications: a review

Well-known Betti bases are the products obtained by the one-pot multicomponent reaction of 1-naphthol/2-naphthol, aliphatic/aromatic aldehydes, and secondary amines, and this reaction is known as the Betti reaction. During recent years, due to the unveiling of the pharmacological and synthetic potential of Betti bases, a tremendous increase in the studies reporting novel synthetic methods for the efficient synthesis of Betti bases was observed. This review presents the recent key developments in the green synthesis of the Betti bases and accounts for the significant number of the literature reported during 2019-2022. Both catalyst free as well as the catalyst promoted synthesis (nanocatalyst, biocatalyst, transition metal catalyst, etc.) along with the synthetic applications (catalyst, ligands/chiral auxiliaries, and valuable synthons), optoelectronic applications (fluorescence sensors for phosgene gas, Hg²⁺, and Cr³⁺ detection, quasi-reversible redox potential) and biological properties (anticancer agents, antioxidant, anti-inflammatory agents, antitubercular agents, pesticidal agents, anti-Alzheimer agents, Topoisomerase I inhibitors, YAP-TEAD interaction inhibitors, and DNA binding and cleavage activity) are discussed. There is a surge of interest for the development of the green and efficient Betti reaction for the construction of C-C and C-N bond in a single-step reaction accessing Betti bases as products. Along with key methodological developments for the green synthesis of Betti bases, their applications in synthetic organic chemistry, optoelectronic sensors, advanced materials synthesis, agrochemicals and pharmaceutically active scaffolds, during the period of 2019-2022, have been considered.

Antiproliferative Activity of Aminobenzylnaphthols Deriving from the Betti Reaction

Two aminobenzylnaphthols, which are representative items of the family of compounds synthesized with the Betti reaction, were investigated as antiproliferative agents against adenocarcinoma human colorectal (Caco-2) and human neuroblastoma (SH-SY5Y) cell lines, using cisplatin as a positive control. A better antiproliferative activity was recorded after 24 h of incubation for the first tested molecule, whereas the other one was more effective after 72 h of incubation. These results support the hypothesis that both of the tested aminobenzylnaphthols could potentially be endowed with a biological activity.

A review on the design, synthesis, and structure-activity relationships of benzothiazole derivatives against hypoxic tumors

There has been a growing body of studies on benzothiazoles and benzothiazole derivatives as strong and effective antitumor agents against lung, liver, pancreas, breast, and brain tumors. Due to highly proliferative nature of the tumor cells, the oxygen levels get lower than that of a normal tissue in the tumor microenvironment. This situation is called as hypoxia and has been associated with increased ability for carcinogenesis. For the drug design and development strategies, hypoxic nature of the tumor tissues has been exploited more aggressively. Hypoxia itself acts as a signal initiating system to activate the pathways that eventually lead to the spread of the tumor cells into the different tissues, increases the rate of DNA damage and eventually ends up with more mutation levels that may increase the drug resistance. As one of the major mediators of hypoxic response, hypoxia inducible factors (HIFs) has been shown to activate to angiogenesis, metastasis, apoptosis resistance, and many other protumorigenic responses in cancer development. In the current review, we will be discussing the design, synthesis and structure-activity relationships of benzothiazole derivatives against hypoxic tumors such lung, liver, pancreas, breast and brain as potential anticancer drug candidates. The focus points of the study will be the biology behind carcinogenesis and how hypoxia contributes to the process, recent studies on benzothiazole and its derivatives as anti-cancer agents against hypoxic cancers, conclusions and future perspectives. We believe that this review will be useful for the researchers in the field of drug design during their studies to generate novel benzothiazole-containing hybrids against hypoxic tumors with higher efficacies.

Preparation and Physicochemical Characterization of Water-Soluble Pyrazole-Based Nanoparticles by Dendrimer Encapsulation of an Insoluble Bioactive Pyrazole Derivative

2-(4-Bromo-3,5-diphenyl-pyrazol-1-yl)-ethanol (BBB4) was synthetized and successfully evaluated concerning numerous biological activities, except for antimicrobial and cytotoxic effects. Due to the antimicrobial effects possessed by pyrazole nucleus, which have been widely reported, and the worldwide need for new antimicrobial agents, we thought it would be interesting to test BBB4 and to evaluate its possible antibacterial effects. Nevertheless, since it is water-insoluble, the future clinical application of BBB4 will remain utopic unless water-soluble BBB4 formulations are developed. To this end, before implementing biological evaluations, BBB4 was herein re-synthetized and characterized, and a new water-soluble BBB4-based nano-formulation was developed by its physical entrapment in a biodegradable non-cytotoxic cationic dendrimer (G4K), without recovering harmful solvents as DMSO or surfactants. The obtained BBB4 nanoparticles (BBB4-G4K NPs) showed good drug loading (DL%), satisfying encapsulation efficiency (EE%), and a biphasic quantitative release profile governed by first-order kinetics after 24 h. Additionally, BBB4-G4K was characterized by ATR-FTIR spectroscopy, NMR, SEM, dynamic light scattering analysis (DLS), and potentiometric titration experiments. While, before the nanotechnological manipulation, BBB4 was completely water-insoluble, in the form of BBB4-G4K NPs, its water-solubility resulted in being 105-fold higher than that of the pristine form, thus establishing the feasibility of its clinical application.

Organocatalytic enantioselective aza-Friedel-Crafts reaction between benzothiazolimines and 2-naphthols for the preparation of chiral 2'-aminobenzothiazolomethyl naphthols

A bifunctional cinchona squaramide catalyzed enantioselective aza-Friedel-Crafts reaction between 2-naphthols and benzothiazolimines has been developed, and a series of chiral 2'-aminobenzothiazolomethyl naphthols with potential antiproliferative and anthelmintic activities have been successfully and effectively prepared in good to excellent yields (up to 98%) with excellent enantioselectivities (up to >99% ee) even in a scale-up preparation under mild conditions.

Advances in 2-substituted benzothiazole scaffold-based chemotherapeutic agents

Targeted therapy plays a pivotal role in cancer therapeutics by countering the drawbacks of conventional treatment like adverse events and drug resistance. Over the last decade, heterocyclic derivatives have received considerable attention as cytotoxic agents by modulating various signaling pathways. Benzothiazole is an important heterocyclic scaffold that has been explored for its therapeutic potential. Benzothiazole-based derivatives have emerged as potent inhibitors of enzymes such as EGFR, VEGFR, PI3K, topoisomerases, and thymidylate kinases. Several researchers have designed, synthesized, and evaluated benzothiazole scaffold-based enzyme inhibitors. Of these, several inhibitors have entered various phases of clinical trials. This review describes the recent advances and developments of benzothiazole architecture-based derivatives as potent anticancer agents.

Design, Synthesis, Anticancer Evaluation, Enzymatic Assays, and a Molecular Modeling Study of Novel Pyrazole-Indole Hybrids

The molecular hybridization concept has recently emerged as a powerful approach in drug discovery. A series of novel indole derivatives linked to the pyrazole moiety were designed and developed via a molecular hybridization protocol as antitumor agents. The target compounds (5a-j and 7a-e) were prepared by the reaction of 5-aminopyrazoles (1a-e) with N-substituted isatin (4a,b) and 1H-indole-3-carbaldehyde (6), respectively. All products were characterized via several analytical and spectroscopic techniques. Compounds (5a-j and 7a-e) were screened for their cytotoxicity activities in vitro against four human cancer types [human colorectal carcinoma (HCT-116), human breast adenocarcinoma (MCF-7), human liver carcinoma (HepG2), and human lung carcinoma (A549)] using the MTT assay. The obtained results showed that the newly synthesized compounds displayed good-to-excellent antitumor activity. For example, 5-((1H-indol-3-yl)methyleneamino)-N-phenyl-3-(phenylamino)-1H-pyrazole-4-carboxamide (7a) and 5-((1H-indol-3-yl)methyleneamino)-3-(phenylamino)-N-(4-methylphenyl)-1H-pyrazole-4-carboxamide (7b) provided excellent anticancer inhibition performance against the HepG2 cancer cell line with IC₅₀ values of 6.1 ± 1.9 and 7.9 ± 1.9 μM, respectively, compared to the standard reference drug, doxorubicin (IC₅₀ = 24.7 ± 3.2 μM). The two powerful anticancer compounds (7a and 7b) were further subjected to cell cycle analysis and apoptosis investigation in HepG2 using flow cytometry. We have also studied the enzymatic assay of these two compounds against some enzymes, namely, caspase-3, Bcl-2, Bax, and CDK-2. Interestingly, the molecular docking study revealed that compounds 7a and 7b could well embed in the active pocket of the CDK-2 enzyme via different interactions. Overall, the prepared pyrazole-indole hybrids (7a and 7b) can be proposed as strong anticancer candidate drugs against various cancer cell lines.

Functional Pyrazolo[1,5-a]pyrimidines: Current Approaches in Synthetic Transformations and Uses As an Antitumor Scaffold

Pyrazolo[1,5-a]pyrimidine (PP) derivatives are an enormous family of N-heterocyclic compounds that possess a high impact in medicinal chemistry and have attracted a great deal of attention in material science recently due to their significant photophysical properties. Consequently, various researchers have developed different synthesis pathways for the preparation and post-functionalization of this functional scaffold. These transformations improve the structural diversity and allow a synergic effect between new synthetic routes and the possible applications of these compounds. This contribution focuses on an overview of the current advances (2015-2021) in the synthesis and functionalization of diverse pyrazolo[1,5-a]pyrimidines. Moreover, the discussion highlights their anticancer potential and enzymatic inhibitory activity, which hopefully could lead to new rational and efficient designs of drugs bearing the pyrazolo[1,5-a]pyrimidine core.

Recent Progress on Anticancer Agents Incorporating Pyrazole Scaffold

The search of new anticancer agents is considered as a dynamic field of medicinal chemistry. In recent years, the synthesis of compounds with anticancer potential has increased and a large number of structurally varied compounds displaying potent anticancer activities have been published. Pyrazole is an important biologically active scaffold that possessed nearly all types of biological activities. The aim of this review is to collate literature work reported by researchers to provide an overview on in vivo and in vitro anticancer activities of pyrazole based derivatives among the diverse biological activities displayed by them and also presents recent efforts made on this heterocyclic moiety regarding anticancer activities. This review has been driven from the increasing number of publications, on this issue, which have been reported in the literature since the ending of the 20th century (from 1995-to date).

α-Aminoazoles/azines: key reaction partners for multicomponent reactions

Aromatic α-aminoazaheterocycles are the focus of significant investigations and exploration by researchers owing to their key role in diverse biological and physiological processes. The existence of their derivatives in numerous drugs and alkaloids is due to their heterocyclic nitrogenous nature. Therefore, the synthesis of a structurally diverse range of their derivatives through simple and convenient methods represents a vital field of synthetic organic chemistry. Multicomponent reactions (MCRs) provide a platform to introduce desirable structure diversity and complexity into a molecule in a single operation with a significant reduction in the use of harmful organic waste, and hence have attracted particular attention as an excellent tool to access these derivatives. This review covers the advances made from 2010 to the beginning of 2020 in terms of the utilization of α-aminoazaheterocycles as synthetic precursors in MCRs.

Synthesis and Anti-Proliferative Evaluations of New Heterocyclic Derivatives Using 5,6,8,9-Tetrahydropyrazolo[5,1-b]quinazolin-7(3H)-one Derivatives Derived from Cyclohexa-1,4-dione

BACKGROUND

Recentlty, pyrazoloquinazoline derivatives acquired a special attention due to their wide range of pharmacological activities, especially therapeutic. Through the market, it was found that many pharmacological drugs containing the quinazoline nucleus were known.

OBJECTIVE

The aim of this work is to synthesize target molecules possessing not only anti-tumor activities but also kinase inhibitors. The target molecules were obtained through the synthesis of a series of 5,6,8,9- tetrahydropyrazolo[5,1-b]quinazolin-7(3H)-one derivatives 4a-i using the multi-component reactions of cyclohexane- 1,4-dione (1), the 5-amino-4-(2-arylhydrazono)-4H-pyrazol-3-ol derivatives 2a-c, the aromatic aldehydes 3a-c, respectively. The synthesized compounds were evaluated against c-Met kinase, PC-3 cell line, and different kinds of cancer cell lines together with normal cell line, tyrosine kinases, and Pim-1 kinase.

METHODS

Multi-component reactions were adopted using compound 1 to get different 5,6,8,9- tetrahydropyrazolo[5,1-b]quinazolin-7(3H)-one derivatives which underwent further heterocyclization reactions. The c-Met kinase activity of all compounds was evaluated using Homogeneous Time-Resolved Fluorescence (HTRF) assay, taking foretinib as the positive control. The anti-proliferative activity of all target compounds against the human prostatic cancer PC-3 cell line was measured using MTT assay using SGI-1776 as the reference drug. All the synthesized compounds were assessed for inhibitory activities against A549 (non-small cell lung cancer), H460 (human lung cancer), HT-29 (human colon cancer), and MKN-45 (human gastric cancer) cancer cell lines together with foretinib as the positive control by an MTT assay.

RESULTS

Antiproliferative evaluations and c-Met kinase, Pim-1 kinase inhibitions were performed for the synthesized compounds, where the varieties of substituents through the aryl ring and the thiophene moiety afforded compounds with high activities.

CONCLUSION

The compounds with high antiproliferative activity were tested towards c-Met and the results showed that compounds 4e, 4f, 4g, 4i, 6i, 6k, 6l, 8f, 8i, 10d, 10e, 10f, 10h, 12e, 12f, 12g, 12h, 12i, 14f, 14g, 14h, and 14i were the most potent compounds. A further selection of compounds for the Pim-1 kinase inhibition activity showed that compounds 4f, 6i, 6l, 8h, 8i, 8g, 10d, 12i, and 14f were the most active compounds to inhibit Pim-1.

Synthesis, cytotoxicity of some pyrazoles and pyrazolo[1,5-a]pyrimidines bearing benzothiazole moiety and investigation of their mechanism of action

A novel series of pyrazoles and pyrazolo[1,5-a]pyrimidines bearing benzothiazole moiety were designed and synthesized. Chemical structures were confirmed by spectral data and elemental analyses. Nine compounds were selected and screened for their cytotoxic activity at the National Cancer Institute (NCI), USA against 60 cancer cell lines in a single dose assay. Compounds 4 and 5 exerted the most potent growth inhibitory activity against most cancer cell lines with growth inhibition (GI%) ranges from 44.86% to 84.59% and 31.20% to 52.36%, respectively. Consequently, they were further investigated through IC₅₀ determination using five dose MTT colorimetric assay against three sensitive cell lines, leukemia CCRF-CEM, non-small cell lung cancer HOP-92 and liver cancer Hep-G2. Compound 4 exhibited potent cytotoxic activity against the three tested cell lines with IC₅₀ 16.34, 3.45 and 7.79 μM, respectively representing half potency, 3.5 folds potency and nearly equipotent to roscovitine. To investigate its mechanism of action, cell cycle analysis of compound 4 was conducted and showed that it induced cell cycle arrest at G2/M phase and apoptosis in HOP-92 cells. In correlation with the previous results, caspase-3 activation was tested and illustrated elevation in its concentration by nearly 14 folds than control. Besides, enzyme inhibition assay of compound 4 was evaluated towards two common antitumor targets namely KDM1 and CDK1 showing significant inhibitory activity with IC₅₀ 0.096 and 0.078 μM, respectively.

A Review on Recent Advances in Nitrogen-Containing Molecules and Their Biological Applications

The analogs of nitrogen-based heterocycles occupy an exclusive position as a valuable source of therapeutic agents in medicinal chemistry. More than 75% of drugs approved by the FDA and currently available in the market are nitrogen-containing heterocyclic moieties. In the forthcoming decade, a much greater share of new nitrogen-based pharmaceuticals is anticipated. Many new nitrogen-based heterocycles have been designed. The number of novel N-heterocyclic moieties with significant physiological properties and promising applications in medicinal chemistry is ever-growing. In this review, we consolidate the recent advances on novel nitrogen-containing heterocycles and their distinct biological activities, reported over the past one year (2019 to early 2020). This review highlights the trends in the use of nitrogen-based moieties in drug design and the development of different potent and competent candidates against various diseases.

Pyridazino[1,6-b]quinazolinones as new anticancer scaffold: Synthesis, DNA intercalation, topoisomerase I inhibition and antitumor evaluation in vitro and in vivo

A new anticancer N-containing heterocyclic scaffold was designed and 30 pyridazino[1,6-b]quinazolinone derivatives were synthesized and characterized. Antiproliferation evaluation in vitro against four human cancer cell lines including SK-OV-3(ovarian cell), CNE-2(nasopharyngeal cell), MGC-803(gastric cell) and NCI-H460(lung cell) indicated that most of them exhibited potent anticancer activity and the IC₅₀ value of the most potent compound lowered to sub-μM. DNA interaction assay indicated that compounds 4e, 4g, 6o, 6p, 8o can intercalate into DNA. Compounds 6 and 8 also demonstrated potent topoisomerase I (topo I) activity. Annexin V- FITC/propidium iodide dual staining assay and cell cycle analysis indicated that 2-(4-bromophenyl)-4-((3-(diethylamino)propyl)amino) -10H-pyridazino [1,6-b]quinazolin- 10-one (8p) could induce arrest cell cycle at G2 phase and apoptosis in MGC-803 cells in a dose-dependent manner. The in vivo antitumor efficiency of compound 8p was also evaluated on MGC-803 xenograft nude mice, and the relative tumor growth inhibition was up to 55.9% at a dose of 20 mg/kg per two days. The results suggested that pyridazino[1,6-b]-quinazolinones might serve as a promising novel scaffold for the development of new antitumor agents.

Synthesis, pharmacological evaluation and structure-activity relationship of recently discovered enzyme antagonist azoles

Global people are suffering from the legion of diseases. Cytotoxic property of the chemical compound would not solely influence effective drug properties and reduce unnecessary side effects. Proteins/enzymes responsible for microbe proliferation or survival are specifically targeted and inhibited successfully making the cells to undergo apoptosis. Furthermore, isoforms of essential enzymes have distinct physiological functions; thereby inhibition of essential enzyme isoforms is an apt way to the clinical approach of disease neutralization. Drugs are designed so as to play significant roles such as signaling pathways in the oncogenic process including cell proliferation, invasion, and angiogenesis. The present review comprises collective information of the recent synthesis of various organic drug compounds in brief, which could inhibit particular enzyme. The review also covers the correlation of the structure of a drug molecule designed and its inhibitory activity. Also, the most significant enzyme inhibitors are highlighted and structural moieties/core units responsible for remarkable inhibitory values are emphasized.