Design, synthesis and cytotoxic evaluation of a novel series of benzo[d]thiazole-2-carboxamide derivatives as potential EGFR inhibitors

Thiazole and Related Heterocyclic Systems as Anticancer Agents: A Review on Synthetic Strategies, Mechanisms of Action and SAR Studies

Background:

Cancer is the second leading cause of death throughout the world. Many anticancer drugs are commercially available, but lack of selectivity, target specificity, cytotoxicity and development of resistance lead to serious side effects. There have been several experiments going on to develop compounds with minor or no side effects.

Objective:

This review mainly emphasizes synthetic strategies, SAR studies, and mechanism of action for thiazole, benzothiazole, and imidazothiazole containing compounds as anticancer agents.

Methods:

Recent literature related to thiazole and thiazole-related derivatives endowed with encouraging anticancer potential is reviewed. This review emphasizes contemporary strategies used for the synthesis of thiazole and related derivatives, mechanistic targets, and comprehensive structural activity relationship studies to provide perspective into the rational design of high-efficiency thiazole-based anticancer drug candidates.

Results:

Exhaustive literature survey indicated that thiazole derivatives are associated with properties of inducing apoptosis and disturbing tubulin assembly. Thiazoles are also associated with the inhibition of NFkB/mTOR/PI3K/AkT and regulation of estrogen-mediated activity. Furthermore, thiazole derivatives have been found to modulate critical targets such as topoisomerase and HDAC.

Conclusion:

Thiazole derivatives seem to be quite competent and act through various mechanisms. Some of the thiazole derivatives, such as compounds 29, 40, 62, and 74a with IC50 values of 0.05 μM, 0.00042 μM, 0.18 μM, and 0.67 μM, respectively not only have anticancer activity but they also have lower toxicity and better absorption. Therefore, some other similar compounds could be investigated to aid in the development of anticancer pharmacophores.

A medicinal chemist's perspective towards structure activity relationship of heterocycle based anti-cancer agents

AIM

To describe structure activity relationship of heterocyclic derivatives with multi-targeted anticancer activity.

OBJECTIVES

With the following goals in mind, this review tries to describe significant recent advances in the medicinal chemistry of heterocycle-based compounds: (1) To shed light on recent literature focused on heterocyclic derivatives' anticancer potential; (2) To discuss recent advances in the medicinal chemistry of heterocyclic derivatives, as well as their biological implications for cancer eradication; (3) To summarise the comprehensive correlation of structure activity relationship (SAR) with pharmacological outcomes in cancer therapy.

BACKGROUND

Cancer remains one of the major serious health issues devastating the world today. Cancer is a complex disease in which improperly altered cells proliferate at an uncontrolled, rapid, and severe rate. Variables such as poor dietary habits, high stress, age, and smoking, can all contribute to the development of cancer. Cancer can affect almost any organ or tissue, although the brain, breast, liver, and colon are the most frequently affected organs. From several years, surgical operations and irradiation are in use along with chemotherapy as a primary treatment of cancer but still effective treatment of cancer remains a huge challenge. Chemotherapy is now one of the most effective strategies to eradicate cancer, although it has been shown to have a number of cytotoxic and unfavourable effects on normal cells. Despite all of these cancer treatments, there are several other targets for anticancer drugs. Cancer can be effectively eradicated by focusing on these targets, which include both cell-specific and receptor-specific targets such as tyrosine kinase receptors (TKIs). Heterocyclic scaffolds also have a variety of applications in drug development and are a common moiety in the pharmaceutical, agrochemical, and textile industries.

METHODS

The association between structural activity relationship data of many powerful compounds and their anticancer potential in vitro and in vivo has been studied. SAR of powerful heterocyclic compounds can also be generated using molecular docking simulations, as reported vastly in literature.

CONCLUSIONS

Heterocycles have a wide range of applications, from natural compounds to synthesised derivatives with powerful anticancer properties. To avoid cytotoxicity or unfavourable effects on normal mammalian cells due to a lack of selectivity towards the target site, as well as to reduce the occurrence of drug resistance, safer anticancer lead compounds with higher potency and lower cytotoxicity are needed. This review emphasizes on design and development of heterocyclic lead compounds with promising anticancer potential.

Epidermal growth factor receptor inhibitors as potential anticancer agents: An update of recent progress

Epidermal growth factor receptor (EGFR) is a vital intermediate in cell signaling pathway including cell proliferation, angiogenesis, apoptosis, and metastatic spread and also having four divergent members with similar structural features, such as EGFR (HER1/ErbB1), ErbB2 (HER2/neu), ErbB3 (HER3), and ErbB4 (HER4). Despite this, clinically exploited inhibitors of EGFR (including erlotinib, lapatinib, gefitinib, selumetinib, etc.) are not specific thus provoking unenviable adverse effects. Some of the paramount obstacles to generate and develop new lead molecules of EGFR inhibitors are drug resistance, mutation, and also selectivity which inspire medicinal chemists to generate novel chemotypes. The discovery of therapeutic agents that inhibit the precise stage in tumorous cells such as EGFR is one of the chief successful targets in many cancer therapies, including lung and breast cancers. This review aims to compile the various recent progressions (2016-2021) in the discovery and development of diverse epidermal growth factor receptor (EGFR) inhibitors belonging to distinct structural classes like pyrazoline, pyrazole, imidazole, pyrimidine, coumarin, benzothiazole, etc. We have summarized preclinical and clinical data, structure-activity relationships (SAR) containing mechanistic and in silico studies to provide proposals for the design and invention of new EGFR inhibitors with therapeutic significance. The detailed progress of the work in the field will provide inexorable scope for the development of novel drug candidates with greater selectivity and efficacy.

Design, Synthesis and Anticancer Activity of a New Series of N-aryl-N'-[4-(pyridin-2-ylmethoxy)benzyl]urea Derivatives

The development of cancer treatments requires continuous exploration and improvement, in which the discovery of new drugs for the treatment of cancer is still an important pathway. In this study, based on the molecular hybridization strategy, a new structural framework with an N-aryl-N'-arylmethylurea scaffold was designed, and 16 new target compounds were synthesized and evaluated for their antiproliferative activities against four different cancer cell lines A549, MCF7, HCT116, PC3, and human liver normal cell line HL7702. The results have shown seven compounds with 1-methylpiperidin-4-yl groups having excellent activities against all four cancer cell lines, and they exhibited scarcely any activities against HL7702. Among them, compound 9b and 9d showed greatly excellent activity against the four kinds of cells, and the IC₅₀ for MCF7 and PC3 cell lines were even less than 3 μM.

Synthesis and biological evaluation of a new series of 1-aryl-3-[4-(pyridin-2-ylmethoxy)phenyl]urea derivatives as new anticancer agents

The diaryl ureas are very important fragments in medicinal chemistry. By means of computer-aided design, 1-aryl-3-[4-(pyridin-2-ylmethoxy)phenyl]urea derivatives were designed and synthesized, and evaluated for their antiproliferative activity against A549, HCT-116, PC-3 cancer cell lines, and HL7702 human normal liver cell lines in vitro by using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide colorimetric assay. Most of the target compounds demonstrate significant antiproliferative effects on all the selective cancer cell lines. The calculated IC₅₀ values were reported. The target compound 1-(4-chlorophenyl)-3-{4-{[3-methyl-4-(2,2,2-trifluoroethoxy)pyridin-2-yl]methoxy}phenyl}urea (7u) demonstrated the most potent inhibitory activity (IC₅₀ = 2.39 ± 0.10 μM for A549 and IC₅₀ = 3.90 ± 0.33 μM for HCT-116), comparable to the positive-control sorafenib (IC₅₀ = 2.12 ± 0.18 μM for A549 and IC₅₀ = 2.25 ± 0.71 μM for HCT-116). Conclusively, 1-aryl-3-[4-(pyridin-2-ylmethoxy)phenyl]urea derivatives as the new anticancer agents were discovered, and could be used as the potential BRAF inhibitors for further research.

Design, Synthesis, Biological Evaluation and In Silico Studies of Few Novel 2-Substituted Benzothiazole Derivatives as Potential EGFR Inhibitors

Background:

There is a great unmet medical need for new anticancer small molecule therapeutics. Exhaustive literature review suggests that benzothiazole derivatives have good potential to exhibit anticancer activity. Compounds that inhibit the kinase activity of EGFR are of potential interest as new antitumor agent.

Objective:

To design, synthesize and carry out in silico along with biological evaluation of 2- substituted benzothiazole compounds with EGFR inhibitory activity.

Methods:

Benzothiazole derivatives designed from molecular docking method for potential EGFR tyrosine kinase inhibition have been synthesized based on the docking results and characterized. Insilico studies were carried out to understand the mode of EGFR enzyme inhibition by our molecules. As a preliminary study, these compounds were first screened for antioxidant activity and then for anticancer activity against MCF-7 cell lines and A549 cell line.

Results:

Compound B5 showed potent anticancer activity on MCF-7 cell line with IC50 value of 9.7µM and compound B8 showed significant anticancer activity on A549 cell line with IC50 value of 49.7μM in comparison with the standard drug Doxorubicin (IC50 = 1.4µM on MCF-7 and 1.0µM on A549 cell lines). In EGFR inhibitory activity B8 showed maximum activity on A549 cell line by inactivating 69.10% of EGFR phosphorylation and B7 showed maximum activity on MCF-7 cell line by inactivating 41.90% of EGFR phosphorylation in comparison with the reference drug Gefitinib. Molecular dynamics simulation studies suggest that benzothiazole derivative could also bind to allosteric site and inhibit the EGFR enzyme activity.

Conclusion:

Reported compounds have shown potent anticancer activity through EGFR inhibition by possibly binding at allosteric site.

Design, Synthesis and Biological Evaluation of a New Series of 1-Aryl-3-{4-[(pyridin-2-ylmethyl)thio]phenyl}urea Derivatives as Antiproliferative Agents

To discover new antiproliferative agents with high efficacy and selectivity, a new series of 1-aryl-3-{4-[(pyridin-2-ylmethyl)thio]phenyl}urea derivatives (7a–7t) were designed, synthesized and evaluated for their antiproliferative activity against A549, HCT-116 and PC-3 cancer cell lines in vitro. Most of the target compounds demonstrated significant antiproliferative effects on all the selective cancer cell lines. Among them, the target compound, 1-[4-chloro-3-(trifluoromethyl)phenyl]-3-{4-{{[3-methyl-4-(2,2,2-trifluoroethoxy)pyridin-2-yl]methyl}thio}phenyl}urea (7i) was identified to be the most active one against three cell lines, which was more potent than the positive control with an IC₅₀ value of 1.53 ± 0.46, 1.11 ± 0.34 and 1.98 ± 1.27 μM, respectively. Further cellular mechanism studies confirmed that compound 7i could induce the apoptosis of A549 cells in a concentration-dependent manner and elucidated compound 7i arrests cell cycle at G1 phase by flow cytometry analysis. Herein, the studies suggested that the 1-aryl-3-{4-[(pyridin-2-ylmethyl)thio]phenyl}urea skeleton might be regarded as new chemotypes for designing effective antiproliferative agents.

Synthesis, Characterization, and Biological Activity of a Novel Series of Benzo[4,5]imidazo[2,1-b]thiazole Derivatives as Potential Epidermal Growth Factor Receptor Inhibitors

Based on the analysis of epidermal growth factor receptor (EGFR) complexes with gefitinib with molecular docking, the scaffold-hopping strategy, combination of the active substructures, and structural optimization of EGFR inhibitors, a novel series of benzo[4,5]imidazo[2,1-b]thiazole derivatives was designed, synthesized, and evaluated for antitumor activity in human cancer cell lines and cellular toxicity against human normal cell lines using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) colorimetric assay and EGFR inhibitory activities in vitro. Some target compounds such as 2-(benzo[4,5]imidazo[2,1-b]thiazol-3-yl)-N-(2-hydroxyphenyl)acetamide (D04) and 2-(benzo[4,5]imidazo[2,1-b]thiazol-3-yl)-N-(naphthalen-1-yl)acetamide (D08) have shown significant antitumor activity against the EGFR high-expressed human cell line HeLa. All the target compounds showed hardly any antitumor activity against the EGFR low-expressed human cell line HepG2, and nearly no cellular toxicity against the human normal cell lines HL7702 and human umbilical vein endothelial cell lines (HUVEC). The inhibitory activities against EGFR kinase in vitro of the three target compounds were greatly consistent with the anti-proliferative activities. The preliminary structure⁻activity relationships of the target compounds were summarized. Conclusively, the novel benzo[4,5]imidazo[2,1-b]thiazole derivatives as novel potential EGFR inhibitors may be used as the potential lead compounds for the development of antitumor agents.