Synthesis, anti-breast cancer activity, and molecular modeling of some benzothiazole and benzoxazole derivatives

Current status of N-, O-, S-heterocycles as potential alkaline phosphatase inhibitors: a medicinal chemistry overview

Heterocycles are a class of compounds that have been found to be potent inhibitors of alkaline phosphatase (AP), an enzyme that plays a critical role in various physiological processes such as bone metabolism, cell growth and differentiation, and has been linked to several diseases such as cancer and osteoporosis. AP is a widely distributed enzyme, and its inhibition has been considered as a therapeutic strategy for the treatment of these diseases. Heterocyclic compounds have been found to inhibit AP by binding to the active site of the enzyme, thereby inhibiting its activity. Heterocyclic compounds such as imidazoles, pyrazoles, and pyridines have been found to be potent AP inhibitors and have been studied as potential therapeutics for the treatment of cancer, osteoporosis, and other diseases. However, the development of more potent and selective inhibitors that can be used as therapeutics for the treatment of various diseases is an ongoing area of research. Additionally, the study of the mechanism of action of heterocyclic AP inhibitors is an ongoing area of research, which could lead to the identification of new targets and new therapeutic strategies. The enzyme known as AP has various physiological functions and is present in multiple tissues and organs throughout the body. This article presents an overview of the different types of AP isoforms, their distribution, and physiological roles. It also discusses the structure and mechanism of AP, including the hydrolysis of phosphate groups. Furthermore, the importance of AP as a clinical marker for liver disease, bone disorders, and cancer is emphasized, as well as its use in the diagnosis of rare inherited disorders such as hypophosphatasia. The potential therapeutic applications of AP inhibitors for different diseases are also explored. The objective of this literature review is to examine the function of alkaline phosphatase in various physiological conditions and diseases, as well as analyze the structure-activity relationships of recently reported inhibitors. The present review summarizes the structure-activity relationship (SAR) of various heterocyclic compounds as AP inhibitors. The SAR studies of these compounds have revealed that the presence of a heterocyclic ring, particularly a pyridine, pyrimidine, or pyrazole ring, in the molecule is essential for inhibitory activity. Additionally, the substitution pattern and stereochemistry of the heterocyclic ring also play a crucial role in determining the potency of the inhibitor.

Synthesis, biological evaluation, and molecular modeling studies of new benzoxazole derivatives as PARP-2 inhibitors targeting breast cancer

Many benzoxazole-based and similar scaffolds were reported to have wide-range of anticancer activities. In this study, four series of benzoxazole derivatives were designed by combining benzoxazole scaffold with different amines via a reversed phenyl amide linker to produce the compounds of series A, B and C. A fourth new hybrid of benzoxazole with 1,2,3 triazole ring (series D) was also designed. The designed compounds were synthesized and screened for their anti-breast cancer activity against MDA-MB-231 and MCF-7 cell lines using MTT assay. The most potent cytotoxic compounds; 11–14, 21, 22, 25–27 were further evaluated for their in vitro PARP-2 enzyme inhibition. Compounds 12 and 27 proved to be the most active PARP-2 inhibitors with IC₅₀ values of 0.07 and 0.057 µM, respectively. Compounds 12 and 27 caused cell cycle arrest in mutant MCF-7 cell line at G2/M and G1/S phase, respectively and they possessed significant apoptosis-promoting activity. Docking results of compounds 12 and 27 into PARP-2 pocket demonstrated binding interactions comparable to those of olaparib. Their predicted pharmacokinetic parameters and oral bioavailability appeared to be appropriate. Collectively, it could be concluded that compounds 12 and 27 are promising anti-breast cancer agents that act as PARP-2 inhibitors with potent apoptotic activity.

Novel Benzothiazole-Based Dual VEGFR-2/EGFR Inhibitors Targeting Breast and Liver Cancers: Synthesis, Cytotoxic Activity, QSAR and Molecular Docking Studies

A novel series of benzothiazole-based derivatives linked to various amino acids and their corresponding ethyl ester analogues were synthesized and were initially screened for their cytotoxic activity against human breast cancer cell line (MCF-7) and human liver carcinoma (HepG-2) and were further assessed as VEGFR-2 inhibitors. All the newly synthesized benzothiazole derivatives showed promising cytotoxic activities against the tested cell lines. Derivatives exhibited potent cytotoxic and VEGFR-2 inhibitory activities were then evaluated further as anticancer agents against the resistant triple-negative breast cancer (TNBC) cell line (MDA-MB-231) and as EGFR inhibitors. The carboxylic acid derivatives 10-12 and their ester analogues 21-23 displayed the highest anticancer activities with IC₅₀ of 0.73-0.89 µM, against MCF-7 and IC₅₀ of 2.54-2.80 µM, against HepG-2; compared to doxorubicin (IC₅₀ = 1.13 and 2.75 µM, respectively). In addition to their safety towards the normal cell line, the ethyl ester derivatives 21-23 showed a potent activity against the resistant MDA-MB-231 cell line with IC₅₀ of 5.45-7.28 µM, relative to doxorubicin (IC₅₀ = 7.46 µM) surpassing their carboxylic acid analogues 10-12 (IC₅₀ of 8.88-11.02 µM). Furthermore, the promising derivatives 10-12 and 21-23 displayed promising VEGFR-2 inhibitory activity (IC₅₀ = 0.15-0.19 µM) comparable to that of sorafenib (IC₅₀ = 0.12 µM). Against EGFR, the ethyl ester derivatives 21-23 showed superior inhibitory activity relative to the used reference standard, erlotinib, with IC₅₀ of 0.11-0.16 vs. 0.18 µM, respectively. The QSAR study revealed that the molecular bulkiness and molecular partial charge distribution govern the kinase inhibition potency in this series. Furthermore, the molecular docking study in VEGFR-2 active site showed that the newly synthesized benzothiazole derivatives adopted the common binding pattern of type II PK inhibitors.

Synthesis, anticancer evaluation and molecular docking of new benzothiazole scaffolds targeting FGFR-1

This work deals with the design and synthesis of a series of new substituted 2-arylbenzothiazole compounds attached to 4-oxothiazolidin-2-ylidene ring 2-12 and chain elongation with different amino acids and their corresponding ester derivatives 13-18. All prepared derivatives were screened for their in vitro cytotoxicity activities against two cancer cell lines (HepG-2 and MCF-7) in comparison with doxorubicin; in addition to their safety towards thenormal cell line. Furthermore, all compounds 2-18 were evaluated as FGFR-1 inhibitors using AZD4547 as a reference. The 4-oxothiazolidin-2-ylidene derivatives 3 and 8 exhibited the highest cytotoxic activity (IC_{50 HepG-2} = 2.06, 2.21 µM and IC_{50 MCF-7} = 0.73, 0.77 µM, respectively) through their promising FGFR-1 suppression effects (IC₅₀ = 16.31 and 18.08 nM, respectively) in comparison to AZD4547 (IC₅₀ = 21.45 nM). Cell cycle and apoptosis analysis indicated that compounds 3 and 8 induce pronounced increase in the cell percentages at pre-G₁ and G₂/M phase compared to the untreated MCF-7 cancer cells, in addition to their up regulation of caspase-3/7/9. The molecular docking simulation was created to elucidate the binding modes of benzothiazole derivatives 1-18 bearing various scaffolds within the ATP-binding pocket of FGFR-1 enzyme compared with AZD4547.

Base-Mediated Direct C-H Germylation of Heteroarenes and Arenes

The direct C-H germylation of heteroarenes, arenes, and benzylic C-H bonds promoted by lithium tetramethylpiperidide (LiTMP) is reported. The method is rapid, selective, and operationally simple, consisting of direct addition of all reagents at room temperature (one-pot procedure). The synthetic utility of these newly accessed aryl germanes as viable coupling partners in Pd catalysis is also showcased.

New Benzoxazole Derivatives as Antiprotozoal Agents: In Silico Studies, Synthesis, and Biological Evaluation

Background. Benzoxazole derivatives have different biological activities. In pursuit of designing novel chemical entities with antiprotozoal and antimicrobial activities, benzoxazolyl aniline was utilized as a privileged scaffold of a series of (3-benzoxazole-2-yl) phenylamine derivatives, 3-benzoxazoloyl acetamide, and butyramide derivatives. Methods. These novel analogs were synthesized in straightforward simple chemistry without any quantitative chromatographic separations in reasonable yields. The biological evaluation of all target compounds as potential antimalarial, antileishmanial, antitrypanosomal, and antimicrobial agents was performed by various well-established cell-based methods. Results. Compounds 6d and 5a showed promising biological screening data. The amidation of 3-benzoxazolyl aniline 1 with the chloroacetyl functional group resulted in a good antimalarial activity and showed moderate inhibitory activities against leishmanial and trypanosomal spp. Moreover, chloroacetyl functionalization of benzoxazolyl aniline serves as a good early goal for constructing and synthesizing new antimicrobial and antiprotozoal agents. The molecular docking study rationalizes the relative inhibitory activity of compound 5a as an antimalarial agent with the deregulation of PfPNP activity which has emerged as a major mechanism of these targets.

A New CDK2 Inhibitor with 3-Hydrazonoindolin-2-One Scaffold Endowed with Anti-Breast Cancer Activity: Design, Synthesis, Biological Evaluation, and In Silico Insights

Background: Cyclin-dependent kinases (CDKs) regulate mammalian cell cycle progression and RNA transcription. Based on the structural analysis of previously reported CDK2 inhibitors, a new compound with 3-hydrazonoindolin-2-one scaffold (HI 5) was well designed, synthesized, and biologically evaluated as a promising anti-breast cancer hit compound. Methods: The potential anti-cancerous effect of HI 5 was evaluated using cytotoxicity assay, flow cytometric analysis of apoptosis and cell cycle distribution, ELISA immunoassay, in vitro CDK2/cyclin A2 activity, and molecular operating environment (MOE) virtual docking studies. Results: The results revealed that HI 5 exhibits pronounced CDK2 inhibitory activity and cytotoxicity in human breast cancer MCF-7 cell line. The cytotoxicity of HI 5 was found to be intrinsically mediated apoptosis, which in turn, is associated with low Bcl-2 expression and high activation of caspase 3 and p53. Besides, HI 5 blocked the proliferation of the MCF-7 cell line and arrested the cell cycle at the G2/M phase. The docking studies did not confirm which one of geometric isomers (syn and anti) is responsible for binding affinity and intrinsic activity of HI 5. However, the molecular dynamic studies have confirmed that the syn-isomer has more favorable binding interaction and thus is responsible for CDK2 inhibitory activity. Discussion: These findings displayed a substantial basis of synthesizing further derivatives based on the 3-hydrazonoindolin-2-one scaffold for favorable targeting of breast cancer.

Anticancer activity of benzoxazole derivative (2015 onwards): a review

Background

According to the report published recently by the World Health Organization, the number of cancer cases in the world will increase to 22 million by 2030. So the anticancer drug research and development is taking place in the direction where the new entities are developed which are low in toxicity and are with improved activity. Benzoxazole and its derivative represent a very important class of heterocyclic compounds, which have a diverse therapeutic area. Recently, many active compounds synthesized are very effective; natural products isolated with benzoxazole moiety have also shown to be potent towards cancer.

Main text

In the last few years, many research groups have designed and developed many novel compounds with benzoxazole as their backbone and checked their anticancer activity. In the review article, the recent developments (mostly after 2015) made in the direction of design and synthesis of new scaffolds with very potent anticancer activity are briefly described. The effect of various heterocycles attached to the benzoxazole and their effect on the anticancer activity are thoroughly studied and recorded in the review.

Conclusion

These compiled data in the article will surely update the scientific community with the recent development in this area and will provide direction for further research in this area.

A new series of benzoxazole-based SIRT1 modulators for targeted therapy of non-small-cell lung cancer

In an attempt to identify potential anticancer agents for non-small-cell lung cancer (NSCLC) targeting sirtuin 1 (SIRT1), the synthesis of a new series of benzoxazoles (3a - i) was carried out through a facile and versatile synthetic route. The compounds were evaluated for their cytotoxic effects on A549 human lung adenocarcinoma and NIH/3T3 mouse embryonic fibroblast cells using the MTT assay. 2-[(5-Nitro-1H-benzimidazol-2-yl)thio]-N-(2-methylbenzoxazol-5-yl)acetamide (3e) and 2-[(5-chloro-1H-benzimidazol-2-yl)thio]-N-(2-methylbenzoxazol-5-yl)acetamide (3g) were the most potent and selective anticancer agents in this series against the A549 cell line, with IC₅₀ values of 46.66 ± 11.54 and 55.00 ± 5.00 µM, respectively. The flow cytometry-based apoptosis detection assay was performed to determine their effects on apoptosis in A549 cells. Both compounds induced apoptosis in a dose-dependent manner. The effects of compounds 3e and 3g on SIRT1 activity were determined. On the basis of in vitro studies, it was observed that compound 3g caused a significant decrease in SIRT1 levels in a dose-dependent manner, whereas compound 3e increased the SIRT1 levels. According to molecular docking studies, the substantial alteration in the type of action could be attributed to the difference between the interactions of compounds 3e and 3g with the same residues in the active site of SIRT1 (PDB code: 4IG9). On the basis of in silico ADME (absorption, distribution, metabolism, and excretion) studies, these compounds are predicted to possess favorable ADME profiles. According to the in vitro and in silico studies, compounds 3e and 3g, small-molecule SIRT1 modulators, were identified as potential orally bioavailable anticancer agents for the targeted therapy of NSCLC.

2-substituted benzothiazoles as antiproliferative agents: Novel insights on structure-activity relationships

Given the wide spectrum of biological activities, benzothiazoles represent privileged scaffolds in medicinal chemistry, useful in drug discovery programs to modulate biological activities of lead compounds. A large body of knowledge about benzothiazoles has been reported in scientific literature, describing their antimicrobial, anticonvulsant, neuroprotective, anti-inflammatory, and antiproliferative effects. This review summarizes the results obtained in the structure-activity relationship studies on antiproliferative benzothiazoles, focusing on 2-substituted derivatives and on mechanism of action responsible for the antitumor effects of this class of compounds.

Benzoxazole Derivative K313 Induces Cell Cycle Arrest, Apoptosis and Autophagy Blockage and Suppresses mTOR/p70S6K Pathway in Nalm-6 and Daudi Cells

Benzoxazole derivative K313 has previously been reported to possess anti-inflammatory effects in lipopolysaccharide-induced RAW264.7 macrophages. To date, there have been no related reports on the anticancer effects of K313. In this study, we found that K313 reduced the viability of human B-cell leukemia (Nalm-6) and lymphoma (Daudi) cells in a dose-dependent manner without affecting healthy peripheral blood mononuclear cells (PBMCs) and induced moderate cell cycle arrest at the G0/G1 phase. Meanwhile, K313 mediated cell apoptosis, which was accompanied by the activation of caspase-9, caspase-3, and poly ADP-ribose polymerase (PARP). Furthermore, cells treated with K313 showed a significant decrease in mitochondrial membrane potential (MMP), which may have been caused by the caspase-8-mediated cleavage of Bid, as detected by Western blot analysis. We also found that K313 led to the downregulation of p-p70S6K protein, which plays an important role in cell survival and cell cycle progression. In addition, treatment of these cells with K313 blocked autophagic flux, as reflected in the accumulation of LC3-II and p62 protein levels in a dose- and time-dependent manner. In conclusion, K313 decreases cell viability without affecting normal healthy PBMCs, induces cell cycle arrest and apoptosis, reduces p-p70S6K protein levels, and mediates strong autophagy inhibition. Therefore, K313 and its derivatives could be developed as potential anticancer drugs or autophagy blockers in the future.

Benzoxazole derivatives as new generation of anti-breast cancer agents

New 2-substituted benzoxazole derivatives were synthesized and screened for their in vitro anti-proliferative activities against MCF-7 and MDA-MB-231 cell lines. Compounds 4b, 4d and 11c eliciting the highest activity against MCF-7 cells were further assayed for their cytotoxic activities against A431 and HCC827 cancer cells in addition to their in vitro inhibition of wild and mutated epidermal growth factor receptor (EGFR) enzymes. Compound 11c was the most active against A431 cells and it displayed a potent inhibition of EGFR^WT while compounds 4b and 4d elicited higher potencies than erlotinib against mutated EGFR^L858R. Compounds 4a, 6c and 8a showed the most potent cytotoxic activity against MDA-MB-231 cancer cells where compounds 4a and 6c were slightly less potent aromatase (ARO) inhibitors than letrozole. MCF-7 cells treated with compounds 4b, 4d, 11c and MDA-MB-231 cells treated with compounds 4a, 6c and 8a showed remarkable over-expression of caspase-9 protein level and elicited pre G1 apoptosis and cell cycle arrest at G2/M phase in addition to high annexin V binding affinity indicating significant apoptosis. Chemo-informatic and docking properties were also predicted. Docking results revealed that docked compounds displayed binding modes with EGFR and ARO enzymes comparable to that of the reference ligands. The benzoxazole derivatives 11c and 6c possessing amide and dithiocarbamate moieties respectively were found to be potent apoptosis-inducing anti-breast cancer agents with acceptable physicochemical properties. They exert their activity via inhibition of EGFR and ARO enzymes respectively.

First Attempts of the Use of 195Pt NMR of Phenylbenzothiazole Complexes as Spectroscopic Technique for the Cancer Diagnosis

Platinum complexes have been studied for cancer treatment for several decades. Furthermore, another important platinum characteristic is related to its chemical shifts, in which some studies have shown that the ¹⁹⁵Pt chemical shifts are very sensitive to the environment, coordination sphere, and oxidation state. Based on this relevant feature, Pt complexes can be proposed as potential probes for NMR spectroscopy, as the chemical shifts values will be different in different tissues (healthy and damaged) Therefore, in this paper, the main goal was to investigate the behavior of Pt chemical shifts in the different environments. Calculations were carried out in vacuum, implicit solvent, and inside the active site of P13K enzyme, which is related with breast cancer, using the density functional theory (DFT) method. Moreover, the investigation of platinum complexes with a selective moiety can contribute to early cancer diagnosis. Accordingly, the Pt complexes selected for this study presented a selective moiety, the 2-(4′aminophenyl)benzothiazole derivative. More specifically, two Pt complexes were used herein: One containing chlorine ligands and one containing water in place of chlorine. Some studies have shown that platinum complexes coordinated to chlorine atoms may suffer hydrolyses inside the cell due to the low chloride ion concentration. Thus, the same calculations were performed for both complexes. The results showed that both complexes presented different chemical shift values in the different proposed environments. Therefore, this paper shows that platinum complexes can be a potential probe in biological systems, and they should be studied not only for cancer treatment, but also for diagnosis.

Design and synthesis of benzothiazole/thiophene-4H-chromene hybrids

A library of 4H-chromene derivatives with heterocyclic substituent's at the 3 and 4-positions was synthesized in a convenient DBU catalysed three component synthesis between salicylaldehyde, acetonitrile derivatives and thiazolidinedione to afford 2-amino-3-benzothiazole-4-heterocycle-4H-chromenes and 2-amino-3-thiophenoyl-4-heterocycle-4H-chromenes derivatives in ethanol and a mixture of ethanol and water (1 : 1) at room temperature. The significance of this protocol is the feasibility of incorporating substituents simultaneously at the 3 and 4 positions of 4H-chromenes in an efficient three component reaction.

A comprehensive review in current developments of benzothiazole-based molecules in medicinal chemistry

Benzothiazole (BTA) and its derivatives are the most important heterocyclic compounds, which are common and integral feature of a variety of natural products and pharmaceutical agents. BTA shows a variety of pharmacological properties, and its analogs offer a high degree of structural diversity that has proven useful for the search of new therapeutic agents. The broad spectrum of pharmacological activity in individual BTA derivative indicates that, this series of compounds is of an undoubted interest. The related research and developments in BTA-based medicinal chemistry have become a rapidly developing and increasingly active topic. Particularly, numerous BTA-based compounds as clinical drugs have been extensively used in practice to treat various types of diseases with high therapeutic potency. This work systematically gives a comprehensive review in current developments of BTA-based compounds in the whole range of medicinal chemistry as anticancer, antibacterial, antifungal, antiinflammatory, analgesic, anti-HIV, antioxidant, anticonvulsant, antitubercular, antidiabetic, antileishmanial, antihistaminic, antimalarial and other medicinal agents. It is believed that, this review article is helpful for new thoughts in the quest for rational designs of more active and less toxic BTA-based drugs, as well as more effective diagnostic agents and pathologic probes.

Modulation of cyclins, p53 and mitogen-activated protein kinases signaling in breast cancer cell lines by 4-(3,4,5-trimethoxyphenoxy)benzoic acid

Despite the advances in cancer therapy and early detection, breast cancer remains a leading cause of cancer-related deaths among females worldwide. The aim of the current study was to investigate the antitumor activity of a novel compound, 4-(3,4,5-trimethoxyphenoxy)benzoic acid (TMPBA) and its mechanism of action, in breast cancer. Results indicated the relatively high sensitivity of human breast cancer cell-7 and MDA-468 cells towards TMPBA with IC₅₀ values of 5.9 and 7.9 μM, respectively compared to hepatocarcinoma cell line Huh-7, hepatocarcinoma cell line HepG2, and cervical cancer cell line Hela cells. Mechanistically, TMPBA induced apoptotic cell death in MCF-7 cells as indicated by 4′,6-diamidino-2-phenylindole (DAPI) nuclear staining, cell cycle analysis and the activation of caspase-3. Western blot analysis revealed the ability of TMPBA to target pathways mediated by mitogen-activated protein (MAP) kinases, 5′ adenosine monophosphate-activated protein kinase (AMPK), and p53, of which the concerted action underlined its antitumor efficacy. In addition, TMPBA induced alteration of cyclin proteins’ expression and consequently modulated the cell cycle. Taken together, the current study underscores evidence that TMPBA induces apoptosis in breast cancer cells via the modulation of cyclins and p53 expression as well as the modulation of AMPK and mitogen-activated protein kinases (MAPK) signaling. These findings support TMPBA’s clinical promise as a potential candidate for breast cancer therapy.