Synthesis of amide and urea derivatives of benzothiazole as Raf-1 inhibitor

Comprehensive analysis and outcomes of hybridization of physiologically active heterocycles targeting epidermal growth factor receptor (EGFR)

Epidermal growth factor receptors (EGFR) are primarily engaged in the regulation of fundamental cellular processes. Overexpression and mutations in these tyrosine kinases cause a variety of malignancies, including lung cancer. The current study addresses the suppression of inactive and mutant variants of the EGFR target site via two primary proposals: (1) To prevent the formation of its mutant form by inhibiting inactive EGFR. (2) To suppress the mutant EGFR directly. After the virtual screening of a newly designed series of hybrid models, selected molecules were synthesized and well-characterized from various spectroscopic and spectrometric methods. The critical analysis and chemistry behind the structural interactions of the selected compounds with three target sites were discussed i.e., inactive EGFR (PDB code: 1XKK), mutant EGFR (PDB code: 3W2O), and allosteric site of mutant EGFR (PDB code: 6P1L). It was observed that compound 7 showed effective results in terms of docking score, structural interactions as well as orientation in the binding pocket towards the inactive target site. Whereas, compound 8 exhibited all the above-mentioned features excellently against mutant EGFR. Apart from that, the investigations were expanded to study the structural behaviour in the allosteric site, where compound 8 once again performed effectively. Such proposals were further clarified by running molecular dynamics (MD) simulation for 100 ns towards inactive, mutant, and allosteric sites of mutant EGFR. Where compounds 7, and 8 demonstrated highly consistence behaviour during the whole simulation trajectory. Further, in vitro results of EGFR inhibition assay and anti-proliferative activity were found in accordance with the computational findings. For the EGFR inhibition assay, compounds 7, and 8 showed excellent IC50 values of 20.7, and 22.5 μM respectively. Moreover, IC50 values exhibited by both the compounds in anti-proliferative activity were observed to be 27.5, and 11.7 μM respectively. Thus, compounds 7 and 8 may have potential to become good anticancer agents.

Anticancer Potential of the S-Heterocyclic Ring Containing Drugs and its Bioactivation to Reactive Metabolites

Sulfur-containing heterocyclic derivatives have been disclosed for binding with a wide range of cancer-specific protein targets. Various interesting derivatives of sulfur-containing heterocyclics such as benzothiazole, thiazole, thiophene, thiazolidinedione, benzothiophene, and phenothiazine, etc have been shown to inhibit diverse signaling pathways implicated in cancer. Significant progress has also been made in molecular targeted therapy against specific enzymes such as kinase receptors due to potential binding interactions inside the ATP pocket. Sulfur-containing heterocyclic ring metal complexes i. e., benzothiazole, thiazole, thiophene, benzothiophene and phenothiazines are among the most promising active anticancer compounds. However, sulfur heteroaromatic rings, particularly thiophene, are of high structural alert due to their metabolism to reactive metabolites. The mere presence of a structural alert itself does not determine compound toxicity therefore, this review focuses on some specific findings that shed light on factors influencing the toxicity. In the current review, synthetic strategies of introducing the sulfur core ring in the synthesized derivatives are discussed with their structure-activity relationships to enhance our understanding of toxicity mechanisms and develop safer therapeutic options. The sulfur-containing marketed anticancer drugs included in this review direct the synthesis of novel compounds and will help in the development of potent, safer sulfur-based anticancer drugs in near future.

Highly Selective Electrochemical Synthesis of Urea Derivatives Initiated from Oxygen Reduction in Ionic Liquids

The development of more efficient and sustainable methods for synthesizing substituted urea compounds and directly utilizing CO₂ has long been a major focus of synthetic organic chemistry as these compounds serve critical environmental and industrial roles. Herein, we report a green approach to forming the urea compounds directly from CO₂ gas and primary amines, triggered by oxygen electroreduction in ionic liquids (ILs). These reactions were carried out under mild conditions, at very low potentials, and achieved high conversion rates. The fact that O₂ gas was utilized as the sole catalyst in this electrochemical loop, without additional reagents, is a significant milestone for eco-friendly syntheses of C-N compounds and establishes an effective and green CO₂ scavenging method.

Synthesis and Biological Importance of 2-(thio)ureabenzothiazoles

The (thio)urea and benzothiazole (BT) derivatives have been shown to have a broad spectrum of biological activities. These groups, when bonded, result in the 2-(thio)ureabenzothizoles (TBT and UBT), which could favor the physicochemical and biological properties. UBTs and TBTs are compounds of great importance in medicinal chemistry. For instance, Frentizole is a UBT derivative used for the treatment of rheumatoid arthritis and systemic lupus erythematosus. The UBTs Bentaluron and Bethabenthiazuron are commercial fungicides used as wood preservatives and herbicides in winter corn crops. On these bases, we prepared this bibliography review, which covers chemical aspects of UBTs and TBTs as potential therapeutic agents as well as their studies on the mechanisms of a variety of pharmacological activities. This work covers synthetic methodologies from 1935 to nowadays, highlighting the most recent approaches to afford UBTs and TBTs with a variety of substituents as illustrated in 42 schemes and 13 figures and concluded with 187 references. In addition, this interesting review is designed on chemical reactions of 2-aminobenzothiazoles (2ABTs) with (thio)phosgenes, iso(thio)cyanates, 1,1′-(thio)carbonyldiimidazoles [(T)CDI]s, (thio)carbamoyl chlorides, and carbon disulfide. This topic will provide information of utility for medicinal chemists dedicated to the design and synthesis of this class of compounds to be tested with respect to their biological activities and be proposed as new pharmacophores.

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.

Benzothiazolyl Ureas are Low Micromolar and Uncompetitive Inhibitors of 17β-HSD10 with Implications to Alzheimer's Disease Treatment

Human 17β-hydroxysteroid dehydrogenase type 10 is a multifunctional protein involved in many enzymatic and structural processes within mitochondria. This enzyme was suggested to be involved in several neurological diseases, e.g., mental retardation, Parkinson's disease, or Alzheimer's disease, in which it was shown to interact with the amyloid-beta peptide. We prepared approximately 60 new compounds based on a benzothiazolyl scaffold and evaluated their inhibitory ability and mechanism of action. The most potent inhibitors contained 3-chloro and 4-hydroxy substitution on the phenyl ring moiety, a small substituent at position 6 on the benzothiazole moiety, and the two moieties were connected via a urea linker (4at, 4bb, and 4bg). These compounds exhibited IC₅₀ values of 1-2 μM and showed an uncompetitive mechanism of action with respect to the substrate, acetoacetyl-CoA. These uncompetitive benzothiazolyl inhibitors of 17β-hydroxysteroid dehydrogenase type 10 are promising compounds for potential drugs for neurodegenerative diseases that warrant further research and development.

Synthesis, SAR, Molecular Docking and Anti-Microbial Study of Substituted N-bromoamido-2-aminobenzothiazoles

BACKGROUND

Benzothiazoles are reported to have bioorganic and pharmaceutical chemistry applications.

INTRODUCTION

A series of substituted N-bromoamido-2-aminobenzothiazoles was synthesized from substituted anilines via 2-aminobenzothiazoles and it was further evaluated for its antimicrobial activity.

METHODS

All the newly synthesized compounds were characterized by FT-IR, NMR and mass spectra and purity profiles were studied by HPLC analysis. The antimicrobial testing (MIC determination) was newly performed with agar micro-broth dilution method for these analogs.

RESULTS

Among the synthesized compound 3b showed the highest activity with MIC value of 3.12 μg/mL against Bacillus, E. coli, S. aureus and Klebsiella and 6.25 μg/mL against C. albicans. The ADME properties as calculated by using Qikprop were found within acceptable range. Derivatives shows a good-moderate binding affinity towards target Cytochrome P450 14 alpha-sterol demethylase (CYP51) (PDB ID: 1EA1).

CONCLUSION

Our in-silico and in-vitro studies on a series of substituted aminobenzothiazoles may be helpful for further designing of more potent antimicrobials in future.

A modern and practical laccase-catalysed route suitable for the synthesis of 2-arylbenzimidazoles and 2-arylbenzothiazoles

Heterocyclic aromatic compounds containing an imine (C[double bond, length as m-dash]N) bond such as benzimidazoles and benzothiazoles are important active pharmaceutical ingredients. The synthesis of 2-aryl-1H-benzimidazoles and 2-arylbenzothiazoles in good to excellent yields was achieved by reacting 2-aminoaromatics with various benzaldehyde derivatives catalysed by the commercial laccases Novoprime and Suberase® at room temperature and in the presence of atmospheric oxygen.

Contemporary progress in the synthesis and reactions of 2-aminobenzothiazole: a review

Various protocols for the synthesis and reactions of 2-aminobenzothiazole.

The Novel 4-Phenyl-2-Phenoxyacetamide Thiazoles modulates the tumor hypoxia leading to the crackdown of neoangiogenesis and evoking the cell death

Tumor microenvironment is a complex multistep event which involves several hallmarks that transform the normal cell into cancerous cell. Designing the novel antagonistic molecule to reverse the tumor microenvironment with specific target is essential in modern biological studies. The novel 4-phenyl-2-phenoxyacetamide thiazole analogues 8_a-ab were synthesized in multistep process, then screened and assessed for cytotoxic and anti-proliferative effects in vitro against multiple cancer cells of different origin such as MCF-7, A549, EAC and DLA cells which revealed that compound 8f with fluoro and methyl substitute has potential cytotoxic efficacy with an average IC₅₀ value of ˜ 13 μM. The mechanism of cytotoxicity assessed for anti-tumor studies both in ascites and solid tumor models in-vivo inferred the regressed tumor activity. This is due to changes in the cause of tumor microenvironment with crackdown of neovascularization and evoking apoptosis process as assessed by CAM, corneal vascularization and apoptotic hallmarks in 8f treated cells. The molecular gene studies inferred involvement of HIF-1upregulation and stabilization of p53 which are interlinked in signaling as conferred by immunoblot analysis.

Crystal structure of 3-(adamantan-1-yl)-1-(4-bromophenyl)urea, C17H21BrN2O

C17H21BrN2O, orthorhombic, Pna21 (no. 33), a = 9.2558(12) Å, b = 13.0186(17) Å, c = 13.4684(18) Å, V = 1622.9(4) Å3, Z = 4, R gt(F) = 0.0471, wR ref(F 2) = 0.1059, T = 100 K.

Facile synthesis of N-acyl 2-aminobenzothiazoles by NHC-catalyzed direct oxidative amidation of aldehydes

NHC-catalyzed direct amidation of aldehydes with 2-aminobenzothiazoles allowed the synthesis of N-acyl 2-aminobenzothiazoles proceeding via acyl azolium intermediates.

Design and synthesis of new potent anticancer benzothiazole amides and ureas featuring pyridylamide moiety and possessing dual B-Raf(V600E) and C-Raf kinase inhibitory activities

A new series of benzothiazole amide and urea derivatives tethered with the privileged pyridylamide moiety by ether linkage at the 6-position of benzothiazole (22 final compounds) has been designed and synthesized as potent anticancer sorafenib analogs. A selected group of twelve derivatives was appraised for its antiproliferative activity over a panel of 60 human cancer cell lines at a single dose concentration of 10 μM at National Cancer Institute (NCI, USA). Compounds 4b, 5a, 5b and 5d exhibited promising growth inhibitions and thus were further tested in advanced 5-dose testing assay to determine their GI50 values. The cellular based assay results revealed that 3,5-bis-trifluoromethylphenyl (5b) urea member is the best derivative with superior potency and efficacy compared to sorafenib as well as notable extended spectrum activity covering 57 human cancer cell lines. Kinase screening of compound 5b showed its kinase inhibitory effect against both B-Raf(V600E) and C-Raf. Moreover, the most potent derivatives in cells were investigated for their RAF inhibitory activities, and the results were rationalized with the molecular docking study. Profiling of CYP450 and hERG channel inhibitory effects for the active compounds revealed their low possibilities to exhibit undesirable drug-drug interactions and cardiac side effects.

Identification of a Small Benzamide Inhibitor of Influenza Virus Using a Cell-Based Screening

BACKGROUND

The zoonotic transmission of highly pathogenic avian influenza viruses and the global pandemic of H1N1 influenza in 2009 signified the need for a wider coverage of therapeutic options for the control of influenza.

METHODS

An in-house compound library was screened using a cytopathic effect inhibition assay. Selected hits were then tested in vivo and used as a core skeleton for derivative synthesis.

RESULTS

The hit compound (BMD-2601505) was effective [50% effective concentration (EC50) of 60-70 μM] in reducing the death rate of cells infected with human influenza A and B viruses as well as avian influenza A virus. Furthermore, BMD-2601505 reduced the weight loss and increased the survival after lethal infection. The compound was further modified to enhance its antiviral potency. Results show that one derivative with bromobenzene moiety was most effective (EC50 of 22-37 μM) against the influenza viruses tested.

CONCLUSION

We identified a small benzamide compound exhibiting antiviral activity against influenza viruses. The results warrant further evaluation of antiviral activities against drug-resistant influenza isolates.

Considering organic mechanisms and the optimization of current flow in an electrochemical oxidative condensation reaction

Careful consideration of the chemical mechanism for an oxidative condensation reaction led to improved current flow for the electrolysis.

Solvolysis, Electrochemistry, and Development of Synthetic Building Blocks from Sawdust

Either aldehyde or cinnamyl ether products can be selectively extracted from raw sawdust by controlling the temperature and pressure of a solvolysis reaction. These materials have been used as platform chemicals for the synthesis of 15 different synthetic substrates. The conversion of the initial sawdust-derived materials into electron-rich aryl substrates often requires the use of oxidation and reduction chemistry, and the role electrochemistry can play as a sustainable method for these transformations has been defined.

A novel inhibitor of Rho GDP-dissociation inhibitor α improves the therapeutic efficacy of paclitaxel in Lewis lung carcinoma

Molecular-targeted therapies are considered a promising strategy for the treatment of most types of human cancer. Rho GDP-dissociation inhibitor α (RhoGDIα), which functions mainly by controlling the cellular distribution and activity of Rho GTPases and is associated with tumor progression and poor prognosis of cancer patients, has become a new promising target for anticancer treatment. Recently, a specific RhoGDIα inhibitor (no. SKLB-163) was developed via computer-aided drug design and de novo synthesis. Previous studies have shown that SKLB-163 had extremely good antitumor activities against diverse cancer cell lines. In the present study, SKLB-163 was used in combination with paclitaxel in order to determine the synergistic effect of the antitumor activity. The findings showed that the combination therapy clearly inhibited cell proliferation and induced apoptosis of LL/2 in vitro. The LL/2 mice model also showed that the combination therapy inhibited tumor growth in vivo. Proliferative cell nuclear antigen (PCNA) immunohistochmeistry and terminal deoxynucleotidyl transferase dUTP nick end-labeling showed that combination therapy inhibited cell proliferation and increased apoptosis compared to the treatment with SKLB-163 or paclitaxel alone. The data suggests that the combination therapy exerted synergistic antitumor effects, providing a novel way to augment the antitumor efficacy of cytotoxic chemotherapy.

SKLB-163, a new benzothiazole-2-thiol derivative, exhibits potent anticancer activity by affecting RhoGDI/JNK-1 signaling pathway

Small-molecule inhibitors are an attractive therapeutic approach for most types of human cancers. SKLB-163, a novel benzothiazole-2-thiol derivative, was developed via computer-aided drug design and de novo synthesis. MTT assay showed it had potent anti-proliferative activity on various human cancer cells. Treatment of cancer cells with SKLB-163 induced obvious apoptosis and inhibited proliferation in vitro. SKLB-163 administered p.o. showed a marked antitumor activity in vivo. Proteomic techniques were employed to identify possible drug target proteins. The data showed molecular mechanism of action might be involved in downregulation of RhoGDI, which finally contributed to increased apoptosis and inhibited proliferation. These findings provided the potential value of SKLB-163 as a novel candidate antitumor drug.

A novel benzothiazole derivative YLT322 induces apoptosis via the mitochondrial apoptosis pathway in vitro with anti-tumor activity in solid malignancies

Benzothiazole derivatives are known for various biological activities, and their potency in cancer therapy has received considerable attention in recent years. YLT322, a novel synthesized benzothiazole derivative, exhibits potent anti-tumor activity via inducing apoptosis both in vitro and in vivo. In this study, we found that YLT322 showed growth inhibition against a broad spectrum of human cancer cells and induced apoptosis of HepG2 cells in a dose- and time-dependent manner. The occurrence of its apoptosis was associated with activation of caspases-3 and -9, but not caspase-8. YLT322 increased the expression of Bax, decreased the expression of Bcl-2, and induced the release of cytochrome c which activates the mitochondrial apoptotic pathway. The down-regulation of phosphorylated p42/44 MAPK and phosphorylated Akt was also observed. Moreover, YLT322 suppressed the growth of established tumors in xenograft models in mice without obvious side effects. Histological and immunohistochemical analyses revealed an increase in TUNEL and caspase-3-positive cells and a decrease in Ki67-positive cells upon YLT322. These results suggest that YLT322 may be a potential candidate for cancer therapy.

Synthesis and evaluation of 2,5-di(4-aryloylaryloxymethyl)-1,3,4-oxadiazoles as anti-cancer agents

A series of 2,5-di(4-aryloylaryloxymethyl)-1,3,4-oxadiazoles 9a-j were obtained via multistep synthesis from hydroxybenzophenones 4a-e. The cytotoxicity of compounds 9a-j was evaluated against human leukemia cell lines (K562 and CEM). The compounds exhibited moderate to good anti-cancer activity with compounds 9b and 9i having a chloro group exhibiting the best activity (IC50 = 10 μM). Compound 9i exhibited activity against both the cell lines and 9b only exhibited activity against CEM. Further, a lactate dehydrogenase (LDH) assay and DNA fragmentation studies of the compounds 9a-j were also performed.

Applying ligands profiling using multiple extended electron distribution based field templates and feature trees similarity searching in the discovery of new generation of urea-based antineoplastic kinase inhibitors

This study provides a comprehensive computational procedure for the discovery of novel urea-based antineoplastic kinase inhibitors while focusing on diversification of both chemotype and selectivity pattern. It presents a systematic structural analysis of the different binding motifs of urea-based kinase inhibitors and the corresponding configurations of the kinase enzymes. The computational model depends on simultaneous application of two protocols. The first protocol applies multiple consecutive validated virtual screening filters including SMARTS, support vector-machine model (ROC = 0.98), Bayesian model (ROC = 0.86) and structure-based pharmacophore filters based on urea-based kinase inhibitors complexes retrieved from literature. This is followed by hits profiling against different extended electron distribution (XED) based field templates representing different kinase targets. The second protocol enables cancericidal activity verification by using the algorithm of feature trees (Ftrees) similarity searching against NCI database. Being a proof-of-concept study, this combined procedure was experimentally validated by its utilization in developing a novel series of urea-based derivatives of strong anticancer activity. This new series is based on 3-benzylbenzo[d]thiazol-2(3H)-one scaffold which has interesting chemical feasibility and wide diversification capability. Antineoplastic activity of this series was assayed in vitro against NCI 60 tumor-cell lines showing very strong inhibition of GI₅₀ as low as 0.9 uM. Additionally, its mechanism was unleashed using KINEX™ protein kinase microarray-based small molecule inhibitor profiling platform and cell cycle analysis showing a peculiar selectivity pattern against Zap70, c-src, Mink1, csk and MeKK2 kinases. Interestingly, it showed activity on syk kinase confirming the recent studies finding of the high activity of diphenyl urea containing compounds against this kinase. Allover, the new series, which is based on a new kinase scaffold with interesting chemical diversification capabilities, showed that it exhibits its “emergent” properties by perturbing multiple unexplored kinase pathways.

Substituted thiazoles VII. Synthesis and antitumor activity of certain 2-(substituted amino)-4-phenyl-1,3-thiazole analogs

A novel series of 2-acetamido- or 2-propanamido-4-(4-substituted phenyl)-1,3-thiazoles (11-34) was designed and synthesized. Compounds were subjected to National Cancer Institute (NCI) in vitro assessment for their antitumor activity, at a single dose of 10 μM. Most of the investigated compounds exhibited broad-spectrum antitumor activity. Compounds 19 and 28 believed to be the most active members in this study, with MG-MID GI(50), TGI, and LC(50) values of 2.8, 11.4, 44.7; and 3.3, 13.1, 46.8, respectively. Compounds 19 and 28 proved to be nine and sevenfold more active than the standard antitumor drug 5-FU, respectively.

Synthesis and biological evaluation of novel benzothiazole-2-thiol derivatives as potential anticancer agents

A series of novel benzothiazole-2-thiol derivatives were synthesized and their structures determined by ¹H-NMR, ¹³C-NMR and HRMS (ESI). The effects of all compounds on a panel of different types of human cancer cell lines were investigated. Among them, pyridinyl-2-amine linked benzothiazole-2-thiol compounds 7d, 7e, 7f and 7i exhibited potent and broad-spectrum inhibitory activities. Compound 7e displayed the most potent anticancer activity on SKRB-3 (IC₅₀ = 1.2 nM), SW620 (IC₅₀ = 4.3 nM), A549 (IC₅₀ = 44 nM) and HepG2 (IC₅₀ = 48 nM) and was found to induce apoptosis in HepG2 cancer cells.

High throughput screening of a library based on kinase inhibitor scaffolds against Mycobacterium tuberculosis H37Rv

Kinase targets are being pursued in a variety of diseases beyond cancer, including immune and metabolic as well as viral, parasitic, fungal and bacterial. In particular, there is a relatively recent interest in kinase and ATP-binding targets in Mycobacterium tuberculosis in order to identify inhibitors and potential drugs for essential proteins that are not targeted by current drug regimens. Herein, we report the high throughput screening results for a targeted library of approximately 26,000 compounds that was designed based on current kinase inhibitor scaffolds and known kinase binding sites. The phenotypic data presented herein may form the basis for selecting scaffolds/compounds for further enzymatic screens against specific kinase or other ATP-binding targets in Mycobacterium tuberculosis based on the apparent activity against the whole bacteria in vitro.

Synthesis, structure-activity relationships and preliminary antitumor evaluation of benzothiazole-2-thiol derivatives as novel apoptosis inducers

A series of novel benzothiazole-2-thiol derivatives were synthesized, and their anti-proliferative activities on HepG2 and MCF-7 cells were investigated. Most compounds had inhibitory effects on cell growth, and some of them were more effective than cisplatin. Compounds 6m and 6t displayed good inhibitory activities against a panel of different types of human cancer cell lines, with IC(50) values in the low micromolar range. Further biological evaluation indicated that 6m induced apoptosis in HepG2 cancer cells. Structure-activity relationships were also proposed.

Anticancer activity of N-bis(trifluoromethyl)alkyl-N'-(polychlorophenyl) and N'-(1,2,4-triazolyl) ureas

A number of N-bis(trifluoromethyl)alkyl-N'-substituted ureas have been synthesized and evaluated for their in vitro anticancer activity against the human cancer cell lines at the National Cancer Institute (NCI, USA). Marked activity was shown for compounds 4a and 5a. The most sensitive cell lines relative to the tested compounds were: 4a UO-31 (renal cancer, logGI(50) -5.62), HS 578T (breast cancer, logGI(50) -5.50), 5a HCC-2998 (colon cancer, logGI(50) -5.94), NCI-H322M (lung cancer, logGI(50) -5.75) and PC-3 (prostate cancer, logGI(50) -5.66).

Microwave-Assisted Synthesis of Benzothiazoleurea Derivatives

A simple and efficient method has been developed for the synthesis of 1-substituted-3-(4-chlorobenzo[d]thiazol-2-yl) ureas (5), from substituted aromatic or aliphatic amino compounds and phenyl 4-chlorobenzo[d]thiazol-2-yl carbamate 4 using microwave irradiation without phosgene in good yields. The title products were characterised by 1H NMR, ESIMS, and elemental analysis.