Discovery of 2-amino-heteroaryl-benzothiazole-6-anilides as potent p56(lck) inhibitors

Recent Advances in the Application of 2-Aminobenzothiazole to the Multicomponent Synthesis of Heterocycles

Heterocycles are a vital class of compounds in numerous fields, including drug discovery, agriculture, and materials science. Efficient methods for the synthesis of heterocycles remain critical for meeting the demands of these industries. Recent advances in multicomponent reactions (MCRs) utilizing 2-aminobenzothiazole (ABT) have shown promising results for the formation of heterocycles. The versatility of 2-aminobenzothiazole in this context has enabled the rapid and efficient construction of diverse heterocyclic structures. Various synthetic methodologies and reactions involving 2-aminobenzothiazole are discussed, highlighting its importance as a valuable building block in the synthesis of complex heterocycles. The potential applications of these heterocycles in drug discovery and material science are also explored. Overall, this review provides a comprehensive overview of the current state of research in the field and offers insights into the future directions of this promising area of study. We highlight the potential of ABT as a versatile and sustainable starting material in heterocyclic synthesis via MCRs, with significant implications for the chemical industry.

FDA-approved small molecule kinase inhibitors for cancer treatment (2001-2015): Medical indication, structural optimization, and binding mode Part I

The dysregulation of kinases has emerged as a major class of targets for anticancer drug discovery given its node roles in the etiology of tumorigenesis, progression, invasion, and metastasis of malignancies, which is validated by the FDA approval of 28 small molecule kinase inhibitor (SMKI) drugs for cancer treatment at the end of 2015. While the preclinical and clinical data of these drugs are widely presented, it is highly essential to give an updated review on the medical indications, design principles and binding modes of these anti-tumor SMKIs approved by the FDA to offer insights for the future development of SMKIs with specific efficacy and safety.

Phenylthiazoles with potent & optimum selectivity toward Clostridium difficile

Clostridium difficile (C. difficile) is one of the most threatening bacteria globally, causing high mortality and morbidity in humans and animals, and is considered a public health threat that requires urgent and aggressive action. Interruption of the human gut microbiome and the development of antibiotic resistance urgently require development and synthesis of effective alternative antibiotics with minimal effects on the normal gut microbial flora. In this study, cyclization of the aminoguanidine head to the thiazole nucleus while maintaining its other pharmacophoric features leads to selective targeting of Clostridioides difficile as shown in the graphical abstract. The most promising compound, 5, was significantly more efficient than vancomycin and metronidazole against six strains of C. diff with MIC values as low as 0.030 μg mL-1. Additionally, compound 5 was superior to vancomycin and metronidazole, showing no inhibition toward nine tested strains of the normal human gut microbiota (>64 μg mL-1). The high safety profile of compound 5 was also observed with two cell lines HRT-18 and Vero cells.

Current Development of Thiazole-Containing Compounds as Potential Antibacterials against Methicillin-Resistant Staphylococcus aureus

The emergence of multi-drug-resistant bacteria is threatening to human health and life around the world. In particular, methicillin-resistant Staphylococcus aureus (MRSA) causes fatal injuries to human beings and serious economic losses to animal husbandry due to its easy transmission and difficult treatment. Currently, the development of novel, highly effective, and low-toxicity antimicrobials is important to combat MRSA infections. Thiazole-containing compounds with good biological activity are widely used in clinical practice, and appropriate structural modifications make it possible to develop new antimicrobials. Here, we review thiazole-containing compounds and their antibacterial effects against MRSA reported in the past two decades and discuss their structure-activity relationships as well as the corresponding antimicrobial mechanisms. Some thiazole-containing compounds exhibit potent antibacterial efficacy in vitro and in vivo after appropriate structural modifications and could be used as antibacterial candidates. This Review provides insights into the development of thiazole-containing compounds as antimicrobials to combat MRSA infections.

Materials for restoring lost Activity: Old drugs for new bugs

The escalation of bacterial resistance to conventional medical antibiotics is a serious concern worldwide. Improvements to current therapies are urgently needed to address this problem. The synergistic combination of antibiotics with other agents is a strategic solution to combat multi-drug-resistant bacteria. Although these combinations decrease the required high dosages and therefore, reduce the toxicity of both agents without compromising the bactericidal effect, they cannot stop the development of further resistance. Recent studies have shown certain elements restore the ability of antibiotics to destroy bacteria that have acquired resistance to them. Due to these synergistic activities, organic and inorganic molecules have been investigated with the goal of restoring antibiotics in new approaches that mitigate the risk of expanding resistance. Herein, we summarize recent studies that restore antibiotics once thought to be ineffective, but have returned to our armamentarium through innovative, combinatorial efforts. A special focus is placed on the mechanisms that allow the synergistic combinations to combat bacteria. The promising data that demonstrated restoration of antimicrobials, supports the notion to find more combinations that can combat antibiotic-resistant bacteria.

Recent advances in the synthesis of benzothiazole and its derivatives

Abstract:

Benzothiazoles have recognized pharmacophores in the field of research, predominantly in synthetic and medicinal chemistry, on account of their significant pharmaceutical properties. This important class of derivatives endows an extensive range of biological activities like anti-inflammatory, antidiabetic, anticancer, anticonvulsant, antibacterial, antiviral, antioxidant, antituberculosis, enzyme inhibitors, etc. Hence, various methodologies have been accomplished to synthesize benzothiazole compounds considering the purity, yield, and selectivity of the products. This review provides different reaction methods that are involved in the synthesis of a variety of benzothiazole derivatives.

Benzothiazoles from Condensation of o-Aminothiophenoles with Carboxylic Acids and Their Derivatives: A Review

Nowadays, organic chemists are interested in the field of heterocyclic chemistry due to its use in the synthesis of a great variety of biologically active compounds. Heterocyclic compounds are widely found in nature and are essential for life. Among these, some natural nitrogen containing heterocyclic compounds have been used as chemotherapeutic agents. Their attachment to sugar molecules either as thioglycosides or as nucleosides analogues plays an important role in vital biological processes as well as in synthetic organic chemistry. Molecules containing benzothiazole (BT) nuclei are of this interesting class of compounds because some of them have been found to have a wide variety of biological activities. In this sense, we selected this topic to review and to then summarize the procedures related to the condensation reactions of o-aminothiophenoles (ATPs) as well as their disulfides with carboxylic acids, esters, orthoesters, acyl chlorides, amides, and nitriles. The condensation reactions with carbon dioxide (CO₂) are included. Conventional methods with the use of acid and metal catalysts as well as recent green techniques, such as microwave irradiation, the use of ionic liquids, and ultrasound (US) chemistry, which have proven to have many advantages, were found in the review.

Recent Advances in Synthesis of Benzothiazole Compounds Related to Green Chemistry

Benzothiazoles have played an important role in the field of biochemistry and medicinal chemistry due to their highly pharmaceutical and biological activity. The development of synthetic processes is undoubtedly one of the most significant problems facing researchers. In this review paper, we provided recent advances in the synthesis of benzothiazole compounds related to green chemistry from condensation of 2-aminobenzenethiol with aldehydes/ketones/acids/acyl chlorides and the cyclization of thioamide or carbon dioxide (CO2) as raw materials, and the future development trend and prospect of the synthesis of benzothiazoles were anticipated.

Crystal structure of potassium [4-amino-5-(benzo[d]thia-zol-2-yl)-6-(methyl-sulfan-yl)pyrimidin-2-yl](phenyl-sulfon-yl)aza-nide di-methyl-formamide monosolvate hemihydrate

The title compound, K+·C18H14N5O2S3 -·C3H7NO·0.5H2O, was obtained in a reaction designed to deliver a neutral 2-pyrimidylbenzo-thia-zole. The anion is deprotonated at the sulfonamide nitro-gen. The asymmetric unit of the title compound contains two potassium cations, two anions, two mol-ecules of DMF and one of water. The anions display some conformational differences but each contains an intra-molecular N-H⋯Nbenzo-thia-zole hydrogen bond. The potassium ions both display a highly irregular six-coordination, different for each potassium ion. The anions, together with the DMF and water mol-ecules, are linked by four classical hydrogen bonds to form chains parallel to the b-axis direction.

RITA Mimics: Synthesis and Mechanistic Evaluation of Asymmetric Linked Trithiazoles

The established cytotoxic agent RITA contains a thiophene-furan-thiophene backbone and two terminal alcohol groups. Herein we investigate the effect of using thiazoles as the backbone in RITA-like molecules and modifying the terminal groups of these trithiazoles, thereby generating 41 unique structures. Incorporating side chains with varied steric bulk allowed us to investigate how size and a stereocenter impacted biological activity. Subjecting compounds to growth inhibition assays on HCT-116 cells showed that the most potent compounds 7d, 7e, and 7h had GI₅₀ values of 4.4, 4.4, and 3.4 μM, respectively, versus RITA (GI₅₀ of 800 nM). Analysis of these compounds in apoptosis assays proved that 7d, 7e, and 7h were as effective as RITA at inducing apoptosis. Evaluating the impact of 7h on proteins targeted by RITA (p53, c-Myc, and Mcl-1) indicated that it acts via a different mechanism of action to that of RITA. RITA suppressed Mcl-1 protein via p53, whereas compound 7h suppressed Mcl-1 expression via an alternative mechanism independent of p53.

Anti-biofilm activity and synergism of novel thiazole compounds with glycopeptide antibiotics against multidrug-resistant staphylococci

Methicillin-resistant Staphylococcus aureus (MRSA) infections are a leading cause of death among all fatalities caused by antibiotic-resistant bacteria. With the rise of increasing resistance to current antibiotics, new antimicrobials and treatment strategies are urgently needed. Thiazole compounds have been shown to possess potent antimicrobial activity. A lead thiazole 1 and a potent derivative 2 were synthesized and their activity in combination with glycopeptide antibiotics was determined against an array of MRSA and vancomycin-resistant S. aureus (VRSA) clinical isolates. In addition, the anti-biofilm activity of the novel thiazoles was investigated against S. epidermidis. Compound 2 behaved synergistically with vancomycin against MRSA and was able to resensitize VRSA to vancomycin, reducing its MIC by 512-fold in two strains. In addition, both thiazole compounds were superior to vancomycin in significantly reducing S. epidermidis biofilm mass. Collectively, the results obtained demonstrate that compounds 1 and 2 possess potent antimicrobial activity alone or in combination with vancomycin against multidrug-resistant staphylococci and show potential for use in disrupting staphylococcal biofilm.

Synthesis and biological evaluation of benzothiazole derivatives bearing the ortho-hydroxy-N-acylhydrazone moiety as potent antitumor agents

A novel series of benzothiazole derivatives bearing the ortho-hydroxy-N-acylhydrazone moiety were designed, synthesized, and evaluated for their procaspase-3 kinase activation activities and antiproliferative activities against five cancer cell lines (NCI-H226, SK-N-SH, HT29, MKN-45, and MDA-MB-231). Most target compounds showed moderate to excellent cytotoxic activity against all five tested cancer lines. The most promising compound 18e (procaspase-3 EC50  = 0.31 µM) with IC50 values ranging from 0.24 to 0.92µM against all tested cell lines was 4.24-12.2 times more active than PAC-1 (procaspase-3 EC50  = 0.41 µM). Structure-activity relationship studies indicated that the phenyl group on the 2-hydroxyphenyl ring (moiety A) was critical for pharmacological activity in vitro. In addition, introduction of a benzyloxyl group on moiety A and a mono-electron-withdrawing group at the 4-position of the benzyloxyl group were more favorable for antitumor activity. Moreover, reduction of the electron density in the phenyl ring of the benzyloxy group led to a dramatic decrease in the procaspase-3 kinase activation activity.

Design, synthesis, and structure-activity relationships of novel benzothiazole derivatives bearing the ortho-hydroxy N-carbamoylhydrazone moiety as potent antitumor agents

A series of novel benzothiazole derivatives bearing the ortho-hydroxy N-carbamoylhydrazone moiety were designed and synthesized and their cytotoxic activities against five cancer cell lines (NCI-H226, SK-N-SH, HT29, MKN45, and MDA-MB-231) were screened in vitro. Most of them showed moderate to excellent activity against all the tested cell lines. Among them, compounds 15g (procaspase-3 EC50 = 1.42 μM) and 16b (procaspase-3 EC50 = 0.25 μM) exhibited excellent antitumor activity with IC50 values ranging from 0.14 μM to 0.98 μM against all cancer cell lines, which were 1.8-8.7 times more active than the first procaspase activating compound (PAC-1) (procaspase-3 EC50 = 4.08 μM). The structure-activity relationship (SAR) analyses indicated that the introduction of a lipophilic group (a benzyloxy or heteroaryloxy group) at the 4-position of the 2-hydroxy phenyl ring was beneficial to antitumor activity, and the presence of substituents containing nitrogen that are positively charged at physiological pH could also improve antitumor activity. It was also confirmed that the steric effect of the 4-position substituent of the benzyloxy group had a significant influence on cytotoxic activity.

Discovery and characterization of potent thiazoles versus methicillin- and vancomycin-resistant Staphylococcus aureus

Methicillin- and vancomycin-resistant Staphylococcus aureus (MRSA and VRSA) infections are growing global health concerns. Structure-activity relationships of phenylthiazoles as a new antimicrobial class have been addressed. We present 10 thiazole derivatives that exhibit strong activity against 18 clinical strains of MRSA and VRSA with acceptable PK profile. Three derivatives revealed an advantage over vancomycin by rapidly eliminating MRSA growth within 6 h, and no derivatives are toxic to HeLa cells at 11 μg/mL.

When tight is too tight: Dasatinib and its lower affinity analogue for profiling kinase inhibitors in a three-hybrid split-luciferase system

We report new CIDs based on Dasatinib and its analogues for profiling kinase inhibitors using a split-luciferase screen.

(2E)-2-(1,3-Benzo-thia-zol-2-yl)-3-(di-methyl-amino)-prop-2-ene-nitrile

The mol-ecular conformation of title compound, C12H11N3S, is almost planar [maximum deviation = 0.063 (2) Å]; an intra-molecular C-H⋯N hydrogen bond is noted. In the crystal, mol-ecules inter-act with each other via π-π stacking inter-actions between thia-zole rings [centroid-centroid distance = 3.7475 (9) Å] and methyl-H⋯π(C6) inter-actions, forming columns along the a axis.

Recent advances in the synthesis of 2-substituted benzothiazoles: a review

Recent advances in various synthetic protocols of 2-substituted benzothiazole derivatives.

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

A new series of benzothiazoles and benzoxazoles was synthesized using 4-benzothiazol-2-yl-phenylamine and 4-benzoxazol-2-yl-phenylamine as starting materials. All the prepared compounds were evaluated for their antitumor activities against human breast cancer cell lines, MCF-7 and MDA-231, using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) cell viability analysis. Almost all the tested compounds revealed potent antitumor activity, especially the N-methyl piperazinyl substituted derivatives 6f and 6c, which displayed the most potent inhibitory activity with IC50 values ranging from 8 to 17 nM. Docking the synthesized compounds into the epidermal growth factor receptor (EGFR), which is highly expressed in breast cancer, was employed to explore the possible interactions of these compounds with the EGFR. The activity of the reported compounds supports its clinical promise as a component of therapeutic strategies for cancer, for which high concentrations of chemotherapeutic agents are always a major limitation.

Synthesis of pyrazolo[1,5-a]pyrimidine linked aminobenzothiazole conjugates as potential anticancer agents

A series of pyrazolo[1,5-a]pyrimidine linked 2-aminobenzothizole conjugates (6a-t) were synthesized and evaluated for their anticancer activity against five human cancer cell lines. Among them two compounds 6p and 6m showed significant anticancer activity with IC50 values ranging from 2.01 to 7.07 and 1.94-3.46 μM, respectively. Moreover, cell cycle arrest in G2/M and reduction in Cdk1 expression level were observed upon treatment of these compounds and they also induced caspase-3 dependent apoptosis. This was further confirmed by staining as well as DNA fragmentation analysis.

Design and synthesis of novel 4-benzothiazole amino quinazolines Dasatinib derivatives as potential anti-tumor agents

Three series of novel 4-benzothiazole amino quinazolines Dasatinib derivatives have been designed and synthesized. The entire target compounds were investigated for their in vitro cytotoxic activity by the MTT-based assay against 6 human cancer cell lines. Compared with the parental Dasatinib, most of the new compounds, especially 2, 4, 6-trimethylaniline series (3), demonstrated significant inhibitory activities against six cell lines. Furthermore, the target compounds were screened for Src and Abl kinase inhibitory activity. Among them, 1a, 1f and 3a-3f are more potential dual Src/Abl kinase inhibitors. Thus they may be promising lead compounds to be developed as an alternative for current Dasatinib therapy or for Imatinib-resistant patients, potentially via simultaneously blocking multiple RTK signaling pathways.

New anticancer active and selective phenylene-bisbenzothiazoles: synthesis, antiproliferative evaluation and DNA binding

Novel amidino-derivatives of phenylene-bisbenzothiazoles were synthesized and tested for their antiproliferative activity against several human cancer cell lines, as well as DNA-binding properties. The synthetic approach used for preparation of isomeric amidino substituted-phenylene-bis-benzothyazoles 3a-3f was achieved by condensation reaction of isophthaloyl dichloride 1a and terephthaloyl dichloride 1b or with phthalic acid 1c with 5-amidinium-2-aminobenzothiolate 2a and 5-(imidazolinium-2-yl)-2-aminobenzothiolate 2b in good yields. The targeted compounds were converted in the desired water soluble dihydrochloride salts by reaction of appropriate free base with concd HCl in ethanol or acetic acid. All tested compounds (3a-3f) showed antiproliferative effects on tumour cells in a concentration-dependant manner. The strongest activity and cytotoxicity was observed for diimidazolinyl substituted phenylene-bisbenzothiazole compound 3b. These effects were shown to be related to DNA-binding properties, topoisomerase I and II poisoning effects and apoptosis induction. The highest tested selectivity towards tumour cells was observed for the imidazolyl substituted phenylene-benzothiazole 3d that showed no cytotoxic effects on normal fibroblasts making it an excellent candidate for further chemical optimization and preclinical evaluation.

Synthesis and antiproliferative evaluation of some new amidino-substituted bis-benzothiazolyl-pyridines and pyrazine

Novel diamidino substituted conformationally restricted derivatives of bis-benzothiazolyl-pyridines and pyrazine were synthesized and their antiproliferative activity against several human cancer cell lines were determinated. The synthetic approach used for preparation of isomeric amidinobenzotiazolyl disubstituted pyridines 3a-3k and pyrazine 3l was achieved by condenzation reaction of commercially available pyridine and pyrazine dicarboxylic acids with amidino- 2a and 2-imidazolinyl-substituted 2-aminothiophenol 2b in polyphosphoric acid in moderate to good yield. The condenzation reaction was greatly optimized. The targeted compounds were converted in the desired water soluble dihydrochloride salts by reaction of appropriate free base with concd HCl in ethanol or acetic acid. Antiproliferative assays revealed significant differences in antiproliferative activities of diamidino- and diimidazolinyl-derivatives, the latter exerting stronger concentration-dependent antiproliferative effects on tested tumor cell lines and thus being a prominent compound class for further chemical optimization and biological studies. Biological studies on SW620 cell line and BJ fibroblasts performed for the diimidazolinyl-derivative 3b revealed oxidative stress as a possible mechanism of antiproliferative action and predicted antineoplastic properties for this class of compounds.

Benzothiazoles: search for anticancer agents

Novel derivatives of 2-amino benzothiazoles 4(a-j) have been synthesized and tested for their antitumor activity using National Cancer Institute (NCI) disease oriented antitumor screen protocol against nine panel of cancer cell lines. Among the synthesized compounds, two compounds were granted NSC code and screened at National Cancer Institute (NCI)-USA for anticancer activity at a single high dose (10(-5) M) and five dose in full NCI 60 cell panel. Among the selected compounds, 7-chloro-N-(2,6-dichlorophenyl)benzo[d]thiazol-2-amine (4i) with GI(50) values of 7.18 × 10(-8) M against Non-Small Cell HOP-92 Lung Cancer cell line proved to be the most active members in this study. Virtual screening was carried out through docking the designed compounds into the ATP binding site of epidermal growth factor receptor (EGFR) to predict if these compounds have analogous binding mode to the EGFR inhibitors.

Antimicrobial prospect of newly synthesized 1,3-thiazole derivatives

A new series of 1,3-thiazole and benzo[d]thiazole derivatives 10-15 has been developed, characterized, and evaluated for in vitro antimicrobial activity at concentrations of 25-200 μg/mL against Gram+ve organisms such as methicillin-resistant Staphylococcus aureus (MRSA), Gram-ve organisms such as Escherichia coli (E. coli), and the fungal strain Aspergillus niger (A. niger) by the cup plate method. Ofloxacin and ketoconazole (10 μg/mL) were used as reference standards for antibacterial and antifungal activity, respectively. Compounds 11 and 12 showed notable antibacterial and antifungal activities at higher concentrations (125-200 μg/mL), whereas benzo[d]thiazole derivatives 13 and 14 were found to display significant antibacterial or antifungal activity (50-75 μg/mL) against the Gram+ve, Gram-ve bacteria, or fungal cells used in the present study. In addition, a correlation between calculated and determined partition coefficient (log P) was established which allows future development of compounds within this series to be carried out based on calculated log P values. Moreover, compounds 13 and 14 show that the optimum logarithm of partition coefficient (log P) should be around 4.