Synthesis of benzothiazole derivatives and their biological evaluation as anticancer agents

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.

Synthesis of new horizons in benzothiazole scaffold and used in anticancer drug development

Benzothiazole scaffolds exhibit exciting medicinal properties including anticancer. In recent time most complicated job for every researcher is to discover a novel drug that can treat cancer with minimal side effects. Some heterocyclic anticancer drugs including daunorubicin, 5-flourouracil, doxorubicin, methotrexate, etc. are markedly available. In addition, few natural products such as vincristine alongwith vinblastine are used as anticancer drugs. More than 90% of the novel drugs bearing heterocyclic moieties have always been main portions in the development of anticancer drugs. Heterocyclic compounds containing benzothiazole moiety show a superior pharmaceutical effect than non-nitrogen compounds. These N-/S-containing benzothiazole compounds, the heart of drug discovery, present a significant and valuable group of molecules that play a chief and vital role in our living cells. This chapter recites the weightage of benzothiazole nuclei in the progress of anticancer drugs.

Design, synthesis and evaluation of benzothiazole derivatives as multifunctional agents

Oxidative stress is the product or aetiology of various multifactorial diseases; on the other hand, the development of multifunctional compounds is a recognized strategy for the control of complex diseases. To this end, a series of benzothiazole derivatives was synthesized and evaluated for their multifunctional effectiveness as antioxidant, sunscreen (filter), antifungal and antiproliferative agents. Compounds were easily synthesized via condensation reaction between 2-aminothiophenols and different benzaldehydes. SAR study, particularly in position 2 and 6 of benzothiazoles, led to the identification of 4g and 4k as very interesting potential compounds for the design of multifunctional drugs. In particular, compound 4g is the best blocker of hERG potassium channels expressed in HEK 293 cells exhibiting 60.32% inhibition with IC₅₀ = 4.79 μM.

Synthesis of New Benzothiazole Acylhydrazones as Anticancer Agents

During the last five decades, a large number of BT (Benzothiazole) derivatives formed one of the eligible structures in medicinal chemistry as anticancer agents. Most of the studies reveal that various substitutions at specific positions on BT scaffold modulate the antitumor property. The potential of BTs encouraged us to synthesize a number of new 2-((5-substitutedbenzothiazol-2-yl)thio)-N’-(2-(4-(substitutedphenyl)ethylidene)acetohydrazide derivatives and investigate their probable anticancer activity. 4-Substitued benzaldehyde derivatives (1a–1e) were afforded by the reaction of appropriate secondary amine and 4-fluorobenzaldehyde in DMF. Equimolar quantitates of 5-substitutedbenzothiazole-2-thiol, ethyl chloroacetate and K₂CO₃ were refluxed in acetone to obtain 2-((5-substitutedbenzothiazol-2-yl)thio)acetate derivatives (2a,2b), which reacted with excess of hydrazine hydrate to get 2-((5-substitutebenzothiazol-2-yl)thio)acetohydrazides (3a,3b). In the last step, 2-((5-substitutedbenzothiazol-2-yl)thio)-N’-(4-substitutedbenzylidene)acetohydrazide derivatives (4a–4j) were synthesized by the reaction of 1a–1e and 3a–3b in EtOH. The anticancer activity of target compounds was evaluated in three steps. First, an MTT test (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) was performed to observe cytotoxic activity of the compounds against carcinogenic C6 (Rat brain glioma cell line), A549 (Human lung adenocarcinoma epithelial cell line), MCF-7 (Human breast adenocarcinoma cell line), and HT-29 (Human colorectal adenocarcinoma cell line) cancer cell lines. Healthy NIH3T3 (Mouse embryo fibroblast cell line) cells were also subjected to MTT assay to determine selectivity of the compounds towards carcinogenic cell lines. Secondly, inhibitory effects of selected compounds 4d, 4e, and 4h on DNA synthesis of C6 cells were investigated. Finally, flow cytometric analysis were performed to identify the death pathway of the carcinogenic cells.

Click with a boronic acid handle: a neighboring group-assisted click reaction that allows ready secondary functionalization

The feasibility of a neighboring boronic acid-facilitated facile condensation of an aldehyde is described. This reaction is bio-orthogonal, complete at room temperature within minutes, and suitable for bioconjugation chemistry. The boronic acid group serves the dual purpose of catalyzing the condensation reaction and being a handle for secondary functionalization.

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.

Biological Aspects of Emerging Benzothiazoles: A Short Review

In recent years heterocyclic compounds analogues and derivatives have attracted wide attention due to their useful biological and pharmacological properties. Benzothiazole is among the usually occurring heterocyclic nuclei in many marine as well as natural plant products. Benzothiazole is a privileged bicyclic ring system with multiple applications. It is known to exhibit a wide range of biological properties including anticancer, antimicrobial, and antidiabetic, anticonvulsant, anti-inflammatory, antiviral, antitubercular activities. A large number of therapeutic agents are synthesized with the help of benzothiazole nucleus. During recent years there have been some interesting developments in the biological activities of benzothiazole derivatives. These compounds have special significance in the field of medicinal chemistry due to their remarkable pharmacological potentialities. This review is mainly an attempt to present the research work reported in the recent scientific literature on different biological activities of benzothiazole compounds.