Eco-friendly synthesis, in vitro anti-proliferative evaluation, and 3D-QSAR analysis of a novel series of monocationic 2-aryl/heteroaryl-substituted 6-(2-imidazolinyl)benzothiazole mesylates

Applications of innovative synthetic strategies in anticancer drug discovery: The driving force of new chemical reactions

The discovery of novel anticancer agents remains a critical goal in medicinal chemistry, with innovative synthetic methodologies playing a pivotal role in advancing this field. Recent breakthroughs in CH activation reactions, cyclization reactions, multicomponent reactions, cross-coupling reactions, and photo- and electro-catalytic reactions have enabled the efficient synthesis of new molecular scaffolds exhibiting potent biological activities, including anticancer properties. These methodologies have facilitated the functionalization of natural products, the modification of bioactive molecules, and the generation of entirely new compounds, many of which demonstrate strong antitumor activity. This review summarizes the latest synthetic strategies employed over the past five years for discovering anticancer agents, focusing on their influence on drug design. Additionally, the role of new chemical reactions in expanding chemical space and overcoming challenges, such as drug resistance and selectivity, is highlighted, further emphasizing the importance of discovering novel reactions as a key trend in future drug development.

Stability and reversibility of organic molecule modifications of CVD-synthesized monolayer MoS2

We investigated the stability of monolayer MoS2samples synthesized using chemical vapor deposition and subsequently modified with organic molecules under ambient conditions. By analyzing the optical signatures of the samples using photoluminescence spectroscopy, Raman spectroscopy, and surface quality using atomic force microscopy, we observed that this modification of monolayer MoS2with organic molecules is stable and retains its optical signature over time under ambient conditions. Furthermore, we show the reversibility of the effects induced by the organic molecules, as heating the modified samples restores their original optical signatures, indicating the re-establishment of the optical properties of the pristine monolayer MoS2.

Recent Literature on the Synthesis of Thiazole Derivatives and their Biological Activities

The thiazole ring is naturally occurring and is primarily found in marine and microbial sources. It has been identified in various compounds such as peptides, vitamins (thiamine), alkaloids, epothilone, and chlorophyll. Thiazole-containing compounds are widely recognized for their antibacterial, antifungal, anti-inflammatory, antimalarial, antitubercular, antidiabetic, antioxidant, anticonvulsant, anticancer, and cardiovascular activities. The objective of this review is to present recent advancements in the discovery of biologically active thiazole derivatives, including their synthetic methods and biological effects. This review comprehensively discusses the synthesis methods of thiazole and its corresponding biological activities within a specific timeframe, from 2017 until the conclusion of 2022.

Synthesis and biological evaluation of fluoroquinolones containing a pyridoxine derivatives moiety

We report herein the design, synthesis and biological evaluation of series of 7-substituted fluoroquinolones with pyridoxine derivatives. In vitro screening of antibacterial activity and toxicity of 39 synthesized fluoroquinolones defined compounds 7 and 28 as lead compounds for further investigations. On various clinical isolates lead compounds 7 and 28 exhibited antibacterial activity comparable with reference fluoroqinolones. Mutagenic effects haven't been observed for these compounds in SOS-chromotest. Compound 7 are non-toxic in vivo on mice (LD50 > 2000 mg/kg, oral) and rats (LD50 > 2000 mg/kg, oral). Compound 28 was more toxic (LD50 = 474 mg/kg, oral, mice). Moreover compound 7 showed greater in vivo efficacy compared to ciprofloxacin in a murine model of staphylococcal sepsis. Taken together the described active compound are promising candidate for preclinical trials.

Bis-6-amidino-benzothiazole Derivative that Cures Experimental Stage 1 African Trypanosomiasis with a Single Dose

We designed and synthesized a series of symmetric bis-6-amidino-benzothiazole derivatives with aliphatic central units and evaluated their efficacy against bloodstream forms of the African trypanosome Trypanosoma brucei. Of these, a dicationic benzothiazole compound (9a) exhibited sub-nanomolar in vitro potency with remarkable selectivity over mammalian cells (>26,000-fold). Unsubstituted 5-amidine groups and a cyclohexyl spacer were the crucial determinants of trypanocidal activity. In all cases, mice treated with a single dose of 20 mg kg-1 were cured of stage 1 trypanosomiasis. The compound displayed a favorable in vitro ADME profile, with the exception of low membrane permeability. However, we found evidence that uptake by T. brucei is mediated by endocytosis, a process that results in lysosomal sequestration. The compound was also active in low nanomolar concentrations against cultured asexual forms of the malaria parasite Plasmodium falciparum. Therefore, 9a has exquisite cross-species efficacy and represents a lead compound with considerable therapeutic potential.

Synthesis and Biological Activity of 2-Benzo[b]thienyl and 2-Bithienyl Amidino-Substituted Benzothiazole and Benzimidazole Derivatives

Novel benzo[b]thienyl- and 2,2'-bithienyl-derived benzothiazoles and benzimidazoles were synthesized to study their antiproliferative and antitrypanosomal activities in vitro. Specifically, we assessed the impact that amidine group substitutions and the type of thiophene backbone have on biological activity. In general, the benzothiazole derivatives were more active than their benzimidazole analogs as both antiproliferative and antitrypanosomal agents. The 2,2'-bithienyl-substituted benzothiazoles with unsubstituted and 2-imidazolinyl amidine showed the most potent antitrypanosomal activity, and the greatest selectivity was observed for the benzimidazole derivatives bearing isopropyl, unsubstituted and 2-imidazolinyl amidine. The 2,2'-bithiophene derivatives showed most selective antiproliferative activity. Whereas the all 2,2'-bithienyl-substituted benzothiazoles were selectively active against lung carcinoma, the benzimidazoles were selective against cervical carcinoma cells. The compounds with an unsubstituted amidine group also produced strong antiproliferative effects. The more pronounced antiproliferative activity of the benzothiazole derivatives was attributed to different cytotoxicity mechanisms. Cell cycle analysis, and DNA binding experiments provide evidence that the benzimidazoles target DNA, whereas the benzothiazoles have a different cellular target because they are localized in the cytoplasm and do not interact with DNA.

Influence of Solvents and Adsorption of Organic Molecules on the Properties of CVD Synthesized 2D MoS2

We present a simple method for modification of 2D materials by drop-casting of the organic molecule in solution on the 2D material under ambient conditions. Specifically, we investigated the adsorption of 6-(4,5-Dihydro-1H-imidazol-3-ium-2-yl)-2-(naphthalene-2-yl)benzothiazole methanesulfonate (L63MS) organic molecule on 2D MoS2. To better understand the effect of the organic molecule on the 2D material, we also investigated the impact of solvents alone on the materials' properties. The MoS2 samples were synthesized using ambient pressure chemical vapor deposition. Atomic force microscopy, Raman spectroscopy, photoluminescence spectroscopy and optical microscopy were used to characterize the samples. The measurements were performed after synthesis, after the drop-casting of solvents and after the drop-casting of organic molecule solutions. Our results indicate that the used organic molecule effectively adsorbs on and prompts discernible changes in the (opto)electronic properties of the 2D material. These changes encompass variations in the Raman spectra shape, alterations in the photoluminescence (PL) signal characteristics and modifications in excitonic properties. Such alterations can be linked to various phenomena including doping, bandgap modifications, introduction or healing of defects and that the solvent plays a crucial role in the process. Our study provides insights into the modification of 2D materials under ambient conditions and highlights the importance of solvent selection in the process.

Synthetic Approaches to Biologically Active C-2-Substituted Benzothiazoles

Numerous benzothiazole derivatives are used in organic synthesis, in various industrial and consumer products, and in drugs, with a wide spectrum of biological activity. As the properties of the benzothiazole moiety are strongly affected by the nature and position of substitutions, in this review, covering the literature from 2016, we focus on C-2-substituted benzothiazoles, including the methods of their synthesis, structural modification, reaction mechanisms, and possible pharmacological activity. The synthetic approaches to these heterocycles include both traditional multistep reactions and one-pot atom economy processes using green chemistry principles and easily available reagents. Special attention is paid to the methods of the thiazole ring closure and chemical modification by the introduction of pharmacophore groups.

Recognition of ATT Triplex and DNA:RNA Hybrid Structures by Benzothiazole Ligands

Interactions of an array of nucleic acid structures with a small series of benzothiazole ligands (bis-benzothiazolyl-pyridines—group 1, 2-thienyl/2-benzothienyl-substituted 6-(2-imidazolinyl)benzothiazoles—group 2, and three 2-aryl/heteroaryl-substituted 6-(2-imidazolinyl)benzothiazoles—group 3) were screened by competition dialysis. Due to the involvement of DNA:RNA hybrids and triplex helices in many essential functions in cells, this study’s main aim is to detect benzothiazole-based moieties with selective binding or spectroscopic response to these nucleic structures compared to regular (non-hybrid) DNA and RNA duplexes and single-stranded forms. Complexes of nucleic acids and benzothiazoles, selected by this method, were characterized by UV/Vis, fluorescence and circular dichroism (CD) spectroscopy, isothermal titration calorimetry, and molecular modeling. Two compounds (1 and 6) from groups 1 and 2 demonstrated the highest affinities against 13 nucleic acid structures, while another compound (5) from group 2, despite lower affinities, yielded higher selectivity among studied compounds. Compound 1 significantly inhibited RNase H. Compound 6 could differentiate between B- (binding of 6 dimers inside minor groove) and A-type (intercalation) helices by an induced CD signal, while both 5 and 6 selectively stabilized ATT triplex in regard to AT duplex. Compound 3 induced strong condensation-like changes in CD spectra of AT-rich DNA sequences.

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.

Amidino substituted 2-aminophenols: biologically important building blocks for the amidino-functionalization of 2-substituted benzoxazoles

Unlike the closely related and widely investigated amidino-substituted benzimidazoles and benzothiazoles with a range of demonstrated biological activities, the matching benzoxazole analogues still remain a largely understudied and not systematically evaluated class of compounds. To address this challenge, we utilized the Pinner reaction to convert isomeric cyano-substituted 2-aminophenols into their amidine derivatives, which were isolated as hydrochlorides and/or zwitterions, and whose structure was confirmed by single crystal X-ray diffraction. The key step during the Pinner synthesis of the crucial carboximidate intermediates was characterized through mechanistic DFT calculations, with the obtained kinetic and thermodynamic parameters indicating full agreement with the experimental observations. The obtained amidines were subjected to a condensation reaction with aryl carboxylic acids that allowed the synthesis of a new library of 5- and 6-amidino substituted 2-arylbenzoxazoles. Their antiproliferative features against four human tumour cell lines (SW620, HepG2, CFPAC-1, HeLa) revealed sub-micromolar activities on SW620 for several cyclic amidino 2-naphthyl benzoxazoles, thus demonstrating the usefulness of the proposed synthetic strategy and promoting amidino substituted 2-aminophenols as important building blocks towards biologically active systems.

Mekheimer R, M. Hayallah A, A. Abo Elsoud F, U. Sadek K. Recent Advances in the Utility of Glycerol as a Benign and Biodegradable Medium in Heterocyclic Synthesis

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Glycerol is a non-toxic, recyclable and biodegradable organic waste produced as a byproduct in the production of biodiesel fuel. Currently, glycerol is considered a green solvent and catalyst for a large variety of applications. This work discusses the significance of glycerol for heterocyclic synthesis. All the reported studies consider glycerol as an efficient and sustainable benign medium.

Green synthesis and biological evaluation of 6-substituted-2-(2-hydroxy/methoxy phenyl)benzothiazole derivatives as potential antioxidant, antibacterial and antitumor agents

We present a new efficient green synthetic protocol for introduction of substituents to the C-6 position of 2-arylbenzothiazole nuclei. Newly synthesized compounds were designed to study the influence of the hydroxy and methoxy groups on the 2-arylbenzothiazole scaffold, as well as the influence of the type of substituents placed on the C-6 position of benzothiazole moiety on biological activity, including antibacterial, antitumor and antioxidant activity. Modest activity was observed against the tested Gram-positive and Gram-negative bacterial strains for only amidino derivatives 5d and 6d. The tested compounds exhibited moderate to strong antiproliferative activity towards the tumor cell lines tested. The SAR study revealed that the introduction of substituents into the benzene ring of the benzothiazole nuclei is essential for antiproliferative activity, while introduction of the hydroxy group into the 2-aryl moiety of the 2-arybenzothiazole scaffold significantly improved selectivity against tumor cell lines. The observed results revealed several novel 6-substituted-2-arylbenzothiazole compounds, 5b, 5c, 5f and 6f, with strong and selective antiproliferative activity towards HeLa cells in micro and submicromolar concentrations, with the most selective compounds being 6-ammonium-2-(2-hydroxy/methoxyphenyl)benzothiazoles 5f and 6f. The compound 5f bearing the hydroxy group on the 2-arylbenzothiazole core showed the most promising antioxidative activity evaluated by DPPH, ABTS and FRAP in vitro assays. The presence of the amino protonated group attached at the benzothiazole moiety was essential for the antiproliferative and antioxidant activity observed, exerted through a change in the levels of the reactive oxygen species-modulated HIF-1 protein.