Synthesis of novel quinoxaline-alkynyl derivatives and their anti-Mycobacterium tuberculosis activity

Micelle-mediated synthesis of quinoxaline, 1,4-benzoxazine and 1,4-benzothiazine scaffolds from styrenes

A range of heterocycles based on quinoxalines, 1,4-benzoxazines and 1,4-benzothiazines have been accessed from styrenes by reacting them with benzene-1,2-diamine, 2-aminophenol and 2-aminothiophenol respectively in micellar medium. This reaction occurring in a less explored cetylpyridinium bromide (CPB) micellar medium operates in the presence of NBS through a tandem hydrobromination-oxidation cascade, converting styrenes to phenacyl bromides. Its subsequent nucleophilic addition with aromatic 1,2-dinucleophiles and further transformations led to the formation of heterocyclic constructs. The locus of the reaction site was confirmed through NMR studies and the types of interactions between the CPB and solubilizates were established by DFT calculations.

Exploring quinoxaline derivatives: An overview of a new approach to combat antimicrobial resistance

Antimicrobial resistance (AMR) has emerged as a long-standing global issue ever since the introduction of penicillin, the first antibiotic. Scientists are constantly working to develop innovative antibiotics that are more effective and superior. Unfortunately, the misuse of antibiotics has resulted in their declining effectiveness over the years. By 2050, it is projected that approximately 10 million lives could be lost annually due to antibiotic resistance. Gaining insight into the mechanisms behind the development and transmission of AMR in well-known bacteria including Escherichia coli, Bacillus pumilus, Enterobacter aerogenes, Salmonella typhimurium, and the gut microbiota is crucial for researchers. Environmental contamination in third world and developing countries also plays a significant role in the increase of AMR. Despite the availability of numerous recognized antibiotics to combat bacterial infections, their effectiveness is diminishing due to the growing problem of AMR. The overuse of antibiotics has led to an increase in resistance rates and negative impacts on global health. This highlights the importance of implementing strong antimicrobial stewardship and improving global monitoring, as emphasized by the World Health Organization (WHO) and other organizations. In the face of these obstacles, quinoxaline derivatives have emerged as promising candidates. They are characterized by their remarkable efficacy against a broad spectrum of harmful bacteria, including strains that are resistant to multiple drugs. These compounds are known for their strong structural stability and adaptability, making them a promising and creative solution to the AMR crisis. This review aims to assess the effectiveness of quinoxaline derivatives in treating drug-resistant infections, with the goal of making a meaningful contribution to the global fight against AMR.

Radical relay cyclization/C-C bond formation of allyloxy-tethered aryl iodides with quinoxalin-2(1H)-ones via polysulfide anion photocatalysis

A visible-light-induced radical relay cyclization/C-C bond formation of quinoxalin-2(1H)-ones with allyloxy-tethered aryl iodides using polysulfide anions as a photocatalyst is described. This protocol allows efficient access to a variety of complicated molecules bearing both quinoxalin-2(1H)-one and 2,3-dihydrobenzofuran motifs in high yields under mild reaction conditions with a broad range of substrates.

Recent Methods for the Synthesis of Quinoxaline Derivatives and their Biological Activities

Quinoxaline derivatives have been incorporated into numerous marketed drugs used for the treatment of various diseases. Examples include glecaprevir (Mavyret), voxilaprevir (Vosevi), Balversa (L01EX16) (erdafitinib), carbadox, XK469R (NSC698215), and becampanel (AMP397). These quinoxaline derivatives exhibit a diverse range of pharmacological activities, including antibacterial, antitubercular, antiviral, anti-HIV, anti-inflammatory, antifungal, anticancer, antiproliferative, antitumor, kinase inhibition, antimicrobial, antioxidant, and analgesic effects. Recognizing the significance of these bioactive quinoxaline derivatives, researchers have dedicated their efforts to developing various synthetic methods for their production. This review aimed to compile the most recent findings on the synthesis and biological properties of quinoxaline derivatives from 2015 to 2023.

3-Methoxy-2-phenylimidazo[1,2-b]pyridazines highly active against Mycobacterium tuberculosis and Mycobacterium marinum

A series of 3-methoxy-2-phenylimidazo[1,2-b]pyridazine derivatives which were highly active against autoluminescent Mycobacterium tuberculosis (Mtb) and Mycobacterium marinum (Mm) in an in vitro assay were identified. SAR analysis showed that the most active compounds, which included a phenyl group bearing fluoro substituent(s) at C2, a methoxy function at C3, and a benzyl-heteroatom moiety at C6, exhibited in vitro MIC90 values generally around 0.63-1.26 μM against Mtb and Mm. However, these compounds were inactive against Mtb in vivo (mice), and investigations revealed very short metabolic half-lives (<10 min) when incubated with mouse liver microsomes. Multiple observations of side products produced from oxidative cleavage of the imidazole moiety during the chemical synthesis work suggested that this is a likely metabolic pathway leading to the lack of observed activity in vivo.

Synthesis and biological evaluation of 2-(Tetrazol-5-yl)sulfonylacetamides as inhibitors of Mycobacterium tuberculosis and Mycobacterium marinum

A series of 2-(tetrazol-5-yl)sulfonylacetamide derivatives were synthesized and evaluated for their in vitro inhibitory activity against Mycobacterium tuberculosis (Mtb) and Mycobacterium marinum (Mm). The most active compounds exhibited in vitro MIC90 values of 1.25 μg/mL against Mtb, but they were less effective against Mm (MIC90 ≥ 10 μg/mL). Despite the most active compounds having favourable physicochemical properties and one of them having a half-life of ∼3 h when incubated with mouse liver microsomes, two representative highly active compounds showed strong chemical reactivity to cysteine derivatives, as surrogate in vivo sulfur-centred nucleophiles, indicating excessive electrophilicity, and therefore, likely indiscriminate chemical reactivity in vivo, representing an unacceptably high risk of general toxicity, and low likelihood of being therapeutically effective.

Metal-free sulfonylation of quinoxalinones to access 2-sulfonyl-oxylated quinoxalines via oxidative O-S cross coupling

The C2 sulfonylation of quinoxalinones via a metal-free oxidative S-O cross-coupling strategy for synthesizing 2-sulfonyloxylated quinoxalines is established. It effectively solved the long-standing problems in the C2 transformation of quinoxalinones via a metal-free oxidative O-S coupling strategy. Compared with the traditional C2 transformed quinoxalinones-C2 chlorination method, this protocol is mild, facile, and environmentally friendly and exhibits good atomic economy and excellent functional group tolerance. Moreover, the utility of this methodology and the sulfonyloxyl handles was demonstrated through the synthesis of 2-substituted quinoxaline-based bioactive molecules.

Discovery of potent antitubercular agents: Design, synthesis and biological evaluation of 4-(3-(4-substitutedpiperazin-1-yl)-quinoxalin-2-yl)-naphthalen-1-ol analogues

A series of twenty-five novel 4-(3-(4-substituted piperazin-1-yl)-quinoxalin-2-yl)-naphthalen-1-ol analogues were synthesized, characterized and screened for in vitro antitubercular activity against Mycobacterium tuberculosis H37Rv strain. These compounds exhibited minimum inhibitory concentration in the range of 1.56-50 μg/mL. Among these derivatives, compounds 5a, 5b, 5f, 5m, 5p, and 5r displayed moderate activity (MIC 6.25 μg/mL). Compounds 5c, 5d, 5g, 5l, and 5o showed significant antitubercular activity (MIC 3.125 μg/mL), while compounds 5h, 5n, and 5q exhibited potent antitubercular activity (MIC 1.56 μg/mL). In addition, MTT assay was performed on the active analogues of the series against mouse macrophage cells to assess the cytotoxic effect of the newly synthesized compounds, and a selectivity index of the compounds was established. Selectivity index values of the most active compounds (5h, 5n, and 5q) are >47, indicating the compounds' suitability for further potential drug development. A molecular docking study was performed to understand the putative binding mode and binding strength of the selected significantly active and weakly active compounds with the target enzyme mycobacterial topoisomerase II using moxifloxacin as standard. In-silico ADME prediction and bioavailability studies of the titled compounds obey Lipinski's rule of five and Jorgensen's rule of three. To further ascertain the structure of the compounds, a suitable single crystal for the compounds 5a, 6, and 7d was developed and studied.

Quinoxaline Moiety: A Potential Scaffold against Mycobacterium tuberculosis

Background. The past decades have seen numerous efforts to develop new antitubercular agents. Currently, the available regimens are lengthy, only partially effective, and associated with high rates of adverse events. The challenge is therefore to develop new agents with faster and more efficient action. The versatile quinoxaline ring possesses a broad spectrum of pharmacological activities, ensuring considerable attention to it in the field of medicinal chemistry. Objectives. In continuation of our program on the pharmacological activity of quinoxaline derivatives, this review focuses on potential antimycobacterial activity of recent quinoxaline derivatives and discusses their structure-activity relationship for designing new analogs with improved activity. Methods. The review compiles recent studies published between January 2011 and April 2021. Results. The final total of 23 studies were examined. Conclusions. Data from studies of quinoxaline and quinoxaline 1,4-di-N-oxide derivatives highlight that specific derivatives show encouraging perspectives in the treatment of Mycobacterium tuberculosis and the recent growing interest for these scaffolds. These interesting results warrant further investigation, which may allow identification of novel antitubercular candidates based on this scaffold.

Recent advances in the synthesis and reactivity of quinoxaline

Quinoxalines are observed in several bioactive molecules and have been widely employed in designing molecules for DSSC's, optoelectronics, and sensing applications. Therefore, developing newer synthetic routes as well as novel ways for their functionalization is apparent.