- Metal-Free Synthesis of Heteroaryl Amines or Their Hydrochlorides via an External-Base-Free and Solvent-Free C-N Coupling Protocol
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Herein, a metal-free and solvent-free protocol was developed for the C-N coupling of heteroaryl halides and amines, which afforded numerous heteroaryl amines or their hydrochlorides without any external base. Further investigations elucidated that the basicity of amines and specific interactions derived from the X-ray crystallography analysis of 3j′·HCl played pivotal roles in the reactions. Moreover, this protocol was scalable to gram scales and applicable to drug molecules, which demonstrated its practical value for further applications.
- Fan, Guang-Gao,Jiang, Bo-Wen,Sang, Wei,Cheng, Hua,Zhang, Rui,Yu, Bao-Yi,Yuan, Ye,Chen, Cheng,Verpoort, Francis
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p. 14627 - 14639
(2021/11/01)
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- Multistage Antiplasmodium Activity of Astemizole Analogues and Inhibition of Hemozoin Formation as a Contributor to Their Mode of Action
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A drug repositioning approach was leveraged to derivatize astemizole (AST), an antihistamine drug whose antimalarial activity was previously identified in a high-throughput screen. The multistage activity potential against the Plasmodium parasite's life cycle of the subsequent analogues was examined by evaluating against the parasite asexual blood, liver, and sexual gametocytic stages. In addition, the previously reported contribution of heme detoxification to the compound's mode of action was interrogated. Ten of the 17 derivatives showed half-maximal inhibitory concentrations (IC50s) of 50 100). Screening of AST and its analogues against gametocytes revealed their moderate activity (IC50: 1-5 μM) against late stage P. falciparum gametocytes, while the evaluation of activity against P. berghei liver stages identified one compound (3) with 3-fold greater activity than the parent AST compound. Mechanistic studies showed a strong correlation between in vitro inhibition of β-hematin formation by the AST derivatives and their antiplasmodium IC50s. Analyses of intracellular inhibition of hemozoin formation within the parasite further yielded signatures attributable to a possible perturbation of the heme detoxification machinery.
- Kumar, Malkeet,Okombo, John,Mambwe, Dickson,Taylor, Dale,Lawrence, Nina,Reader, Janette,Van Der Watt, Mari?tte,Fontinha, Diana,Sanches-Vaz, Margarida,Bezuidenhout, Belinda C.,Lauterbach, Sonja B.,Liebenberg, Dale,Birkholtz, Lyn-Marie,Coetzer, Theresa L.,Prudêncio, Miguel,Egan, Timothy J.,Wittlin, Sergio,Chibale, Kelly
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p. 303 - 315
(2019/01/15)
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- Astemizole analogues with reduced hERG inhibition as potent antimalarial compounds
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Astemizole is a H1-antagonist endowed with antimalarial activity, but has hERG liabilities. Systematic structural modifications of astemizole led to the discovery of analogues that display very potent activity as inhibitors of the growth of the Plasmodium parasite, but show a decreased hERG inhibition, when compared to astemizole. These compounds can be used as starting point for the development of a new class of antimalarials.
- Tian, Junjun,Vandermosten, Leen,Peigneur, Steve,Moreels, Lien,Rozenski, Jef,Tytgat, Jan,Herdewijn, Piet,Van den Steen, Philippe E.,De Jonghe, Steven
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p. 6332 - 6344
(2017/10/23)
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- Synthesis and anti-Plasmodium activity of benzimidazole analogues structurally related to astemizole
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A series of compounds structurally related to astemizole were designed and synthesized with the goal of determining their anti-Plasmodium activity. Several modifications of the astemizole structure, namely the removal of the 4-fluorobenzyl and/ or 4-methoxyphenethyl moieties, substitution of the benzene ring of the benzimidazole scaffold, replacement of the fluorine atom in the 4-fluorobenzyl group, and variation of the 4-aminopiperidine moiety, were explored. In vitro evaluation of the anti-Plasmodium activity of these compounds using the ItG strain showed that astemizole and some of its structurally similar derivatives have IC50 values in the nanomolar range and exhibit toxicity towards the parasite over Chinese ovarian hamster (CHO) cells with a selectivity as high as 200. The presence of a secondary cyclic amine at position 2 and substitution with chlorine at positions 4 and 5 in the benzimidazole moiety are two modifications that resulted in potent and selective antimalarials based on astemizole.
- Roman, Gheorghe,Crandall, Ian E.,Szarek, Walter A.
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p. 1795 - 1804
(2014/01/06)
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- New antihistaminic N-heterocyclic 4-piperidinamines. 1. Synthesis and antihistaminic activity of N-(4-piperidinyl)-1H-benzimidazol-2-amines
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The synthesis of a series N-(4-piperidinyl)-1H-benzimidazol-2-amines and the preliminary evaluation of their in vitro and in vivo antihistaminic activity are described. Cyclodesulfurization of (2-aminophenyl) thioureas with mercury(II) oxide resulted in 2-aminobenzimidazole intermediates, which were monoalkylated on the endo-nitrogen atom. After deprotection of the piperideine nitrogen atom with 48% aqueous hydrobromic acid solution, the title compounds were obtained by three different methods, viz. alkylation, reductive amination, or oxirane ring-opening reactions. The in vivo antihistaminic activity was evaluated by the compound 48/80 induced lethality test in rats and histamine-induced lethality test in guinea pigs after oral and/or subcutaneous administration. The duration of action, for a selected number of compounds, was studied in the guinea pig. The phenylethyl derivatives showed the most potent antihistamine properties after oral administration in both animal species.
- Janssens,Torremans,Janssen,Stokbroekx,Luyckx
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p. 1925 - 1933
(2007/10/02)
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