Attenuation of Mycobacterium species through direct and macrophage mediated pathway by unsymmetrical diaryl urea

Tuberculosis is a major threat for mankind and the emergence of resistance strain of Mycobacterium tuberculosis (Mtb) against first line antibiotics makes it lethal for human civilization. In this study, we have synthesized different diaryl urea derivatives targeting the inhibition of mycolic acid biosynthesis. Among the 39 synthesized molecules, compounds 46, 57, 58 and 86 showed MIC values ≤ 10 μg/ml against H37Rv and mc26030 strains. The best molecule with a methyl at ortho position of the first aromatic ring and prenyl group at the meta position of the second aromatic ring showed the MIC value of 5.2 μg/ml and 1 μg/ml against H37Rv and mc26030 respectively, with mammalian cytotoxicity of 163.4 μg/ml. The effective compounds showed selective inhibitory effect on mycolic acid (epoxy mycolate) biosynthesis in14C-radiolabelled assay. At the same time these molecules also executed their potent immunomodulatory activity by up-regulation of IFN-γ and IL-12 and down-regulation of IL-10.Fil: Velappan, Anand Babu. Sastra University; IndiaFil: Charan Raja, Mamilla R.. Sastra University; IndiaFil: Datta, Dhrubajyoti. Indian Institute of Science Education and Research Pune; IndiaFil: Tsai, Yi Ting. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Biología Molecular y Celular de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Biología Molecular y Celular de Rosario; ArgentinaFil: Halloum, Iman. Université de Montpellier; Francia. Centre National de la Recherche Scientifique; FranciaFil: Wan, Baojie. University of Illinois; Estados UnidosFil: Kremer, Laurent. Université de Montpellier; Francia. Inserm; Francia. Centre National de la Recherche Scientifique; FranciaFil: Gramajo, Hugo Cesar. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Biología Molecular y Celular de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Biología Molecular y Celular de Rosario; ArgentinaFil: Franzblau, Scott G.. University of Illinois; Estados UnidosFil: Kar Mahapatra, Santanu. Sastra University; IndiaFil: Debnath, Joy. Sastra University; Indi

Repositioning Antitubercular 6-Nitro-2,3-dihydroimidazo[2,1-b][1,3]oxazoles for Neglected Tropical Diseases: Structure-Activity Studies on a Preclinical Candidate for Visceral Leishmaniasis.

6-Nitro-2,3-dihydroimidazo[2,1-b][1,3]oxazole derivatives were initially studied for tuberculosis within a backup program for the clinical trial agent pretomanid (PA-824). Phenotypic screening of representative examples against kinetoplastid diseases unexpectedly led to the identification of DNDI-VL-2098 as a potential first-in-class drug candidate for visceral leishmaniasis (VL). Additional work was then conducted to delineate its essential structural features, aiming to improve solubility and safety without compromising activity against VL. While the 4-nitroimidazole portion was specifically required, several modifications to the aryloxy side chain were well-tolerated e.g., exchange of the linking oxygen for nitrogen (or piperazine), biaryl extension, and replacement of phenyl rings by pyridine. Several less lipophilic analogues displayed improved aqueous solubility, particularly at low pH, although stability toward liver microsomes was highly variable. Upon evaluation in a mouse model of acute Leishmania donovani infection, one phenylpyridine derivative (37) stood out, providing efficacy surpassing that of the original preclinical lead

Development of (6 R)-2-Nitro-6-[4-(trifluoromethoxy)phenoxy]-6,7-dihydro-5 H-imidazo[2,1- b][1,3]oxazine (DNDI-8219): A New Lead for Visceral Leishmaniasis.

Discovery of the potent antileishmanial effects of antitubercular 6-nitro-2,3-dihydroimidazo[2,1- b][1,3]oxazoles and 7-substituted 2-nitro-5,6-dihydroimidazo[2,1- b][1,3]oxazines stimulated the examination of further scaffolds (e.g., 2-nitro-5,6,7,8-tetrahydroimidazo[2,1- b][1,3]oxazepines), but the results for these seemed less attractive. Following the screening of a 900-compound pretomanid analogue library, several hits with more suitable potency, solubility, and microsomal stability were identified, and the superior efficacy of newly synthesized 6 R enantiomers with phenylpyridine-based side chains was established through head-to-head assessments in a Leishmania donovani mouse model. Two such leads ( R-84 and R-89) displayed promising activity in the more stringent Leishmania infantum hamster model but were unexpectedly found to be potent inhibitors of hERG. An extensive structure-activity relationship investigation pinpointed two compounds ( R-6 and pyridine R-136) with better solubility and pharmacokinetic properties that also provided excellent oral efficacy in the same hamster model (>97% parasite clearance at 25 mg/kg, twice daily) and exhibited minimal hERG inhibition. Additional profiling earmarked R-6 as the favored backup development candidate

O sistema PBL, problem-based learning, no ensino de medicina no Brasil : análise bibliográfica sobre a sua execução

Introdução: Entre as estratégias de ensino e aprendizagem utilizadas nas práticas pedagógicas, a Problem Based Learning (PBL) (Aprendizagem Baseada em Problemas) é utilizada desde 1960, em especial nos cursos de Medicina. Mesmo sendo uma estratégia valiosa, um dos seus obstáculos é a pouca prática dos alunos em atividades autodirigidas, pesquisa e construção coletiva do conhecimento. Objetivo: Rastrear elementos constitutivos da PBL através de dados colhidos em artigos pesquisados em sítios de divulgação científica; Avaliar, nos estudos selecionados, os aspectos positivos e negativos que estejam relacionados com a metodologia do Sistema PBL aplicada ao ensino médico no Brasil. Metodologia: Estudo bibliográfico de 13 textos utilizando um modelo de desconstrução, denominada Análise Textual Discursiva (ATD) que consiste em: transformação dos artigos em pedaços menores; análise textual; identificação de padrões convergentes e divergentes em relação a PBL; organização e síntese dos dados, culminando com a elaboração de estratégia adaptativa da PBL para o curso de Medicina. Resultados: Foram encontradas 116 citações que convergiam para referências positivos acerca da metodologia PBL e 40 citações que divergiam acerca dos pontos positivos. Os aspectos positivos como o desenvolvimento de atitudes e habilidades; desenvolvimento de competências anteriores ao curso; efeitos positivos depois de terminada a graduação, como autonomia de estudo e a articulação entre currículo e realidade profissional, representam pontos a serem reforçados na aula. Em contraponto, foi observado que dentre os negativos a não compreensão do papel do professor como tutor; necessidade de conteúdo formal tradicional pelos alunos e a expectativa que o professor retire as suas dúvidas são pontos a serem evitados. Conclusões: A metodologia PBL deverá servir como metodologia ativa para aproveitar ao máximo as habilidades que os alunos já apresentam, potencializando o aprendizado na educação médica em sala de aula. Palavras-Chave: PBL; curso de medicina; metodologia ativa; educação médica.ABSTRACT Introduction: Among the teaching and learning strategies used in teaching practices, the Problem Based Learning (PBL) (Problem Based Learning) has been used since 1960, especially in medical courses. Although a valuable strategy, one of its obstacles is the lack of practice of students in self-directed activities, research and collective construction of knowledge. Objective: Tracking constitutive elements of PBL through data collected on items surveyed in science communication sites and arrange them in order to develop a student's adaptation strategy to this methodological way. Evaluate the selected studies, the positive and negative aspects that are related to the methodology of PBL system applied to medical education in Brazil. Methodology: bibliographic study of 13 texts using a deconstruction model, called Discursive Textual Analysis (DTA) consisting of: transforming items into smaller pieces; textual analysis; identifying convergent and divergent patterns in relation to PBL; organization and synthesis of data, culminating with in the development of adaptive strategy of PBL to Medical Course. Results: It has been found 116 quotes that converged into positive notes about the PBL methodology and 40 quotes that differed about the positive ones. These quotations are placed in lines of analysis, based on a model of adaptation of the PBL student body. The positive aspects represent points to be reinforced in the classroom and the negative ones to be avoided. Conclusions: The PBL methodology should serve as active methodology to make the most of the skills that students already have, enhancing learning in medical education in the classroom Keywords: PBL; medical schools; active methodology; medical education

Ruthenium(II) phosphine/diimine/picolinate complexes: inorganic compounds as agents against tuberculosis

This paper describes the synthesis and characterization of four new ruthenium complexes containing 1,4 bis(diphenylphosphino)butane (dppb), 2-pyridinecarboxylic acid anion (pic) and the diimines [(2,2′-bipyridine (bipy), 4,4′-dimethyl-2,2′-bipyridine (Me-bipy), 4,4′-dichloro-2,2′-bipyridine (Cl-bipy) and 1,10-phenanthroline (phen) as ligands, with formulae [Ru(pic)(dppb)(bipy)]PF6 (SCAR01), [Ru(pic)(dppb)(Me-bipy)]PF6 (SCAR02), [Ru(pic)(dppb)(Cl-bipy)]PF6 (SCAR03) and [Ru(pic)(dppb)(phen)]PF6 (SCAR04). Additionally, the in vitro anti-Mycobacterium tuberculosis (MTB) activity, cytotoxicity and activity against in vitro infection of these complexes and two more complexes, cis-[Ru(pic)(dppe)2]PF6 (SCAR05) and cis-[RuCl2(dppb)(bipy)] (SCAR06), and their free ligands are described and discussed. All compounds showed excellent MIC against MTB, low cytotoxicity and a selectivity index higher than 10. Also, all compounds showed significant intracellular inhibition and the compound SCAR05 showed a better activity than rifampin and SQ109. This is the first report of activity against in vitro infection of ruthenium compounds.CNPqFAPESP (08/10390-2; 09/06499-1)CYTEDRed Iberoamericana de Investigación y Desarrollo de Fármacos Basados en Compuestos Metálicos (RIIDFCM

Ruthenium(II) phosphine/diimine/picolinate complexes: inorganic compounds as agents against tuberculosis

This paper describes the synthesis and characterization of four new ruthenium complexes containing 1,4 bis(diphenylphosphino)butane (dppb), 2-pyridinecarboxylic acid anion (pic) and the diimines [(2,2′-bipyridine (bipy), 4,4′-dimethyl-2,2′-bipyridine (Me-bipy), 4,4′-dichloro-2,2′-bipyridine (Cl-bipy) and 1,10-phenanthroline (phen) as ligands, with formulae [Ru(pic)(dppb)(bipy)]PF6 (SCAR01), [Ru(pic)(dppb)(Me-bipy)]PF6 (SCAR02), [Ru(pic)(dppb)(Cl-bipy)]PF6 (SCAR03) and [Ru(pic)(dppb)(phen)]PF6 (SCAR04). Additionally, the in vitro anti-Mycobacterium tuberculosis (MTB) activity, cytotoxicity and activity against in vitro infection of these complexes and two more complexes, cis-[Ru(pic)(dppe)2]PF6 (SCAR05) and cis-[RuCl2(dppb)(bipy)] (SCAR06), and their free ligands are described and discussed. All compounds showed excellent MIC against MTB, low cytotoxicity and a selectivity index higher than 10. Also, all compounds showed significant intracellular inhibition and the compound SCAR05 showed a better activity than rifampin and SQ109. This is the first report of activity against in vitro infection of ruthenium compounds.CNPqFAPESP (08/10390-2; 09/06499-1)CYTEDRed Iberoamericana de Investigación y Desarrollo de Fármacos Basados en Compuestos Metálicos (RIIDFCM

In vitro and in vivo antimycobacterial activities of ketone and amide derivatives of quinoxaline 1,4-di-N-oxide

Abstract: Objectives: To evaluate a novel series of quinoxaline 1,4-di-N-oxides for in vitro activity against Mycobacterium tuberculosis and for efficacy in a mouse model of tuberculosis (TB). Methods: Ketone and amide derivatives of quinoxaline 1,4-di-N-oxide were evaluated in in vitro and in vivo tests including: (i) activity against M. tuberculosis resistant to currently used antitubercular drugs including multidrug-resistant strains (MDR-TB resistant to isoniazid and rifampicin); (ii) activity against non-replicating persistent (NRP) bacteria; (iii) MBC; (iv) maximum tolerated dose, oral bioavailability and in vivo efficacy in mice; and (v) potential for cross-resistance with another bioreduced drug, PA-824. Results: Ten compounds were tested on single drug-resistant M. tuberculosis. In general, all compounds were active with ratios of MICs against resistant and non-resistant strains of <= 4.00. One compound, 5, was orally active in a murine model of TB, bactericidal, active against NRP bacteria and active on MDR-TB and poly drug-resistant clinical isolates (resistant to 3-5 antitubercular drugs). Conclusions: Quinoxaline 1,4-di-N-oxides represent a new class of orally active antitubercular drugs. They are likely bioreduced to an active metabolite, but the pathway of bacterial activation was different from PA-824, a bioreducible nitroimidazole in clinical trials. Compound 5 was bactericidal and active on NRP organisms indicating that activation occurred in both growing and non-replicating bacteria leading to cell death. The presence of NRP bacteria is believed to be a major factor responsible for the prolonged nature of antitubercular therapy. If the bactericidal activity and activity on non-replicating bacteria in vitro translate to in vivo conditions, quinoxaline 1,4-di-N-oxides may offer a path to shortened therapy

Efficacy of quinoxaline-2-carboxylate 1,4-di-N-oxide derivatives in experimental tuberculosis

This study extends earlier reports regarding the in vitro efficacies of the 1,4-di-N-oxide quinoxaline derivatives against Mycobacterium tuberculosis and has led to the discovery of a derivative with in vivo efficacy in the mouse model of tuberculosis. Quinoxaline-2-carboxylate 1,4-di-N-oxide derivatives were tested in vitro against a broad panel of single-drug-resistant M. tuberculosis strains. The susceptibilities of these strains to some compounds were comparable to those of strain H(37)Rv, as indicated by the ratios of MICs for resistant and nonresistant strains, supporting the premise that 1,4-di-N-oxide quinoxaline derivatives have a novel mode of action unrelated to those of the currently used antitubercular drugs. Specific derivatives were further evaluated in a series of in vivo assays, including evaluations of the maximum tolerated doses, the levels of oral bioavailability, and the efficacies in a low-dose aerosol model of tuberculosis in mice. One compound, ethyl 7-chloro-3-methylquinoxaline-2-carboxylate 1,4-dioxide, was found to be (i) active in reducing CFU counts in both the lungs and spleens of infected mice following oral administration, (ii) active against PA-824-resistant Mycobacterium bovis, indicating that the pathway of bioreduction/activation is different from that of PA-824 (a bioreduced nitroimidazole that is in clinical trials), and (iii) very active against nonreplicating bacteria adapted to low-oxygen conditions. These data indicate that 1,4-di-N-oxide quinoxalines hold promise for the treatment of tuberculosis

Identification of a small molecule with activity against drug-resistant and persistent tuberculosis

A cell-based phenotypic screen for inhibitors of biofilm formation in mycobacteria identified the small molecule TCA1, which has bactericidal activity against both drug-susceptible and -resistant Mycobacterium tuberculosis (Mtb) and sterilizes Mtb in vitro combined with rifampicin or isoniazid. In addition, TCA1 has bactericidal activity against nonreplicating Mtb in vitro and is efficacious in acute and chronic Mtb infection mouse models both alone and combined with rifampicin or isoniazid. Transcriptional analysis revealed that TCA1 down-regulates genes known to be involved in Mtb persistence. Genetic and affinity-based methods identified decaprenyl-phosphoryl-beta-D-ribofuranose oxidoreductase DprE1 and MoeW, enzymes involved in cell wall and molybdenum cofactor biosynthesis, respectively, as targets responsible for the activity of TCA1. These in vitro and in vivo results indicate that this compound functions by a unique mechanism and suggest that TCA1 may lead to the development of a class of antituberculosis agents