RESUMO

Objectives: To define the genetic basis of clarithromycin resistance among isolates of the Mycobacterium abscessus group (MAG). Methods: We analysed 133 isolates identified as MAG. Species identification was confirmed by sequencing the rpoB gene. Clarithromycin susceptibility testing was performed according to CLSI recommendations, with an extended 14 day incubation. Known resistance genotypes of erm(41) and rrl were identified by sequencing; the presence of deletions in erm(41) was detected by PCR. Results: The 133 MAG isolates included 82 M. abscessus, 27 Mycobacterium massiliense and 24 Mycobacterium bolletii. After the 3 day incubation, only five isolates demonstrated clarithromycin resistance (R); after 14 days of extended incubation, an additional 92 exhibited inducible resistance (IR), with the remaining being susceptible (S). The distribution of susceptibility phenotypes varied among the species. Among M. abscessus isolates, 11% were S, 84% IR and 5% R; among M. bolletii isolates, 96% were IR and 4% R; and among M. massiliense isolates 100% were S. Sequencing of rrl identified only a single isolate with the A2058G mutation. Deletions in erm(41) were present in 30 susceptible isolates; among the remaining 103 isolates, 97 were R or IR (sensitivity, 83%; specificity, 100%; positive predictive value, 100%; negative predictive value, 94%). Among the six susceptible isolates without deletions, all carried the erm(41) T28C point mutation. Conclusions: A significant proportion of MAG isolates demonstrate inducible resistance to clarithromycin that is only detectable with an extended 14 day incubation. Further, the majority of clarithromycin-susceptible MAG isolates have characteristic deletions in erm(41) that can rapidly and reliably be detected by a simple PCR.

Assuntos

Antibacterianos/farmacologia , Claritromicina/farmacologia , Farmacorresistência Bacteriana , Genótipo , Mycobacterium abscessus/genética , Reação em Cadeia da Polimerase/métodos , tRNA Metiltransferases/genética , Proteínas de Bactérias/genética , RNA Polimerases Dirigidas por DNA/genética , Regulação Bacteriana da Expressão Gênica , Humanos , Infecções por Mycobacterium não Tuberculosas/microbiologia , Mycobacterium abscessus/efeitos dos fármacos , Mycobacterium abscessus/enzimologia , Análise de Sequência de DNA , Deleção de Sequência

RESUMO

Cisplatin and its derivatives are the main metallodrugs used in cancer therapy. However, low selectivity, toxicity and drug resistance are associated with their use. The zinc(II) (Zn(II)) thiosemicarbazone complexes [Zn(atc-Et)2] (1) and [Zn(atc-Ph)2] (2) (atc-R: monovalent anion of 2-acetylpyridine N4-R-thiosemicarbazone) were synthesized and fully characterized in the solid state and in solution via elemental analysis, Fourier transform infrared (FTIR), ultraviolet-visible (UV-Vis) and proton nuclear magnetic resonance (¹H NMR) spectroscopy, conductometry and single-crystal X-ray diffraction. The cytotoxicity of these complexes was evaluated in the HepG2, HeLa, MDA-MB-231, K-562, DU 145 and MRC-5 cancer cell lines. The strongest antiproliferative results were observed in MDA-MB-231 and HepG2 cells, in which these complexes displayed significant selective toxicity (3.1 and 3.6, respectively) compared with their effects on normal MRC-5 cells. In vivo studies were performed using an alternative model (Artemia salina L.) to assure the safety of these complexes, and the results were confirmed using a conventional model (BALB/c mice). Finally, tests of oral bioavailability showed maximum plasma concentrations of 3029.50 µg/L and 1191.95 µg/L for complexes 1 and 2, respectively. According to all obtained results, both compounds could be considered as prospective antiproliferative agents that warrant further research.

Assuntos

Antineoplásicos/síntese química , Antineoplásicos/farmacocinética , Tiossemicarbazonas/síntese química , Tiossemicarbazonas/farmacocinética , Zinco/química , Animais , Antineoplásicos/administração & dosagem , Antineoplásicos/química , Artemia , Disponibilidade Biológica , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Células HeLa , Células Hep G2 , Humanos , Técnicas In Vitro , Camundongos , Estrutura Molecular , Tiossemicarbazonas/administração & dosagem , Tiossemicarbazonas/química , Testes de Toxicidade Aguda

RESUMO

In the search for new therapeutic tools against tuberculosis and to further address the therapeutic potential of pyridine-2-thiol 1-oxide (Hmpo) metal complexes, two new octahedral [M(III)(mpo)3] complexes, with M = Ga or Bi, were synthesized and characterized in the solid state and in solution. Attempts to crystallize [Ga(III)(mpo)3] in CH2Cl2 led to single crystals of the reaction product [GaCl(mpo)2], where the gallium(III) ion is in a square basis pyramidal environment, trans-coordinated at the basis to two pyridine-2-thiolato 1-oxide anions acting as bidentate ligands through their oxygen and sulfur atoms. The biological activity of the new [M(III)(mpo)3] complexes together with that of the previously reported Fe(III) analogous compound and the pyridine-2-thiol 1-oxide sodium salt (Na mpo) was evaluated on Mycobacterium tuberculosis. The compounds showed excellent activity, both in the standard strain H37Rv ATCC 27294 (pan-susceptible) and in five clinical isolates that are resistant to the standard first-line anti-tuberculosis drugs isoniazid and rifampicin. These pyridine-2-thiol 1-oxide derivatives are promising compounds for the treatment of resistant tuberculosis.

Assuntos

Antibacterianos/química , Antibacterianos/farmacologia , Complexos de Coordenação/química , Complexos de Coordenação/farmacologia , Mycobacterium tuberculosis/efeitos dos fármacos , Animais , Antibacterianos/toxicidade , Bismuto/química , Chlorocebus aethiops , Complexos de Coordenação/toxicidade , Cristalografia por Raios X , Gálio/química , Ferro/química , Testes de Sensibilidade Microbiana , Células Vero

RESUMO

Through a systematic variation on the structure of a series of manganese complexes derived from 2-acetylpyridine-N(4)-R-thiosemicarbazones (Hatc-R), structural features have been investigated with the aim of obtaining complexes with potent anti-Mycobacterium tuberculosis activity. The analytical methods used for characterization included FTIR, EPR, UV-visible, elemental analysis, cyclic voltammetry, magnetic susceptibility measurement and single crystal X-ray diffractometry. Density functional theory (DFT) calculations were performed in order to evaluate the contribution of the thiosemicarbazonate ligands on the charge distribution of the complexes by changing the peripheral groups as well as to verify the Mn-donor atoms bond dissociation predisposition. The results obtained are consistent with the monoanionic N,N,S-tridentate coordination of the thiosemicarbazone ligands, resulting in octahedral complexes of the type [Mn(atc-R)2], paramagnetic in the extension of 5 unpaired electrons, whose EPR spectra are consistent for manganese(II). The electrochemical analyses show two nearly reversible processes, which are influenced by the peripheral substituent groups at the N4 position of the atc-R(1-) ligands. The minimal inhibitory concentration (MIC) of these compounds against M. tuberculosis as well as their in vitro cytotoxicity on VERO and J774A.1 cells (IC50) was determined in order to find their selectivity index (SI) (SI=IC50/MIC). The results evidenced that the compounds described here can be considered as promising anti-M. tuberculosis agents, with SI values comparable or better than some commercial drugs available for the tuberculosis treatment.

Assuntos

Antibacterianos/química , Antibacterianos/farmacologia , Manganês/química , Mycobacterium tuberculosis/efeitos dos fármacos , Tiossemicarbazonas/química , Tiossemicarbazonas/farmacologia , Animais , Chlorocebus aethiops , Cristalografia por Raios X , Testes de Sensibilidade Microbiana , Estrutura Molecular , Células Vero

RESUMO

Rifampicin, discovered more than 50 years ago, represents the last novel class of antibiotics introduced for the first-line treatment of tuberculosis. Drugs in this class form part of a 6-month regimen that is ineffective against MDR and XDR TB, and incompatible with many antiretroviral drugs. Investments in R&D strategies have increased substantially in the last decades. However, the number of new drugs approved by drug regulatory agencies worldwide does not increase correspondingly. Ruthenium complexes (SCAR) have been tested in our laboratory and showed promising activity against Mycobacterium tuberculosis. These complexes showed up to 150 times higher activity against MTB than its organic molecule without the metal (free ligand), with low cytotoxicity and high selectivity. In this study, promising results inspired us to seek a better understanding of the biological activity of these complexes. The in vitro biological results obtained with the SCAR compounds were extremely promising, comparable to or better than those for first-line drugs and drugs in development. Moreover, SCAR 1 and 4, which presented low acute toxicity, were assessed by Ames test, and results demonstrated absence of mutagenicity.

Assuntos

Antituberculosos/farmacologia , Complexos de Coordenação/farmacologia , Iminas/farmacologia , Mycobacterium tuberculosis/efeitos dos fármacos , Fosfinas/farmacologia , Ácidos Picolínicos/farmacologia , Rutênio/farmacologia , Animais , Antituberculosos/efeitos adversos , Antituberculosos/síntese química , Antituberculosos/química , Complexos de Coordenação/síntese química , Complexos de Coordenação/química , Farmacorresistência Bacteriana/efeitos dos fármacos , Feminino , Humanos , Iminas/síntese química , Iminas/química , Camundongos , Camundongos Endogâmicos C57BL , Testes de Sensibilidade Microbiana , Mutagênese/efeitos dos fármacos , Testes de Mutagenicidade , Mycobacterium tuberculosis/crescimento & desenvolvimento , Mycobacterium tuberculosis/isolamento & purificação , Fosfinas/síntese química , Fosfinas/química , Ácidos Picolínicos/síntese química , Ácidos Picolínicos/química , Rutênio/química , Testes de Toxicidade Aguda

RESUMO

Paepalanthus spp., Eriocaulaceae, are native plants from Brazil known as "sempre-vivas" (everlasting flowers). In this work, we evaluated the potential anti-mycobacterial activity of two methoxylated flavonoids (flavonoid 7-methylquercetagetin and 7-methylquercetagetin-4'-O-β-D-glucopyranoside) isolated and identified from P. latipes and the naphthopyranone fractions from P. bromeliodes ethanolic extracts. The MIC value of 500 µg/mL was verified for all compounds tested against M. tuberculosis H37Rv. For M. avium, the MIC value ranged from 1000-2000 µg/mL excepting to naphthopyranone fractions with MIC of 500 µg/mL. This is the first report of activity determination of Paepalanthus spp. flavonoids activity against Mycobacterium tuberculosis and M. avium.

RESUMO

This paper describes the synthesis and in vitro biological activities of imidazolidine and hexahydropyrimidine derivatives against bacteria (Escherichia coli, Staphylococcus aureus and Mycobacterium tuberculosis) and Leishmania protozoa. Out of sixteen heterocyclic derivatives tested, none were cytotoxic against mammalian cells. The compounds showed significant bacterial effects and leishmanicidal activity. Compounds 4a and 4c were active against S. aureus and E. coli, respectively. Compounds 3a-3f, 4h and 4i presented promising results against M. tuberculosis, with MIC values ranging from 12.5 to 25.0 µg/mL, comparable to the "first and second line" drugs used to treat tuberculosis. Compounds 4a, 4c and 4e were active against L major. Three of them were structurally characterized by single-crystal X-ray diffraction.

Assuntos

Antibacterianos/síntese química , Antibacterianos/farmacologia , Antiparasitários , Bactérias/efeitos dos fármacos , Imidazolidinas , Leishmania/efeitos dos fármacos , Pirimidinas , Animais , Antibacterianos/química , Antiparasitários/síntese química , Antiparasitários/química , Antiparasitários/farmacologia , Células Cultivadas , Cristalografia por Raios X , Humanos , Imidazolidinas/síntese química , Imidazolidinas/química , Imidazolidinas/farmacologia , Camundongos , Viabilidade Microbiana/efeitos dos fármacos , Modelos Moleculares , Estrutura Molecular , Mycobacterium tuberculosis/efeitos dos fármacos , Pirimidinas/síntese química , Pirimidinas/química , Pirimidinas/farmacologia

RESUMO

A new dihydropyranexanthone derived from the natural xanthone lichexanthone (1) was synthesised and, together with other 18 derivatives including ω-bromo and ω-aminoalkoxylxanthones (containing methyl, ethyl, propyl, tertbutylamino and piperidinyl moieties), were tested against Mycobacterium tuberculosis. Nine ω-aminoalkoxylxanthones showed good antimycobacterial activity, and their in vitro cytotoxicity was determined using VERO cells in order to calculate the selectivity index (SI). One of these nitrogenated xanthone derivatives showed very promising results, with MIC of 2.6 µM and SI of 48. This MIC is comparable to values found in "first and second line" drugs commonly used to treat TB. In order to understand better about this compound, it was evaluated together with two other ones that showed good SI, against resistant clinical strains of M. tuberculosis to verify the existence of cross-resistance. A chemometrical approach was useful to establish a pattern of antitubercular activity among the group of ω-aminoalkoxylxanthones, according to some structural and chemical features.

Assuntos

Antituberculosos/química , Antituberculosos/farmacologia , Mycobacterium tuberculosis/efeitos dos fármacos , Xantonas/química , Animais , Antituberculosos/síntese química , Chlorocebus aethiops , Humanos , Testes de Sensibilidade Microbiana , Estrutura Molecular , Células Vero , Xantonas/síntese química , Xantonas/farmacologia

RESUMO

Our purpose was to determine the anti-Mycobacterium tuberculosis activity of the metabolites produced by the endophitic fungus Phomopsis stipata (Lib.) B. Sutton, (Diaporthaceae), cultivated in different media. The antimycobacterial activity was assessed through the Resazurin Microtiter Assay (REMA) and the cytotoxicity test performed on macrophage cell line. The extracts derived from fungi grown on Corn Medium and Potato Dextrose Broth presented the smallest values of Minimum Inhibitory Concentration (MIC) and low cytotoxicity, which implies a high selectivity index. This is the first report on the chemical composition and antitubercular activity of metabolites of P. stipata, as well as the influence of culture medium on these properties.

Assuntos

Antifúngicos/metabolismo , Técnicas In Vitro , Infecções por Mycobacterium , Macrófagos Alveolares/metabolismo , Mycobacterium tuberculosis/isolamento & purificação , Mycobacterium tuberculosis/metabolismo , Técnicas e Procedimentos Diagnósticos , Metodologia como Assunto

RESUMO

Our purpose was to determine the anti-Mycobacterium tuberculosis activity of the metabolites produced by the endophitic fungus Phomopsis stipata (Lib.) B. Sutton, (Diaporthaceae), cultivated in different media. The antimycobacterial activity was assessed through the Resazurin Microtiter Assay (REMA) and the cytotoxicity test performed on macrophage cell line. The extracts derived from fungi grown on Corn Medium and Potato Dextrose Broth presented the smallest values of Minimum Inhibitory Concentration (MIC) and low cytotoxicity, which implies a high selectivity index. This is the first report on the chemical composition and antitubercular activity of metabolites of P. stipata, as well as the influence of culture medium on these properties.