Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Results 1 - 7 de 7
Filter
Add more filters










Database
Language
Publication year range
1.
Med Chem ; 15(1): 17-27, 2019.
Article in English | MEDLINE | ID: mdl-29792151

ABSTRACT

BACKGROUND: We screened a large library of differently decorated imidazo-pyrazole and pyrazole derivatives as possible new antitubercular agents and this preliminary screening showed that many compounds are able to totally inhibit Mycobacterium growth (>90 %). Among the most active compounds, we selected some new possible hits based on their similarities and, at the same time, on their novelty with respect to the pipeline drugs. METHODS: In order to increase the potency and obtain more information about structure-activity relationship (SAR), we designed and synthesized three new series of compounds (2a-e, 3a-e, and 4a-l). CONCLUSION: Performed tests confirmed that both new pyrazoles and imidazo-pyrazoles could represent a new starting point to obtain more potent compounds and further work is now underway to identify the protein targets of this new class of anti-TB agents.


Subject(s)
Antitubercular Agents/pharmacology , Imidazoles/pharmacology , Pyrazoles/pharmacology , Small Molecule Libraries/pharmacology , Animals , Antitubercular Agents/chemical synthesis , Antitubercular Agents/chemistry , Antitubercular Agents/toxicity , Chlorocebus aethiops , Imidazoles/chemical synthesis , Imidazoles/chemistry , Imidazoles/toxicity , Microbial Sensitivity Tests , Mycobacterium tuberculosis/drug effects , Pyrazoles/chemical synthesis , Pyrazoles/chemistry , Pyrazoles/toxicity , Small Molecule Libraries/chemistry , Structure-Activity Relationship , Vero Cells
2.
ChemMedChem ; 11(10): 1078-89, 2016 05 19.
Article in English | MEDLINE | ID: mdl-27097919

ABSTRACT

Tuberculosis (TB) remains one of the major causes of death worldwide, in particular because of the emergence of multidrug-resistant TB. Herein we explored the potential of an alternative class of molecules as anti-TB agents. Thus, a series of novel 3-substituted triazolophthalazines was quickly and easily prepared from commercial hydralazine hydrochloride as starting material and were further evaluated for their antimycobacterial activities and cytotoxicities. Four of the synthesized compounds were found to effectively inhibit the Mycobacterium tuberculosis (M.tb) H37 Rv strain with minimum inhibitory concentration (MIC) values <10 µg mL(-1) , whereas no compounds displayed cytotoxicity against HCT116 human cell lines (IC50 >100 µm). More remarkably, the most potent compounds proved to be active to a similar extent against various multidrug-resistant M.tb strains, thus uncovering a mode of action distinct from that of standard antitubercular agents. Overall, their ease of preparation, combined with their attractive antimycobacterial activities, make such triazolophthalazine-based derivatives promising leads for further development.


Subject(s)
Antitubercular Agents/pharmacology , Mycobacterium tuberculosis/drug effects , Phthalazines/pharmacology , Antitubercular Agents/chemistry , Antitubercular Agents/toxicity , Cell Survival/drug effects , Cinnamates/chemistry , Drug Resistance, Bacterial/drug effects , HCT116 Cells , Humans , Microbial Sensitivity Tests , Phthalazines/chemistry , Phthalazines/toxicity , Tuberculosis
3.
J Am Chem Soc ; 134(2): 912-5, 2012 Jan 18.
Article in English | MEDLINE | ID: mdl-22188377

ABSTRACT

Benzothiazinones (BTZs) are antituberculosis drug candidates with nanomolar bactericidal activity against tubercle bacilli. Here we demonstrate that BTZs are suicide substrates of the FAD-dependent decaprenylphosphoryl-ß-D-ribofuranose 2'-oxidase DprE1, an enzyme involved in cell-wall biogenesis. BTZs are reduced by DprE1 to an electrophile, which then reacts in a near-quantitative manner with an active-site cysteine of DprE1, thus providing a rationale for the extraordinary potency of BTZs. Mutant DprE1 enzymes from BTZ-resistant strains reduce BTZs to inert metabolites while avoiding covalent inactivation. Our results explain the basis for drug sensitivity and resistance to an exceptionally potent class of antituberculosis agents.


Subject(s)
Antitubercular Agents/pharmacology , Bacterial Proteins/antagonists & inhibitors , Mycobacterium/enzymology , Oxidoreductases/antagonists & inhibitors , Antitubercular Agents/chemistry , Molecular Structure , Structure-Activity Relationship
4.
PLoS One ; 5(11): e15494, 2010 Nov 15.
Article in English | MEDLINE | ID: mdl-21085589

ABSTRACT

The selection and soaring spread of Mycobacterium tuberculosis multidrug-resistant (MDR-TB) and extensively drug-resistant strains (XDR-TB) is a severe public health problem. Currently, there is an urgent need for new drugs for tuberculosis treatment, with novel mechanisms of action and, moreover, the necessity to identify new drug targets. Mycobacterial phosphoribosylpyrophosphate synthetase (MtbPRPPase) is a crucial enzyme involved in the biosynthesis of decaprenylphosphoryl-arabinose, an essential precursor for the mycobacterial cell wall biosynthesis. Moreover, phosphoribosylpyrophosphate, which is the product of the PRPPase catalyzed reaction, is the precursor for the biosynthesis of nucleotides and of some amino acids such as histidine and tryptophan. In this context, the elucidation of the molecular and functional features of MtbPRPPase is mandatory. MtbPRPPase was obtained as a recombinant form, purified to homogeneity and characterized. According to its hexameric form, substrate specificity and requirement of phosphate for activity, the enzyme proved to belong to the class I of PRPPases. Although the sulfate mimicked the phosphate, it was less effective and required higher concentrations for the enzyme activation. MtbPRPPase showed hyperbolic response to ribose 5-phosphate, but sigmoidal behaviour towards Mg-ATP. The enzyme resulted to be allosterically activated by Mg(2+) or Mn(2+) and inhibited by Ca(2+) and Cu(2+) but, differently from other characterized PRPPases, it showed a better affinity for the Mn(2+) and Cu(2+) ions, indicating a different cation binding site geometry. Moreover, the enzyme from M. tuberculosis was allosterically inhibited by ADP, but less sensitive to inhibition by GDP. The characterization of M. tuberculosis PRPPase provides the starting point for the development of inhibitors for antitubercular drug design.


Subject(s)
Bacterial Proteins/metabolism , Cell Wall/metabolism , Mycobacterium tuberculosis/enzymology , Ribose-Phosphate Pyrophosphokinase/metabolism , Bacterial Proteins/chemistry , Bacterial Proteins/genetics , Binding Sites/genetics , Biocatalysis/drug effects , Cations, Divalent/pharmacology , Circular Dichroism , Enzyme Activation/drug effects , Enzyme Stability , Hot Temperature , Kinetics , Magnesium/pharmacology , Manganese/pharmacology , Models, Molecular , Mycobacterium tuberculosis/genetics , Mycobacterium tuberculosis/metabolism , Protein Denaturation , Protein Multimerization , Protein Structure, Tertiary , Recombinant Proteins/chemistry , Recombinant Proteins/metabolism , Ribose-Phosphate Pyrophosphokinase/chemistry , Ribose-Phosphate Pyrophosphokinase/genetics , Substrate Specificity
5.
BMC Microbiol ; 9: 200, 2009 Sep 17.
Article in English | MEDLINE | ID: mdl-19761586

ABSTRACT

BACKGROUND: Burkholderia cenocepacia are opportunistic Gram-negative bacteria that can cause chronic pulmonary infections in patients with cystic fibrosis. These bacteria demonstrate a high-level of intrinsic antibiotic resistance to most clinically useful antibiotics complicating treatment. We previously identified 14 genes encoding putative Resistance-Nodulation-Cell Division (RND) efflux pumps in the genome of B. cenocepacia J2315, but the contribution of these pumps to the intrinsic drug resistance of this bacterium remains unclear. RESULTS: To investigate the contribution of efflux pumps to intrinsic drug resistance of B. cenocepacia J2315, we deleted 3 operons encoding the putative RND transporters RND-1, RND-3, and RND-4 containing the genes BCAS0591-BCAS0593, BCAL1674-BCAL1676, and BCAL2822-BCAL2820. Each deletion included the genes encoding the RND transporter itself and those encoding predicted periplasmic proteins and outer membrane pores. In addition, the deletion of rnd-3 also included BCAL1672, encoding a putative TetR regulator. The B. cenocepacia rnd-3 and rnd-4 mutants demonstrated increased sensitivity to inhibitory compounds, suggesting an involvement of these proteins in drug resistance. Moreover, the rnd-3 and rnd-4 mutants demonstrated reduced accumulation of N-acyl homoserine lactones in the growth medium. In contrast, deletion of the rnd-1 operon had no detectable phenotypes under the conditions assayed. CONCLUSION: Two of the three inactivated RND efflux pumps in B. cenocepacia J2315 contribute to the high level of intrinsic resistance of this strain to some antibiotics and other inhibitory compounds. Furthermore, these efflux systems also mediate accumulation in the growth medium of quorum sensing molecules that have been shown to contribute to infection. A systematic study of RND efflux systems in B. cenocepacia is required to provide a full picture of intrinsic antibiotic resistance in this opportunistic bacterium.


Subject(s)
Bacterial Outer Membrane Proteins/metabolism , Burkholderia cepacia/genetics , Drug Resistance, Multiple, Bacterial/genetics , Membrane Transport Proteins/metabolism , Acyl-Butyrolactones/analysis , Bacterial Outer Membrane Proteins/genetics , Burkholderia cepacia/drug effects , Burkholderia cepacia/metabolism , DNA, Bacterial/genetics , Gene Expression Regulation, Bacterial , Genes, Bacterial , Membrane Transport Proteins/genetics , Microbial Sensitivity Tests , Mutagenesis , Ofloxacin/metabolism , Operon , Quorum Sensing
6.
J Bacteriol ; 189(3): 730-40, 2007 Feb.
Article in English | MEDLINE | ID: mdl-17098899

ABSTRACT

The proteins belonging to the Fur family are global regulators of gene expression involved in the response to several environmental stresses and to the maintenance of divalent cation homeostasis. The Mycobacterium tuberculosis genome encodes two Fur-like proteins, FurA and a protein formerly annotated FurB. Since in this paper we show that it represents a zinc uptake regulator, we refer to it as Zur. The gene encoding Zur is found in an operon together with the gene encoding a second transcriptional regulator (Rv2358). In a previous work we demonstrated that Rv2358 is responsible for the zinc-dependent repression of the Rv2358-zur operon, favoring the hypothesis that these genes represent key regulators of zinc homeostasis. In this study we generated a zur mutant in M. tuberculosis, examined its phenotype, and characterized the Zur regulon by DNA microarray analysis. Thirty-two genes, presumably organized in 16 operons, were found to be upregulated in the zur mutant. Twenty-four of them belonged to eight putative transcriptional units preceded by a conserved 26-bp palindrome. Electrophoretic mobility shift experiments demonstrated that Zur binds to this palindrome in a zinc-dependent manner, suggesting its direct regulation of these genes. The proteins encoded by Zur-regulated genes include a group of ribosomal proteins, three putative metal transporters, the proteins belonging to early secretory antigen target 6 (ESAT-6) cluster 3, and three additional proteins belonging to the ESAT-6/culture filtrate protein 10 (CFP-10) family known to contain immunodominant epitopes in the T-cell response to M. tuberculosis infection.


Subject(s)
Bacterial Proteins/genetics , Mycobacterium tuberculosis/genetics , Regulon , Repressor Proteins/genetics , Bacterial Proteins/metabolism , Base Sequence , Binding Sites , DNA-Binding Proteins/genetics , DNA-Binding Proteins/metabolism , Deoxyribonuclease I/metabolism , Gene Expression Regulation, Bacterial , Models, Genetic , Molecular Sequence Data , Mycobacterium tuberculosis/pathogenicity , Oligonucleotide Array Sequence Analysis , Protein Binding , Repressor Proteins/metabolism , Reverse Transcriptase Polymerase Chain Reaction , Virulence/genetics
7.
Antimicrob Agents Chemother ; 49(11): 4775-7, 2005 Nov.
Article in English | MEDLINE | ID: mdl-16251328

ABSTRACT

The Mycobacterium tuberculosis mmpL7 gene, encoding a hypothetical resistance nodulation division transporter, confers a high resistance level to isoniazid when overexpressed in Mycobacterium smegmatis. The resistance level decreased in the presence of the efflux pump inhibitors reserpine and CCCP (carbonyl cyanide m-chlorophenylhydrazone). Energy-dependent efflux of isoniazid from M. smegmatis cells expressing the mmpL7 gene was observed.


Subject(s)
Antitubercular Agents/pharmacokinetics , Genes, Bacterial/physiology , Isoniazid/pharmacokinetics , Mycobacterium smegmatis/metabolism , Mycobacterium tuberculosis/genetics , Drug Resistance, Bacterial , Microbial Sensitivity Tests , Mycobacterium smegmatis/drug effects
SELECTION OF CITATIONS
SEARCH DETAIL
...