Although the classical antibiotic spectinomycin is a potent bacterial protein synthesis inhibitor, poor antimycobacterial activity limits its clinical application for treating tuberculosis. Using ...structure-based design, we generated a new semisynthetic series of spectinomycin analogs with selective ribosomal inhibition and excellent narrow-spectrum antitubercular activity. In multiple murine infection models, these spectinamides were well tolerated, significantly reduced lung mycobacterial burden and increased survival. In vitro studies demonstrated a lack of cross resistance with existing tuberculosis therapeutics, activity against multidrug-resistant (MDR) and extensively drug-resistant tuberculosis and an excellent pharmacological profile. Key to their potent antitubercular properties was their structural modification to evade the Rv1258c efflux pump, which is upregulated in MDR strains and is implicated in macrophage-induced drug tolerance. The antitubercular efficacy of spectinamides demonstrates that synthetic modifications to classical antibiotics can overcome the challenge of intrinsic efflux pump-mediated resistance and expands opportunities for target-based tuberculosis drug discovery.
Background and objectives
Fusilli pasta enriched with sea bass concentrate (Dicentrarchus labrax) was developed with the aim of increasing its content in proteins and especially in polyunsaturated ...fatty acids (PUFA) like Ω‐3. Pasta made from two types of cereals (wheat and spelt) and fish by‐product with or without a natural antioxidant were cooking prior to consumption, and nutritional and physicochemical characteristics were evaluated.
Findings
Enriched developed pasta showed high levels of protein, fat, and fiber, and the fatty acid profiles confirmed a substantial enrichment in bioactive compounds (Ω‐3 fatty acids). The cooking of pasta before consumption was able to reduce bacterial loads guaranteeing food safety and improving nutritional availability. Furthermore, an increase in the MUFA and PUFA content was revealed, which could represent an advantage to offer a better source of functional ingredients (EPA & DHA).
Conclusions
The combination of heat from cooking with formulations containing antioxidants seems to offer a remarkable synergistic effect to preserve unsaturated fatty acids with desirable nutritional properties.
Significance and novelty
Pasta enriched with bioactive compounds from fish by‐product after cooking treatment before consumption appears to be an effectiveness option to improve healthy human nutrition.
whiI is one of several loci originally described as essential for sporulation in Streptomyces coelicolor A3(2). We have characterized whiI at the molecular level. It encodes an atypical member of the ...response regulator family of proteins, lacking at least two of the residues strongly conserved in the conventional phosphorylation pocket. It is not adjacent to a potential sensor kinase gene. Fifteen mutant alleles of whiI were sequenced, revealing, among others, six mutations affecting conserved amino acids, several frameshift mutations and one mutation in the promoter. The whiI promoter is specifically transcribed by the sporulation‐specific σWhiG‐containing form of RNA polymerase. Transcription of whiI is temporally controlled, reaching a maximum level coincident with the formation of spores. Further transcriptional studies suggested that WhiI is involved directly or indirectly in repressing its own expression and that of another σWhiG‐dependent sporulation‐specific regulatory gene, whiH.
New treatments for diseases caused by antimicrobial-resistant microorganisms can be developed by identifying unexplored therapeutic targets and by designing efficient drug screening protocols. In ...this study, we have screened a library of compounds to find ligands for the flavin-adenine dinucleotide synthase (FADS) -a potential target for drug design against tuberculosis and pneumonia- by implementing a new and efficient virtual screening protocol. The protocol has been developed for the in silico search of ligands of unexplored therapeutic targets, for which limited information about ligands or ligand-receptor structures is available. It implements an integrative funnel-like strategy with filtering layers that increase in computational accuracy. The protocol starts with a pharmacophore-based virtual screening strategy that uses ligand-free receptor conformations from molecular dynamics (MD) simulations. Then, it performs a molecular docking stage using several docking programs and an exponential consensus ranking strategy. The last filter, samples the conformations of compounds bound to the target using MD simulations. The MD conformations are scored using several traditional scoring functions in combination with a newly-proposed score that takes into account the fluctuations of the molecule with a Morse-based potential. The protocol was optimized and validated using a compound library with known ligands of the Corynebacterium ammoniagenes FADS. Then, it was used to find new FADS ligands from a compound library of 14,000 molecules. A small set of 17 in silico filtered molecules were tested experimentally. We identified five inhibitors of the activity of the flavin adenylyl transferase module of the FADS, and some of them were able to inhibit growth of three bacterial species: C. ammoniagenes, Mycobacterium tuberculosis, and Streptococcus pneumoniae, where the last two are human pathogens. Overall, the results show that the integrative VS protocol is a cost-effective solution for the discovery of ligands of unexplored therapeutic targets.
Treatment of infections caused by multi-drug resistant (MDR) enterobacteria remains challenging due to the limited therapeutic options available. Drug repurposing could accelerate the development of ...new urgently needed successful interventions. This work aimed to identify and characterise novel drug combinations against Klebsiella pneumoniae based on the concepts of synergy and drug repurposing. We first performed a semi-qualitative high-throughput synergy screen (sHTSS) with tigecycline, colistin and fosfomycin (last-line antibiotics against MDR Enterobacteriaceae) against a FDA-library containing 1430 clinically approved drugs; a total of 109 compounds potentiated any of the last-line antibiotics. Selected hits were further validated by secondary checkerboard (CBA) and time-kill (TKA) assays, obtaining 15.09% and 65.85% confirmation rates, respectively. Accordingly, TKA were used for synergy classification based on determination of bactericidal activities at 8, 24 and 48 h, selecting 27 combinations against K. pneumoniae. Among them, zidovudine or azithromycin combinations with last-line antibiotics were further evaluated by TKA against a panel of 12 MDR/XDR K. pneumoniae strains, and their activities confronted with those clinical combinations currently used for MDR enterobacteria treatment; these combinations showed better bactericidal activities than usual treatments without added cytotoxicity. Our studies show that sHTSS paired to TKA are powerful tools for the identification and characterisation of novel synergistic drug combinations against K. pneumoniae. Further pre-clinical studies might support the translational potential of zidovudine- and azithromycin-based combinations for the treatment of these infections.
The increase of bacterial strains resistant to most of the available antibiotics shows a need to explore novel antibacterial targets to discover antimicrobial drugs. Bifunctional bacterial FAD ...synthetases (FADSs) synthesise the flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD). These cofactors act in vital processes as part of flavoproteins, making FADS an essential enzyme. Bacterial FADSs are potential antibacterial targets because of differences to mammalian enzymes, particularly at the FAD producing site. We have optimised an activity-based high throughput screening assay targeting Corynebacterium ammoniagenes FADS (CaFADS) that identifies inhibitors of its different activities. We selected the three best high-performing inhibitors of the FMN:adenylyltransferase activity (FMNAT) and studied their inhibition mechanisms and binding properties. The specificity of the CaFADS hits was evaluated by studying also their effect on the Streptococcus pneumoniae FADS activities, envisaging differences that can be used to discover species-specific antibacterial drugs. The antimicrobial effect of these compounds was also evaluated on C. ammoniagenes, S. pneumoniae, and Mycobacterium tuberculosis cultures, finding hits with favourable antimicrobial properties.
The antimicrobial resistance of
(
) currently poses a threat to available treatment regimens. Developing antimicrobial drugs targeting new bacterial targets is crucial, and one such class of drugs ...includes
-flavodoxin (
-fld) inhibitors that target an essential metabolic pathway in
. Our study demonstrated that combining these new drugs with conventional antibiotics used for
infection treatment prevented the regrowth observed with drugs used alone.
-fld inhibitors show promise as new drugs to be incorporated into the treatment of
infection, potentially reducing the development of resistance and shortening the treatment duration.
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