Synthesis of azide derivative and discovery of glyoxalase pathway inhibitor against pathogenic bacteria

Cascade Cyclization of N-Cyanamide Alkenes for the Divergent Synthesis of Azido-, Nitro-, and Alkenyl-Containing Pyrroloquinazolinones

Radical cascade cyclizations of N-cyanamide alkenes have been developed for the divergent synthesis of pyrroloquinazolinones bearing azido, alkenyl, and nitro groups by controlling the reaction conditions. The reaction temperature and the loading of the base play important roles in the different reaction pathways. These reactions are characterized by wide functional group compatibility and mild conditions.

Oxidative cascade cyclization of N-arylacrylamides with TMSN3

An azido-radical-triggered cyclization of N-(o-cyanobiaryl)acrylamides with TMSN3via a C(sp3)-N/C(sp2)-C(sp3)/C(sp2)-N bond formation cascade is described. This reaction features mild conditions and high bond-forming efficiency, making it an efficient method for the construction of azide-substituted pyridophenanthridines.

Probing the substrate binding modes and catalytic mechanisms of BLEG-1, a promiscuous B3 metallo-β-lactamase with glyoxalase II properties

BLEG-1 from Bacillus lehensis G1 is an evolutionary divergent B3 metallo-β-lactamase (MBL) that exhibited both β-lactamase and glyoxalase II (GLXII) activities. Sequence, phylogeny, biochemical and structural relatedness of BLEG-1 to B3 MBL and GLXII suggested BLEG-1 might be an intermediate in the evolutionary path of B3 MBL from GLXII. The unique active site cavity of BLEG-1 that recognizes both β-lactam antibiotics and S-D-lactoylglutathione (SLG) had been postulated as the key factor for its dual activity. In this study, dynamic ensembles of BLEG-1 and its substrate complexes divulged conformational plasticity and binding modes of structurally distinct substrates to the enzyme, providing better insights into its structure-to-function relationship and enzymatic promiscuity. Our results highlight the flexible nature of the active site pocket of BLEG-1, which is governed by concerted loop motions involving loop7+α3+loop8 and loop12 around the catalytic core, thereby moulding the binding pocket and facilitate interactions of BLEG-1 with both ampicillin and SLG. The distribution of (i) predominantly hydrophobic amino acids in the N-terminal domain, and (ii) flexible amino acids with polar and/or charged side chains in both N- and C-termini provide additional advantages to BLEG-1 in confining the aromatic group of ampicillin, and polar groups of SLG, respectively. The importance of these residues for substrates binding was further confirmed by the reduction in MBL and GLXII activities upon alanine substitutions of Ile-10, Phe-57, Arg-94, Leu-95, and Arg-159. Based on molecular dynamics simulation, mutational, and biochemical data presented herein, the catalytic mechanisms of BLEG-1 toward the hydrolysis of β-lactams and SLG were proposed.

Irisin injection mimics exercise effects on the brain proteome

Physical inactivity can endanger human health and increase the incidence of neurodegenerative disease. Exercise has tremendous beneficial effects on brain health and cognitive function, especially in older adults. It also improves brain-related outcomes in depression, epilepsy and neurodegenerative disorders, such as Parkinson's disease and Alzheimer's disease. Irisin is a mediator of the beneficial effects of exercise. This study aimed to assess the proteome alterations in adult male National Maritime Research Institute (NMRI) mice brain tissue upon three different conditions including endurance exercise, resistance exercise and irisin injection. Quantification of irisin levels in blood was performed using irisin-ELISA Kit. Quantification and identification of proteins via two-dimensional gel electrophoresis and matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry (MS)/MS showed the alteration of at least 21 proteins due to different treatments. Cellular pathway analysis revealed common beneficial effects of sole irisin treatment and different exercise procedures suggesting the capability of irisin injection to substitute the exercise when physical activity is not possible.

Comprehensive Examination of the Mouse Lung Metabolome Following Mycobacterium tuberculosis Infection Using a Multiplatform Mass Spectrometry Approach

The mechanisms whereby Mycobacterium tuberculosis (Mtb) rewires the host metabolism in vivo are surprisingly unexplored. Here, we used three high-resolution mass spectrometry platforms to track altered lung metabolic changes associated with Mtb infection of mice. The multiplatform data sets were merged using consensus orthogonal partial least squares-discriminant analysis (cOPLS-DA), an algorithm that allows for the joint interpretation of the results from a single multivariate analysis. We show that Mtb infection triggers a temporal and progressive catabolic state to satisfy the continuously changing energy demand to control infection. This causes dysregulation of metabolic and oxido-reductive pathways culminating in Mtb-associated wasting. Notably, high abundances of trimethylamine-N-oxide (TMAO), produced by the host from the bacterial metabolite trimethylamine upon infection, suggest that Mtb could exploit TMAO as an electron acceptor under anaerobic conditions. Overall, these new pathway alterations advance our understanding of the link between Mtb pathogenesis and metabolic dysregulation and could serve as a foundation for new therapeutic intervention strategies. Mass spectrometry data has been deposited in the Metabolomics Workbench repository (data-set identifier: ST001328).

Divergent synthesis of chiral cyclic azides via asymmetric cycloaddition reactions of vinyl azides

Vinyl azides, bearing conjugated azide and alkene functional groups, have been recognized as versatile building blocks in organic synthesis. In general vinyl azides act as 3-atom (CCN) synthons through the fast release of molecular nitrogen and have been extensively utilized in the construction of structurally diverse N-heterocycles. Keeping the azide moiety intact in organic transformations to synthesis chiral azides is an important but challenging task. Herein, we report an enantioselective copper(II)/BOX-catalyzed cycloaddition of vinyl azides, generating diverse chiral cyclic azides. α-Aryl substituted vinyl azides react with unsaturated keto esters through an inverse-electron-demand hetero-Diels-Alder reaction to afford chiral azido dihydropyrans with excellent enatioselectivities. In contrast, cyclohexenyl azides undergo a diastereo- and enantio-selective Diels-Alder reaction giving important azido octahydronaphthalenes with three continuous stereogenic centers. Notable features of these reactions include a very broad scope, mild reaction conditions and 100% atom economy.

Vinyl azides generally act as 3-atom synthon through the fast release of molecular nitrogen, whereas keeping the azide group intact is more challenging. Here, the authors show a copper-catalyzed enantioselective cycloaddition of two types of vinyl azides generating a diverse pool of valuable chiral cyclic azides.

Neuroprotection through flavonoid: Enhancement of the glyoxalase pathway

The glyoxalase pathway functions to detoxify reactive dicarbonyl compounds, most importantly methylglyoxal. The glyoxalase pathway is an antioxidant defense mechanism that is essential for neuroprotection. Excessive concentrations of methylglyoxal have deleterious effects on cells, leading to increased levels of inflammation and oxidative stress. Neurodegenerative diseases - including Alzheimer's, Parkinson's, Aging and Autism Spectrum Disorder - are often induced or exacerbated by accumulation of methylglyoxal. Antioxidant compounds possess several distinct mechanisms that enhance the glyoxalase pathway and function as neuroprotectants. Flavonoids are well-researched secondary plant metabolites that appear to be effective in reducing levels of oxidative stress and inflammation in neural cells. Novel flavonoids could be designed, synthesized and tested to protect against neurodegenerative diseases through regulating the glyoxalase pathway.

Catalytic enantioselective synthesis of α-chiral azides

The catalytic asymmetric synthesis of α-chiral azides is of current interest and three synthetic strategies have been developed. This review summarizes the recent progress in this research area, discusses the advantages and limitations of each strategy, and outlines synthetic opportunities for future research.

Flavonoid Enhances the Glyoxalase Pathway in Cerebellar Neurons to Retain Cellular Functions

Oxidative stress is damaging to cells and contributes to aging and neurodegenerative disease. This state is mediated by production of imbalanced molecules, and reactive dicarbonyl compounds - mainly methylglyoxal. The glyoxalase pathway is an antioxidant defense system utilized to detoxify methylglyoxal and neutralize free radicals. Pathway dysfunction leads to overproduction and accumulation of toxic, prooxidant compounds. We hypothesize flavonoid treatment as a means to enhance the glyoxalase pathway’s ability to detoxify in neurons. This study found that flavonoid treatment in methylglyoxal treated cerebellar neurons increased the functioning of glyoxalase pathway by enhancing expression of glyoxalase-1 and glyoxalase-2 proteins, decreased cell death and increased cellular viability. Flavonoids also significantly contributed in the retention of synaptic functions (VGLUT1 and GAD65) in cerebellar neurons. In addition, flavonoids were found to be involved in pAkt - NF-κB signaling pathway through a reduction in phosphorylation of Akt. The data here show flavonoid compounds have the potential to protect the brain from aging and neurodegenerative disease.

Discovery of bicyclic inhibitors against menaquinone biosynthesis

INTRODUCTION

Menaquinone is used for transporting electrons and is essential for the aerobic and anaerobic respiratory systems of all pathogens and prokaryotes. Many Gram-positive bacteria use only menaquinone in the electron transport system. Thus, menaquinone biosynthesis is a potential target for the development of inhibitors against bacteria including drug-resistant pathogens.

RESULTS

After modeling, synthesis and in vitro testing, we determined that 7-methoxy-2-naphthol-based inhibitors targeted the MenA enzyme of the menaquinone biosynthesis pathway. The developmental compounds 1 and 2 were active against Mycobacterium tuberculosis and methicillin-resistant Staphylococcus aureus with a minimal inhibitory concentration of 3-5 μg/ml.

CONCLUSION

Nontraditional bicyclic inhibitors, compounds 1 and 2 could serve as lead compounds for the development of an antimicrobial agent, with activities against M. tuberculosis and methicillin-resistant S. aureus.

Development of potential broad spectrum antimicrobials using C2-symmetric 9-fluorenone alkyl amine

DNA-dependent RNA primase is essential for de novo primer synthesis during DNA replication in all living organisms. Bacterial DnaG primase is an attractive target for inhibition because it is essential, low in copy number and structurally distinct from eukaryotic and archaeal primases. DnaG primase is sensitive to known inhibitors including suramin and doxorubicin. Recently, tilorone was discovered by high throughput screening to be an inhibitor of Bacillus anthracis primase DnaG but it failed to reduce the growth of B. anthracis in vitro. In this study we determined that tilorone also inhibited DnaG primase from Staphylococcus aureus. C2-Symmetric fluorenone-based compounds, similar to tilorone chemical structure were synthesized and tested to identify potential lead compounds that inhibit bacterial growth in B. anthracis, MRSA and Burkholderia thailandensis. These compounds were evaluated by determining the minimum inhibitory concentration (MIC) against several different bacterial species which demonstrated 17.5 and 16 μg/ml MIC profiles. Importantly, some of the fluorenone-based compounds with a long carbon chain showed a relatively low MIC against B. anthracis, S. aureus, MRSA, Francisella tularensis, and B. thailandensis, suggesting it may be a promising lead compound.

Prolonged-acting, multi-targeting gallium nanoparticles potently inhibit growth of both HIV and mycobacteria in co-infected human macrophages

Human immunodeficiency virus (HIV) infection and Mycobacterium tuberculosis (TB) are responsible for two of the major global human infectious diseases that result in significant morbidity, mortality and socioeconomic impact. Furthermore, severity and disease prevention of both infections is enhanced by co-infection. Parallel limitations also exist in access to effective drug therapy and the emergence of resistance. Furthermore, drug-drug interactions have proven problematic during treatment of co-incident HIV and TB infections. Thus, improvements in drug access and simplified treatment regimens are needed immediately. One of the key host cells infected by both HIV and TB is the mononuclear phagocyte (MP; monocyte, macrophage and dendritic cell). Therefore, we hypothesized that one way this can be achieved is through drug-targeting by a nanoformulated drug that ideally would be active against both HIV and TB. Accordingly, we validated macrophage targeted long acting (sustained drug release) gallium (Ga) nanoformulation against HIV-mycobacterium co-infection. The multi-targeted Ga nanoparticle agent inhibited growth of both HIV and TB in the macrophage. The Ga nanoparticles reduced the growth of mycobacterium and HIV for up to 15 days following single drug loading. These results provide a potential new approach to treat HIV-TB co-infection that could eventually lead to improved clinical outcomes.

Long-acting antituberculous therapeutic nanoparticles target macrophage endosomes

Eradication of Mycobacterium tuberculosis (MTB) infection requires daily administration of combinations of rifampin (RIF), isoniazid [isonicotinylhydrazine (INH)], pyrazinamide, and ethambutol, among other drug therapies. To facilitate and optimize MTB therapeutic selections, a mononuclear phagocyte (MP; monocyte, macrophage, and dendritic cell)-targeted drug delivery strategy was developed. Long-acting nanoformulations of RIF and an INH derivative, pentenyl-INH (INHP), were prepared, and their physicochemical properties were evaluated. This included the evaluation of MP particle uptake and retention, cell viability, and antimicrobial efficacy. Drug levels reached 6 μg/10(6) cells in human monocyte-derived macrophages (MDMs) for nanoparticle treatments compared with 0.1 μg/10(6) cells for native drugs. High RIF and INHP levels were retained in MDM for >15 d following nanoparticle loading. Rapid loss of native drugs was observed in cells and culture fluids within 24 h. Antimicrobial activities were determined against Mycobacterium smegmatis (M. smegmatis). Coadministration of nanoformulated RIF and INHP provided a 6-fold increase in therapeutic efficacy compared with equivalent concentrations of native drugs. Notably, nanoformulated RIF and INHP were found to be localized in recycling and late MDM endosomal compartments. These were the same compartments that contained the pathogen. Our results demonstrate the potential of antimicrobial nanomedicines to simplify MTB drug regimens.