NMR identification of monstrous mycobacterial lipids in cell wall of Mycobacterium abcessus

” Trehalose polyphleates, external cell wall lipids in Mycobacterium abcessus, are associated with the formation of clumps with cording morphology, which have been associated with virulence” by M. Llorens-Fons, M. Pérez-Trujillo, E. Julián, C. Brambilla, F. Alcaide, T. F. Byrd and M. Luquin. Frontiers in Microbiology, 2017, 8:1402. DOI: http://dx.doi.org/10.3389/fmicb.2017.01402

Mycobacterium abscessus is a reemerging pathogen that causes pulmonary diseases similar to tuberculosis, which is caused by Mycobacterium tuberculosis. When grown in agar medium, M. abscessus strains generate rough (R) or smooth colonies (S). R morphotypes are more virulent than S morphotypes. In searching for the virulence factors responsible for this difference, R morphotypes have been found to form large aggregates (clumps) that, after being phagocytozed, result in macrophage death. Furthermore, the aggregates released to the extracellular space by damaged macrophages grow, forming unphagocytosable structures that resemble cords. In contrast, bacilli of the S morphotype, which do not form aggregates, do not damage macrophages after phagocytosis and do not form cords. Cording has also been related to the virulence of M. tuberculosis. A comparative study of the pattern and structure of mycolic acids was performed on R (cording) and S (non-cording) morphotypes derived from the same parent strains, and no differences were observed between morphotypes. Furthermore, cords formed by R morphotypes were disrupted with petroleum ether (PE), and the extracted lipids were analyzed by thin layer chromatography, nuclear magnetic resonance spectroscopy and mass spectrometry. Substantial amounts of trehalose polyphleates (TPP) were recovered as major lipids from PE extracts, and images obtained by transmission electron microscopy suggested that these lipids are localized to the external surfaces of cords and R bacilli. The structure of M. abscessus TPP was revealed to be similar to those previously described in Mycobacterium smegmatis. Although the exact role of TPP is unknown, our results demonstrated that TPP are not toxic by themselves and have a function in the formation of clumps and cords in M. abscessus, thus playing an important role in the pathogenesis of this species.


Folding peptides studied by NMR

The relevance of the relative configuration in the folding of hybrid peptides containing β-cyclobutane amino acids and γ-amino-L-proline residues

O. Illa, J.A. Olivares, P. Nolis, R.M. Ortuño

DOI: 10.1016/j.tet.2017.09.011

Four new series of diastereomeric β,γ-di- and β,γ-tetrapeptides derived from conveniently protected (1R,2S)- and (1S,2S)-2-aminocyclobutane-1-carboxylic acid and cis- and trans-γ-amino-l-proline joined in alternation have been synthesized. High resolution NMR experiments show that peptides containing trans-cyclobutane amino acid residues adopt a more folded structure in solution than those containing a cis-cyclobutane residue, which adopt a strand-like structure. The cis/trans relative configuration of the cyclobutane residue is the origin of the folding pattern of each peptide due to either intra- or inter-residue hydrogen-bonded ring formation, whereas the cis/trans isomerism of the γ-amino-l-proline residue does not have a significantly relevant role on the folding ability of these peptides.

Solid-state NMR supports a study on Rh nanoparticles

NHC-stabilised Rh nanoparticles: Surface study and application in the catalytic hydrogenation of aromatic substrates

F. Martinez-Espinar, P. Blondeau, P. Nolis, B. Chaudret, C. Claver, S. Castillón and C. Godard

DOI: 10.1016/j.jcat.2017.08.010

Highlights

  • Synthesis and characterisation of small RhNPs stabilised by N-heterocyclic carbenes.
  • Evidence of the location of the ligands on the faces, edges and apexes of the NPs.
  • Hydrogenation of aromatic ketones, phenols and N-heteroaromatic substrates.
  • Tuning of the selectivity as a function of the reaction conditions.
  • Full reduction of quinoline under mild conditions with total selectivity.

13C{1H} CP-MAS spectra of (a) L, (b) Rh0.4, (c) Rh0.4 + CO and (d) 13C-Rh0.4.

Removal of pharmaceuticals from hospital wastewater by Pleurotus ostreatus. Identification of pharmaceuticals metabolites by NMR

“Preliminary evaluation of Pleurotus ostreatus for the removal of selected pharmaceuticals from hospital wastewater” by L. Palli,* F. Castellet‐Rovira, M. Pérez‐Trujillo, D. Caniani, M. Sarrà‐Adroguer, R. Gori Biotechnology Progress, 2017. DOI: http://dx.doi.org/10.1002/btpr.2520

The fungus Pleurotus ostreatus was investigated to assess its ability to remove diclofenac, ketoprofen, and atenolol in hospital wastewater. The degradation test was carried out in a fluidized bed bioreactor testing both the batch and the continuous mode. In batch mode, diclofenac disappeared in less than 24 h, ketoprofen was degraded up to almost 50% in 5 days while atenolol was not removed. In continuous mode, diclofenac and ketoprofen removals were about 100% and 70% respectively; atenolol degradation was negligible during the first 20 days but it increased up to 60% after a peak of laccase production and notable biomass growth. In order to identify the enzymatic system involved, further experiments were carried out in flasks. Two intermediates of diclofenac and ketoprofen were detected by nuclear magnetic resonance (NMR) spectroscopy. Moreover P. ostreatus was able to reduce chemical oxygen demand of the hospital wastewater which is an important advantage comparing to other fungi in order to develop a wastewater treatment process.

 

Pd-complex characterization by NMR

Dissimilar catalytic behavior of molecular or colloidal palladium systems with a new NHC ligand

Fernando Gómez-Villarraga,  Jonathan De Tovar,  Miguel Guerrero,  Pau Nolis,  Teodor Parella,  Pierre Lecante,  Nuria Romero,  Lluís Escriche,  Roger Bofill,  Josep Ros,  Xavier Sala,  Karine Philippot  and  Jordi García-Antón 

DOI: 10.1039/C7DT02729J

Abstract

In this work, we describe the synthesis of a new N-heterocyclic carbene (NHC) ligand, derived from a hybrid pyrazole-imidazolium scaffold, namely 1-[2-(3,5-dimethylpyrazol-1-yl)ethyl]-3-((S)-1-phenylethyl)-3H-imidazol-2-ylidene (L). This ligand has been used as a stabilizer for the organometallic synthesis of palladium(0) nanoparticles (Pd NPs). L presents a better stabilizing effect than its pre-carbenic HLCl counterpart, allowing the formation of isolated Pd NPs while HLCl yields aggregated ones. Additionally, molecular Pd(II) coordination compounds of L and HLCl were synthesized and characterized to better understand the coordination modes of these ligands. Both molecular and colloidal Pd systems have been further tested in catalytic C–C coupling processes. Three different types of reactions have been observed depending on the catalytic system: (i) the Suzuki–Miyaura reaction takes place with Pd molecular complexes; (ii) a secondary reaction, the dehalogenation of the substrate, is always detected and (iii) the C–C homocoupling between two molecules of bromoarenes is observed with colloidal catalysts.

Metronomic treatment in immunocompetent preclinical glioblastoma

“Metronomic treatment in immunocompetent preclinical GL261 glioblastoma: effects of cyclophosphamide and temozolomide” by by L. Ferrer-Font,  N. Arias-Ramos, S. Lope-Piedrafita, M. Julià-Sapé , M. Pumarola, C. Arús  and A. P. Candiota. NMR Biomed. 2017. DOI: 10.1002/nbm.3748. 

Glioblastoma (GBM) causes poor survival in patients even when applying aggressive treatment. In preceding years, efforts have focused in new therapeutic regimens with conventional drugs to activate immune responses that may enhance tumor regression and prevent regrowth, as for example the “metronomic” approaches.

We have evaluated whether metronomic CPA or TMZ administration could increase survival in orthotopic GL261 in C57BL/6 mice, an immunocompetent model. Longitudinal in vivo studies with CPA (140 mg/Kg) or TMZ (range 140-240 mg/Kg) metronomic administration (every 6 days) were performed in tumor-bearing mice. Tumor evolution was monitored at 7T with T2-weighted MRI, Diffusion weighted imaging and MRSI-based nosological images of response to therapy. Obtained results demonstrated that both treatments resulted in increased survival (38.6+21.0 days, n=30) compared to control (19.4+2.4 days, n=18). Also, it was found a clear edema appearance during chemotherapeutic treatment suggesting inflammatory associated processes. The necropsy performed in mice cured from GBM after high TMZ cumulative dosage (980-1400 mg/Kg) revealed lymphoma incidence.

Multi-Slice MRSI Analysis of Therapy Response in Preclinical Glioblastoma

Metabolomics of Therapy Response in Preclinical Glioblastoma: A Multi-Slice MRSI-Based Volumetric Analysis for Noninvasive Assessment of Temozolomide Treatment” by N. Arias-Ramos, L. Ferrer-Font,  S. Lope-Piedrafita,  V. Mocioiu, M. Julià-Sapé , M. Pumarola, C. Arús  and A. P. Candiota. Metabolites, 2017, 18;7(2). pii: E20. DOI: 10.3390/metabo7020020.

Glioblastoma (GBM) is the most common and aggressive glial primary tumor with a survival average of 14-15 months, even after application of standard treatment. Non-invasive surrogate biomarkers of therapy response may be relevant for improving patient survival. Nosological images of therapy response using a semi-supervised source extraction approach in preclinical GBM based on single slice Magnetic Resonance Spectroscopic Imaging (MRSI) was previously describe by our group. However, because of GBM heterogeneity, relevant response information could be missed just by studying one slice. Therefore, the goal of this work was to acquire 3D-like information from preclinical GBM under a longitudinal treatment protocol, using a multi-slice MRSI approach.

Nosological maps were obtained based on semi-supervised convex Non-negative Matrix Factorization and each voxel was colored according to the contribution to the spectral pattern of each one of the three sources or characteristic spectral patterns: Normal brain, actively proliferating tumour or responding tumour.

Heterogeneous response levels were observed and three arbitrary groups of treated animals were defined as: high response, intermediate response, and low response. Histopathological studies showed an inverse correlation between the responding pattern level and Ki67 proliferation rate.

 

Long-term fertilization determines different metabolomic profiles and responses in saplings of three rainforest tree species with different adult canopy position

Long-term fertilization determines different metabolomic profiles and responses in saplings of three rainforest tree species with different adult canopy position” by  A. Gargallo-Garriga, S. J. Wright, J. Sardans, M. Pérez-Trujillo, M. Oravec, K. Večeřová,O. Urban, M. Fernández-Martínez, T. Parella, J. Peñuelas.

Plos One, 2017, 1-21. DOI: 10.1371/journal.pone.0177030

Tropical rainforests are frequently limited by soil nutrient availability. However, the response of the metabolic phenotypic plasticity of trees to an increase of soil nutrient availabilities is poorly understood. We expected that increases in the ability of a nutrient that limits some plant processes should be detected by corresponding changes in plant metabolome profile related to such processes. We studied the foliar metabolome of saplings of three abundant tree species in a 15 year field NPK fertilization experiment in a Panamanian rainforest. The largest differences were among species and explained 75% of overall metabolome variation.

Chiral Recognition by Dissolution DNP NMR Spectroscopy of 13C-Labeled DL-Methionine

“Chiral Recognition by Dissolution DNP NMR Spectroscopy of 13C-Labeled DL-Methionine” By Eva Monteagudo, Albert Virgili, Teodor Parella and Míriam Pérez-Trujillo.Anal. Chem., 2017, 89 (9), pp 4939–4944 DOI: 10.1021/acs.analchem.7b00156

A method based on d-DNP NMR spectroscopy to study chiral recognition is described for the first time. The enantiodifferentiation of a racemic metabolite in a millimolar aqueous solution using a chiral solvating agent was performed. Hyperpolarized 13C-labeled DL-methionine enantiomers were differently observed with a single-scan 13C NMR experiment, while the chiral auxiliary at thermal equilibrium remained unobserved. The method developed entails a step forward in the chiral recognition of small molecules by NMR spectroscopy, opening new possibilities in situations where the sensitivity is limited, for example, when a low concentration of analyte is available or when the measurement of an insensitive nucleus, like 13C, is required. The advantages and current limitations of the method, as well as future perspectives, are discussed.