Posts describing the use of the nmr spectroscopy (MRS) methodology, either from a practical point of view (how to perform certain experiment), or from a more theoretical perspective (description of techniques and their application).
Chirality plays a fundamental role in nature, but its detection and quantification still face many limitations. To date, the enantiospecific analysis of mixtures necessarily requires prior separation of the individual components. The simultaneous enantiospecific detection of multiple chiral molecules in a mixture represents a major challenge, which would lead to a significantly better understanding of the underlying biological processes; e.g. via enantiospecifically analysing metabolites in their native environment. Here, we report on the first in situ enantiospecific detection of a thirty‐nine‐component mixture. As a proof of concept, eighteen essential amino acids at physiological concentrations were simultaneously enantiospecifically detected using NMR spectroscopy and a chiral solvating agent. This work represents a first step towards the simultaneous multicomponent enantiospecific analysis of complex mixtures, a capability that will have substantial impact on metabolism studies, metabolic phenotyping, chemical reaction monitoring, and many other fields where complex mixtures containing chiral molecules require efficient characterisation.
Dibromomethane (DBM) and 1,2‐dibromoethane (DBA) are two brominated volatile contaminants used in several industrial applications which are often detected in groundwater. The electrochemical degradation of DBM and DBA was studied at different cathode potentials (−0.8, −1 and −1.2 V versus Standard Hydrogen Electrode) in aqueous solution using an inexpensive graphite fiber brush electrode.
The degradation followed first‐order kinetics with respect to the nominal concentration of the brominated compounds, and the kinetic constant increased concomitantly with the decrease of the cathode potential. During the electrochemical dehalogenation 96.8% and 99.8% of the bromide in DBM and DBA was released as bromine ions, respectively. The main non‐brominated compounds detected during the degradation of DBM and DBA were methane and ethene, respectively. In addition, traces of formic acid for DBM and acetic acid for DBA degradation were detected by NMR spectroscopy. The non‐toxicity of the effluent was confirmed by a Microtox test. The efficient electrochemical degradation of DBM and DBA and the lack of toxic products open the door for a simple and non‐toxic electrochemical approach for removing aliphatic brominated compounds from aquifers and other water sources.
31P-NMR Metabolomics Revealed Species-Specific Use of Phosphorous in Trees of a French Guiana Rainforest, by Gargallo-Garriga, A.; Sardans, J.; Llusià, J.; Peguero, G.; Asensio, D.; Ogaya, R.; Urbina, I.; Langenhove, L.V.; Verryckt, L.T.; Courtois, E.A.; Stahl, C.; Grau, O.; Urban, O.; Janssens, I.A.; Nolis, P.; Pérez-Trujillo, M.; Parella, T.; Peñuelas, J. Molecules2020, 25, 3960. https://doi.org/10.3390/molecules25173960
Productivity of tropical lowland moist forests is often limited by availability and functional allocation of phosphorus (P) that drives competition among tree species and becomes a key factor in determining forestall community diversity. We used non-target 31P-NMR metabolic profiling to study the foliar P-metabolism of trees of a French Guiana rainforest. The objective was to test the hypotheses that P-use is species-specific, and that species diversity relates to species P-use and concentrations of P-containing compounds, including inorganic phosphates, orthophosphate monoesters and diesters, phosphonates and organic polyphosphates. We found that tree species explained the 59% of variance in 31P-NMR metabolite profiling of leaves. A principal component analysis showed that tree species were separated along PC 1 and PC 2 of detected P-containing compounds, which represented a continuum going from high concentrations of metabolites related to non-active P and P-storage, low total P concentrations and high N:P ratios, to high concentrations of P-containing metabolites related to energy and anabolic metabolism, high total P concentrations and low N:P ratios. These results highlight the species-specific use of P and the existence of species-specific P-use niches that are driven by the distinct species-specific position in a continuum in the P-allocation from P-storage compounds to P-containing molecules related to energy and anabolic metabolism.
Progression of Alzheimer’s disease and effect of scFv-h3D6 immunotherapy in the 3xTg-AD mouse model: An in vivo longitudinal study using Magnetic Resonance Imaging and Spectroscopy by Güell-Bosch J, Lope-Piedrafita S, Esquerda-Canals G, Montoliu-Gaya L, and Villegas S. NMR in Biomedicine 33(5):e4263; DOI: 10.1002/nbm.4263.
Alzheimer’s disease (AD) is an incurable disease that affects most of the 47 million people estimated as living with dementia worldwide. The main histopathological hallmarks of AD are extracellular β-amyloid (Aβ) plaques and intracellular neurofibrillary tangles (NFTs) composed of hyperphosphorylated tau protein. In recent years, Aβ-immunotherapy has been revealed as a potential tool in AD treatment. One strategy consists of using single-chain variable fragments (scFvs), which avoids the fragment crystallizable (Fc) effects that are supposed to trigger a microglial response, leading to microhemorrhages and vasogenic edemas, as evidenced in clinical trials with bapineuzumab. The scFv-h3D6 generated by our research group derives from this monoclonal antibody, which targets the N-terminal of the Aβ peptide and recognizes monomers, oligomers and fibrils.
In this study, 3xTg-AD mice were intraperitoneally and monthly treated with 100 μg of scFv-h3D6 (a dose of ~3.3 mg/kg) or PBS, from 5 to 12 months of age (-mo), the age at which the mice were sacrificed and samples collected for histological and biochemical analyses. During treatments, four monitoring sessions using magnetic resonance imaging and spectroscopy (MRI/MRS) were performed at 5, 7, 9, and 12 months of age. MRI/MRS techniques allow, in a non-invasive manner, to draw an in vivo picture of concrete aspects of the pathology and to monitor its development across time. Compared with the genetic background, 3xTg-AD mice presented a smaller volume in almost all cerebral regions and ages examined, an increase in both the intra and extracellular Aβ1-42 at 12-mo, and an inflammation process at this age, in both the hippocampus (IL-6 and mIns) and cortex (IL-6). In addition, treatment with scFv-h3D6 partially recovered the values in brain volume, and Aβ, IL-6, and mIns concentrations, among others, encouraging further studies with this antibody fragment.
“Supramolecular Fullerene Sponges as Catalytic Masks for Regioselective Functionalization of C60“, by Carles Fuertes-Espinosa, Cristina García-Simón, Míriam Pujals, Marc Garcia-Borràs, Laura Gómez, Teodor Parella, Judit Juanhuix, Inhar Imaz, Daniel Maspoch, Miquel Costas and Xavi Ribas.
The supramolecular mask protocol is a significant step forward for the regioselective functionalization of fullerenes. The exquisite ability to form pure-isomer poly-functionalized C60 adducts, overcoming tedious and non-practical chromatographic separations, allows for their direct testing in solar cell prototypes. Furthermore, the supramolecular mask strategy can be applied to C70 or higher fullerenes, opening a plethora of poly-functionalized fullerene derivatives to be synthesized and tested. Moreover, apart from the nucleophilic cyclopropanations reported herein, the protocol is currently being expanded to Diels-Alder (DA), 1,3-dipolar cycloadditions and PC60BM-type cyclopropanations, thus enabling a variety of regioselective functionalization reactions. This supramolecular mask strategy can help the discovery of the next generation of improved solar cells (organic or perovskite based) or new drug candidates.
This research has been carried out in close collaboration with Dr. Xavi Ribas (from the QBIS-CAT research group of the University of Girona (UdG)), the Catalan Institute of Nanotechnology (ICN2), the ALBA-BCN synchrotron and the NMR Service of the Autonomous University of Barcelona ( UAB). The results have just been published in the online version of the prestigious CHEM scientific journal .
This is the first report on the obtention of functionalized MSN by a co-condensation procedure with a structurally complex chiral precursor. The functionalized MSN have been characterized by elemental analysis, 29Si and 13C CP MAS NMR, transmission electron microscopy, scanning electron microscopy, N2-sorption measurements, dynamic light scattering, ζ-potential, and powder X-ray diffraction. We have evaluated the activity of these materials as recyclable catalysts in the asymmetric aldol reaction. The use of organosilica nanoparticles reduces the problems of diffusion and low reaction rates encountered with bulk organosilicas.
Kumar Motiram-Corral presented a poster titled “Implementing one-shot multiple-FID acquisition into homonuclear and heteronuclear NMR experiments” at SMASH 19 in Porto (Portugal).
To date, time-efficient approaches are a challenged task for spectroscopists. The goal is to obtain chemical information reducing experimental time without considerably losing of sensitivity.
Different time-efficient approaches have been described over the years. Time sharing (Parella et. al.) tactic acquires the 15N and 13C nuclei in the same spectrum in spectrometers which have a triple channel hardware configuration. Non-Uniform Sampling (NUS)  algorithm has achieved a substantial reduction of experimental time reducing the number of t1 increments needed by multidimensional experiments. Recently, NOAH  (NMR by ordered Acquisition using 1H detection) has been developed by Kupče (Bruker Co.) and Claridge (University of Oxford) provides the way to get proper experiments in different spectra with the same spectral quality.
MFA (Multiple FID Acquisition) consists in obtaining up to four different experiments decreasing close to 60% of time. MFA provides a new novel proof concept of COSY, TOCSY and HMBC experiments in small molecules. Actually, MFA strategy was proposed many years ago with the COCONOSY experiment [5-7], which could be collected 2D COSY and NOESY data with a single pulse scheme. MFA has also been implemented in magic-angle-spinning solid-state NMR experiments devoted for biomacromolecules using standard spectrometer configuration. Despite its limitations related to the use of long acquisition of free-induction decays (FIDs) to accurately digitalize the data and the mandatory use of long phase cycles for convenient pathway selection, nowadays, the use of pulsed field gradients (PFGs) is the solution for this drawback. MFA is based on the relaxation of the remaining transverse magnetization, which usually relaxes to its original magnetization, can be manipulated by an appropriate additional mixing process and recorded again to obtain a second or third NMR data provided that T2 (transverse relaxation times) are long enough. Its main advantage is that each experiment is acquired in a different display. MFA is a powerful experiment for the sequential structural assignment of a whole spin system without ambiguities. This method is also useful for selective experiments as SE-TOCSY.
Nolis, P., Pérez, M., & Parella, T. (2006). Time-sharing evolution and sensitivity enhancements in 2D HSQC-TOCSY and HSQMBC experiments. Magnetic Resonance in Chemistry, 44, 11, 1031-1036, 2006
K. Kazimierczuk and V. Y. Orekhov , Angew. Chem., Int. Ed., 2011, 50 , 5556 -5559
Kupče, E., & Claridge, T. D. W. (2018). Molecular structure from a single NMR supersequence. Chemical Communications, 54, 7139-7142, 2018.
Motiram-Corral, K., Pérez-Trujillo, M., Nolis, P., & Parella, T. (2018). Implementing one-shot multiple-FID acquisition into homonuclear and heteronuclear NMR experiments. Chemical Communications, 54(96), 13507–13510, 2018.
A. Z. Gurevich , I. L. Barsukov , A. S. Arseniev and V. F. Bystrov , J. Magn. Reson.,56, 471 -478, 1984.
C. A. G. Haasnoot , F. J. M. van de Ven and C. W. Hilbers , J. Magn. Reson., 56 , 343 -349, 1984.
J. Cavanagh and M. Rance , J. Magn. Reson., 14 , 408 -414, 1990.
Some of the SeRMN staff will present our last research works at the annual meeting of the European magnetic resonance community ISMAR EUROMAR 2019 Conference that will take place from 25th to 30th August in Berlin. Find below a summary of our contributions.
Speeding-up NMR molecular analysis is an
important research field which has been continuously advancing since NMR early
days. The relevant benefits are clear and evident: reduce the time per analysis
directly reduce its cost and gaining spectrometer time to analyze new samples. Many
interesting tools and concepts have been appearing in last decades. Concretely,
our experience focuses on the development of new NMR experiments using TS
(Time-Shared), SA (Spectral Aliasing) and MFA (Multiple Fid Acquisition). MFA
strategy is an interesting strategy that allows the acquisition of different structural
information in a single experiment. Basically, MFA experiments consist in the
design of pulse sequence experiments which accommodate several acquisition
windows per experi-ment, each registering different relevant information for
the structural molecular character-ization. The methodology brings a
corresponding important time benefit. Last year, we have reported several new
NMR experiments designed with MFA stratey and herein we would present the most
relevant achievements. The overall discussion will be mainly focused on the
sensitivity gains per time unit of the presented experiments.
commonly named pentaspiroglycol
(PSG) or spiroglycol (SPG) is a high molecular weight rigid alicy-clic diol widely used in the chemical
industry. SPG has no hazardous classification, it is not mutagenic and is a safe alternative to
Bisphenol A, a well-known chemical which is rising concern due to his proved endocrine
disruptor activity. Moreover, some of the SPG main applications are focused on epoxy resins,
liquid polyester resins, radiation curing resins and
in polymer film material field. However, the spiroglycol structure,
configuration and conformation
have never been deeply studied. Herein,
we perform for the first time a preliminary NMR and computational study of the spiroglycol structure. SPG is a highly
symmetrical molecule but it should be chiral due to
the presence of a chiral axis. The presence of two enantiomers was demonstrated
enantiodifferentiation experiments using α,α’-bis(trifluoromethyl)-9,10-an-thracenedimethanol (ABTE) as chiral
solvating agent (CSA). The addition of 0.6 equivalents of ABTE allows the differentiation of
several spiroglycol proton signals. The lack of resolu-tion observed in the proton spectrum can be
tackled through the corresponding 13C NMR spectrum
where a significant enantiodifferentiation at the spirocarbon atom was observed.In order to physically separate both
enantiomers, a SPG derivatization with camphor-sulphonic
acid was performed affording the corresponding diastereoisomeric ester mixture.
Jiménez-Xarrié, Elena, Belén Pérez, Ana Paula Dantas, Lídia Puertas-Umbert, Joan Martí-Fabregas, Ángel Chamorro, Anna Maria Planas, Elisabet Vila, Francesc Jiménez-Altayó. 2018. Uric Acid Treatment After Stroke Prevents Long-Term Middle Cerebral Artery Remodelling and Attenuates Brain Damage in Spontaneously Hypertensive Rats. Translational Stroke Research. DOI: 10.1007/s12975-018-0661-8
Hypertension is the most important modifiable risk factor for stroke and is associated with poorer post-stroke outcomes. The antioxidant uric acid is protective in experimental normotensive ischaemic stroke. However, it is unknown whether this treatment exerts long-term protection in hypertension. The authors aimed to evaluate the impact of transient intraluminal middle cerebral artery (MCA) occlusion (90min)/reperfusion (1–15 days) on brain and vascular damage progression in adult and spontaneously hypertensive rats (SHR) treated with uric acid. Ischaemic brain damage was assessed longitudinally with magnetic resonance imaging at the Nuclear Magnetic Resonance Service of the Universitat Autònoma de Barcelona.
In SHR rats, more severe brain damage and poorer neurofunctional outcomes were coupled to higher cortical cerebral blood flow at the onset of reperfusion, a transient increase in oxidative stress and long-lasting stroke-induced MCA hypertrophic remodelling. Thus, stroke promotes larger brain and vascular damage in hypertensive rats that persists for long-time. Uric acid administered during early reperfusion attenuated short- and long-term brain injuries in both normotensive and hypertensive rats, an effect that was associated with abolishment of the acute oxidative stress response and prevention of stroke-induced long lasting MCA remodelling in hypertension. These results suggest that uric acid might be an effective strategy to improve stroke outcomes in hypertensive subjects.
Montoliu-Gaya, Laia, Jofre Güell-Bosch, Gisela Esquerda-Canals, Alejandro R. Roda, Gabriel Serra-Mir, Silvia Lope-Piedrafita, José Luís Sánchez-Quesada & Sandra Villegas. 2018. Differential effects of apoE and apoJ mimetic peptides on the action of an anti-Aβ scFv in 3xTg-AD mice. Biochemical Pharmacology 155. 380–392. DOI: 10.1016/j.bcp.2018.07.012
Anti-Aβ immunotherapy has emerged as a promising approach to treat Alzheimer’s disease (AD). The single-chain variable fragment scFv-h3D6 is an anti-Aβ antibody fragment that lacks the Fc region, which is associated with the induction of microglial reactivity by the full-length monoclonal antibody bapineuzumab. ScFv-h3D6 was previously shown to restore the levels of apolipoprotein E (apoE) and apolipoprotein J (apoJ) in a tripletransgenic- AD (3xTg-AD) mouse model. Since apoE and apoJ play an important role in the development of AD, we aimed to study the in vivo effect of the combined therapy of scFv-h3D6 with apoE and apoJ mimetic peptides (MPs).