Insights into (S)-rivastigmine inhibition of butyrylcholinesterase (BuChE): Molecular docking and saturation transfer difference NMR (STD-NMR)

Rivastigmine is a very important drug prescribed for the treatment of Alzheimer's disease (AD) symptoms. It is a dual inhibitor, in that it inhibits both acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE). For our screening program on the discovery of new rivastigmine analogue hits for human butyrylcholinesterase (hBuChE) inhibition, we investigated the interaction of this inhibitor with BuChE using the complimentary approach of the biophysical method, saturation transfer difference (STD)-NMR and molecular docking. This allowed us to obtain essential information on the key binding interactions between the inhibitor and the enzyme to be used for screening of hit compounds. The main conclusions obtained from this integrated study was that the most dominant interactions were (a) H-bonding between the carbamate carbonyl of the inhibitor and the NH group of the imidazole unit of H434, (b) stacking of the aromatic unit of the inhibitor and the W82 aromatic unit in the choline binding pocket via pi-pi interactions and (c) possible CH/pi interactions between the benzylic methyl group and the N-methyl groups of the inhibitor and W82 of the enzyme.

Use of chemometrics to characterize tropical wines from different vintages and grape cultivars according to the 1H NMR spectroscopy data.

2011

Sequential exhaustive extraction of a Mollisol soil, and characterizations of humic components, including humin, by solid and solution state NMR.

A comprehensive sequential extraction procedure was applied to isolate soil organic components using aqueous solvents at different pH values, base plus urea (base-urea), and finally dimethylsulfoxide (DMSO) plus concentrated H2SO4 (DMSO-acid) for the humin-enriched clay separates. The extracts from base-urea and DMSO-acid would be regarded as 'humin' in the classical definitions. The fractions isolated from aqueous base, base-urea and DMSO-acid were characterized by solid and solution state NMR spectroscopy. The base-urea solvent system isolated ca. 10% (by mass) additional humic substances. The combined base-urea and DMSO-acid solvents isolated ca. 93% of total organic carbon from the humin-enriched fine clay fraction (<2 ?m). Characterization of the humic fractions by solid-state NMR spectroscopy showed that oxidized char materials were concentrated in humic acids isolated at pH 7, and in the base-urea extract. Lignin-derived materials were in considerable abundance in the humic acids isolated at pH 12.6. Only very small amounts of char-derived structures were contained in the fulvic acids and fulvic acids-like material isolated from the base-urea solvent. After extraction with base-urea, the 0.5 m NaOH extract from the humin-enriched clay was predominantly composed of aliphatic hydrocarbon groups, and with lesser amounts of aromatic carbon (probably including some char material), and carbohydrates and peptides. From the combination of solid and solution-state NMR spectroscopy, it is clear that the major components of humin materials, from the DMSO-acid solvent, after the exhaustive extraction sequence, were composed of microbial and plant derived components, mainly long-chain aliphatic species (including fatty acids/ester, waxes, lipids and cuticular material), carbohydrate, peptides/proteins, lignin derivatives, lipoprotein and peptidoglycan (major structural components in bacteria cell walls). Black carbon or char materials were enriched in humic acids isolated at pH 7 and humic acids-like material isolated in the base-urea medium, indicating that urea can liberate char-derived material hydrogen bonded or trapped within the humin matrix.

Metabolic fingerprint of açaí (Euterpe oleracea) berry pulp using 1H NMR spectroscopy and chemometric analysis.

Portanto, o objetivo deste trabalho foi avaliar a influência de diferentes cultivares e sazonalidade do açaí utilizando a técnica de 1H NMR para criação de perfis de impressão digital associada a métodos quimiométricos, obtidos a partir de frutos geneticamente modificados (cultivada no controle agronômico) e o comércio na cidade de Belém

1H NMR Relaxation Characterization Of Hydrates

To distinguish the components of NMR signals from hydrated materials and to monitor their evolution after the addition of water to the powders, during the first two days of hydration. To implement the 3 Tau Model in a MATLAB script, called 3TM, provided with a Graphical User Interface (GUI), to easily use the 3 Tau Model with NMRD profiles. The 3 Tau Model, developed a few years ago is used for interpreting the dispersion (NMRD profiles, dependence on the Larmor frequency) of the longitudinal relaxation times, for liquids confined in porous media. This model describes the molecular dynamics of confined molecules by introducing three characteristic correlation times and additional outputs.

1H NMR-based metabolomics investigation on the impacts of feeding in aquaculture of Gilthead sea bream (Sparus aurata)

In questo lavoro di tesi sono stati analizzati campioni di orate (Sparus aurata) da acquacoltura allevate con differenti diete, commerciali o innovative, con lo scopo di verificare se le diverse formulazioni dei mangimi hanno un effetto sul profilo molecolare dei pesci. A tal proposito, è stata utilizzata la spettroscopia di Risonanza Magnetica Nucleare (1H NMR) accoppiata ad un approccio metabolomico poiché, rispetto ad altre tecniche, consente la determinazione simultanea di un’ampia classe di metaboliti che caratterizzano il campione attraverso la generazione di spettri che contengono un ampio spettro di informazioni. Questo lavoro di tesi si sposa bene con l’attuale tendenza di sviluppo dell’acquacoltura, che viene vista come uno strumento interessante per fornire cibo e migliorare la sicurezza alimentare, ma allo stesso tempo esso è in accordo anche con la sempre più elevata attenzione verso sostenibilità, qualità e conformità alle richieste dei consumatori, che sono oggi le principali tendenze nel settore alimentare. Negli ultimi anni si è assistito ad un ampio sviluppo dell’acquacoltura e questo ha portato alla necessità di ricercare strategie per migliorare l’efficienza, la produttività, ma anche la sostenibilità di questi sistemi. Questo ha condotto ad un elevato aumento delle ricerche riguardanti questi aspetti dell’acquacoltura, e l’impatto che la dieta ha sul metabolismo dei pesci è uno di questi. I dati spettroscopici sono stati interpretati attraverso analisi statistica multivariata, nello specifico attraverso l’analisi delle componenti principali, PCA, per individuare eventuali differenze significative tra i tre gruppi a seguito della diversa tipologia di alimentazione. Dal presente lavoro di tesi è stato possibile concludere che i campioni vengono distribuiti e classificati in funzione della dieta. Inoltre, è stato possibile individuare i metaboliti che maggiormente determinano questa separazione.

A single-sided NMR approach to study structural differences of bovine articular tissue

This thesis work has been developed in collaboration between the Department of Physics and Astronomy of the University of Bologna and the IRCCS Rizzoli Orthopedic Institute during an internship period. The study aims to investigate the sensitivity of single-sided NMR in detecting structural differences of the articular cartilage tissue and their correlation with mechanical behavior. Suitable cartilage indicators for osteoarthritis (OA) severity (e.g., water and proteoglycans content, collagen structure) were explored through four NMR parameters: T2, T1, D, and Slp. Structural variations of the cartilage among its three layers (i.e., superficial, middle, and deep) were investigated performing several NMR pulses sequences on bovine knee joint samples using the NMR-MOUSE device. Previously, cartilage degradation studies were carried out, performing tests in three different experimental setups. The monitoring of the parameters and the best experimental setup were determined. An NMR automatized procedure based on the acquisition of these quantitative parameters was implemented, tested, and used for the investigation of the layers of twenty bovine cartilage samples. Statistical and pattern recognition analyses on these parameters have been performed. The results obtained from the analyses are very promising: the discrimination of the three cartilage layers shows very good results in terms of significance, paving the way for extensive use of NMR single-sided devices for biomedical applications. These results will be also integrated with analyses of tissue mechanical properties for a complete evaluation of cartilage changes throughout OA disease. The use of low-priced and mobile devices towards clinical applications could concern the screening of diseases related to cartilage tissue. This could have a positive impact both economically (including for underdeveloped countries) and socially, providing screening possibilities to a large part of the population.

Characterization of first sorption cycle of white Portland cement by 1H NMR

The work carried out is focused on the exploration of processes occurring in cement materials during sorption cycles by using Nuclear Magnetic Resonance (NMR) relaxometry. Long (months) and short (days-weeks) sorption cycles of cement materials were explored. The long cycle consists of around 6 months of drying and re-wetting cement samples of different sizes and water-to-cement (w/c) ratios in a homemade relative humidity (RH) chamber. Short cycles were performed by drying samples of different sizes and w/c ratios in the oven at 60 ˚C and re-wetting underwater. Different NMR techniques, such as one- and two-dimensional relaxometry and solid-signal analyses, were used to study the samples. Firstly, by the interpretation of quasi-continuous distributions of T2 relaxation time, we demonstrated that some reversible and irreversible changes concerning smaller porosity happened during the first sorption cycle. Secondly, using 2D NMR and a new 2D NMR inversion algorithm we showed preliminary results on the cement T1-T2 maps. Data obtained during sorption processes indicated possible water exchange between different pore populations inside the cement samples. Thirdly, the solid structure of cement samples was qualitatively investigated with T1 measurements and, as far as we know, for the first time interpreted with the Pake-Doublet theory. Changes in the solid structure were observed. Precisely variations of the amount of Ettringite during drying/wetting were proposed to take place. Finally, a work on NMR single-sided equipment design for in situ cement investigation was shown. The multi-cubic-blocks magnet structure design was performed using different specific CAD software, and the magnetic fields generated by RF coils of different geometries were investigated using a customized Matlab script. The single-sided NMR instrument equipped with the designed single-sided magnet and coil was built by the ERICA partner company MR Solutions (Abingdon, UK), and the preliminary results resultsated the correctness of the developed design.

Utilizzo della tecnologia NMR per la caratterizzazione metabolomica del Mugil cephalus

La ricerca in campo agroalimentare ha da sempre messo in evidenza l'importanza della conservazione degli alimenti nel tempo. Alcune nuove tecnologie basate sulle alte pressioni, e dunque non termiche, di stabilizzazione ai fini della conservazione, come l’High Hydrostatic Pressure (HHP) o High Pressure Processing (HPP), possono risultare fondamentali nel preservare aspetti microbiologici, qualitativi e nutrizionali dell'alimento. In questo elaborato verranno osservati alcuni aspetti del metaboloma, l’insieme delle molecole di piccola dimensione con funzioni metaboliche, di campioni di Mugil cephalus trattati con HHP. Tali aspetti permetteranno di ottenere informazioni sul profilo amminoacidico e sulla freschezza del pesce. Lo studio del profilo amminoacidico permette di tracciare la tendenza del sapore dello specifico campione analizzato dal momento che ogni amminoacido contribuisce a definire uno specifico gusto fondamentale. La freschezza del pesce sarà descritta attraverso il K index che, tramite lo studio della degradazione dei nucleotidi nel periodo post-mortem, rappresenta uno strumento utile al fine dello studio dei cambiamenti della freschezza nel tempo e secondo la tecnologia applicata. L’analisi del metaboloma del cefalo è stata eseguita mediante la spettroscopia di risonanza magnetica nucleare al protone (1H-NMR) di cui si descrivono i principi fisici nel primo capitolo. Nel secondo capitolo sono descritti i software utilizzati per indentificare le molecole che compongono il metaboloma dei campioni analizzati. Infine, nel terzo capitolo, si valuta l’effetto del trattamento HHP (a 400, 500 e 600MPa) sul profilo amminoacidico e sul K index durante il periodo di conservazione.

Indagine sul metaboloma del latte di asina tramite spettroscopia 1H-NMR

La metabolomica è una delle discipline più innovative tra quelle integrate al settore agroalimentare e, nonostante ciò, è già ampiamente sfruttata ed apprezzata. La risonanza magnetica nucleare (che verrà ampiamente trattata in seguito) è la tecnica d’elezione che permette di svolgere analisi in questo ambito. Nonostante l’utilità indiscussa di questa analisi, molti alimenti non sono stati protagonisti di studi in questo settore. Il latte d'asina è solo uno dei prodotti che per via della loro poca diffusione e centralità nel mercato non sono conosciuti e sfruttati appieno. Lo scopo di questo lavoro è quello di indagare il metaboloma del latte d'asina, come primo tassello per studi più avanzati.

Valutazione dello stato dell'acqua nei formaggi a diverso grado di salatura e stagionatura mediante TD-NMR

L’obiettivo iniziale di questo lavoro era quello di studiare il fenomeno della proteolisi nel formaggio, al variare del tempo di stagionatura e di salatura, mediante lo studio dello stato dell’acqua, con una metodica non distruttiva e innovativa per questa tematica: il TD-NMR. I formaggi oggetto di studio sono stati prodotti con un impianto pilota presente in Dipartimento, con lo stesso latte, nella stessa giornata e nelle medesime condizioni di caseificazione. Il primo passo è stato quello di assegnare un nome alle 4 popolazioni di protoni corrispondenti alle 4 curve esponenziali in cui si traducevano i risultati di T2. Dato che gli studi bibliografici consultati non erano concordi su questo aspetto e nessuno aveva svolto esperimenti che potessero confermare le supposizioni formulate, abbiamo proceduto all’analisi di un formaggio simile ai nostri campioni, addizionato di una soluzione dopante a base di Fe(III)Cl2. Questo passaggio ci ha permesso di identificare i tipi di molecole rappresentati dalle 4 popolazioni. Successivamente siamo stati in grado di fare ipotesi concrete sull’evoluzione dei risultati di T2 e intensità relativa al variare del tempo di stagionatura e di salatura. Dalle nostre osservazioni è emerso che è possibile correlare l’andamento di T2 e I a quello di diversi parametri che caratterizzano il formaggio. Le ipotesi emerse da questo studio sono solamente intuizioni preliminari riguardo l’impiego di questo metodo di analisi per il formaggio, che però ha la potenzialità di essere molto utile nella ricerca e anche nell’industria. Si tratta infatti di un metodo caratterizzato da estrema facilità nella preparazione dei campioni, che può essere adattato ad analisi non distruttive e che impiega uno strumento molto economico rispetto ad altri tipi di analisi NMR. Possiamo inoltre concludere che, avendo messo a punto questi aspetti di base, l’interpretazione dei dati sarà senz’altro più semplice rispetto ad altre analisi NMR.

The Applicability Of Ordered Mesoporous Sba-15 And Its Hydrophobic Glutaraldehyde-bridge Derivative To Improve Ibuprofen-loading In Releasing System.

The mesoporous SBA-15 silica with uniform hexagonal pore, narrow pore size distribution and tuneable pore diameter was organofunctionalized with glutaraldehyde-bridged silylating agent. The precursor and its derivative silicas were ibuprofen-loaded for controlled delivery in simulated biological fluids. The synthesized silicas were characterized by elemental analysis, infrared spectroscopy, (13)C and (29)Si solid state NMR spectroscopy, nitrogen adsorption, X-ray diffractometry, thermogravimetry and scanning electron microscopy. Surface functionalization with amine containing bridged hydrophobic structure resulted in significantly decreased surface area from 802.4 to 63.0 m(2) g(-1) and pore diameter 8.0-6.0 nm, which ultimately increased the drug-loading capacity from 18.0% up to 28.3% and a very slow release rate of ibuprofen over the period of 72.5h. The in vitro drug release demonstrated that SBA-15 presented the fastest release from 25% to 27% and SBA-15GA gave near 10% of drug release in all fluids during 72.5 h. The Korsmeyer-Peppas model better fits the release data with the Fickian diffusion mechanism and zero order kinetics for synthesized mesoporous silicas. Both pore sizes and hydrophobicity influenced the rate of the release process, indicating that the chemically modified silica can be suggested to design formulation of slow and constant release over a defined period, to avoid repeated administration.

Emergent Antiferromagnetism Out Of The Hidden-order" State In Uru2si2: High Magnetic Field Nuclear Magnetic Resonance To 40 T."

Very high field (29)Si-NMR measurements using a fully (29)Si-enriched URu(2)Si(2) single crystal were carried out in order to microscopically investigate the hidden order (HO) state and adjacent magnetic phases in the high field limit. At the lowest measured temperature of 0.4 K, a clear anomaly reflecting a Fermi surface instability near 22 T inside the HO state is detected by the (29)Si shift, (29)K(c). Moreover, a strong enhancement of (29)K(c) develops near a critical field H(c) ≃ 35.6 T, and the ^{29}Si-NMR signal disappears suddenly at H(c), indicating the total suppression of the HO state. Nevertheless, a weak and shifted (29)Si-NMR signal reappears for fields higher than H(c) at 4.2 K, providing evidence for a magnetic structure within the magnetic phase caused by the Ising-type anisotropy of the uranium ordered moments.

Sargassum Filipendula Alginate From Brazil: Seasonal Influence And Characteristics.

The aim of this work is focused on the extraction and characterization of the Brazilian seaweed Sargassum filipendula alginate. Alginates obtained at different seasons were characterized by liquid state nuclear magnetic resonance spectroscopy and scanning electron microscopy. The alginate extraction efficiency was about 20%. Different seasons of the year and different stages in the life cycle of Sargassum sp. in southeastern Brazil influenced the M/G and, consequently, the technological properties of extracted alginates.

Esi(+)-ms And Gc-ms Study Of The Hydrolysis Of N-azobenzyl Derivatives Of Chitosan.

New N-p-chloro-, N-p-bromo-, and N-p-nitrophenylazobenzylchitosan derivatives, as well as the corresponding azophenyl and azophenyl-p-sulfonic acids, were synthesized by coupling N-benzylvchitosan with aryl diazonium salts. The synthesized molecules were analyzed by UV-Vis, FT-IR, 1H-NMR and 15N-NMR spectroscopy. The capacity of copper chelation by these materials was studied by AAS. Chitosan and the derivatives were subjected to hydrolysis and the products were analyzed by ESI(+)-MS and GC-MS, confirming the formation of N-benzyl chitosan. Furthermore, the MS results indicate that a nucleophilic aromatic substitution (SnAr) reaction occurs under hydrolysis conditions, yielding chloroaniline from N-p-bromo-, and N-p-nitrophenylazo-benzylchitosan as well as bromoaniline from N-p-chloro-, and N-p-nitrophenylazobenzyl-chitosan.