Application of NMR spectroscopy for the detection and quantification of phthalic acid in fish muscles: The case of Atlantic Cod from Norwegian Sea.

Plastic litter might contain phthalates that can be transferred to marine environment or can be introduced into the marine food chain. Phthalic acid is the final product of phthalate decomposition in marine organisms. Here we used NMR spectroscopy to determine and quantify phthalic acid and dimethyl phthalate in fish muscles. Spike-and-recovery experiments were carried out to confirm assignment of phthalates resonance signals in NMR spectra and to evaluate the method specificity, accuracy, and linearity. The LOQ and LOD of the rapid 1H NMR experiment with a standard setting were respectively 23.0 and 8.0 mg of phthalic acid in kg of fish muscles. Phthalic acid was detected in 13 out of 113 Atlantic cod and none in farmed Atlantic salmon from Norwegian sea.

Nutritionally Enriched Muffins from Roselle Calyx Extract Using Response Surface Methodology.

Hibiscus sabdariffa, often called Roselle, is a flowering plant with a variety of traditional medicinal uses. Its calyx, with a bright and attractive red color, produces a tart and pleasant acidic taste. The purpose of this study was to develop a Roselle muffin and assess the acceptability, nutrition, and shelf life of the muffin using its ingredients. The muffin was developed using different formulations in different proportions resulting from Response Surface Methodology (RSM). Sensory parameters were used to assess the muffin's acceptability. According to the findings, the combination of extract volume 45.37 mL, citric acid 1.11 g, and sodium bicarbonate 1.67 g produces the best muffin, with the panelist's sensory scores reaching up to 84%. The outcome of the study suggests muffins baked with the Roselle calyx extract have high antioxidant (12.53 ± 0.13)%, anthocyanin (126.63 ± 1.96) mg Cyn-3-glu/100 g, phenolic (12.91 ± 0.69) mg GAE/100 g, and ascorbic acid (12.10 ± 0.89) mg/100 g contents. The microbial shelf life of the developed muffin is estimated to be 6 days at room temperature. The study findings can therefore be utilized in the development of foods containing Roselle calyx extract.

Effect of Different Drying Methods on the Nutritional Value of Hibiscus sabdariffa Calyces as Revealed by NMR Metabolomics.

Red mature calyces of Hibiscus sabdariffa were collected from 16 different locations in Meghalaya, India. Samples were processed using shade drying (SD) and tray drying (TD). NMR spectroscopy was used to assess the metabolic composition of the calyces. In this study, 18 polar metabolites were assigned using 1D and 2D NMR spectra, and 10 of them were quantified. Proximate analysis showed that the TD method is more efficient at reducing moisture and maintaining the ash content of the Hibiscus biomass. NMR metabolomics indicates that the metabolite composition significantly differs between SD and TD samples and is more stable in TD plant processing. The differences in post-harvest drying has a greater impact on the metabolite composition of Hibiscus than the plant location.

Emerging Techniques for Differentiation of Fresh and Frozen-Thawed Seafoods: Highlighting the Potential of Spectroscopic Techniques.

Fish and other seafood products have a limited shelf life due to favorable conditions for microbial growth and enzymatic alterations. Various preservation and/or processing methods have been developed for shelf-life extension and for maintaining the quality of such highly perishable products. Freezing and frozen storage are among the most commonly applied techniques for this purpose. However, frozen-thawed fish or meat are less preferred by consumers; thus, labeling thawed products as fresh is considered a fraudulent practice. To detect this kind of fraud, several techniques and approaches (e.g., enzymatic, histological) have been commonly employed. While these methods have proven successful, they are not without limitations. In recent years, different emerging methods have been investigated to be used in place of other traditional detection methods of thawed products. In this context, spectroscopic techniques have received considerable attention due to their potential as being rapid and non-destructive analytical tools. This review paper aims to summarize studies that investigated the potential of emerging techniques, particularly those based on spectroscopy in combination with chemometric tools, to detect frozen-thawed muscle foods.

Assessment of Astaxanthin Accumulation in Hepatocytes of Atlantic Salmon Fed Different Diets Using NMR Spectroscopy.

This study aimed to assess the astaxanthin (Ax) accumulation in hepatocytes isolated from farmed Atlantic salmon fed different diets (rich marine, poor, poor with marine phospholipids (MPL) and poor with docosahexaenoic acid (DHA)). Nuclear magnetic resonance (NMR) spectroscopy was used for the Ax detection and quantification. The use of the 13C-enriched Ax allowed the assessment of short-time Ax metabolism. The substitution of fish oil and meal in fish feed on plant analogs and the addition of MPL caused further catabolism and decrease of Ax accumulation in hepatocytes from 17 to about 6 mg/kg or to almost zero in the case of DHA addition. Signals assignment of the native and 13C-enriched astaxanthin in acetone were performed using 1D and 2D NMR spectra.

Determination of Glyphosate in Dried Wheat by 1H-NMR Spectroscopy.

A wheat field was sprayed with a dosage of 1.1 kg a.i./ha Roundup PowerMax 10 days before harvest. The 1H Nuclear Magnetic Resonance (NMR) spectroscopy was used for the detection and quantification of the glyphosate (GLYP) in dried wheat spikelets, leaves, and stems. The quantification was done by the integration of the CH2-P groups doublet at 3.00 ppm with good linearity. The GLYP content varied between different samples and parts of the plant. On average, the largest content of herbicide was found in leaves (20.0 mg/kg), followed by stems (6.4 mg/kg) and spikelets (6.3 mg/kg). Our study shows that the 1H-NMR spectroscopy can be a rapid and reliable tool for GLYP detection and quantification in the field studies.

Differentiation of fresh and thawed Atlantic salmon using NMR metabolomics.

NMR metabolomics approach was used to distinguish fresh and thawed Atlantic salmon. Statistical analysis revealed significant differences in the concentration of some metabolites in reference and frozen-thawed fish during its storage. It was found that salmon freezing/thawing caused a significant increase in the concentration of fumarate and phenylalanine in stored salmon muscle. The concentration of fumarate increased until the 3rd-5th day after thawing and then gradually decreased, reaching zero after two weeks of storage. The concentration of phenylalanine was constantly increased during the storage time. Furthermore, it was detected that aspartate was formed in the flesh of only thawed fish after the second day of storage. Its concentration followed the same trend as fumarate reaching its maximal concentration on the 3rd-5th day after thawing (up to 3.8 mg in 100 g of muscle) and gradually decreased to zero. Aspartate formation was influenced by storage time after thawing and not by the time after slaughter. We propose to use the formation of aspartate in stored salmon flesh as a marker of salmon freezing/thawing.

Changes in the Composition of Atlantic Salmon upon the Brown Seaweed (Saccharina latissima) Treatment.

This study shows the potential of improving the taste and shelf life of salmon by storing it in conjunction with sugar kelp. The influence of the addition of wet sugar kelp to Atlantic salmon fillet was assessed using a Nuclear Magnetic Resonance (NMR) metabolomics approach. Seaweed treatment caused significant changes in the polar and non-polar metabolic composition of salmon muscle upon its storage. The mutual diffusion of sugar kelp and salmon metabolites caused a significant decrease of the formation of the off-smelling compound trimethylamine and the biogenic amines, along with an increase of umami-related compounds (aspartate and succinic acid). Carotenoid composition of the seaweed-treated samples significantly differs from the reference samples. The amount of wet seaweeds used for the treatment and the time passed after the fish slaughter influence salmon quality parameters.

Development of a statistical model to detect quality and storage conditions of Atlantic salmon.

The ever-increasing demand for fish as a food, has led to the development of new handling and packaging technologies resulting in premium quality fish products. In order to avoid frauds reaching the market, fish quality assurance methods need to be developed. In this study, two statistical models of biochemical processes that occur in Atlantic salmon during two weeks of storage at 0 and 4 °C were developed. These models were further used to detect salmon quality and its storage conditions. The biochemical processes were monitored using Nuclear Magnetic Resonance (NMR) spectroscopy and principal component analysis (PCA). The Soft Independent Modeling of Class Analogy (SIMCA) approach was applied to develop and evaluate the models. The fraud detection potential of the models was tested using samples of various quality and storage parameters. It was shown that the developed models are able to discriminate quality, time and temperature of stored Atlantic salmon.

Complete Genome Sequence of Human Adenovirus 7 Associated with Fatal Adult Pneumonia.

Human adenovirus 7 (hAdv7) 19BOVLB/Volgograd/Rus/2014 was isolated from the autopsy material from an adult with fatal pneumonia in Volgograd, Russia, in March 2014. Whole-genome sequencing of the virus isolate was performed.

Quality changes of salmon by-products during storage: Assessment and quantification by NMR.

Safe utilization of fish by-products is an important task due to increasing fish consumption. It can provide new valuable food/feed and will increase the economical profit and sustainability of the fishery industry. NMR spectroscopy is a reliable tool able to monitor qualitative and quantitative changes in by-products. In this work the trichloroacetic acid extracts of salmon backbones, heads and viscera stored at industrially relevant temperatures (4 and 10°C) were studied using NMR. Twenty-five metabolites were detected and the possibility of salmon by-products utilization as a source of anserine, phosphocreatine and taurine was discussed. Statistical data elaboration allowed determining the main processes occurring during by-products storage: formation of trimethylamine and biogenic amines, proteolysis and different types of fermentations. By-products freshness was evaluated using a multi-parameter approach: the trimethylamine and biogenic amines concentration changes were compared with Ki and H-values and safe temperatures and times for storage of salmon by-products were proposed.

Sequential transformation of the structural and thermodynamic parameters of the complex particles, combining covalent conjugate (sodium caseinate + maltodextrin) with polyunsaturated lipids stabilized by a plant antioxidant, in the simulated gastro-intestinal conditions in vitro.

The present work is focused on the structural transformation of the complexes, formed between covalent conjugate (sodium caseinate + maltodextrin) and an equimass mixture of the polyunsaturated lipids (PULs): (soy phosphatidylcholine + triglycerides of flaxseed oil) stabilized by a plant antioxidant (an essential oil of clove buds), in the simulated conditions of the gastrointestinal tract. The conjugate was used here as a food-grade delivery vehicle for the PULs. The release of these PULs at each stage of the simulated digestion was estimated.

Biopolymer nanovehicles for essential polyunsaturated fatty acids: Structure-functionality relationships.

Design of stimuli-sensitive (i.e., smart) nano-sized delivery systems for nutraceuticals, having both a nutritional and pharmaceutical value, is very important for the formulation of novel functional food. Omega-3 and omega-6 polyunsaturated fatty acids (PUFAs) are among the most needed nutraceuticals for the maintenance of good health. It is medically proven that in order to get the best effect on the human health the weight ratio of ω-6/ω-3 PUFAs should be within the range between 1/1 and 5/1. Thus, our work was focused on the molecular design of the delivery systems based on the nano-sized complexes formed between covalent conjugate (sodium caseinate+maltodextrin (a dextrose equivalent=2)) and the combinations of polyunsaturated lipids, which are mutually complementary in the ω-6 and ω-3 PUFAs content: α-linolenic (ALA)+linoleic (LA) acids; liposomes of soy phosphatidylcholine (PC)+ALA; and micelles of soy lysophosphatidylcholine (LPC)+ALA. For such complex particles the high extent (>95%) of encapsulation of these all combinations of lipids by the conjugate was found along with both the high protection of the lipids against oxidation and their high solubility in an aqueous medium. To gain a better insight into such functionality of the complex particles a number of their structural (the weight-averaged molar weight, Mw; the radius of gyration, RG; the hydrodynamic radius, Rh; the architecture; the volume; the density; the ζ-potential; the microviscosity of both the bilayers of PC liposomes and LPC micelles), and thermodynamic (the osmotic second virial coefficient, A2, reflecting the nature and intensity of both the complex-complex and complex-solvent pair interactions) parameters were measured by a combination of such basic physico-chemical methods as static and dynamic multiangle laser light scattering, particle electrophoresis, atomic-force microscopy and electron spin resonance spectroscopy.

Antibody titers against vaccine and contemporary wild poliovirus type 1 in children immunized with IPV+OPV and young adults immunized with OPV.

In 2010, a type 1 poliovirus outbreak in Congo with 445 lethal cases was caused by a virus that was neutralized by sera of German adults vaccinated with inactivated polio vaccine with a reduced efficiency. This seroprevalence study was done in two cohorts immunized with other vaccination schedules. Russian children aged 3-6 years immunized with a combination of inactivated and live polio vaccines were reasonably well protected against any wild type poliovirus 1, including the Congolese isolate. Adults aged 20-29 years immunized only with live vaccine were apparently protected against the vaccine strain (92% seropositive), but only 50% had detectable antibodies against the Congo-2010 isolate. Both waning immunity and serological divergence of the Congolese virus could contribute to this result.

NMR approach for monitoring post-mortem changes in Atlantic salmon fillets stored at 0 and 4°C.

High resolution NMR technique has been used to monitor post-mortem changes in salmon (Salmo salar) fillets upon storage at 4 and 0°C. Thirty-one different fish metabolites influencing freshness and taste properties have been unequivocally assigned by NMR using either available standard compounds or ad hoc acquired 2D (1)H-(1)H TOCSY and (1)H-(13)С HSQC spectra. The monitored fish metabolites include amino acids, dipeptides, sugars, vitamins, biogenic amines, as well as different products of the ATP degradation. The detection and monitoring of biogenic amines by NMR, upon fish storage, is information of interest for consumers, since some of these compounds are toxic. The data from this study shows that NMR spectroscopy also provides the amount of all metabolites necessary for the calculation of the K-index used to express fish freshness. A good correlation was found between the K-index increase and the formation of the undesired biogenic amines. The metabolite concentrations and the K-index found in this work were compared and found coherent with literature data. The performed study reveals the strengths and the suitability of the NMR approach to monitor different biochemical processes occurring during fish storage and qualitatively and quantitatively characterise fish metabolites determining fish quality.

Molecular epidemiology of echoviruses 11 and 30 in Russia: different properties of genotypes within an enterovirus serotype.

Over 100 known enterovirus serotypes differ in their epidemiological and pathogenic properties. Much less is known about variation of these features on a sub-serotype level, such as genotypes. Echovirus 11 (E11) and E30 are amongst the most frequent causative agents of aseptic meningitis. We studied the molecular epidemiology of these pathogens to evaluate potential epidemiological and pathogenic dissimilarities of their genotypes. The complete VP1 genome region was sequenced for 97 E11 and 62 E30 isolates collected in Russia from 2008 to 2012, and they were studied in comparison with all 140 E11 and 432 E30 sequences available in GenBank. A geographic pattern of genotype prevalence was observed for both types. Russian E11 isolates belonged mainly to A genotype, which is common in Asia, and D5, which is predominant in Europe. For E30, genotype III by classification of Ke et al. (2011), also termed genotype a by Bailly et al. (2009), was endemic in Russia from 2003 to 2012, while it was not detected in Europe and North America during this time. The E30 genotypes VI-B, VI-G, and VI-H (e, f and h) were regularly introduced from different countries, became predominant and vanished after no more than 4years. In addition to geographic patterns, E11 genotypes also differed by isolation source. Genotype A2 viruses were significantly more often found in sewage, compared to genotype D5 that was isolated from both sewage and human samples. In addition, there was evidence of a different capacity for international transfers among E11 GtA subclusters.

Recombination strategies and evolutionary dynamics of the Human enterovirus A global gene pool.

We analysed natural recombination in 79 Human enterovirus A strains representing 13 serotypes by sequencing of VP1, 2C and 3D genome regions. The half-life of a non-recombinant tree node in coxsackieviruses 2, 4 and 10 was only 3.5 years, and never more than 9 years. All coxsackieviruses that differed by more than 7 % of the nucleotide sequence in any genome region were recombinants relative to each other. Enterovirus 71 (EV71), on the contrary, displayed remarkable genetic stability. Three major EV71 clades were stable for 19-29 years, with a half-life of non-recombinant viruses between 13 and 18.5 years in different clades. Only five EV71 strains out of over 150 recently acquired non-structural genome regions from coxsackieviruses, while none of 80 contemporary coxsackieviruses had non-structural genes transferred from the three EV71 clades. In contrast to earlier observations, recombination between VP1 and 2C genome regions was not more frequent than between 2C and 3D regions.

Competitive cobalt for zinc substitution in mammalian methionine sulfoxide reductase B1 overexpressed in E. coli: structural and functional insight.

Expression of the mammalian enzyme methionine sulfoxide reductase B1 (MsrB1) in Escherichia coli growing in cobalt-containing media resulted in the reproducible appearance of the stable cobalt-containing protein MsrB1-Co. NMR studies and biocomputing using the programs AnisoFit and Amber allowed us to generate a structure of MsrB1-Co sharing the overall fold with the native zinc-containing protein MsrB1-Zn. Our data suggest that the N-terminus containing resolving cysteine tends to be closer to the protein's catalytic center than was previously reported. It is argued that this proximity supports the proposed catalytic mechanism and ensures high catalytic efficiency of MsrB1. Functional studies showed that both MsrB1-Zn and MsrB1-Co exhibit similar levels of activity, in agreement with the structural studies performed. The proposed metal ion substitution approach may have a methodological significance in determining whether methionine sulfoxide reductase B proteins contain a metal ion.

Structural insights into interaction between mammalian methionine sulfoxide reductase B1 and thioredoxin.

Maintenance of the cellular redox balance has vital importance for correcting organism functioning. Methionine sulfoxide reductases (Msrs) are among the key members of the cellular antioxidant defence system. To work properly, methionine sulfoxide reductases need to be reduced by their biological partner, thioredoxin (Trx). This process, according to the available kinetic data, represents the slowest step in the Msrs catalytic cycle. In the present paper, we investigated structural aspects of the intermolecular complex formation between mammalian MsrB1 and Trx. NMR spectroscopy and biocomputing were the two mostly used through the research approaches. The formation of NMR detectable MsrB1/Trx complex was monitored and studied in attempt to understand MsrB1 reduction mechanism. Using NMR data, molecular mechanics, protein docking, and molecular dynamics simulations, it was found that intermediate MsrB1/Trx complex is stabilized by interprotein ß-layer. The complex formation accompanied by distortion of disulfide bond within MsrB1 facilitates the reduction of oxidized MsrB1 as it is evidenced by the obtained data.