Analysis of nucleosides and monophosphate nucleotides from mushrooms with reversed-phase HPLC

Optimizing mycelial protein yield in Pleurotus djamor via ARTP mutagenesis and hybridization strategies

With the world's population rapidly increasing, the demand for high-quality protein is on the rise. Edible fungi breeding technology stands as a crucial avenue to obtain strains with high yield, high-quality protein, and robust stress resistance. To address the protein supply gap, Atmospheric and Room Temperature Plasma (ARTP) mutagenesis, and spore hybridization techniques were employed to enhance Pleurotus djamor mycelium protein production. Beginning with the original strain Pleurotus djamor JD-1, ARTP was utilized to mutate spore suspension. The optimal treatment time for Pleurotus djamor spores, determined to achieve optimal mortality, was 240 s. Through primary and secondary screenings, 6 mutant strains out of 39 were selected, exhibiting improved protein yield and growth rates compared to the original strain. Among these mutagenic strains, 240S-4 showcased the highest performance, with a mycelial growth rate of 9.5±0.71 mm/d, a biomass of 21.45±0.54 g/L, a protein content of 28.75±0.92%, and a remarkable protein promotion rate of 128.03±7.29%. Additionally, employing spore hybridization and breeding, 7 single-nuclei strains were selected for pin-two hybridization, resulting in 21 hybrid strains. The biomass and protein content of 9 hybrid strains surpassed those of the original strains. One hybrid strain, H-5, exhibited remarkable mycelial protein production, boasting a mycelial growth rate of 26.5±0.7 mm/d, a biomass of 21.70±0.46 g/L, a protein content of 28.44±0.22%, and a protein promotion rate of 128.02±1.73%. Notably, both strains demonstrated about a 28% higher mycelial protein yield than the original strains, indicating comparable effectiveness between hybrid breeding and mutagenesis breeding. Finally, we analyzed the original and selected strains by molecular biological identification, which further proved the effectiveness of the breeding method. These findings present novel insights and serve as a reference for enhancing edible fungi breeding, offering promising avenues to meet the escalating protein demand.

Determination of umami compounds in edible fungi and evaluation of salty enhancement effect of Antler fungus enzymatic hydrolysate

The demand for low-salt foods is increasing due to their health benefits. Umami is known to enhance salty, and a large amount of umami components have been identified in edible fungi. 5'-nucleotides and umami amino acids from nine species of edible fungi were quantified. The equal umami concentration (EUC) in nine edible fungi was within the range of 37.7-1317.72 g MSG/100 g, and umami intensity as determined by electronic tongue and sensory evaluation was within the range of 11.22-13.53 and 2.85-5.55, respectively. Antler fungus had the highest umami intensity. Umami amino acids and nucleotides could increase salty intensity of NaCl at medium and high concentrations. The enzymatic hydrolysate of Antler fungus at higher concentrations could more effectively enhance salty taste of NaCl at lower concentration. This synergistic effect between umami and salty indicates that Antler fungus can potentially be used as an ingredient in low-salt foods.

KI Essence extract (a spleen-tonifying formula) promotes neurite outgrowth, alleviates oxidative stress and hypomyelination, and modulates microbiome in maternal immune activation offspring

Mushrooms and Chinese traditional herbs have bioactive nutraceuticals with multiple therapeutic functions, including antioxidant and antibacterial activities and microbiome modulation properties. Mushroom-derived bioactive compounds are used in medicines for the treatment of neurological disorders with abnormal brain–gut–microbiome axis. This study examined the effects of KI Essence extract, a spleen-tonifying formula, on neurite growth, antioxidant activity, hypomyelination modulation, and the microbiome profile in lipopolysaccharide (LPS)-induced maternal immune activation (MIA) offspring. The KI Essence extract induced PC12 cell neurite growth by increasing extracellular signal–regulated kinase (ERK) phosphorylation, promoting 2,2′-diphenyl-1-picrylhydrazyl radical scavenging activity, reducing the level of tert-butylhydroperoxide–induced lipid peroxidation in brain homogenates, protecting PC12 cells from H2O2-induced cell death (through the inhibition of ERK phosphorylation), alleviating hypomyelination, and downregulating interleukin‐1β through LPS-activated microglia production; moreover, the numbers of Enterobacteriaceae, Actinobacteria, Peptostreptococcaceae, Erysipelotrichaceae, and Bifidobacterium bacteria in MIA offspring increased. In summary, the KI Essence extract promotes neurite outgrowth, alleviates oxidative stress and hypomyelination, and modulates microbiota dysbiosis in MIA offspring.

The yield, nutritional value, umami components and mineral contents of the first-flush and second-flush Pleurotus pulmonarius mushrooms grown on three forestry wastes

This study was carried out to evaluate the yields and quality of the first-flush and second-flush Pleurotus pulmonarius mushrooms grown on three forestry wastes (pine, poplar, and honeysuckle rattan). The biological efficiency (BE) of the substrates varied from 61.89% to 81.01%. The total protein content, gamma-aminobutyric acid (GABA) content and equivalent umami concentration (EUC) values of the mushrooms were greatly influenced by the flush number and the substrate, however, the total sugar content and ergosterol content of the mushrooms were not significantly affected. The first-flush mushrooms that were grown on the pine sawdust-based substrate had the highest protein content, and the first-flush mushrooms that were grown on the honeysuckle rattan sawdust-based substrate had the highest GABA content and EUC values. All the mushroom samples accumulated Cu but excluded Ca, Mn, Pb, Cr, and Cd, and the concentrations of Mg, Fe, and Mn are species and flush number dependent.

Analytical characterization of nucleotides and their concentration variation in drinking water treatment process

Nucleotides, as the basic building blocks of nucleic acids, widely exist in aqueous environment. In this study, we developed a solid phase extraction-high performance liquid chromatography-tandem mass spectrometry (SPE-UPLC-MS/MS) method for the analysis of 5'-adenosine monophosphate (AMP), 5'-uridine monophosphate (UMP), 5'-cytidine monophosphate (CMP) and 5'-guanosine monophosphate (GMP). The method achieved limits of detection (LODs) of 0.1-1.0 ng/L, and recoveries of 85-95% for the four tested nucleotides. The occurrence and concentrations of the four nucleotides in water from eight representative drinking water treatment and distribution systems in China were determined using this method. All four nucleotides were detectable in water treatment plant (WTP) influent and effluent, at concentrations of up to 30 ng/L and with occurrence frequency of around 90%. The concentrations of identified nucleotides increased 3-10 times after 10 km of water age in the water distribution system. Biological filters and coagulation increased the concentrations of nucleotides, conversely, active carbon, ozonation, and ultrafiltration membrane removed nucleotides in water. The effects of active carbon and coagulation were further confirmed using laboratory-controlled experiment. In addition, monochlorinated nucleotides were identified as the chlorination products of nucleotides.

Comparison of the Nutritional and Taste Characteristics of 5 Edible Fungus Powders Based on the Composition of Hydrolyzed Amino Acids and Free Amino Acids

The nutritional characteristics and taste of some edible fungus powders were scientifically evaluated and compared. Five common edible fungus powders were used as test materials (Agrocybe chaxinggu edible fungus powder, Pleurotus citrinopileatus edible fungus powder, Flammulina velutipes edible fungus powder, Lentinus edodes edible fungus powder, and Hericium erinaceus edible fungus powder). The hydrolyzed amino acid and free amino acid content were measured by an automatic amino acid analyzer, and the ratios of hydrolyzed amino acid and free amino acid components and the taste characteristics of these eatables were systematically compared. The results showed that the total amount of hydrolyzed amino acids contained in the 5 edible fungus powders was between 2.583 and 14.656 g/100 g. The total amount of free amino acids contained in the 5 edible fungus powders was between 0.550 and 2.612 g/100 g. Comparative analysis of the mass fractions and composition of amino acids indicated that Pleurotus citrinopileatus edible fungus powder best met the ideal protein standard. The taste characteristics of protein were evaluated by calculating the taste active value (TAV) of taste-producing free amino acids. The most significant TAV values of the 5 edible fungus powders appeared in glutamic acid, and this amino acid is an umami amino acid. Principal component analysis (PCA) suggested that four principal components could reflect all the information on the free amino acids with a total cumulative variance contribution rate of 100%, and three principal components could reflect most of the information on the hydrolyzed amino acids with a total cumulative variance contribution rate of 99.143%, which could represent the main trends of free amino acids and hydrolyzed acids in edible fungus powder. The comprehensive evaluation model was established, and the comprehensive score indicated that Agrocybe chaxinggu edible fungus powder had the best comprehensive amino acid quality.

An Overview of Pretreatment and Analysis of Nucleotides in Different Samples (Update since 2010)

Nucleotides, which are important low-molecular-weight compounds present in organisms, are precursors of nucleic acids and participate in various regulatory and metabolic functions. Sensitive and valid methods for monitoring and determining nucleotides and nucleosides in different samples are urgently required. Due to the presence of numerous endogenous interferences in complex matrices and the high polarity of the molecules of the phosphate moiety, the determination of nucleotide content is challenging. This review summarizes the pretreatment and analysis methods of nucleotides in different samples. Advanced pretreatment methods, including different microextraction methods, solid-phase extraction based on novel materials, QuEChERS, are clearly displayed, and continuous progress which has been made in LC, LC-MS/MS and capillary electrophoresis methods are discussed. Moreover, the strengths and weaknesses of different methods are discussed and compared. Highlight:Advanced pretreatment and detection methods of nucleotides were critically reviewed.Microextraction technology was one of the trends of nucleotides pretreatment in the future.Applications of novel materials and supercritical fluid were highlighted.The evolution and advance of HRMS analyzers were in detailed.

Two-stage selective enzymatic hydrolysis generates protein hydrolysates rich in Asn-Pro and Ala-His for enhancing taste attributes of soy sauce

This study demonstrated the contribution of peptides to umami soy sauce taste. Asn-Pro and Ala-His with remarkable umami taste and umami-enhancing capacity were found in original soy sauce, possessing umami thresholds of 175 and 160 mg/L and umami-enhancing thresholds of 10 and 13 mg/L, respectively. Firstly, an industrially viable two-stage hydrolysis at 55 °C (a 12-h hydrolysis with the neutral protease, then a 12-h hydrolysis with the aminopeptidase) was established to produce protein hydrolysates rich in umami-tasting and umami-enhancing peptides (e.g. Asn-Pro and Ala-His) from non-soy sauce protein preparations (soy protein isolate, rice proteins, wheat proteins, peanut proteins or pea proteins). The soy protein isolate hydrolysate produced via the two-stage hydrolysis had Asn-Pro and Ala-His contents 3.32 and 1.15 times higher than those produced via the one-stage hydrolysis using the neutral protease only. Adding the hydrolysate to original soy sauce at 5% w/v significantly increased umami and reduced bitterness.

Anti-Microbiological, Anti-Hyperglycemic and Anti-Obesity Potency of Natural Antioxidants in Fruit Fractions of Saskatoon Berry

The aim of the present work was to evaluate for content of phytochemicals (monophosphate nucleotides, free amino acids, polyphenols), and for anti-microbiological, anti-diabetic (ability to inhibit pancreatic lipase, α-glucosidase, and α-amylase), and antioxidant activities in seven selected fruit and fruit fractions of Amelanchier alnifolia. Most of the fruit and fruit fractions analyzed in this study have not been examined in this respect until now. The content of monophosphate nucleotides and free amino acids were tested by ultra-performance liquid chromatography coupled with photodiode array detector and electrospray ionization-mass spectrometry (UPLC-PDA-ESI-MS). The distribution of the examined compounds and biological activity differed significantly depending on the tested fruit and parts of the fruit. Cultivars “Smoky” and “Thiessen” had a high content of essential free amino acids, monophosphate nucleotides, and the highest antioxidant activity. They were also accountable for the high ability to inhibit Enterococcus hirae (anti-bacterial activity), of activity toward α-amylase, α-glucosidase, and pancreatic lipase. Moreover, the fruit peel was abundant in polyphenolic compounds and showed the highest antioxidative activity, which were strongly correlated with each other. In addition, the peel was characterized by a high concentration of monophosphate nucleotides, free amino acids, and were responsible above all for the strong ability to inhibit pancreatic lipase enzymes contributing to the development of obesity. The seeds were rich in uridine 5’-monophosphate, and total essential and non-essential free amino acids, whose contents correlated with the inhibitory activity toward α-amylase and α-glucosidase. The fruit flesh showed a high content of total free amino acids (hydroxy-L-proline, O-phosphoethanolamine, L-citruline). There was a positive correlation between antioxidant capacity and the content of polyphenolic compounds, nucleotide, and ability to inhibit pancreatic lipase, and between anti-hyperglycemic and free amino acids in fruits and fruit fractions. Therefore, the tested fruit of A. alnifolia and their fractions could be essential ingredients of new functional products and/or probiotic food.

Metabolic Profiling of Water-Soluble Compounds from the Extracts of Dark Septate Endophytic Fungi (DSE) Isolated from Scots Pine (Pinus sylvestris L.) Seedlings Using UPLC-Orbitrap-MS

Endophytes are microorganisms living inside plant hosts and are known to be beneficial for the host plant vitality. In this study, we isolated three endophytic fungus species from the roots of Scots pine seedlings growing on Finnish drained peatland setting. The isolated fungi belonged to dark septate endophytes (DSE). The metabolic profiles of the hot water extracts of the fungi were investigated using Ultrahigh Performance Liquid Chromatography with Diode Array Detection and Electron Spray Ionization source Mass Spectrometry with Orbitrap analyzer (UPLC-DAD-ESI-MS-Orbitrap). Out of 318 metabolites, we were able to identify 220, of which a majority was amino acids and peptides. Additionally, opine amino acids, amino acid quinones, Amadori compounds, cholines, nucleobases, nucleosides, nucleotides, siderophores, sugars, sugar alcohols and disaccharides were found, as well as other previously reported metabolites from plants or endophytes. Some differences of the metabolic profiles, regarding the amount and identity of the found metabolites, were observed even though the fungi were isolated from the same host. Many of the discovered metabolites have been described possessing biological activities and properties, which may make a favorable contribution to the host plant nutrient availability or abiotic and biotic stress tolerance.

Development and validation of an HPLC-DAD-MS method for determination of four nucleoside compounds in the New Zealand native mushroom Hericium sp

To identify and quantify the content of nucleoside compounds in the New Zealand native edible mushroom Hericium sp., a high-performance liquid chromatography coupled with a triple quadrupole detector mass method was developed and validated. Four nucleoside substitutes, namely cytidine, uridine, adenosine, and guanosine, were identified. Optimization was conducted to study the effect of extraction method type, solvent pH, and extraction time. The optimal conditions were obtained using ultrasonic treatment in water at pH 3.8 for 30 min. For chromatographic separation, a C₁₈ column was applied using 0.1% formic acid (pH 3.4) as the mobile phase with detection at 260 nm. The total concentration of the four nucleoside compounds was high, at 10.7 mg/g dry weight, indicating a potential benefit for human health. The excellent validation results based on selectivity, linearity, precision, accuracy and robustness revealed the reliability of the newly developed analytical method, which could be applied routinely in research laboratories.

Black Truffle Aqueous Extract Attenuates Oxidative Stress and Inflammation in STZ-Induced Hyperglycemic Rats via Nrf2 and NF-κB Pathways

Background and Purpose: Tuber melanosporum (black truffle) has been considered as a medicinal mushroom for a long time. T. melanosporum has the ability to attenuate oxidative stress and in turn diabetes mellitus (DM). DM has become an awfully common chronic unwellness, threatening people's well-being. There are nearly 1 in 10 people in the world affected by diabetes. Oxidative stress plays a crucial role in vascular complications related to DM. Our study aimed to attain an effective treatment method to alleviate oxidative stress by scavenging free radicals and reducing inflammation, to display how truffle aqueous extract (TE) attenuates hyperglycemia. Methods: Streptozotocin (STZ)-induced hyperglycemic rat model was accustomed to check the hypoglycemic effect of black truffle by relating it with Nrf2 and NF-κB pathways. Varied biomarkers and inflammatory markers were analyzed. Results: Rats treated with TE showed reduced glucose levels, attenuated oxidative stress through regulation of SOD, CAT, VIT-E, and VIT-C. The gene expression of Nrf2 and NF-κB in rats treated with TE was increased to normal group level. The mRNA expression of inflammatory pathway genes and oxidative stress pathway genes in rats treated with TE was brought back normal. Similar results were achieved in the rats treated with standard drug, glibenclamide (GB). TE conjointly inhibits the state of inflammation within the tissues generally littered with the symptoms of hyperglycemia. Conclusion: The results of our study show the hypoglycemic impact of black truffle on STZ-induced hyperglycemia in rats via Nrf2 and NF-κB pathways, and both pathways have significant improvement that may support the hypoglycemic impact of truffle.

UPLC-QqQ/MS combined with similarity assessment of 17 nucleic acid constituents in 147 edible fungi from Sichuan Basin, China

Nucleic acid constituents are the main functional ingredients in edible fungi, therefore understanding the nucleic acid constituents of edible fungi often eaten on the table by the Chinese people is of significant value. In this study, Sichuan Provincial Center for Disease Control and Prevention collected 147 samples of edible fungi (including certain species that the Chinese often eat) from different parts of the Sichuan Basin. A new UPLC-QqQ/MS method has been developed to determine the 17 nucleic acid constituents in these 147 samples, including guanosine, adenosine, uridine, cytidine, inosine, thymidine, xanthosine dehydrate, 2'-deoxyguanosine, 2'-deoxyadenosine, 2'-deoxyuridine, 2'-deoxycytidine, 2'-deoxyinosine, guanosine 5'-monophosphate, adenosine 5'-monophosphate, uridine 5'-monophosphate, cytidine 5'-monophosphate, and inosine 5'-monophosphate. Finally, similarity assessment of the main edible fungus was performed using vectorial angle cosine method, and hierarchical cluster analysis was used to classify all the 147 samples. The results showed that some edible fungi have high similarities, especially in Lentinula edodes (Berk.) Pegler, the monogenic nucleotides content of which (55.84 ± 8.4 mg/100 g) is far greater than any other edible fungus, which is directly related to its taste. For quality control, this paper proposed to use the reference values of total nucleic acid compounds in edible fungi computed by percentile threshold method. This is the first time a comprehensive evaluation of nucleic acid constituents of different edible fungi of daily consumption was conducted for a large region, and the results is conducive to the quality evaluation and quality control of edible fungus.

The effect of cooking on umami compounds in wild and cultivated mushrooms

The effect of cooking on the taste compounds of five mushroom species Agaricus bisporus, Lactarius trivialis, Cantharellus cibarius, Cantharellus tubaeformis and Suillus variegatus were assessed with a special focus on the compounds responsible for the umami taste. Liquid chromatography was used to analyse free amino acids (FAAs) and 5'-nucleotides from fresh and sous vide (SV) cooked mushroom samples and cooking juice. The SV technique enabled analysis of entire mushrooms, including the liquid released during cooking. FAA content decreased when cooking temperature increased, indicating their further chemical reactions. S. variegatus contained highest concentrations of FAAs in analysed wild mushrooms. The umami-enhancing nucleotide 5'-GMP was detected only in cooked samples, concentration being likely dependent on enzymatic activity. The highest concentration of 5'-GMP was detected in cooked L. trivialis samples (17 mg/100 g fw). To our knowledge, the analysed taste compounds of L. trivialis and S. variegatus are documented for the first time.

Discovery of taste modulating octadecadien-12-ynoic acids in golden chanterelles (Cantharellus cibarius)

Activity-guided fractionation in combination with taste dilution and comparative taste dilution analysis, followed by LC-MS and 1D/2D-NMR experiments, enabled the identification of several C₁₈-acetylenic acids in chanterelles among which (9Z,15E)-14,17,18-trihydroxy-9,15-octadecadien-12-ynoic acid, (9Z,15E)-14-oxo-9,15-octadecadien-12-ynoic acid, (10E,15E)-9-hydroxy-14-oxo-10,15-octadecadien-12-ynoic acid, (10E,15E)-9-hydroperoxy-14-oxo-10,15-octadecadien-12-ynoic acid, (10E,15E)-9,14-dioxo-10,15-octadecadien-12-ynoic acid, (9Z,15E)-14-oxo-9,15-octadecadien-12-ynoic acid methyl ester, (9Z,15E)-17(18)-epoxy-14-oxo-9,15-octadecadien-12-ynoic acid methyl ester and (10E,14Z)-9-hydroperoxy-10,14-octadecadien-12-ynoic acid have not yet been reported in literature. Sensory evaluation in a basic taste recombinant revealed taste modulating thresholds for the octadecadien-12-ynoic acids in the range of 19-105 µmol/l. In comparison, three isolated octadecadienoic acids, namely (10E,14Z)-12-hydroxy-10,14-octadecadienoic acid, (9Z,11Z)-14,18-dihydroxy-9,11-octadecadienoic acid, and (9Z,11Z)-14,17,18-trihydroxy-9,11-octadecadienoic acid, respectively, did not show any taste modulating activity, thus pinpointing the putative key role of the acetylene moiety for kokumi enhancement.

Free amino acids and 5'-nucleotides in Finnish forest mushrooms

Edible mushrooms are valued because of their umami taste and good nutritional values. Free amino acids, 5'-nucleotides and nucleosides were analyzed from four Nordic forest mushroom species (Lactarius camphoratus, Boletus edulis, Cantharellus cibarius, Craterellus tubaeformis) using high precision liquid chromatography analysis. To our knowledge, these taste components were studied for the first time from Craterellus tubaeformis and Lactarius camphoratus. The focus was on the umami amino acids and 5'-nucleotides. The free amino acid and 5'-nucleotide/nucleoside contents of studied species differed from each other. In all studied samples, umami amino acids were among five major free amino acids. The highest concentration of umami amino acids was on L. camphoratus whereas B. edulis had the highest content of sweet amino acids and C. cibarius had the highest content of bitter amino acids. The content of umami enhancing 5'-nucleotides were low in all studied species.

A review on the nucleic acid constituents in mushrooms: nucleobases, nucleosides and nucleotides

Mushrooms have become increasingly important as a reliable food source. They have also been recognized as an important source of bioactive compounds of high nutritional and medicinal values. The nucleobases, nucleosides and nucleotides found in mushrooms play important roles in the regulation of various physiological processes in the human body via the purinergic and/or pyrimidine receptors. Cordycepin, a 3'-deoxyadenosine found in Cordyceps sinensis has received much attention as it possesses many medicinal values including anticancer properties. In this review, we provide a broad overview of the distribution of purine nucleobases (adenine and guanine); pyrimidine nucleobases (cytosine, uracil, and thymine); nucleosides (uridine, guanosine, adenosine and cytidine); as well as novel nucleosides/tides in edible and nonedible mushrooms. This review also discusses the latest research focusing on the successes, challenges, and future perspectives of the analytical methods used to determine nucleic acid constituents in mushrooms. Besides, the exotic taste and flavor of edible mushrooms are attributed to several nonvolatile and water-soluble substances, including the 5'-nucleotides. Therefore, we also discuss the total flavor 5'-nucleotides: 5'-guanosine monophosphate (5'-GMP), 5'-inosine monophosphate (5'-IMP), and 5'-xanthosine monophosphate (5'-XMP) in edible mushrooms.

Capillary electrophoresis coupled to mass spectrometry employing hexafluoro-2-propanol for the determination of nucleosides and nucleotide mono-, di- and tri-phosphates in baby foods

The present work describes a method for the simultaneous determination of unmodified nucleosides and nucleotide mono-, di- and tri-phosphates by capillary electrophoresis coupled to mass spectrometry (CE-MS). The use of hexafluoro-2-propanol (HFIP) in the separation medium, and as an additive to the sheath liquid of the electrospray interface (ESI), generated a highly efficient and sensitive method. Instrumental limits of detection in the range of 14-53ngmL^-1 for nucleosides and 7-23, 20-49 and 64-124ngmL^-1 for nucleotide mono-, di-, and tri-phosphates, respectively, were found. Sample treatment involved diluting an aliquot of baby food with ultra-high quality water and applying centrifugation-assisted ultrafiltration (CUF). The proposed method was validated and used to analyse a variety of baby food samples (16 in total) such as fish, meat, fruits, and baby dairy desserts that may endogenously contain these analytes.

Boronate-affinity hollow molecularly imprinted polymers for the selective extraction of nucleosides

Preparation of a boronate-affinity hollow molecularly imprinted polymer and its application as an SPE adsorbent for the selective enrichment of nucleosides.

Determination of nucleosides and nucleotides in baby foods by hydrophilic interaction chromatography coupled to tandem mass spectrometry in the presence of hydrophilic ion-pairing reagents

In this work we propose a rapid and efficient method for the joint determination of nucleosides and nucleotides in dairy and non-dairy baby foods based on hydrophilic interaction chromatography coupled to tandem mass spectrometry in the presence of diethylammonium (DEA) as a hydrophilic ion-pairing reagent (IP-HILIC-MS/MS). Sample treatment of the baby food included dilution with water and centrifugal ultrafiltration (CUF) with an additional washing step that notably improved the global performance of the process. Later dilution of the extract with acetonitrile allowed adequate separation in the HILIC system. With the proposed treatment, we obtained extraction recoveries higher than 80% and, additionally, no matrix effects were observed. The CUF-IP-HILIC-MS/MS method was validated according to the 2002/657/EC decision and was used for the quantification of nucleotides and nucleosides in sixteen samples of commercial baby foods.

Concentration of Umami Compounds in Pork Meat and Cooking Juice with Different Cooking Times and Temperatures

This study examined the concentrations of umami compounds in pork loins cooked at 3 different temperatures and 3 different lengths of cooking times. The pork loins were cooked with the sous vide technique. The free amino acids (FAAs), glutamic acid and aspartic acid; the 5'-nucleotides, inosine-5'-monophosphate (IMP) and adenosine-5'-monophosphate (AMP); and corresponding nucleoside inosine of the cooked meat and its released juice were determined by high-performance liquid chromatography. Under the experimental conditions used, the cooking temperature played a more important role than the cooking time in the concentration of the analyzed compounds. The amino acid concentrations in the meat did not remain constant under these experimental conditions. The most notable effect observed was that of the cooking temperature and the higher amino acid concentrations in the released juice of meat cooked at 80 °C compared with 60 and 70 °C. This is most likely due to the heat induced hydrolysis of proteins and peptides releasing water soluble FAAs from the meat into the cooking juice. In this experiment, the cooking time and temperature had no influence on the IMP concentrations observed. However, the AMP concentrations increased with the increasing temperature and time. This suggests that the choice of time and temperature in sous vide cooking affects the nucleotide concentration of pork meat. The Sous vide technique proved to be a good technique to preserve the cooking juice and the results presented here show that cooking juice is rich in umami compounds, which can be used to provide a savory or brothy taste.

Hydrophilic interaction chromatography coupled to tandem mass spectrometry in the presence of hydrophilic ion-pairing reagents for the separation of nucleosides and nucleotide mono-, di- and triphosphates

A fast and efficient method for the simultaneous separation of highly polar compounds, in this case nucleosides and nucleotide mono-, di- and triphosphates, using hydrophilic interaction chromatography coupled with tandem mass spectrometry (HILIC-MS/MS) is proposed. This new separation method revealed the possibilities of the formation of hydrophilic ion-pairing compounds. Three stationary phases (HILIC XBridge-Amide, HILIC-CoreShell and ZIC-HILIC) were assayed for the separation of 20 target analytes, and a detailed study of the composition of the mobile phase was made using different salts at different concentrations in a organic-rich mobile phase. We report that in order to prevent the adsorption of nucleotides on the LC-MS setup and to enhance their retention on the HILIC stationary phase, a mobile phase containing hexafluoro-2-propanol and different cations should be used. Four cations were evaluated: ammonium, diethylammonium, triethylammonium and tetrabutylammonium. The results revealed the formation of an ionic-association compound between the phosphorylated analytes and the cationic ion-pairing reagents, whose retention increased with the polarity of the cationic ion-pairing reagent. HILIC XBridge-Amide was found to be the most suitable column for the separation of these analytes, and the optimized mobile phase consisted of an ACN/UHQ water mixture (3min of isocratic elution using 82:18%, v/v and then a fast gradient from 18% to 22% of water) with 100mM hexafluoro-2-propanol and 50mM diethylamine (w(w)pH 9-w(s)pH 10). In a total analysis time of 8min, good results were achieved in terms of resolution. Under these optimum conditions, a further comprehensive study of the retention mechanism was carried out.

Characterization of human herpesvirus 6A/B U94 as ATPase, helicase, exonuclease and DNA-binding proteins

Human herpesvirus-6A (HHV-6A) and HHV-6B integrate their genomes into the telomeres of human chromosomes, however, the mechanisms leading to integration remain unknown. HHV-6A/B encode a protein that has been proposed to be involved in integration termed U94, an ortholog of adeno-associated virus type 2 (AAV-2) Rep68 integrase. In this report, we addressed whether purified recombinant maltose-binding protein (MBP)-U94 fusion proteins of HHV-6A/B possess biological functions compatible with viral integration. We could demonstrate that MBP-U94 efficiently binds both dsDNA and ssDNA containing telomeric repeats using gel shift assay and surface plasmon resonance. MBP-U94 is also able to hydrolyze adenosine triphosphate (ATP) to ADP, providing the energy for further catalytic activities. In addition, U94 displays a 3′ to 5′ exonuclease activity on dsDNA with a preference for 3′-recessed ends. Once the DNA strand reaches 8–10 nt in length, the enzyme dissociates it from the complementary strand. Lastly, MBP-U94 compromises the integrity of a synthetic telomeric D-loop through exonuclease attack at the 3′ end of the invading strand. The preferential DNA binding of MBP-U94 to telomeric sequences, its ability to hydrolyze ATP and its exonuclease/helicase activities suggest that U94 possesses all functions required for HHV-6A/B chromosomal integration.

Determination of nucleotides in infant milk formulas using novel dendrimer ion-exchangers

The main aim of the present study was to develop a method for the separation of 5'-monophosphate nucleotides with the use of ion chromatography. Novel dendrimeric stationary phases were used for this purpose. The effects exerted by the type of anion-exchanger support (silica or polymeric) and the number of stationary phase layers on nucleotide retention were studied. A silica-based dendrimeric anion-exchanger was most suitable for analyzing the studied compounds. An increase in the number of layers enhanced nucleotide retention inside the column. The separation efficiency of the studied compounds was tested at various concentrations of the mobile phase buffer. At higher phosphate buffer concentrations, nucleotide resolutions were achieved in 6min. Three commercially available infant milk formulas were analyzed to verify the applicability of the studied method. Solid phase extraction was used for sample cleanup and concentration. The limit of quantification of nucleotides was 0.40μg/ml, and the method was linear in the concentration range of 0.40-20.6μgml(-1.)

Evaluation of Brewer's spent yeast to produce flavor enhancer nucleotides: influence of serial repitching

The present work evaluates the influence of serial yeast repitching on nucleotide composition of brewer's spent yeast extracts produced without addition of exogenous enzymes. Two procedures for disrupting cell walls were compared, and the conditions for low-cost and efficient RNA hydrolysis were selected. A HILIC methodology was validated for the quantification of nucleotides and nucleosides in yeast extracts. Thirty-seven samples of brewer's spent yeast ( Saccharomyces pastorianus ) organized according to the number of serial repitchings were analyzed. Nucleotides accounted for 71.1-88.2% of the RNA products; 2'AMP was the most abundant (ranging between 0.08 and 2.89 g/100 g dry yeast). 5'GMP content ranged between 0.082 and 0.907 g/100 g dry yeast. The sum of 5'GMP, 5'IMP, and 5'AMP represented between 25 and 32% of total nucleotides. This works highlights for the first time that although serial repitching influences the content of monophosphate nucleotides and nucleosides, the profiles of these RNA hydrolysis products are not affected.

Hydrophilic interaction ultra-high performance liquid chromatography coupled with triple quadrupole mass spectrometry for determination of nucleotides, nucleosides and nucleobases in Ziziphus plants

In this study, a rapid and sensitive analytical method was developed for the determination of 20 nucleobases, nucleosides and nucleotides in Ziziphus plants at trace levels by using hydrophilic interaction ultra-high performance liquid chromatography coupled with triple-quadrupole tandem mass spectrometry (HILIC-UHPLC-TQ-MS/MS) in multiple-reaction monitoring (MRM) mode. Under the optimized chromatographic conditions, good separation for 20 target compounds were obtained on a UHPLC Amide column with sub-2μm particles within 10min. The overall LODs and LOQs were between 0.11-3.12ngmL(-1) and 0.29-12.48ngmL(-1) for the 20 analytes, respectively. It is the first report about simultaneous analysis of nucleobases, nucleosides and nucleotides in medicinal plants using HILIC-UHPLC-TQ-MS/MS method, which affords good linearity, precision, repeatability and accuracy. The developed method was successfully applied to Ziziphus plant (Z. jujuba, Z. jujuba var. spinosa and Z. mauritiana) samples. The analysis showed that the fruits and leaves of Ziziphus plants are rich in nucleosides and nucleobases as well as nucleotides, and could be selected as the healthy food resources. Our results in present study suggest that HILIC-UHPLC-TQ-MS/MS method could be employed as a useful tool for quality assessment of the samples from the Ziziphus plants as well as other medicinal plants or food samples using nucleotides, nucleosides and nucleobases as markers.

Characterization of nucleosides and nucleobases in fruits of Ziziphus jujuba by UPLC-DAD-MS

The fruit of Ziziphus jujuba , named dazao in Chinese, has been utilized as food as well as crude drugs in China for thousands of years. To explore the profiles of the nucleosides and nucleobases in this fruit, an ultraperformance liquid chromatograph coupled with a photodiode array detector and electrospray ionization-mass spectrometer method (UPLC-DAD-MS) has been established and validated in this paper. The validated method was successfully applied for the simultaneous characterization and quantitation of 9 nucleosides and nucleobases in 49 dazao samples, which comprised 43 cultivars from 26 cultivation regions. Furthermore, principal component analysis (PCA) was performed to classify the samples on the basis of the contents of the nine analyzed compounds. The results showed that almost all of these dazao samples were rich in nucleosides and nucleobases, although their contents were obviously various, and the proposed method could serve as a prerequisite for quality control of jujube products.