Degradation of water-soluble polysaccharides in pulp of litchi during storage.

Water-soluble polysaccharides (WSP) were extracted from the pulp of litchi. Its main component was identified as arabinogalactan. The dominant monosaccharide constituents were arabinose and galactose. Galactose and mannose accumulated at the end of storage. ATP, ADP and AMP levels declined with increasing pulp breakdown index. WSP depolymerized which was characterized by a decrease in its content and molecular weight, while its structure remained stable during storage. Polygalacturonase and pectate lyase (PL) were active at the early storage time, and ß-galactosidase (GAL) and α-l-arabinofuranosidase followed thereafter. Except for some pectin methylesterase (LcPME), LcPL, LcGAL and LcPME gene expression was downregulated. It was deduced that depolymerization of polysaccharides was mainly caused by the rupture of the branched side chain and glacturonic acid backbone to smaller repeating units, and both cell wall-degrading enzymes and nonenzymatic factors, such as energy level, participated in the degradation of polysaccharides, and consequently pulp breakdown of litchi.

Isolation, identification and characterization of a novel antimicrobial peptide from Moringa oleifera seeds based on affinity adsorption.

This study aimed to characterize a novel antimicrobial peptide (AMP) obtained from Moringa oleifera seed protein hydrolysates. Cell membrane chromatography and live bacteria adsorption were combined into a single step to efficiently isolate the active fraction of the AMP. Five peptides were identified by LC-MS/MS, among which the MCNDCGA peptide (termed MOp3) showed the greatest inhibitory effect against Staphylococcus aureus [minimum inhibitory concentration (MIC): 2 mg/mL]. MOp3 was identified as a hydrophobic anionic AMP rich in ß-sheet structures with negligible hemolytic activity at 2.0 × MIC. MOp3 had good tolerance to salt solutions at 5 % and pH range 6.0-8.0, but was sensitive to high temperatures (>100 °C) and acid protease. Microscopic observation further revealed that MOp3 induced irreversible damage onto the cell membrane of S. aureus and interacted with dihydrofolate reductase and DNA gyrase by hydrogen bonding and hydrophobic interaction. These findings highlight the potential application of a new antimicrobial agent against S. aureus in the food industry.

Study on nucleotide, myofibrillar protein biochemical properties and microstructure of freeze-dried scallop striated muscle during storage and rehydration.

The biochemical properties and microstructural changes of freeze-dried Japanese scallop (Patinopecten yessoensis) striated muscle during room temperature storage and rehydration were investigated. The results showed that the content of ATP in freeze-dried scallop muscle remained stable with no significant difference (p > 0.05). However, ATP was rapidly decomposed and AMP accumulated within 1.5 min of rehydration, and HxR and Hx were gradually produced from AMP decomposition with the extension of rehydration time. Besides, the results of chymotryptic digestion patterns demonstrated that the rod of myosin was unstable after dehydration, reflecting lower salt solubility than that of frozen-thawed scallop. In contrast, the myosin subfragment-1 (S-1) was stable, as indicated by the constant of Ca2+-ATPase activity of freeze-dried scallops throughout the storage and rehydration (p > 0.05). Furthermore, the microstructural analysis revealed that the Z line of the freeze-dried scallop was broken after dehydration process. This study might be useful for developing high-quality dehydrated scallops in the future.

Rapid quantitative analysis and suspect screening of per-and polyfluorinated alkyl substances (PFASs) in aqueous film-forming foams (AFFFs) and municipal wastewater samples by Nano-ESI-HRMS.

A rapid analytical method for per- and polyfluoroalkyl substances (PFASs) combining nano-electrospray ionization and high-resolution mass spectrometry (Nano-ESI-HRMS) was developed and applied to aqueous film-forming foams (AFFFs) and wastewater samples collected from three local wastewater treatment plants (WWTPs). This method exhibited high sensitivity with lower limits of detection (LODs) of 3.2∼36.2 ng/L for 22 target PFAS analytes. In AFFF formulations, Nano-ESI-HRMS enabled the first-time detection of trifluoromethanesulfonic acid (TFMS), perfluoroethyl cyclohexanesulfonate (PFECHS), 6:2 fluorotelomer sulfonyl amido sulfonic acid (6:2 FTSAS-SO2), N-ammoniopropyl perfluoroalkanesulfonamidopropylsulfonate (N-AmP-FASAPS, n = 3-6), ketone-perfluorooctanesulfonic acid (Keto-PFOS), fluorotelomer unsaturated amide sulfonic acid (FTUAmS, n = 7), and 6:2 fluorotelomer amide (6:2 FTAm). Their structures were verified by the tandem MS analysis using collision-induced dissociation. Further, the combination of absolute and semi-quantification results revealed 16 PFASs from 9 PFAS classes as dominant AFFF constituents, accounting for 88.2∼96.5% of the total detected anionic and zwitterionic PFASs, including perfluorinated sulfonic acids (PFSAs, n = 1,4∼8), 6:2 fluorotelomer sulfonates (6:2 FTS), fluorotelomer thioether amido sulfonic acid (FTSAS, n = 6,8), fluorotelomer sulfinyl amido sulfonic acid (FTSAS-SO, n = 6,8), N-AmP-FASAPS (n = 6), 6:2 fluorotelomer sulfonamide alkylbetaine (6:2 FTAB), perfluoroalkylsulfonamido amino carboxylate (PFASAC, n = 6), 2-((perfluorooctyl)thio)acetatic acid (Thio-8:2 FTCA), and 6:2 FTAm. At WWTPs, aerobic and anaerobic biotransformation of PFAS precursors at the aeration tanks and secondary clarifiers were evident by the generation of mid/short-chain perfluoroalkyl acids, such as perfluoroheptanoic acid (PFHpA), perfluorohexanoic acid (PFHxA), perfluoropentanoic acid (PFPeA), as well as the emergence of ultrashort trifluoroacetic acid (TFA) and TFMS and several novel fluorotelomer carboxylic acids (FTCAs). Overall, Nano-ESI-HRMS enabled comprehensive PFAS quantitative analysis and suspect screening, applicable for rapid investigation and assessment of PFAS-related exposure and treatment in environmental matrixes. Our results also revealed that AFFFs and municipal wastewaters are two key sources contributing to the prevalent detection of ultrashort-chain PFASs (e.g., TFMS and TFA) in water.

A Comprehensive Analysis of ATP Tests: Practical Use and Recent Progress in the Total Adenylate Test for the Effective Monitoring of Hygiene.

ABSTRACT: Rapid hygiene monitoring tests based on the presence of ATP have been widely used in the food industry to ensure that adequate cleanliness is maintained. In this study, the practical applications and limitations of these tests and recent technological progress for facilitating more accurate control were evaluated. The presence of ATP on a surface indicates improper cleaning and the presence of contaminants, including organic debris and bacteria. Food residues are indicators of insufficient cleaning and are direct hazards because they may provide safe harbors for bacteria, provide sources of nutrients for bacterial growth, interfere with the antimicrobial activity of disinfectants, and support the formation of biofilms. Residues of allergenic foods on a surface may increase the risk of allergen cross-contact. However, ATP tests cannot detect bacteria or allergenic proteins directly. To ensure efficient use of commercially available ATP tests, in-depth knowledge is needed regarding their practical applications, methods for determining pass-fail limits, and differences in performance. Conventional ATP tests have limitations due to possible hydrolysis of ATP to ADP and AMP, which further hinders the identification of food residues. To overcome this problem, a total adenylate test was developed that could detect ATP+ADP+AMP (A3 test). The A3 test is suitable for the detection of adenylates from food residues and useful for verification of hygiene levels. The A3 test in conjunction with other methods, such as microorganism culture and food allergen tests, may be a useful strategy for identifying contamination sources and facilitating effective hygiene management.

Identifying the Metabolic Signatures of PPARD-Overexpressing Gastric Tumors.

Peroxisome proliferator-activated receptor delta (PPARD) is a nuclear receptor known to play an essential role in regulation of cell metabolism, cell proliferation, inflammation, and tumorigenesis in normal and cancer cells. Recently, we found that a newly generated villin-PPARD mouse model, in which PPARD is overexpressed in villin-positive gastric progenitor cells, demonstrated spontaneous development of large, invasive gastric tumors as the mice aged. However, the role of PPARD in regulation of downstream metabolism in normal gastric and tumor cells is elusive. The aim of the present study was to find PPARD-regulated downstream metabolic changes and to determine the potential significance of those changes to gastric tumorigenesis in mice. Hyperpolarized [1-13C] pyruvate magnetic resonance spectroscopy, nuclear magnetic resonance spectroscopy, and liquid chromatography-mass spectrometry were employed for metabolic profiling to determine the PPARD-regulated metabolite changes in PPARD mice at different ages during the development of gastric cancer, and the changes were compared to corresponding wild-type mice. Nuclear magnetic resonance spectroscopy-based metabolomic screening results showed higher levels of inosine monophosphate (p = 0.0054), uracil (p = 0.0205), phenylalanine (p = 0.017), glycine (p = 0.014), and isocitrate (p = 0.029) and lower levels of inosine (p = 0.0188) in 55-week-old PPARD mice than in 55-week-old wild-type mice. As the PPARD mice aged from 10 weeks to 35 weeks and 55 weeks, we observed significant changes in levels of the metabolites inosine monophosphate (p = 0.0054), adenosine monophosphate (p = 0.009), UDP-glucose (p = 0.0006), and oxypurinol (p = 0.039). Hyperpolarized [1-13C] pyruvate magnetic resonance spectroscopy performed to measure lactate flux in live 10-week-old PPARD mice with no gastric tumors and 35-week-old PPARD mice with gastric tumors did not reveal a significant difference in the ratio of lactate to total pyruvate plus lactate, indicating that this PPARD-induced spontaneous gastric tumor development does not require glycolysis as the main source of fuel for tumorigenesis. Liquid chromatography-mass spectrometry-based measurement of fatty acid levels showed lower linoleic acid, palmitic acid, oleic acid, and steric acid levels in 55-week-old PPARD mice than in 10-week-old PPARD mice, supporting fatty acid oxidation as a bioenergy source for PPARD-expressing gastric tumors.

Factors Influencing AMPK Activation During Cycling Exercise: A Pooled Analysis and Meta-Regression.

BACKGROUND: The 5' adenosine monophosphate (AMP)-activated protein kinase (AMPK) is a cellular energy sensor that is activated by increases in the cellular AMP/adenosine diphosphate:adenosine triphosphate (ADP:ATP) ratios and plays a key role in metabolic adaptations to endurance training. The degree of AMPK activation during exercise can be influenced by many factors that impact on cellular energetics, including exercise intensity, exercise duration, muscle glycogen, fitness level, and nutrient availability. However, the relative importance of these factors for inducing AMPK activation remains unclear, and robust relationships between exercise-related variables and indices of AMPK activation have not been established. OBJECTIVES: The purpose of this analysis was to (1) investigate correlations between factors influencing AMPK activation and the magnitude of change in AMPK activity during cycling exercise, (2) investigate correlations between commonly reported measures of AMPK activation (AMPK-α2 activity, phosphorylated (p)-AMPK, and p-acetyl coenzyme A carboxylase (p-ACC), and (3) formulate linear regression models to determine the most important factors for AMPK activation during exercise. METHODS: Data were pooled from 89 studies, including 982 participants (93.8% male, maximal oxygen consumption [[Formula: see text]] 51.9 ± 7.8 mL kg-1 min-1). Pearson's correlation analysis was performed to determine relationships between effect sizes for each of the primary outcome markers (AMPK-α2 activity, p-AMPK, p-ACC) and factors purported to influence AMPK signaling (muscle glycogen, carbohydrate ingestion, exercise duration and intensity, fitness level, and muscle metabolites). General linear mixed-effect models were used to examine which factors influenced AMPK activation. RESULTS: Significant correlations (r = 0.19-0.55, p < .05) with AMPK activity were found between end-exercise muscle glycogen, exercise intensity, and muscle metabolites phosphocreatine, creatine, and free ADP. All markers of AMPK activation were significantly correlated, with the strongest relationship between AMPK-α2 activity and p-AMPK (r = 0.56, p < 0.001). The most important predictors of AMPK activation were the muscle metabolites and exercise intensity. CONCLUSION: Muscle glycogen, fitness level, exercise intensity, and exercise duration each influence AMPK activity during exercise when all other factors are held constant. However, disrupting cellular energy charge is the most influential factor for AMPK activation during endurance exercise.

Calix[n]triazolium based turn-on fluorescent sensing ensemble for selective adenosine monophosphate (AMP) detection.

A novel calix[n]triazolium was synthesized and exhibited excellent selectivity for AMP. The binding between calix[n]triazolium and chromenolate anions forms a non-fluorescent complex and the resulting supramolecular ensemble selectively detects AMP in water and induces "turn-on" fluorescence. The sensing platform is the first macrocyclic system to discriminate AMP from ADP and ATP through fluorescence changes.

Development and Validation of High-Performance Liquid Chromatography Method for the Quantification of Remdesivir in Intravenous Dosage Form.

Corona virus disease 2019 (COVID-19) has posed a mounting threat to public health with worldwide outbreak caused by a novel virus named severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Recently, remdesivir (RDV) has been approved by Food and Drug Administration (FDA) for treating COVID-19 patients ≥12 years old requiring hospitalization. To the best of our knowledge, a simple method to estimate RDV in the pharmaceutical formulations using high-performance liquid chromatography (HPLC) is still unexplored, highlighting the need for a precise analytical method for its quantification. The prime purpose of the current investigation was to develop and validate a well-grounded HPLC method for quantification of RDV in pharmaceutical formulations. The best chromatogram was obtained by means of an Inertsil ODS-3V column using a mobile phase of milli-Q water modified to pH 3.0 with o-phosphoric acid and acetonitrile (50:50, % v/v) at a flow rate of 1.2 mL/min and wavelength of detector set at 246 nm with retention time being achieved at 6.0 min. The method was validated following International Council for Harmonization of Technical Requirements for Pharmaceuticals for Human Use (ICH) Q2 (R1) guidelines for various parameters such as specificity and selectivity, system suitability, linearity, precision, accuracy, limits of detection and quantification, and robustness. The method developed for the quantification of RDV was found to be linear in the concentration range of 25-2,500 ng/mL with limit of detection and limit of quantification of 1.95 and 6.49 ng/mL, respectively. Assay value of 102% ± 1% was achieved for marketed injectable dosage form when estimated by the validated method. Therefore, in this study a simple, rapid, sensitive, selective, accurate, precise, and robust analytical method was developed and validated for the quantification of RDV using HPLC. The established method was successfully employed for quantification of RDV in marketed pharmaceutical formulation.

Element probe based CRISPR/Cas14 bioassay for non-nucleic-acid targets.

Herein, we propose an element probe based CRISPR/Cas14 detection platform and apply it to the detection of non-nucleic-acid targets. Combining metal isotope detection and CRISPR/Cas14 biosensing, the sensitive detection of non-nucleic-acid targets could be realized. We designed and optimized the element probe, which proved that Cas14 has a preference for longer lengths in element probe cleavage. Using this method, the quantitative detection of trace aqueous ampicillin can be achieved within 45 minutes at room temperature (25 °C). A detection limit as low as 2.06 nM is obtained with excellent performance in anti-interference tests and complex matrix detection.

Hydrophilic molecularly imprinted polymers functionalized magnetic carbon nanotubes for selective extraction of cyclic adenosine monophosphate from winter jujube.

In this work, a green strategy was developed to prepare molecularly imprinted polymers functionalized magnetic carbon nanotubes in aqueous phase under mild conditions for cyclic adenosine monophosphate. Thanks to water solubility of chitosan, a natural polysaccharide which is rich in amino and hydroxyl groups, provided the feasibility to synthesize the green molecularly imprinted polymers for water soluble template in aqueous media. Coupled with high-performance liquid chromatography, the method exhibited a short equilibrium time (6 min), high adsorption capacity (22.42 µg/mg), high magnetic susceptibility, and good selectivity to template molecule with the imprinting factor of 2.94. A good linearity in the range of 0.020-3.0 mg/mL for target was obtained with a correlation coefficient of 0.9998. The limit of detection (signal-to-noise ratio = 3) and limit of quantitation (signal-to-noise ratio = 10) of the magnetic solid phase extraction method for cyclic adenosine monophosphate were 5 and 15 ng/mg, respectively. And the practical application of chitosan-based molecularly imprinted polymers as adsorbent to isolate and determine cyclic adenosine monophosphate in real natural samples (winter jujube) was demonstrated.

Analytical methods for the determination of remdesivir as a promising antiviral candidate drug for the COVID-19 pandemic.

Coronavirus disease 2019 (COVID-19), which is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is undoubtedly the most challenging pandemic in the current century. A total of 73,953,702 confirmed cases of COVID-19 and 1,644,416 deaths were reported globally up to December 17, 2020. Therefore, in the absence of a safe and effective vaccine, it is urgent to identify a novel antiviral drug to effectively treat patients with COVID-19. On October 22, the U.S. Food and Drug Administration approved remdesivir, a nucleotide analog prodrug with broad antiviral activity, for adults and children (12 years of age and older and weighing at least 40 kg) who need to be admitted to hospital for covid-19 treatment. In order to monitor the optimization of patient clinical response profile, as well as address the challenges associated with remdesivir metabolism, highly sensitive, selective and accurate analytical methods are necessary. This review clearly covers all the analytical methods developed for the identification and quantitative determination of remdesivir and its metabolites in biological matrices, which helps the researchers in developing new methods for the analysis of remdesivir by considering the pros and cons of the previously reported methods.

Challenges and stepwise fit-for-purpose optimization for bioanalyses of remdesivir metabolites nucleotide monophosphate and triphosphate in mouse tissues using LC-MS/MS.

Remdesivir is a prodrug of the nucleotide analogue and used for COVID-19 treatment. However, the bioanalysis of the active metabolites remdesivir nucleotide triphosphate (RTP) and its precursor remdesivir nucleotide monophosphate (RMP) is very challenging. Herein, we established a novel method to separate RTP and RMP on a BioBasic AX column and quantified them by high-performance liquid chromatography-tandem mass spectrometry in positive electrospray ionization mode. Stepwise, we optimized chromatographic retention on an anion exchange column, improved stability in matrix through the addition of 5,5'-dithiobis-(2nitrobenzoic acid) and PhosSTOP EASYpack, and increased recovery by dissociation of tight protein binding with 2 % formic acid aqueous solution. The method allowed lower limit of quantification of 20 nM for RMP and 10 nM for RTP. Method validation demonstrated acceptable accuracy (93.6%-103% for RMP, 94.5%-107% for RTP) and precision (RSD < 11.9 % for RMP, RSD < 11.4 % for RTP), suggesting that it was sensitive and robust for simultaneous quantification of RMP and RTP. The method was successfully applied to analyze RMP and RTP in mouse tissues. In general, the developed method is suitable to monitor RMP and RTP, and provides a useful approach for exploring more detailed effects of remdesivir in treating diseases.

Assessing the Performance of a Real-Time Total Adenylate (ATP+ADP+AMP) Detection Assay for Surface Hygiene Monitoring in Food Manufacturing Plants and Commercial Kitchens.

ABSTRACT: Environmental hygiene monitoring in the food processing environment has become important in current food safety programs to ensure safe food production. However, conventional monitoring of surface hygiene based on visual inspection and microbial counts is slow, tedious, and thus unable to support the current risk-based management system. Therefore, this study was conducted to assess the performance of a real-time total adenylate assay that detected ATP+ADP+AMP (A3) for food contact surface hygiene in 13 food processing plants and two commercial kitchens in Malaysia. The A3 value was compared with the microbial count (aerobic plate count [APC]) on food contact surfaces. Receiver-operating characteristic (ROC) analysis was performed to assess the reliability of the data and to determine the optimal threshold value for hygiene indication of food contact surfaces. Overall, the A3 value demonstrated a weak positive relationship with APC. However, the A3 value significantly correlated with APC for food processing environments associated with raw meat and raw food ingredients such as fruit that harbor a high microbial load. ROC analysis suggested an optimal threshold for the A3 value of 500 relative light units to balance the sensitivity and specificity at 0.728 and 0.719, respectively. The A3 assay as a hygiene indicator for food contact surfaces had an efficiency of 72.1%, indicating its reliability as a general hygiene indicator.

Brackish water improves the taste quality in meat of adult male Eriocheir sinensis during the postharvest temporary rearing.

We investigated the effect of temporary rearing in brackish water on the taste quality in meat of crab cooked. The main salinity-responsive factors included 5'-nucleotides and free amino acids (FAAs) in crab meat that were identified using tri-step infrared spectroscopy. Compared to the fresh water group, the contents of 5'-adenosine monophosphate and 5'-inosine monophosphate in the brackish water group significantly increased in the 2nd week and decreased in the 6th week, respectively. The contribution ratio of umami FAAs increased from 8.1 to 13.5% in the 4th week in the brackish water group, showing maximum value of equivalent umami concentration. Moreover, Ca2+ and Cl- contents significantly increased in the 4th and 6th weeks, respectively (P < 0.05). Infrared spectroscopy was an effective method to identify the taste components. With respect to the taste quality, four weeks were determined as the best period for temporary rearing of the crab in brackish water.

Validation Study of LuciPacTM A3 Surface for Hygiene Monitoring through Detection of ATP, ADP, and AMP from Stainless Steel Surfaces: AOAC Performance Tested MethodSM 051901.

BACKGROUND: The LuciPac A3 Surface Hygiene Monitoring System based on the detection of total adenylate, ATP+ADP+AMP (A3), has been developed by Kikkoman Biochemifa. OBJECTIVE: This A3 swabbing assay kit was validated for Performance Tested MethodsSM (PTM) certification. METHODS: The LuciPac A3 Surface Hygiene Monitoring System was evaluated for limit of detection (LOD) for each adenylate with pure analyte solutions, detection of food residues and microbial residues on stainless steel surfaces, interference by disinfectants, and selectivity of the method response. RESULTS: Pure analyte studies performed by the method developer and the independent laboratory showed good linearity (R2 > 0.9854) and repeatability precision (RSDr < 20% for ≥2.5 fmol/assay). The LOD values for each adenylate were around 10 relative light units or 2.5 fmol/assay. The repeatability precision in the method developer laboratory for the matrix study (raw chicken breast, sliced deli ham, orange juice, yogurt, and apple pie) and the microbial study (Cronobacter sakazakii, Lactobacillus acidophilus, and Saccharomyces cerevisiae) were 8-30% and 10-35%, respectively. The repeatability precision of independent laboratory testing was 13-27% for orange juice and 16-43% for ham. Interference by several disinfectants indicate that rinsing is recommended to be performed after the use of sanitizing agents and before testing with LuciPac A3 Surface. Selectivity testing revealed that no positive interference and no inhibition were caused by adenylate analogues. Instrument variation, lot-to-lot consistency, accelerated stability (30°C, 5 weeks) were confirmed, and the method was shown to be robust against shaking time. CONCLUSIONS: The LuciPac A3 Surface has been successfully validated. HIGHLIGHTS: This A3 swabbing assay kit was qualified for PTM certification No. 051901.

Development and validation of a UHPLC-MS/MS method for quantification of the prodrug remdesivir and its metabolite GS-441524: a tool for clinical pharmacokinetics of SARS-CoV-2/COVID-19 and Ebola virus disease.

BACKGROUND: Remdesivir has received significant attention for its potential application in the treatment of COVID-19, caused by SARS-CoV-2. Remdesivir has already been tested for Ebola virus disease treatment and found to have activity against SARS and MERS coronaviruses. The remdesivir core contains GS-441524, which interferes with RNA-dependent RNA polymerases alone. In non-human primates, following IV administration, remdesivir is rapidly distributed into PBMCs and converted within 2 h to the active nucleoside triphosphate form, while GS-441524 is detectable in plasma for up to 24 h. Nevertheless, remdesivir pharmacokinetics and pharmacodynamics in humans are still unexplored, highlighting the need for a precise analytical method for remdesivir and GS-441524 quantification. OBJECTIVES: The validation of a reliable UHPLC-MS/MS method for remdesivir and GS-441524 quantification in human plasma. METHODS: Remdesivir and GS-441524 standards and quality controls were prepared in plasma from healthy donors. Sample preparation consisted of protein precipitation, followed by dilution and injection into the QSight 220 UHPLC-MS/MS system. Chromatographic separation was obtained through an Acquity HSS T3 1.8 µm, 2.1 × 50 mm column, with a gradient of water and acetonitrile with 0.05% formic acid. The method was validated using EMA and FDA guidelines. RESULTS: Analyte stability has been evaluated and described in detail. The method successfully fulfilled the validation process and it was demonstrated that, when possible, sample thermal inactivation could be a good choice in order to improve biosafety. CONCLUSIONS: This method represents a useful tool for studying remdesivir and GS-441524 clinical pharmacokinetics, particularly during the current COVID-19 outbreak.

Low-temperature and long-time heating regimes on non-volatile compound and taste traits of beef assessed by the electronic tongue system.

The influence of temperature-time combinations on non-volatile compound and taste traits of beef semitendinosus muscles tested by the electronic tongue was studied. Single-stage sous-vide at 60 and 70 °C (6 and 12 h), and two-stage sous-vide that sequentially cooked at 45 °C (3 h) and 60 °C (either 3 or 9 h) were compared with traditional cooking at 70 °C (30 min). Umami was better explained in the given model of partial least squares regression than astringency, sourness, saltiness, bitterness, and richness. Sous-vide at 70 °C for 12 h characterized the most umami, likely adenosine-5'-monophosphate (AMP) and guanosine-5'-monophosphate (GMP) as significant contributors. Two-stage sous-vide projected higher histidine, leucine, inosine, and hypoxanthine with the astringent and sour taste significant after 6 and 12 h cooking, respectively. Equivalent umami concentration (EUC) between umami amino acids and umami nucleotides showed a strong relationship to umami taste assessed by the electronic tongue.

Determination of adenosine phosphates in mouse myocardium tissue by HPLC with UV detection and using porous graphite carbon column.

A high-performance liquid chromatography (HPLC) method with UV detection was established and validated for the simultaneous determination of adenosine triphosphate (ATP), adenosine diphosphate (ADP) and adenosine monophosphate (AMP) in mouse myocardial tissues. After protein precipitation and compound extraction with pre-cooled perchloric acid and the supernatant was centrifuged with the pH value adjusted to 6.5-7.5, the analytes were separated on a porous graphitic carbon LC column (4.6 mm × 100 mm, 5 µm) using gradient elution with a mobile phase of 10 mmol/L borax solution, pH 9.18(A) and acetonitrile-tetrahydrofuran (1:1, v/v) (B). The LC flow rate was 0.8 mL/min; the UV detection wavelength was 254 nm and the column temperature was maintained at 35 °C. ATP, ADP, and AMP were separated and the intra-day relative standard deviations (RSDs) of peak area repeatability were 1.3-2.5% (n = 6). The correlation coefficients of the linearity between UV responses and adenosine phosphate concentrations were larger than 0.9998 in all cases, within concentration ranges of 0.71-91.6 µg/mL for ATP, 1.3-81.5 µg/mL for ADP and 1.69-108.1 µg/mL for AMP. The limits of detection were within 0.17-0.21 µg/mL. The average standard substance spiked-in recoveries were 93.6-104.7% (n = 3). The established HPLC method was successfully applied to quantitate ATP, ADP, and AMP in mouse myocardial tissues.

Multiplexed Online Monitoring of Microfluidic Free-Flow Electrophoresis via Mass Spectrometry.

Free-flow electrophoresis is a tool for the continuous fractionation of electrically charged analytes. In this study, we introduce a novel method to couple microchip-based free-flow electrophoresis with mass spectrometry. The successive connection of multiple microchip outlets to the electrospray ionization source of a mass spectrometer is automated using a multiposition valve. With this novel setup, it is possible to continuously fractionate and collect compounds while simultaneously monitoring the process online with mass spectrometry. The functionality of the method is demonstrated by the successful separation and identification of the biomolecules AMP, ATP, and CoA, which are fundamental for numerous biochemical processes in every organism.