Agricultural and Environmental Chemistry
Effect of Arbuscular Mycorrhizal Fungi on the Growth and Polyphenol Profile of Marjoram, Lemon Balm, and Marigold
Rita Engel *- ,
Krisztina Szabó - ,
László Abrankó - ,
Kata Rendes - ,
Anna Füzy - , and
Tünde Takács
The aim of this study is to examine the effect of arbuscular mycorrhizal fungi (AMF) colonization on biomass, polyphenol profile, and content of economically important herbs. A pot experiment was performed with marjoram, lemon balm, and marigold applying a commercially available AMF mixture for inoculation. Major polyphenols were identified using HPLC-UV-ESI-qTOFMS on the basis of their UV–vis and mass spectral characteristics, and selected ones were quantified. We showed that AMF can provide different services for each herb. Marjoram had the highest level of fungal colonization (82 M%) followed by lemon balm (62 M%) and marigold (17 M%). AMF inoculation significantly increased the biomass of marjoram (1.5-fold), the number of marigold flowers (1.2-fold), and the yield of rosmarinic acid and lithospermic acid isomers of marjoram (1.5-fold) and lemon balm (1.2-fold). Therefore, the quantity and quality of plant material could be improved by the application of optimized AMF inoculum.
Oxidative Conversion Mediates Antiproliferative Effects of tert-Butylhydroquinone: Structure and Activity Relationship Study
Katherine Z. Sanidad - ,
Elvira Sukamtoh - ,
Weicang Wang - ,
Zheyuan Du - ,
Ellie Florio - ,
Lili He - ,
Hang Xiao - ,
Eric A. Decker - , and
Guodong Zhang *
Previous studies have shown that tert-butylhydroquinone (TBHQ), a widely used food antioxidant, has cytotoxic effects at high doses; however, the underlying mechanisms are not well understood. Here, we found that the effects of TBHQ on cell proliferation, cell cycle progression, and apoptosis are mainly mediated by its oxidative conversion to a quinone metabolite tert-butylquinone (TBQ). Co-addition of cupric ion (Cu2+) caused accelerated oxidative conversion of TBHQ to TBQ and enhanced the biological activities of TBHQ on cell proliferation, cell cycle progression, and apoptosis in MC38 colon cancer cells. In contrast, co-addition of ethylenediaminetetraacetic acid (EDTA) suppressed TBHQ oxidation and inhibited the biological activities of TBHQ in MC38 cells. For example, after 24 h of treatment in basal medium, low-dose TBHQ (1.88–7.5 μM) had little effect on MC38 cell proliferation, while co-addition of 50 μM Cu2+ caused 30–70% inhibition of cell proliferation; in contrast, treatment with high-dose TBHQ (15 μM) inhibited 50 ± 4% MC38 proliferation, which was abolished by co-addition of 50 μM EDTA. We further showed that TBQ had more potent actions on cell proliferation and associated cellular responses than TBHQ, supporting a critical role of TBQ formation in the biological activities of TBHQ. Finally, a structure and activity relationship study showed that the fast-oxidized para-hydroquinones had potent antiproliferative effects in MC38 cells, while the slow-oxidized para-hydroquinones had weak or little biological activities. Together, these results suggest that the biological activities of TBHQ and other para-hydroquinones are mainly mediated by their oxidative metabolism to generate more biologically active quinone metabolites.
Polyphenol Oxidase Containing Sidestreams as Emulsifiers of Rumen Bypass Linseed Oil Emulsions: Interfacial Characterization and Efficacy of Protection against in Vitro Ruminal Biohydrogenation
Frederik Gadeyne - ,
Nympha De Neve - ,
Bruno Vlaeminck - ,
Erik Claeys - ,
Paul Van der Meeren - , and
Veerle Fievez *
The low transfer in ruminants of dietary polyunsaturated fatty acids to the milk or peripheral tissues is largely due to ruminal biohydrogenation. Lipids emulsified by a polyphenol oxidase (PPO) rich protein extract of red clover were shown before to be protected against this breakdown after cross-linking with 4-methylcatechol. Protein extracts of 13 other vegetal resources were tested. Surprisingly, the effectiveness to protect emulsified lipids against in vitro ruminal biohydrogenation largely depended on the origin of the extract and its protein concentration but was not related to PPO activity. Moreover, PPO isoforms in vegetal sources, effectively protecting emulsified lipids, were diverse and their presence at the emulsion interface did not seem essential. Potato tuber peels were identified as an interesting biological source of emulsifying proteins and PPO, particularly since protein extracts of industrial potato sidestreams proved to be suitable for the current application.
Soil Incorporation of Silica-Rich Rice Husk Decreases Inorganic Arsenic in Rice Grain
Angelia L. Seyfferth *- ,
Andrew H. Morris - ,
Rattandeep Gill - ,
Kelli A. Kearns - ,
Jessica N. Mann - ,
Michelle Paukett - , and
Corey Leskanic
Arsenic decreases rice yield, and inorganic grain As threatens human health; thus, strategies to decrease rice As are critically needed. Increased plant-available silica (Si) can decrease rice As, yet the source of Si matters. Rice husk, an underutilized and Si-rich byproduct of rice production that contains less labile C and an order of magnitude less As than rice straw, may be an economically viable Si resource to decrease rice As, yet the impact of rice husk incorporation on As in the rice–soil nexus has not been reported. This proof-of-concept study shows that rice husk incorporation to soil (1% w/w) decreases inorganic grain As by 25–50% without negatively affecting grain Cd, yield, or dissolved CH4 levels. Rice husk is a critical yet perhaps overlooked resource to improve soil quality through enhanced nutrient availability and attenuate human health risks through consumption of As-laden grain.
Bioactive Constituents, Metabolites, and Functions
Discovery and Characterization of Carotenoid-Oxygen Copolymers in Fruits and Vegetables with Potential Health Benefits
Graham W. Burton *- ,
Janusz Daroszewski - ,
Trevor J. Mogg - ,
Grigory B. Nikiforov - , and
James G. Nickerson
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We reported previously that the spontaneous oxidation of β-carotene and other carotenoids proceeds predominantly by formation of carotenoid-oxygen copolymers and that β-carotene copolymers exhibit immunological activity, including priming innate immune function and limiting inflammatory processes. Oxidative loss of carotenoids in fruits and vegetables occurs during processing. Here we report evidence for the occurrence of associated analogous copolymer compounds. Geronic acid, an indirect, low molecular weight marker of β-carotene oxidation at ∼2% of β-carotene copolymers, is found to occur in common fresh or dried foods, including carrots, tomatoes, sweet potatoes, paprika, rosehips, seaweeds, and alfalfa, at levels encompassing an approximately thousand-fold range, from low ng/g in fresh foods to μg/g in dried foods. Copolymers isolated from several dried foods reach mg/g levels: comparable to initial carotenoid levels. In vivo biological activity of supplemental β-carotene copolymers has been previously documented at μg/g levels, suggesting that some foods could have related activity.
Novel Effects of Nanoparticulate Delivery of Zinc on Growth, Productivity, and Zinc Biofortification in Maize (Zea mays L.)
Layam Venkata Subbaiah - ,
Tollamadugu Naga Venkata Krishna Vara Prasad *- ,
Thimmavajjula Giridhara Krishna - ,
Palagiri Sudhakar - ,
Balam Ravindra Reddy - , and
Thalappil Pradeep
In the present investigation, nanoscale zinc oxide particulates (ZnO-nanoparticulates) were prepared using a modified oxalate decomposition method. Prepared ZnO-nanoparticulates (mean size = 25 nm) were characterized using techniques such as transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), and zeta potential analyzer. Different concentrations (50, 100, 200, 400, 600, 800, 1000, 1500, and 2000 ppm) of ZnO-nanoparticulates were examined to reveal their effects on maize crop on overall growth and translocation of zinc along with bulk ZnSO4 and control. Highest germination percentage (80%) and seedling vigor index (1923.20) were observed at 1500 ppm of ZnO-nanoparticulates. The yield was 42% more compared to control and 15% higher compared to 2000 ppm of ZnSO4. Higher accumulation of zinc (35.96 ppm) in grains was recorded with application of 100 ppm followed by 400 ppm (31.05 ppm) of ZnO-nanoparticulates. These results indicate that ZnO-nanoparticulates have significant effects on growth, yield, and zinc content of maize grains, which is an important feature in terms of human health.
Cytotoxic and Antibiotic Cyclic Pentapeptide from an Endophytic Aspergillus tamarii of Ficus carica
Yang-Min Ma *- ,
Xi-Ai Liang - ,
Hong-Chi Zhang - , and
Rui Liu
A new cyclic pentapeptide, disulfide cyclo-(Leu-Val-Ile-Cys-Cys) (1), named malformin E, together with 13 known cyclic dipeptides, was isolated from the culture broth of endophytic fungus FR02 from the roots of Ficus carica. The strain FR02 was identified as Aspergillus tamarii on the basis of morphological characteristics and molecular analyses of internal transcribed spacer (ITS). Their structures were determined by the combination of 1D and 2D NMR spectroscopy, HRMS (ESI), UV, and Marfey’s analysis. Compound 1 exhibited strong cytotoxic activities against human cancer cell strains MCF-7 and A549 with IC50 values of 0.65 and 2.42 μM, respectively. It also displayed remarkable antimicrobial activities against Bacillus subtilis, Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, Penicillium chrysogenum, Candida albicans, and Fusarium solani with MIC values of 0.91, 0.45, 1.82, 0.91, 3.62, 7.24, and 7.24 μM, respectively.
Hypoglycemic Constituents Isolated from Trapa natans L. Pericarps
Hui-Chi Huang *- ,
Chien-Liang Chao - ,
Chia-Ching Liaw - ,
Syh-Yuan Hwang - ,
Yao-Haur Kuo - ,
Tsu-Chung Chang - ,
Chih-Hua Chao - ,
Chao-Jung Chen - , and
Yueh-Hsiung Kuo *
Trapa natans L., called water chestnut or water caltrop, is a floating aquarium plant. Its fruits are widely used as food. Two new tannins, 1 and 2, one new neolignan, 14, one new norlignan, 17, and 20 known compounds, 3–13, 15, 16, and 18–24 were isolated from T. natans pericarps in this study. The 1, 2, 14, and 17 structures were elucidated using a chemical method and extensive spectral evidence. A series of hydrolyzable tannins, 1–8, a lignin, 13, a flavonoid, 16, a norlignan, 17, and phenolic compounds, 18, 20, 21, and 24 resulted in the enhanced glucose uptake activity in C2C12 myotubes. Compounds 4 and 5 significantly increased GLUT4 protein expression in C2C12 myotubes. In addition, 4 and 5 improved the phosphorylation of AMPK, AKT(S473), and AKT(T308). The involvement of AMPK and PI3K in the mechanism of action of compounds 4 and 5 was confirmed by use of AMPK and PI3K inhibitors, which completely suppressed the 4- and 5-mediated activities of glucose uptake in C2C12 myotubes. We also demonstrated that 4 and 5 could increase GLUT4 protein levels in plasma membranes.
Odisolane, a Novel Oxolane Derivative, and Antiangiogenic Constituents from the Fruits of Mulberry (Morus alba L.)
Seoung Rak Lee - ,
Jun Yeon Park - ,
Jae Sik Yu - ,
Sung Ok Lee - ,
Ja-Young Ryu - ,
Sang-Zin Choi - ,
Ki Sung Kang - ,
Noriko Yamabe *- , and
Ki Hyun Kim *
Mulberry, the fruit of Morus alba L., is known as an edible fruit and commonly used in Chinese medicines as a warming agent and as a sedative, tonic, laxative, odontalgic, expectorant, anthelmintic, and emetic. Systemic investigation of the chemical constituents of M. alba fruits led to the identification of a novel oxolane derivative, (R*)-2-((2S*,3R*)-tetrahydro-2-hydroxy-2-methylfuran-3-yl)propanoic acid (1), namely, odisolane, along with five known heterocyclic compounds (2–6). The structure of the new compound was elucidated on the basis of HR-MS, 1D and 2D NMR (1H–1H COSY, HSQC, HMBC, and NOESY) data analysis. Compound 1 has a novel skeleton that consists of 8 carbon units with an oxolane ring, which until now has never been identified in natural products. The isolated compounds were subjected to several activity tests to verify their biological function. Among them, compounds 1, 3, and 5 significantly inhibited cord formation in HUVECs. The action mechanism of compound 3, which had the strongest antiangiogenic activity, was mediated by decreasing VEGF, p-Akt, and p-ERK protein expression. These results suggest that compounds isolated from M. alba fruits might be beneficial in antiangiogenesis therapy for cancer treatment.
Biotechnology and Biological Transformations
Glycinergic–Fipronil Uptake Is Mediated by an Amino Acid Carrier System and Induces the Expression of Amino Acid Transporter Genes in Ricinus communis Seedlings
Yun Xie - ,
Jun-Long Zhao - ,
Chuan-Wei Wang - ,
Ai-Xin Yu - ,
Niu Liu - ,
Li Chen - ,
Fei Lin *- , and
Han-Hong Xu *
Phloem-mobile insecticides are efficient for piercing and sucking insect control. Introduction of sugar or amino acid groups to the parent compound can improve the phloem mobility of insecticides, so a glycinergic–fipronil conjugate (GlyF), 2-(3-(3-cyano-1-(2,6-dichloro-4-(trifluoromethyl)phenyl)-4-((trifluoromethyl)sulfinyl)-1H-pyrazole-5-yl)ureido) acetic acid, was designed and synthesized. Although the “Kleier model” predicted that this conjugate is not phloem mobile, GlyF can be continually detected during a 5 h collection of Ricinus communis phloem sap. Furthermore, an R. communis seedling cotyledon disk uptake experiment demonstrates that the uptake of GlyF is sensitive to pH, carbonyl cyanide m-chlorophenylhydrazone (CCCP), temperature, and p-chloromercuribenzenesulfonic acid (pCMBS) and is likely mediated by amino acid carrier system. To explore the roles of amino acid transporters (AATs) in GlyF uptake, a total of 62 AAT genes were identified from the R. communis genome in silico. Phylogenetic analysis revealed that AATs in R. communis were organized into the ATF (amino acid transporter) and APC (amino acid, polyaminem and choline transporter) superfamilies, with five subfamilies in ATF and two in APC. Furthermore, the expression profiles of 20 abundantly expressed AATs (cycle threshold (Ct) values <27) were analyzed at 1, 3, and 6 h after GlyF treatment by RT-qPCR. The results demonstrated that expression levels of four AAT genes, RcLHT6, RcANT15, RcProT2, and RcCAT2, were induced by the GlyF treatment in R. communis seedlings. On the basis of the observation that the expression profile of the four candidate genes is similar to the time course observation for GlyF foliar disk uptake, it is suggested that those four genes are possible candidates involved in the uptake of GlyF. These results contribute to a better understanding of the mechanism of GlyF uptake as well as phloem loading from a molecular biology perspective and facilitate functional characterization of candidate AAT genes in future studies.
An Alternative Approach to Synthesizing Galactooligosaccharides by Cell-Surface Display of β-Galactosidase on Yarrowia lipolytica
Jin An - ,
Lebin Zhang - ,
Lijuan Li - ,
Dawen Liu - ,
Huiling Cheng - ,
Hengwei Wang - ,
Muhammad Zohaib Nawaz - ,
Hairong Cheng *- , and
Zixin Deng
An alternative strategy for synthesizing galactooligosaccharides (GOS) from an erythritol-producing yeast Yarrowia lipolytica using surface display technology was demonstrated. The engineered strain CGMCC11369 was developed by fusion of the β-galactosidase gene from Aspergillus oryzae to the YlPir1 gene, which codes for a cell wall protein. β-Galactosidase was effectively displayed on the cell surface of Yarrowia lipolytica start strain CGMCC7326. This engineered strain with surface-displayed β-galactosidase efficiently synthesized GOS from lactose. An amount of 160 g/L GOS was produced within 6 h in a solution of 500 g/L lactose and 5 mg/mL cell (dry weight) at pH 5.5 and 60 °C, with a yield of 51% of consumed lactose monohydrate. This newly developed method was applied with waste yeast paste from erythritol industry at least 10 times. The optimal reaction temperature increased to 60 °C, about 20 °C higher than that of free β-galactosidase, which was helpful for enhancing the reaction rate and GOS production.
Highly Efficient Fructooligosaccharides Production by an Erythritol-Producing Yeast Yarrowia lipolytica Displaying Fructosyltransferase
Lebin Zhang - ,
Jin An - ,
Lijuan Li - ,
Hengwei Wang - ,
Dawen Liu - ,
Ning Li - ,
Hairong Cheng *- , and
Zixin Deng
Currently, fructooligosaccharides (FOS) are industrially transformed from sucrose by purified enzymes or fungi cells. However, these methods are expensive and time-consuming. An economical approach to producing FOS using erythritol-producing yeast cells was described in this study. Fructosyltransferase from Aspergillus oryzae was displayed on the cell surface of Yarrowia lipolytica, resulting in an engineered strain capable of transforming sucrose to FOS. An amount of 480 g/L FOS was produced within 3 h in a solution of 800 g/L sucrose and 5 g/L cells (dry cell weight, DCW) at pH 6.0 and 60 °C, with a yield of 60% of total sucrose and a productivity of 160 g/(L·h). The yeast pastes from the erythritol industry can be repeatedly used as the whole-cell catalysts at least 10 times by this newly developed approach. This efficient method is attractive for the large-scale production of FOS from sucrose.
Chemistry and Biology of Aroma and Taste
Comprehensive Study of Volatile Compounds in Two Australian Rosé Wines: Aroma Extract Dilution Analysis (AEDA) of Extracts Prepared Using Solvent-Assisted Flavor Evaporation (SAFE) or Headspace Solid-Phase Extraction (HS-SPE)
Jiaming Wang - ,
Joanna M. Gambetta - , and
David W. Jeffery *
Two rosé wines, representing a tropical and a fruity/floral style, were chosen from a previous study for further exploration by aroma extract dilution analysis (AEDA) and quantitative analysis. Volatiles were extracted using either liquid–liquid extraction (LLE) followed by solvent-assisted flavor evaporation (SAFE) or a recently developed dynamic headspace (HS) sampling method utilizing solid-phase extraction (SPE) cartridges. AEDA was conducted using gas chromatography–mass spectrometry/olfactometry (GC-MS/O) and a total of 51 aroma compounds with a flavor dilution (FD) factor ≥3 were detected. Quantitative analysis of 92 volatiles was undertaken in both wines for calculation of odor activity values. The fruity and floral wine style was mostly driven by 2-phenylethanol, β-damascenone, and a range of esters, whereas 3-SHA and several volatile acids were seen as essential for the tropical style. When extraction methods were compared, HS-SPE was as efficient as SAFE for extracting most esters and higher alcohols, which were associated with fruity and floral characters, but it was difficult to capture volatiles with greater polarity or higher boiling point that may still be important to perceived wine aroma.
Structure–Odor Activity Studies on Monoterpenoid Mercaptans Synthesized by Changing the Structural Motifs of the Key Food Odorant 1-p-Menthene-8-thiol
Sebastian Schoenauer - and
Peter Schieberle *
1-p-Menthene-8-thiol (1) has been discovered as the key odorant in grapefruit juice several decades ago and contributes to the overall odor of the fruit with an extremely low odor threshold of 0.000034 ng/L in air. This value is among the lowest odor thresholds ever reported for a food odorant. To check whether modifications in the structure of 1 would lead to changes in odor threshold and odor quality, 34 mercapto-containing p-menthane and 1-p-menthene derivatives as well as several aromatic and open-chain mercapto monoterpenoids were synthesized. Eighteen of them are reported for the first time in the literature, and their odor thresholds and odor qualities as well as analytical data are supplied. A comparison of the sensory data with those of 1 showed that hydrogenation of the double bond led to a clear increase in the odor threshold. Furthermore, moving the mercapto group into the ring always resulted in higher odor thresholds compared to thiols with a mercapto group in the side chains. Although all tertiary thiols always exhibited low odor thresholds, none of the 31 compounds reached the extremely low threshold of 1. Also, none of the synthesized mercapto monoterpenoids showed a similar odor quality resembling grapefruit. Although the saturated and aromatic analogues exhibited similar scents as 1, the aromas of the majority of the other compounds were described as sulfury, rubber-like, burned, soapy, or even mushroom-like. NMR and MS data as well as retention indices of the 23 newly reported sulfur-containing compounds might aid in future research to identify terpene-derived mercaptans possibly present in trace levels in foods.
Food and Beverage Chemistry/Biochemistry
Effect of Commercial Enzymes on Berry Cell Wall Deconstruction in the Context of Intravineyard Ripeness Variation under Winemaking Conditions
Yu Gao - ,
Jonatan U. Fangel - ,
William G. T. Willats - ,
Melané A. Vivier - , and
John P. Moore *
Significant intravineyard variation in grape berry ripening occurs within vines and between vines. However, no cell wall data are available on such variation. Here we used a checkerboard panel design to investigate ripening variation in pooled grape bunches for enzyme-assisted winemaking. The vineyard was dissected into defined panels, which were selected for winemaking with or without enzyme addition. Cell wall material was prepared and subjected to high-throughput profiling combined with multivariate data analysis. The study showed that significant ripening-related variation was present at the berry cell wall polymer level and occurred within the experimental vineyard block. Furthemore, all enzyme treatments reduced cell wall variation via depectination. Interestingly, cell wall esterification levels were unaffected by enzyme treatments. This study provides clear evidence that enzymes can positively influence the consistency of winemaking and provides a foundation for further research into the relationship between grape berry cell wall architecture and enzyme formulations.
Effects of Several Natural Macromolecules on the Stability and Controlled Release Properties of Water-in-Oil-in-Water Emulsions
Jinlong Li - ,
Yiheng Shi - ,
Yunping Zhu - ,
Chao Teng - , and
Xiuting Li *
Water-in-oil-in-water (W/O/W) emulsions are effective vehicles for embedding application of active compounds but limited by their thermodynamic instability and rapid release properties. The present study added bovine serum albumin, whey protein isolate, whey protein hydrolysate, sodium caseinate, carboxymethylcellulose sodium, fish gelatin, apple pectin, gum arabic, ι-carrageenan, and hydroxypropyl chitosan separately to the internal or external aqueous phase to investigate their effects on the physical stabilities and controlled release properties of W/O/W emulsions. The effects of the natural macromolecules in the internal and external aqueous phases were different and depended upon the macromolecule structure and its mass fraction. The addition of the natural macromolecule strengthened the interfaces of emulsions, which improved the physical stability. The natural macromolecules that improved the stability often did not improve controlled release. Therefore, the balance between these properties needs to be considered when adding natural macromolecules to a W/O/W emulsion.
Kinetics of Forming Aldehydes in Frying Oils and Their Distribution in French Fries Revealed by LC–MS-Based Chemometrics
Lei Wang - ,
A. Saari Csallany - ,
Brian J. Kerr - ,
Gerald C. Shurson - , and
Chi Chen *
In this study, the kinetics of aldehyde formation in heated frying oils was characterized by 2-hydrazinoquinoline derivatization, liquid chromatography–mass spectrometry (LC–MS) analysis, principal component analysis (PCA), and hierarchical cluster analysis (HCA). The aldehydes contributing to time-dependent separation of heated soybean oil (HSO) in a PCA model were grouped by the HCA into three clusters (A1, A2, and B) on the basis of their kinetics and fatty acid precursors. The increases of 4-hydroxynonenal (4-HNE) and the A2-to-B ratio in HSO were well-correlated with the duration of thermal stress. Chemometric and quantitative analysis of three frying oils (soybean, corn, and canola oils) and French fry extracts further supported the associations between aldehyde profiles and fatty acid precursors and also revealed that the concentrations of pentanal, hexanal, acrolein, and the A2-to-B ratio in French fry extracts were more comparable to their values in the frying oils than other unsaturated aldehydes. All of these results suggest the roles of specific aldehydes or aldehyde clusters as novel markers of the lipid oxidation status for frying oils or fried foods.
Food Safety and Toxicology
The Seed Biotinylated Protein of Soybean (Glycine max): A Boiling-Resistant New Allergen (Gly m 7) with the Capacity To Induce IgE-Mediated Allergic Responses
John J. Riascos *- ,
Sandra M. Weissinger - ,
Arthur K. Weissinger - ,
Michael Kulis - ,
A. Wesley Burks - , and
Laurent Pons
Soybean is a common allergenic food; thus, a comprehensive characterization of all the proteins that cause allergy is crucial to the development of effective diagnostic and immunotherapeutic strategies. A cDNA library was constructed from seven stages of developing soybean seeds to investigate candidate allergens. We searched the library for cDNAs encoding a seed-specific biotinylated protein (SBP) based on its allergenicity in boiled lentils. A full-length cDNA clone was retrieved and expressed as a 75.6-kDa His-tagged recombinant protein (rSBP) in Escherichia coli. Western immunoblotting of boiled bacterial extracts demonstrated specific IgE binding to rSBP, which was further purified by metal affinity and anion exchange chromatographies. Of the 23 allergic sera screened by ELISA, 12 contained IgEs specific to the purified rSBP. Circular dichroism spectroscopy revealed a predominantly unordered structure consistent with SBP’s heat stability. The natural homologues (nSBP) were the main proteins isolated from soybean and peanut embryos after streptavidin affinity purification, yet they remained low-abundance proteins in the seed as confirmed by LC-MS/MS. Using capture ELISAs, the soybean and peanut nSBPs were bound by IgEs in 78 and 87% of the allergic sera tested. The soybean nSBP was purified to homogeneity and treatments with different denaturing agents before immunoblotting highlighted the diversity of its IgE epitopes. In vitro activation of basophils was assessed by flow cytometry in a cohort of peanut-allergic children sensitized to soybean. Stronger and more frequent (38%) activations were induced by nSBP-soy compared to the major soybean allergen, Gly m 5. SBPs may represent a novel class of biologically active legume allergens with the structural resilience to withstand many food-manufacturing processes.
Determination of Six Pyrazole Fungicides in Grape Wine by Solid-Phase Extraction and Gas Chromatography–Tandem Mass Spectrometry
Yan Shen *- ,
Zhou Li - ,
Qiang Ma - ,
Chuanxian Wang - ,
Xiangzhun Chen - ,
Qian Miao - , and
Chao Han *
A gas chromatography–tandem mass spectrometry (GC–MS/MS) method was developed for the first simultaneous identification and quantification of six pyrazole fungicides (furametpyr, rabenzazole, fluxapyroxad, penflufen, bixafen, and isopyrazam) in grape wine samples. The grape wine samples were first diluted with water, then purified by solid-phase extraction, and finally examined by GC–MS/MS in multiple reaction monitoring (MRM) mode. Matrix-matched calibration curves were used to correct the matrix effects. The limits of quantification (LOQs), calculated as 10 times the standard deviation, were 0.2–0.8 μg kg–1 for the six pyrazole fungicides. The average recoveries were in the range of 74.3–94.5%, with relative standard deviations (RSDs) below 5.8%, measured at three concentration levels. The proposed method is suitable for the simultaneous determination of six pyrazole fungicides in grape wine samples.
New Analytical Methods
Upconversion Nanoparticles and Monodispersed Magnetic Polystyrene Microsphere Based Fluorescence Immunoassay for the Detection of Sulfaquinoxaline in Animal-Derived Foods
Gaoshuang Hu - ,
Wei Sheng - ,
Yan Zhang - ,
Junping Wang - ,
Xuening Wu - , and
Shuo Wang *
A novel fluorescence immunoassay for detecting sulfaquinoxaline (SQX) in animal-derived foods was developed using NaYF4:Yb/Tm upconversion nanoparticles (UCNPs) conjugated with antibodies as fluorescence signal probes, and monodisperse magnetic polystyrene microspheres (MMPMs) modified with coating antigen as immune-sensing capture probes for trapping and separating the signal probes. Based on a competitive immunoassay format, the detection limit of the proposed method for detecting SQX was 0.1 μg L–1 in buffer and 0.5 μg kg–1 in food samples. The recoveries of SQX in spiked samples ranged from 69.80 to 133.00%, with coefficients of variation of 0.24–25.06%. The extraction procedure was fast, simple, and environmentally friendly, requiring no organic solvents. In particular, milk samples can be analyzed directly after simple dilution. This method has appealing properties, such as sensitive fluorescence response, a simple and fast extraction procedure, and environmental friendliness, and could be applied to detecting SQX in animal-derived foods.
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