Development and validation of a QuEChERS-HPLC-DAD method using polymer-functionalized melamine sponges for the analysis of antipsychotic drugs in milk

The prohibition of antipsychotic drugs in animal foodstuffs has raised significant concerns. In this study, a novel matrix purification adsorbent comprising a polymer (polyaniline and polypyrrole)-functionalized melamine sponge (Ms) was employed for the high performance liquid chromatography-diode array detector (HPLC-DAD) detection of three phenothiazines (chlorpromazine, thioridazine, and promethazine), and a tricyclic imipramine in milk. The as-prepared functionalized Ms was characterized using scanning electron microscopy, Fourier transform infrared spectroscopy, and water contact angle measurements. Excellent linearity with a coefficient of determination (R2) of 0.999 was achieved for all drugs within the concentration range of 0.01-47.00 μg mL-1. The recoveries of the four analytes ranged from 92.1 % to 106.9 % at the three spiked levels. These results demonstrate the successful application of the proposed method for the determination of the four drugs. Cost-effective polymer-functionalized Ms is a viable alternative for matrix purification, enabling rapid determination of drug residues in diverse food samples.

Regulation of 2-Acetyl-1-pyrroline Content in Fragrant Rice under Different Temperatures at the Grain-Filling Stage

2-Acetyl-1-pyrroline (2-AP) is a key volatile organic compound in fragrant rice aroma. However, the effects of temperature on 2-AP biosynthesis in fragrant rice and its regulation mechanism have been rarely reported. In the present study, three fragrant rice varieties were used as plant materials, and four temperature treatments during the grain-filling stage, i.e., (T1) 22/17 °C, (T2) 27/22 °C, (T3) 32/27 °C, and (T4) 37/32 °C, were adopted. The results showed that grain contents of 2-AP, proline, and γ-aminobutyric acid (GABA) significantly (P < 0.05) increased with decreased temperature, while the lowest and highest 2-AP contents were recorded in the T4 and T1 treatments, respectively. Higher pyrroline-5-carboxylic acid (P5C) content was recorded in low-temperature treatments (T1 and T2) than in high-temperature treatments (T3 and T4). The transcript levels of genes BADH2, PRODH, and OAT significantly (P < 0.05) decreased with decreased temperature. Lower transcript levels of genes P5CR, P5CS2, DAO2, DAO4, and DAO5 were recorded in low-temperature treatments (T1 and T2) than in high-temperature treatments (T3 and T4). In conclusion, low temperature increased 2-AP content and high temperature decreased 2-AP content in fragrant rice. We deduced that temperature regulated 2-AP biosynthesis through the metabolism of proline and GABA.

Application of novel adsorbents synthesized with polypyrrole in magnetic solid-phase extraction of fungicides from fresh juice and environmental water

In this work, a magnetic adsorption material based on a metal-organic framework (Fe3O4@PPy@MIL-53(Fe)) was designed and prepared, as well as used as an adsorbent for the extraction of fungicides from fresh juice and environmental water. The material was subjected to a series of characterization analyses, which showed that the material has good potential for application as an adsorbent. The main parameters such as adsorbent dosage, adsorption time, elution time, pH value, and elution solvent which could affect the experiment results were optimized. Under optimal conditions, the method exhibited linearity (R2 ≥ 0.9994) in the concentration range 10-1000 µg/L for three triazole fungicides, and LOD value ranged from 2.1 µg/L to 2.9 µg/L. In addition, the established method was applied to real samples of three fruit juices and two ambient waters, and satisfactory recoveries in the range of 78.6%-105.4% and RSDs of ≤ 5.7% were obtained.

Performance analysis of microbial fuel cell - membrane bioreactor with reduced graphene oxide enhanced polypyrrole conductive ceramic membrane: Wastewater treatment, membrane fouling and microbial community under high salinity

The application of membrane bioreactor (MBR) in high salinity wastewater treatment was mainly hindered by membrane fouling. Microbial fuel cell (MFC)-MBR coupling system was established to alleviate membrane fouling and save energy. Reduced graphene oxide/polypyrrole ceramic membrane (rGO/PPy CM) with high conductivity and stability was innovatively placed in MFC-MBRs as both cathode and filter, with PPy CM, rGO/PPy CM and CM placed in other reactors. MFC-MBR (rGO/PPy) and MFC-MBR (PPy) achieved higher pollutant removal efficiencies (90.73 % and 90.45 % for TOC, 87.22 % and 86.56 % for NH4+-N, respectively) and superior anti-fouling performance (1.86 and 1.93 kPa/d for average membrane fouling rates) than both conventional MBRs (CMBRs). The stable voltage generation was around 287 and 242 mV, respectively. Through high throughput sequencing, electric field showed a positive correlation with the abundance and activity of most dominant phylum (Bacteroidetes, Chloroflexi, Actinobacteria, and Firmicutes) and functional genes (amoA, hao, narG, napA, nirK, norB, and nosZ), thereby improving pollutant removal efficiency. The higher conductivity of rGO/PPy CM resulted in enhanced electric field intensity, leading to superior performance of anti-fouling and pollutant removal. This study inventively explored the effects of conductive membrane property on electricity generation performance, microbial community, pollutant removal and membrane fouling, providing theoretical support for the selection of electrode materials in MFC-MBR.

Removal of an agricultural herbicide (2,4-Dichlorophenoxyacetic acid) using magnetic nanocomposite: A combined experimental and modeling studies

This study focused on modeling the removal of one of the widely used agricultural herbicides known as 2,4-Dichlorophenoxyacetic acid (2,4-D) using polypyrrole-coated Fe2O3 nanoparticles (Fe2O3@PPy). The Fe2O3@PPy nanocomposite was synthesized by surface-coating the Tabebuia aurea leaf extract synthesized Fe2O3 nanoparticles with polypyrrole. After characterization, the adsorptive potential of the nanocomposite for removing 2,4-D from aqueous solution was examined. Central composite design (CCD) was employed for optimizing the adsorption, revealing an adsorption efficiency of 90.65% at a 2,4-D concentration of 12 ppm, a dosage of 3.8 g/L, an agitation speed of 150 rpm, and 196 min. Adsorption dataset fitted satisfactorily to Langmuir isotherm (R2: 0.984 & χ2: 0.054) and pseudo-second-order kinetics (R2: 0.929 & χ2: 0.013) whereas the exothermic and spontaneous nature were confirmed via the thermodynamic study. The predictive models, including adaptive neuro-fuzzy inference system (ANFIS), artificial neural network (ANN), and response surface methodology (RSM), demonstrated good precision for the prediction of 2,4-D adsorption, with respective R2 of 0.9719, 0.9604, and 0.9528. Nevertheless, statistical analysis supported ANFIS as the better forecasting tool, while RSM was the least effective. The maximum adsorption capacity of 2,4-D onto the Fe2O3@PPy nanocomposite was 7.29 mg/g, significantly higher than a few reported values. Therefore, the Fe2O3@PPy nanocomposite could serve as a competent adsorbent to remove 2,4-D herbicide from aqueous streams.

One-step synthesis of nitrogen-functionalized graphene aerogel for efficient removal of hexavalent chromium in water

The efficient removal of hexavalent chromium (Cr(VI)) with high toxicity has attracted widespread concern since it causes serious harm to ecological environment and public health. Herein, we report a novel nitrogen-functionalized graphene aerogel with stereoscopic structure through a simple hydrothermal method and freeze drying for Cr(VI) removal from water. Graphene oxide (GO) and nitrogenous organics polyethyleneimine (PEI) and pyrrole are used as raw materials for preparing PEI/polypyrrole/GO aerogel (PPGA) adsorbent. PEI and pyrrole act as nitrogen sources to introduce nitrogenous functional groups, and also take on the role of cross-linkers for helping GO sheets to form stereoscopic structure. The obtained PPGA has a fast adsorption rate, excellent reusability, and shows a remarkable adsorption capacity for Cr(VI) up to 458.24 mg/g under the optimal conditions (pH 2.0, 298 K, Cr(VI): 600 mg/L, dosage: 0.4 g/L). The adsorption process of Cr(VI) on PPGA can fit the pseudo-second-order kinetic model well. Analysis of intraparticle diffusion shows that the Cr(VI) removal process is a multi-step process. Adsorption thermodynamic and isotherm results demonstrate Cr(VI) adsorption on PPGA is a spontaneous endothermic process. The adsorption mechanism involves electrostatic attraction, redox, and chelation. In general, this work provides a simple and eco-friendly way to prepare PPGA, which has a great potential for actual application of Cr(VI) removal in effluent.

Feature MS fragments-based method for identification of toxic furanoids in biological samples

Numerous furan-containing compounds have been reported to be toxic. The toxicity may be attributed to the metabolic activation of the furan ring to cis-enediones. Identification of unknown furans that undergo bioactivation is challenging. Here, we present a novel approach that enables non-targeted profiling of bioactivation of unknown furanoids both in vitro and in vivo. Cyclic pyrrole-glutathione conjugate was the predominant product of cis-enediones with glutathione. The shared glutathione substructure of conjugates was capable of generating four constant and signature fragments under collision-induced dissociation (CID) in the mass spectrometer, including neutral loss fragments 103.0269 Da and 146.0691 Da and product ions at m/z 130.0499 and 177.0328. The unique structure and high abundance of conjugates in combination with the consistency and specificity of CID fragmentation brought extraordinarily high selectivity and reliability for the four fragments as a fingerprint of bioactivated furanoids. The bioactivated furanoids can be identified by screening the four fragments in high-resolution MS/MS datasets using the neutral loss filtering and diagnostic fragmentation filtering of data post-acquisition software MZmine. The simultaneous formation of four individual signal points in the filtering channel with the same precursor ion and retention time was assigned to be furanoids. The method has been rigorously validated. In the pooled urine samples from nine model furanoids-treated mice, nine cis-enediones from the parent furanoids and two from furanoid metabolites were accurately detected and identified. The method showed great performance in non-targeted profiling bioactivated furanoids and their metabolites in urine samples of herbal extract-treated mice.

Enhanced sorption and reduction of Cr(VI) by the flowerlike nanocomposites combined with molybdenum disulphide and polypyrrole

Developing high-performance adsorbent for hexavalent chromium (Cr(VI)) elimination presents an enticing prospect in environmental remediation. Herein, three-dimensional flowerlike nanospheres composed of molybdenum disulphide and polypyrrole (MoS₂@PPy) were successfully prepared via a one-pot hydrothermal and subsequent carbothermal reduction process for the removal of Cr(VI). The effects of pH, adsorbent dosage, co-existing ions, initial Cr(VI) concentration and temperature were investigated systematically by batch experiments. Benefiting from the incorporation of MoS₂, the obtained MoS₂@PPy composites showed a dramatic increase of specific surface area (149.82 m²·g^-1) and adsorption capacity (230.97 mg·g^-1) when compared with the pure PPy nanoparticles. Based on the thermodynamics study and X-ray photoelectron spectroscopy analyses, the removal process of Cr(VI) was proved to be exothermic and spontaneous, and accessible under-coordinated Mo(IV) and pyrrolic N groups coupled with redox reactions were conducive to the efficient removal of Cr(VI). Attractively, the MoS₂@PPy acted as the electron donor could also activate peroxymonosulphate for the efficient degradation of organic contaminants. These results suggested that the MoS₂@PPy was promising in Cr(VI) elimination and other kinds of organic pollutants removal in wastewater.

Determination of 2-Acetyl-1-pyrroline via a Color-Change Reaction Using Chromium Hexacarbonyl

At present, there is no colorimetric method for the quantitation of the aroma compound 2-acetyl-1-pyrroline (2AP). A novel colorimetric method was developed for the determination of 2AP content using chromium hexacarbonyl (Cr(CO)₆) as a reagent. The reaction of synthetic 2AP with chromium hexacarbonyl reagent solution in the presence of light produced a green product with an absorption maximum (λ_max) at 623 nm. GC–MS was used to confirm the color-change reaction, which showed the loss of 2AP after the addition of Cr(CO)₆. This novel method enables facile and cost-effective determination of 2AP in fragrant rice. A comparative analysis of fragrant and nonfragrant rice grain extracts showed that no color-change reaction occurred with the nonfragrant rice sample. A limit of detection (LOD) of 2.00 mg L⁻¹ was determined by method validation with an effective linear concentration ranging from 5.00 to 60.00 mg L⁻¹ of 2AP. The results obtained using the developed colorimetric method were consistent with those obtained by automated static headspace gas chromatography with nitrogen-phosphorus detection (SHS-GC–NPD).

Formation of Volatile Heterocyclic Compounds and Open-Chain Amides of Theanine in Model Systems with Glucose, Tea Leaves, and Tea Extract under Tea-Roasting Conditions

Theanine is a non-proteinogenic amino acid found in the tea plant Camellia sinensis. At an elevated temperature (>90 °C), it released two major volatile compounds 1-ethyl-1,5-dihydro-2H-pyrrol-2-one and N-ethylsuccinimide. Other products were identified, including 10 pyrroles and 12 amides/imides. The formation of the two major compounds was proposed to be initiated by the deamination of theanine and through the intermediate α-keto acid. In the presence of glucose, the two major products and many other volatiles from theanine thermal degradation were accelerated and further Maillard reactions occurred. A total of 56 compounds were identified in the model system of theanine and glucose, including 12 amides/imides, 16 pyrazines, 16 pyrroles and other N-heterocycles, and 12 furans and other O-heterocycles. Although most of the reaction products were detected in tea leaves and in their aqueous extract with or without the addition of theanine under the same experiment conditions, imides and amides were considerably suppressed, left only minute amounts, or were even no longer detectable. Pyrazines and pyrroles were also shown at reduced concentrations as a result of the interaction with tea components but to a lesser extent. A total of 16 and 12 pyrazines were identified in the theanine/glucose reaction system and tea leaves/aqueous extract after roasting, respectively. The results indicated that pyrazines and other main volatiles in roasted tea leaves were formed from the Maillard reactions of the aqueous fraction of tea leaves. Theanine participated in the formation of pyrazines in tea leaves under roasting conditions.

Effect of rainfall and altitude on the 2-acetyl-1-pyrroline and volatile compounds profile of black glutinous rice (Thai upland rice)

BACKGROUND

The aroma intensity of rice is mixed of more than 100 volatile compounds. Fragrant rice is famous in Thailand due to specific aroma. One important volatile compound that contributes to aromatic intensity and represents a characteristic compound for fragrant rice is 2-acetyl-1-pyrroline (2AP). The production of volatile compounds and 2AP in rice is affected by various environmental factors, such as cultivation area, water content and temperature.

RESULTS

Our research employed 29 samples of fragrant colored rice (Luempua black glutinous rice cultivar) from Phetchabun province, Thailand from three harvested rice seasons (2015-2017). The cultivation areas of rice samples exhibited differences in rainfall (976.6-1260.5 mm y r^-1 ) and altitude (26.26-1033.41 m). All volatile compounds and 2AP were identified by gas chromatography-mass spectrometry (GC-MS). In 29 rice samples, 2AP levels decreased with increasing of rainfall. The increase in altitude seems to increase 2AP levels, but some high-altitude cultivation areas resulted in low 2AP content. A variety of volatile compounds was observed in 29 rice samples from different cultivation areas. The results showed that differences in altitude and rainfall affected the production of volatile compounds in fragrant colored rice. Moreover, our results indicated that different environmental conditions in cultivation areas potentially affect volatile compound production during rice growth.

CONCLUSION

The increase in 2AP levels under low rainfall conditions and the assortment of volatile compound varieties produced in colored rice grown in different cultivation areas may be useful information for rice cultivation management striving to produce rice with high aromatic intensities. © 2021 Society of Chemical Industry.

Evaluation of Dissipation Behavior, Residues, and Dietary Risk Assessment of Fludioxonil in Cherry via QuEChERS Using HPLC-MS/MS Technique

The chemical fungicide fludioxonil is widely used to control post-harvest fungal disease in cherries. This study was implemented to investigate the dissipation behaviours and residues of fludioxonil on cherries. A reliable and efficient analytical method was established. Cherry samples from four product areas were analyzed by QuEChERS and HPLC-MS/MS methods with acceptable linearity (R² > 0.99), accuracy (recoveries of 81–94%), and precision (relative standard deviation of 2.5–11.9%). The limits of quantification (LOQs) and limits of detection (LODs) of cherries were 0.01 mg/kg and 0.005 mg/kg. The dissipation of fludioxonil on cherries followed first order kinetics with half-lives of 33.7–44.7 days. The terminal residues of fludioxonil were all lower than 5.00 mg/kg, which is the MRL recommended by the European Commission. According to Chinese dietary patterns and terminal residue distributions, the risk quotient (RQs) of fludioxonil was 0.61%, revealing that the evaluated cherries exhibited an acceptably low dietary risk to consumers.

Rapid, High-Throughput Quantitation of Odor-Active 2-Acetyl Azaheterocycles in Food Products by UHPLC-MS/MS

A rapid, high-throughput method for the quantitation of the 2-acetyl azaheterocycles, 2-acetyl-1-pyrroline, 2-acetyl-1,4,5,6-tetrahydropyridine, 2-acetylpyrazine, and 2-acetyl-2-thiazoline, in different food products, by liquid chromatography-tandem mass spectrometry (LC-MS/MS), was developed. The quick extraction by bead beater homogenization, fast derivatization by 3-nitrophenylhydrazine (40 °C, 2 h), and efficient LC separation make this method suitable for high-throughput analysis. As established in this study, the highly precise LC-MS/MS method applies to different food products or beverages without requiring further adjustment. The analysis was performed with sample amounts of 0.2-0.5 g, and limit of quantitation values of 0.6, 0.5, 0.6, and 1.0 μg/kg were obtained for 2-acetyl-1-pyrroline, 2-acetyl-1,4,5,6-tetrahydropyridine, 2-acetylpyrazine, and 2-acetyl-2-thiazoline, respectively. Thus, it was possible to quantitate the analytes in the range of their odor thresholds.

Indirect photodegradation of fludioxonil by hydroxyl radical and singlet oxygen in aquatic environment: Mechanism, photoproducts formation and eco-toxicity assessment

Fludioxonil has been proven valuable as a broad-spectrum fungicide. However, there are concerns about its risk posed to non-target organisms in aquatic environments. In this paper, the mechanism, photoproducts transformation and eco-toxicity of fludioxonil during •OH/¹O₂-initiated process were systematically studied using quantum chemistry and computational toxicology. The results indicate that the two favorable pathways of •OH/¹O₂-initiated reactions are both occurred in pyrrole ring. It can conclude that the rate constants of •OH and ¹O₂ are 1.23 × 10¹⁰ and 3.69 × 10⁷ M^-1 s^-1 at 298K, respectively, which results in half-lives of <2 days in surface waters under sunlit near-surface conditions. Based on toxicity assessments, these photoproducts showed a decreased aquatic toxicity but the majority products are still toxic. This study gives more insight into the chemical transformation mechanism of fludioxonil in aquatic environments.

Selenium-silicon (Se-Si) induced modulations in physio-biochemical responses, grain yield, quality, aroma formation and lodging in fragrant rice

Fragrant rice is a high-valued quality rice type which is gaining much popularity over the globe due to its better cooking qualities and special aromatic characteristics. Selenium (Se) and silicon (Si) could improve the growth and yield of rice; however, the combine effects of Se and Si (Se-Si treatments) on rice grain quality, aroma and lodging in fragrant rice were rarely investigated. The pot and field experiments were conducted with two fragrant rice cultivars i.e., Xiangyaxiangzhan and Yuxiangyouzhan, grown under three Se levels i.e., 0, 120, and 240 mg kg^-1 of soil (for pot experiment) and 0, 300, and 600 kg ha^-1 (for field experiment) regarded as LSe, MSe and HSe, respectively and two Si levels i.e., 0 and 60 mg kg^-1 of soil (for pot experiment) and 0 and 150 kg ha^-1 (for field experiment) regarded as -Si and +Si, respectively. Results depicted that the Se-Si treatments regulated head rice yield, grain yield and yield related traits and the HSe+Si treatment sustainably improved the grain yield and head rice yield by regulating plant growth, antioxidant response and malondialdehyde (MDA) contents in fragrant rice. The Se-Si treatments also improved the grain 2AP contents owing to regulation in the proline, pyrroline-5-carboxylate (P5C) and γ-aminobutyric acid (GABA) contents. Besides, Se-Si treatments also regulated the grain quality attributes and influenced the plant Se contents. Moreover, the Si mitigated Se-induced lodging resulted from changes in the lodging parameters i.e., lodging index, fresh weight per tiller, pushing resistance force, plant height and bending moment. Overall, the Se and Si application improved the grain yield and regulated the dry weight accumulation, antioxidant attributes and quality attributes. Meanwhile, the Si application mitigated the negative effect of Se-induced lodging in fragrant rice.

Sediment toxicity of the fungicide fludioxonil to benthic macroinvertebrates -evaluation of the tiered effect assessment procedure

28-Day sediment-spiked laboratory toxicity tests with eight benthic macroinvertebrates and the lipophilic fungicide fludioxonil were conducted to verify the proposed tiered sediment effect assessment procedure as recommended by the European Food Safety Authority (EFSA). The test species were the oligochaetes Lumbriculus variegatus and Tubifex tubifex, the insects Chironomus riparius and Caenis horaria, the crustaceans Hyalella azteca and Asellus aquaticus and the bivalves Corbicula fluminalis and Pisidium amnicum. Toxicity estimates were expressed in terms of total concentration of dry sediment as well as in pore water concentration. Field-collected sediment, also used in a previously performed sediment-spiked microcosm experiment, was used in tests with all species. L. variegatus and C. riparius had similar lowest 28d-L(E)C₁₀ values when expressed in terms of total sediment concentration, but in terms of pore water concentration L. variegatus was more sensitive. Three of the six additional benthic test species (A. aquaticus, C. horaria, C. fluminalis) had 28d-EC₁₀ values a factor of 2-6 lower than that of L. variegatus. Comparing different effect assessment tiers for sediment organisms, i.e. Tier-0 (Modified Equilibrium Partitioning approach), Tier-1 (Standard Test Species approach), Tier-2 (Species Sensitivity Distribution (SSD) approach) and Tier-3 (Model Ecosystem approach), it is concluded that the tiers based on sediment-spiked laboratory toxicity tests provide sufficient protection when compared with the Tier-3 Regulatory Acceptable Concentration (RAC). Differences between Tier-1 and Tier-2 RACs, however, appear to be relatively small and not always consistent, irrespective of expressing the RAC in terms of total sediment or pore water concentration. Derivation of RACs by means of the SSD approach may be a challenge, because it is difficult obtaining a sufficient number of valid chronic EC₁₀ values with appropriate 95% confidence bands for sediment-dwelling macroinvertebrates. Therefore, this paper proposes a Tier-2 Weight-of-Evidence approach to be used in case an insufficient number of valid additional toxicity data is made available. Similar studies with pesticides that differ in fate properties and toxic mode-of-action are necessary for further validation of the tiered effect assessment approach for sediment organisms.

Nucleobase mutants of a bacterial preQ1-II riboswitch that uncouple metabolite sensing from gene regulation

Riboswitches are a class of nonprotein-coding RNAs that directly sense cellular metabolites to regulate gene expression. They are model systems for analyzing RNA-ligand interactions and are established targets for antibacterial agents. Many studies have analyzed the ligand-binding properties of riboswitches, but this work has outpaced our understanding of the underlying chemical pathways that govern riboswitch-controlled gene expression. To address this knowledge gap, we prepared 15 mutants of the preQ1-II riboswitch-a structurally and biochemically well-characterized HLout pseudoknot that recognizes the metabolite prequeuosine1 (preQ1). The mutants span the preQ1-binding pocket through the adjoining Shine-Dalgarno sequence (SDS) and include A-minor motifs, pseudoknot-insertion helix P4, U·A-U base triples, and canonical G-C pairs in the anti-SDS. As predicted-and confirmed by in vitro isothermal titration calorimetry measurements-specific mutations ablated preQ1 binding, but most aberrant binding effects were corrected by compensatory mutations. In contrast, functional analysis in live bacteria using a riboswitch-controlled GFPuv-reporter assay revealed that each mutant had a deleterious effect on gene regulation, even when compensatory changes were included. Our results indicate that effector binding can be uncoupled from gene regulation. We attribute loss of function to defects in a chemical interaction network that links effector binding to distal regions of the fold that support the gene-off RNA conformation. Our findings differentiate effector binding from biological function, which has ramifications for riboswitch characterization. Our results are considered in the context of synthetic ligands and drugs that bind tightly to riboswitches without eliciting a biological response.

Efficient Analysis of 2-Acetyl-1-pyrroline in Foods Using a Novel Derivatization Strategy and LC-MS/MS

2-Acetyl-1-pyrroline (2-AP) is a key odorant in many foods, such as aromatic rice and wheat bread, with a very low odor threshold of 0.05 μg/L in water. The small molecule with a popcornlike, roasty odor is generated biologically or by Strecker degradation within the Maillard-reaction cascades during thermal food processing with methylglyoxal and 1-pyrroline as the main direct precursors. Numerous gas-chromatographic methods for the analysis of 2-AP have been published, but the reactivity of the compound leads to discrimination or degradation during sample workup. We developed a novel derivatization method for 2-AP with o-phenylenediamine followed by HPLC-MS/MS analysis of the resulting stable quinoxaline. The precision (7%), repeatability (14%), recovery (92%), linearity (0.79-500 μg/kg), limit of detection (LOD, 0.26 μg/kg), and limit of quantitation (LOQ, 0.79 μg/kg) were validated for rice matrix and were excellent as compared with those of methods published before. With the novel method, 2-AP levels in typical foods like aromatic rice (131 μg/kg), wheat bread (18 μg/kg), brown bread (18 μg/kg), rye bread (18 μg/kg), and popcorn (38 μg/kg) were determined.

Different profiles of naturally produced and anthropogenic organohalogens in the livers of cetaceans from the Sea of Japan and the North Pacific Ocean

Levels and profiles of naturally produced halogenated bipyrroles (Br₄Cl₂-DBP and Cl₇-MBP), methoxylated tetrabromodiphenyl ethers (6-MeO-BDE47), anthropogenic perfluoroalkyl substances (PFASs) and legacy persistent organic pollutants (POPs) were investigated in the livers of 14 cetaceans from the Sea of Japan and the North Pacific Ocean. The concentrations of Br₄Cl₂-DBP (4 to 4900 ng/g-wet), Cl₇-MBP (16 to 3960 ng/g-wet) and 6-MeO-BDE47 (7 to 190 ng/g-wet) were higher in the order of killer whales > toothed whales > baleen whales. Profiles of PFASs were dominated by perfluoroundecanoic and perfluorotridecanoic acids (10 to 540 ng/g-wet), sum of which accounted for 70% of total measured PFASs. Regional difference was observed for Cl₇-MBP and PFASs, which were higher in the Sea of Japan, whereas Br₄Cl₂-DBP was in the North Pacific Ocean. Specific accumulation pattern of these natural contaminants in cetaceans around northern Japan could help compare the exposure profile of PFASs and POPs among other geographic regions.

Review of pentosidine and pyrraline in food and chemical models: formation, potential risks and determination

Pyrraline and pentosidine are advanced Maillard reaction products derived from the reaction of glucose with the lysine amino group on proteins. They have been implicated in uremia, diabetes, and related complications, including inflammation, retinopathy, and nephropathy. This review focuses on the formation mechanism, human potential risks, and detections of pentosidine and pyrraline and lays the foundation for further study of pentosidine and pyrraline. © 2017 Society of Chemical Industry.

Spray-chilling encapsulation of 2-acetyl-1-pyrroline zinc chloride complex using hydrophobic materials: Feasibility and characterization of microcapsules

A moisture-sensitive 2-acetyl-1-pyrroline zinc chloride complex (2AP-ZnCl₂) was successfully encapsulated by spray-chilling, using a hydrophobic moisture barrier as a practical way to protect the complex and to help facilitate its general use in food applications. Use of octacosane as wall material provided a flavor retention of 65.3%. The results from scanning electron microscopy (SEM) and X-ray micro-computed tomography (X-ray micro-CT) indicated desirable morphological characteristics of the matrix type microcapsules. Gas chromatography (GC) and absorbance spectroscopy were used for chemical quantitation of 2AP and ZnCl₂, respectively, in the microcapsules. Results revealed no degradation of 2AP occurred as a result of the encapsulation process. This study is the first to demonstrate the feasibility of producing high quality microcapsules from labile flavor complexes by spray-chilling. The use of generally recognized as safe (GRAS) substances, including 2AP and ZnCl₂, may allow for widespread commercial use of 2AP as a flavor ingredient.

Tissue-specific bioaccumulation of long-chain perfluorinated carboxylic acids and halogenated methylbipyrroles in Dall's porpoises (Phocoenoides dalli) and harbor porpoises (Phocoena phocoena) stranded in northern Japan

This study investigated accumulation of perfluoroalkyl substances (PFASs), persistent organochlorines (OCs), and naturally produced halogenated compounds (NHCs), including brominated methylbipyrroles and methoxylated bromodiphenyl ethers, in liver, blood, and blubber from Dall's porpoises (Phocoenoides dalli) and harbor porpoises (Phocoena phocoena) stranded in Hokkaido, northern Japan. Profiles of the PFASs were dominated by perfluoroundecanoic acid and perfluorotridecanoic acid, both of which accounted for 70% of the total measured PFAS concentrations in both porpoise species. The mean concentrations of the ∑PFCA were 573ng/g wet weight (ng/g-wet) in liver, 62ng/g-wet in whole blood, and 28ng/g-wet in blubber from the Dall's porpoises, and were significantly higher (p<0.05) than those in the harbor porpoises. The hepatic concentrations of perfluorooctane sulfonate (PFOS) were <14ng/g-wet, and accounted for only 3% of the total measured PFASs. The profiles of PFASs in the porpoises resembled those in fish species in this area, implying a common source of exposure to PFASs in East Asia. On the other hand, in the blubber of Dall's porpoises, NHCs were dominated by 2,3,3',4,4',5,5'-heptachloro-1'-methyl-1,2'-bipyrrole (867ng/g-wet), 5,5'-dichloro-1,1'-dimethyl-3,3',4,4'-tetrabromo-2,2'-bipyrrole (481ng/g-wet), and 6-methoxy-2,2',4,4'-tetrabromodiphenyl ether (30ng/g-wet), which were present at higher concentrations than in harbor porpoises. Factor analysis with varimax rotation revealed that factor 1 had higher eigenvectors (element in eigenvalues) for long-chain PFCAs and PFOS, which was found in the highest concentrations in the liver, whereas factor 2 was mainly associated with lipid soluble NHCs and OCs in both species. No correlations were observed between long-chain PFCAs and NHCs in the porpoises, probably because of the different sources and accumulation kinetics. Future research should assess the temporal trends and long-term effects of PFASs and NHCs in the tissues of mammals from the Asia-Pacific region.

Analysis of volatile compounds in gluten-free bread crusts with an optimised and validated SPME-GC/QTOF methodology

The aroma of bread crust, as one of the first characteristics perceived, is essential for bread acceptance. However, gluten-free bread crusts exhibit weak aroma. A SPME-GC/QTOF methodology was optimised with PCA and RSM and validated for the quantification of 44 volatile compounds in bread crust, extracting 0.75 g of crust at 60 °C for 51 min. LODs ranged between 3.60 and 1760 μg Kg^-1, all the R² were higher than 0.99 and %RSD for precision and %Er for accuracy were lower than 9% and 12%, respectively. A commercial wheat bread crust was quantified, and furfural was the most abundant compound. Bread crusts of wheat starch and of japonica rice, basmati rice and teff flours were also quantified. Teff flour and wheat starch crusts were very suitable for improving gluten-free bread crust aroma, due to their similar content in 2-acetyl-1-pyrroline and 4-hydroxy-2,5-dimethyl-3(2H)-furanone compared to wheat flour crust and also for their high content in pyrazines.

Exposure and effects of sediment-spiked fludioxonil on macroinvertebrates and zooplankton in outdoor aquatic microcosms

Information from effects of pesticides in sediments at an ecosystem level, to validate current and proposed risk assessment procedures, is scarce. A sediment-spiked outdoor freshwater microcosm experiment was conducted with fludioxonil (lipophilic, non-systemic fungicide) to study exposure dynamics and treatment-related responses of benthic and pelagic macroinvertebrates and zooplankton. Besides blank control and solvent control systems the experiment had six different treatment levels (1.7-614mga.s./kg dry sediment) based around the reported 28-d No Observed Effect Concentration (NOEC) for Chironomus riparius (40mga.s./kg dry sediment). Twelve systems were available per treatment of which four were sacrificed on each of days 28, 56 and 84 after microcosm construction. Fludioxonil persisted in the sediment and mean measured concentrations were 53-82% of the initial concentration after 84days. The dissipation rate increased with the treatment level. Also exposure concentrations in overlying water were long-term, with highest concentrations 28days after initiation of the experiment. Sediment-dwelling Oligochaeta and pelagic Rotifera and Cladocera showed the most pronounced treatment-related declines. The most sensitive sediment-dwelling oligochaete was Dero digitata (population NOEC 14.2mga.s./kg dry sediment). The same NOEC was calculated for the sediment-dwelling macroinvertebrate community. The most sensitive zooplankton species was the cladoceran Diaphanosoma brachyurum (NOEC of 1.6μga.s./L in overlying water corresponding to 5.0mga.s./kg dry sediment). At the two highest treatments several rotifer taxa showed a pronounced decrease, while the zooplankton community-level NOEC was 5.6μga.s./L (corresponding to 14.2mga.s./kg dry sediment). Zooplankton taxa calanoid Copepoda and Daphnia gr. longispina showed a pronounced treatment-related increase (indirect effects). Consequently, an assessment factor of 10 to the chronic laboratory NOECs of Chironomus riparius (sediment) and Daphnia magna (water) results in a regulatory acceptable concentration that is sufficiently protective for both the sediment-dwelling and pelagic organisms in the microcosms.

Synthesis, structure elucidation, and determination of polyhalogenated N-methylpyrroles (PMPs) in blue mussels

Polyhalogenated N-methylpyrroles (PMPs) are halogenated natural products (HNPs) recently detected in seagrass, blue mussels, and other marine organisms. In this study, we synthesized 2,3,4,5-tetrachloro-N-methylpyrrole (Cl₄-MP), 2,3,4,5-tetrabrominated-N-methylpyrrole (Br₄-MP, aka TBMP), and mixed tetrahalogenated (Cl and Br) N-methylpyrrole congeners. Use of one- and two-dimensional ¹H and ¹³C NMR verified the structures of isolated/enriched 3,4-dibromo-2,5-dichloro-N-methylpyrrole (3,4-Br₂-2,5-Cl₂-MP), 2,3,4-tribromo-5-chloro-N-methylpyrrole (2,3,4-Br₃-5-Cl-MP), and 3-bromo-2,4,5-trichloro-N-methylpyrrole (3-Br-2,4,5-Cl₃-MP). GC/EI-MS and GC/ECNI-MS mass spectra of the five PMPs were studied with regard to fragmentation pattern and individual responses which were strongly affected by the presence (or absence) of Br in α-position(s). Quantitative solutions of the synthesized standards were used to determine the elution order of isomers and to quantify PMPs in selected blue mussel samples (Mytilus sp.) from the European Atlantic coast (Spain, France), the North Sea (the Netherlands, Germany) and Baltic Sea (Germany). PMPs were detected in all samples and the concentrations ranged between 0.6 and 52 μg/kg lipids with Br₄-MP being the most abundant representative of this substance class.

Comprehensive insight into the binding of sunitinib, a multi-targeted anticancer drug to human serum albumin

Binding studies between a multi-targeted anticancer drug, sunitinib (SU) and human serum albumin (HSA) were made using fluorescence, UV-vis absorption, circular dichroism (CD) and molecular docking analysis. Both fluorescence quenching data and UV-vis absorption results suggested formation of SU-HSA complex. Moderate binding affinity between SU and HSA was evident from the value of the binding constant (3.04×10⁴M^-1), obtained at 298K. Involvement of hydrophobic interactions and hydrogen bonds as the leading intermolecular forces in the formation of SU-HSA complex was predicted from the thermodynamic data of the binding reaction. These results were in good agreement with the molecular docking analysis. Microenvironmental perturbations around Tyr and Trp residues as well as secondary and tertiary structural changes in HSA upon SU binding were evident from the three-dimensional fluorescence and circular dichroism results. SU binding to HSA also improved the thermal stability of the protein. Competitive displacement results and molecular docking analysis revealed the binding locus of SU to HSA in subdomain IIA (Sudlow's site I). The influence of a few common ions on the binding constant of SU-HSA complex was also noticed.

Core-Shell Metal-Organic Frameworks/Molecularly Imprinted Nanoparticles as Absorbents for the Detection of Pyrraline in Milk and Milk Powder

A novel core-shell metal-organic framework coated with a dummy template molecularly imprinted polymer (MOF@DMIP) was synthesized by one-pot bulk polymerization for the detection of pyrraline in food samples. The pyrraline analogue pyrrolidine-3-carboxylic acid was used as the template because of its lower cost, and MIL-101 was used as the MOF core owing to its numerous inherent advantages, including high chemical and hydrothermal stabilities. MIL-101@DMIP was used to detect trace pyrraline in foods by solid-phase extraction combined with high-performance liquid chromatography. It exhibited the advantages of faster mass transport, excellent sensitivity, and selectivity. Under optimum conditions, the detection limit of this system was 40.7 μg L^-1, and a linear range was from 5 × 10^-7 to 2 × 10^-3 mol L^-1, within relative standard deviations of 4.46-6.87%. The recoveries ranged from 92.23 to 103.87%, indicating the excellent ability of the prepared MIL-101@DMIP to recognize pyrraline in complex food matrices and its potential for application in pyrraline detection.

Wastewater treatment high rate algal pond biomass for bio-crude oil production

This study investigates the production potential of bio-crude from wastewater treatment high rate algal pond (WWT HRAP) biomass in terms of yield, elemental/chemical composition and higher heating value (HHV). Hydrothermal liquefaction (HTL) of the biomass slurry (2.2wt% solid content, 19.7kJ/g HHV) was conducted at a range of temperatures (150-300°C) for one hour. The bio-crude yield and HHV varied in range of 3.1-24.9wt% and 37.5-38.9kJ/g, respectively. The bio-crudes were comprised of 71-72.4wt% carbon, 0.9-4.8wt% nitrogen, 8.7-9.8wt% hydrogen and 12-15.7wt% oxygen. GC-MS analysis indicated that pyrroles, indoles, amides and fatty acids were the most abundant bio-crude compounds. HTL of WWT HRAP biomass resulted, also, in production of 10.5-26wt% water-soluble compounds (containing up to 293mg/L ammonia), 1.0-9.3wt% gas and 44.8-85.5wt% solid residue (12.2-18.1kJ/g). The aqueous phase has a great potential to be used as an ammonia source for further algal cultivation and the solid residue could be used as a process fuel source.

RP-HPLC ANALYSIS OF ACIDIC AND BASIC DRUGS IN SYSTEMS WITH DIETHYLAMINE AS ELUENTS ADDITIVE

The chromatographic behavior of some basic and acidic drugs was studied on Cl 8, Phenyl-Hexyl and Polar RP columns with methanol or acetonitrile as organic modifiers of aqueous mobile phases containing addition of diethylamine. Diethylamine plays a double function of silanol blocker reagent in analysis of basic drugs and ion-pair reagent in analysis of acidic drugs. Most symmetrical peaks and highest system efficiency were obtained on Phenyl-Hexyl and Polar RP columns in tested mobile phase systems compared to results obtained on C18 column. A new rapid, simple, specific and accurate reverse phase liquid chromatographic method was developed for the simultaneous determination of atorvastatin - antihyperlipidemic drug and amlodipine - calcium channel blocker in one pharmaceutical formulation. Atorvastatin is an acidic compounds while amlodipine is a basic substance. The chromatographic separation was carried out on Phenyl-Hexyl column by gradient elution mode with acetonitrile as organic modifier, acetate buffer at pH 3.5 and Q.025 M/L diethylamine. The proposed method was validated for specificity, precision, accuracy, linearity, and robustness. The linearity range of atorvastatin and amlodipine for 5 - 100 μg/mL was obtained with limits of-detection (LOD) 3.2750 gg/mL and 3.2102 μg/mL, respectively. The proposed method made use of DAD as a tool for peak identity and purity confirmation.

Free and Protein-Bound Maillard Reaction Products in Beer: Method Development and a Survey of Different Beer Types

The Maillard reaction is important for beer color and flavor, but little is known about the occurrence of individual glycated amino acids in beer. Therefore, seven Maillard reaction products (MRPs), namely, fructosyllysine, maltulosyllysine, pyrraline, formyline, maltosine, MG-H1, and argpyrimidine, were synthesized and quantitated in different types of beer (Pilsner, dark, bock, wheat, and nonalcoholic beers) by HPLC-ESI-MS/MS in the multiple reaction monitoring mode through application of the standard addition method. Free MRPs were analyzed directly. A high molecular weight fraction was isolated by dialysis and hydrolyzed enzymatically prior to analysis. Maltulosyllysine was quantitated for the first time in food. The most important free MRPs in beer are fructosyllysine (6.8-27.0 mg/L) and maltulosyllysine (3.7-21.8 mg/L). Beer contains comparatively high amounts of late-stage free MRPs such as pyrraline (0.2-1.6 mg/L) and MG-H1 (0.3-2.5 mg/L). Minor amounts of formyline (4-230 μg/L), maltosine (6-56 μg/L), and argpyrimidine (0.1-4.1 μg/L) were quantitated. Maltulosyllysine was the most significant protein-bound MRP, but both maltulosyllysine and fructosyllysine represent only 15-60% of the total protein-bound lysine-derived Amadori products. Differences in the patterns of protein-bound and free individual MRPs and the ratios between them were identified, which indicate differences in their chemical, biochemical, and microbiological stabilities during the brewing process.

HS-SPME-GC-MS/MS Method for the Rapid and Sensitive Quantitation of 2-Acetyl-1-pyrroline in Single Rice Kernels

Demand for aromatic rice varieties (e.g., Basmati) is increasing in the US. Aromatic varieties typically have elevated levels of the aroma compound 2-acetyl-1-pyrroline (2AP). Due to its very low aroma threshold, analysis of 2AP provides a useful screening tool for rice breeders. Methods for 2AP analysis in rice should quantitate 2AP at or below sensory threshold level, avoid artifactual 2AP generation, and be able to analyze single rice kernels in cases where only small sample quantities are available (e.g., breeding trials). We combined headspace solid phase microextraction with gas chromatography tandem mass spectrometry (HS-SPME-GC-MS/MS) for analysis of 2AP, using an extraction temperature of 40 °C and a stable isotopologue as internal standard. 2AP calibrations were linear between the concentrations of 53 and 5380 pg/g, with detection limits below the sensory threshold of 2AP. Forty-eight aromatic and nonaromatic, milled rice samples from three harvest years were screened with the method for their 2AP content, and overall reproducibility, observed for all samples, ranged from 5% for experimental aromatic lines to 33% for nonaromatic lines.

LC-MS/MS determination of tralopyril in water samples

A targeted analytical method was established to determine tralopyril (4-bromo-2-(4-chlorophenyl)-5-(trifluoromethyl)-1H-pyrrole-3-carbonitrile) in water. This compound has been recently introduced as a biocide in ship antifouling paints, becoming a potential new environmental contaminant. The method presented here allows for the first time the direct determination of tralopyril in environmental samples without the need of a pre-concentration step. The injected sample is separated by a 30 min HPLC-gradient on a reversed phase column and the compound identified and quantified by negative ion LC-MS/MS. Tralopyril solutions in DMSO, seawater, river Glatt water and E3 medium (used for zebrafish experiments) were analysed to demonstrate the applicability of the method. The method provides good retention time reproducibility and a quantitation limit (LOQ) of 0.025 μg L(-1) for DMSO, seawater and E3 exposure medium and 0.05 μg L(-1) for river Glatt water. Calculated tralopyril half-lives were 6.1 h for seawater, 8.1 h for river Glatt water and 7.4 h for E3 medium at 18 °C.

The influence of the time-of-day administration of sunitinib on the penetration through the blood-brain and blood-aqueous humour barriers in rabbits

OBJECTIVE

Sunitinib is a multiple tyrosine kinase inhibitor (TKI) that exerts anti-tumor and antiangiogenic activity. It is used for the treatment of metastatic gastrointestinal stromal tumours, renal cell carcinoma and pancreatic neuroendocrine tumours. A few studies confirm the anti-tumour activity of sunitinib in brain tumours and uveal melanoma, as well as its efficacy in the reduction of brain metastases of some primary cancers. Therefore, the penetration of sunitinib through the blood-brain barrier (BBB) and blood-aqueous humour barrier (BAB) is an issue of growing interest. The aim of the study was to investigate the influence of the time-of-day administration on the penetration of sunitinib into the cerebrospinal fluid (CSF) and aqueous humour (AH).

MATERIALS AND METHODS

The rabbits were divided into two groups: I (control group)--receiving sunitinib at 8 a.m., and II--receiving sunitinib at 8 p.m. Sunitinib was administered p.o. at a single dose of 25 mg. The concentrations of sunitinib and its active metabolite (SU12662) in the plasma, CSF, AH were measured with the validated HPLC-UV method.

RESULTS

The plasma AUC0-t for sunitinib in group I was 2051.8 ng × h/mL, whereas in group II it was 3069.3 ng × h/mL. The aqueous humour AUC0-t for sunitinib in thr groups were 43.2 and 76.3 ng × h/mL, respectively. The cerebrospinal AUC0-t for sunitinib in groups I and II were 55.5 and 66.3 ng × h/mL, respectively.

CONCLUSIONS

After the evening administration (8 p.m.) the exposure to sunitinib in the rabbits' plasma, AH and CSF was higher than after the morning administration (8 a.m.), but the degree of sunitinib penetration through the BAB and BBB was very low (< 5%) and comparable in both groups.

Forced Degradation and Photodegradation Studies of Pyrrolo[3,4-c]pyridine-1,3-dione Derivatives as Analgesic Active Compounds Using HPLC, UV and IR Spectrometry, and HPLC/MS Methods

The stress and accelerated tests as well as photostability analysis in solutions and the solid phase of three selected derivatives of pyrrolo[3,4-c]pyridine-1,3-dione were carried out according the International Conference on Harmonization guidelines. For observation of the degradation of tested compounds, the RP-HPLC method was used. The study included the effect of temperature, relative humidity, water, H+ and OH- ions, hydrogen peroxide, and light (6.0×10(6), 1.2×10(6) lux·h) on the stability of pyrrolo[3,4-c]pyridine-1,3-dione derivatives. Studies have shown that these derivatives are photolabile, extremely unstable in an alkaline medium, labile in an acidic medium, and stable in a neutral medium. Their sensitivity to oxidizing agents depends on the chemical structure. The shortening of the aliphatic chain leads to an increase in the sensitivity to hydrolytic and oxidizing factors. The presence of the 1,3,4-tetraisoquinoline group promotes an increase in the susceptibility to photodegradation. The introduction of a carbonyl group to the aliphatic chain and the tetrafluoromethyl group to the phenyl ring stabilizes the molecule in the case of hydrolysis and oxidation and also increases sensitivity to light. The analysis of observed photodegradation products using the HPLC-diode array detector, HPLC/MS, and UV and IR spectrometry techniques showed degradation targeted at the breaking of the pyrrolo[3,4-c]pyridine-1,3-dione, piperazine, and/or tetrahydroisoquinoline rings.

Identification and Quantitation of 2-Acetyl-1-pyrroline in Manuka Honey (Leptospermum scoparium)

Manuka honey from New Zealand is known for its exceptional antibacterial activity, which is due to high amounts of the 1,2-dicarbonyl compound methylglyoxal (MGO). MGO in manuka honey is formed via non-enzymatic dehydration from dihydroxyacetone (DHA) during honey maturation. MGO and DHA are highly reactive substances, leading to a variety of unique chemical reactions. During Strecker reaction between proline and MGO, 2-acetyl-1-pyrroline (2-AP), an important aroma compound, is formed. Using liquid-liquid extraction and gas chromatography-mass spectrometry analysis, 2-AP was identified unambiguously in manuka honey for the first time. Quantitation was carried out via external matrix calibration, using a synthetic 2-AP standard and artificial honey. The 2-AP concentration in 11 commercial samples of manuka honey ranged from 0.08 to 0.45 mg/kg. For manuka honey samples containing MGO in concentrations above 250 mg/kg, significantly higher amounts of 2-AP were found when compared to non-manuka honeys. When high amounts of MGO were artificially added to non-manuka multifloral honey, an increase of the 2-AP concentration from 0.07 to 0.40 mg/kg after 12 weeks of storage at 37 °C was observed, concomitant with a significant increase in the concentration of 5-hydroxymethylfurfural (HMF). No increase of 2-AP was found during storage at ambient temperature. 2-AP together with MGO can be a suitable parameter for the quality control of manuka honey.

Determination and analysis of the dissipation and residue of cyprodinil and fludioxonil in grape and soil using a modified QuEChERS method

A simple and accurate method coupled with a gas chromatography-nitrogen phosphorus detector was developed to detect cyprodinil and fludioxonil in grape and soil. The accuracy and precision of the method in detecting the two fungicides were evaluated by conducting intra- and inter-day recovery experiments. The limits of detection were 0.017 mg/kg for cyprodinil and 0.030 mg/kg for fludioxonil. The limits of quantitation were 0.05 mg/kg for cyprodinil and 0.10 mg/kg for fludioxonil in grape and soil. The recoveries of the fungicides in grape and soil were investigated at three spiked levels and were found to range from 85.81 to 102.94% for cyprodinil and from 92.00 to 106.86% for fludioxonil, with relative standard deviations below 7%. Field experiments were conducted in two experimental locations in China. The half-lives of cyprodinil were 9.6-20.8 days in grape and 5.8-15.6 day in soil, and the half-lives of fludioxonil were 6.2-7.2 days in grape and 6.0-12.1 days in soil. When the cyprodinil and fludioxonil 62% water-dispersible granule formulation was sprayed at a low dosage three times, terminal residues of cyprodinil and fludioxonil were below 1.0 mg/kg in grape 14 days after harvest. This work may serve as a reference to establish the maximum residue limits for cyprodinil and fludioxonil in grape and promote the proper and safe use of these two fungicides.

Structural elucidation and estimation of the acute toxicity of the major UV-visible photoproduct of fludioxonil - detection in both skin and flesh samples of grape

Ultraviolet (UV)-visible irradiation of fludioxonil was investigated with two photoreactors using either a mercury or xenon vapor lamp. In both cases, it led to the formation of only one photoproduct in significant amount: 2-(2,2-difluorobenzo[d][1,3]dioxol-4-yl)-2-(nitrosomethylene)-4-oxobutanenitrile, which has been characterized using Liquid Chromatography - High Resolution - Tandem Mass Spectrometry (LC-HR-MS/MS) coupling. A photolysis pathway has been proposed to rationalize its formation in degassed water. In vitro bioassays on Vibrio fischeri bacteria showed that UV-vis irradiation of an aqueous solution of fludioxonil significantly increases its toxicity. Because no other by-product was detected in significant amount, the photoproduct mentioned above may be considered mainly responsible for this increase in toxicity. Grape berries treated with a 50 ppm aqueous solution of fludioxonil were submitted to UV-visible irradiation under laboratory conditions. The fungicide and photoproduct were detected in both skin and flesh of berries, even after they have been rinsed with water. The ability of the photoproduct to pass through the fruit skin is comparable with that of fludioxonil. These results are of concern for consumers because they mean that water tap rinsing does not lead to efficient removing of both compounds.

Comparative study of three modified numerical spectrophotometric methods: an application on pharmaceutical ternary mixture of aspirin, atorvastatin and clopedogrel

Three novel numerical methods were developed for the spectrophotometric multi-component analysis of capsules and synthetic mixtures of aspirin, atorvastatin and clopedogrel without any chemical separation. The subtraction method is based on the relationship between the difference in absorbance at four wavelengths and corresponding concentration of analyte. In this method, the linear determination ranges were 0.8-40 μg mL(-1) aspirin, 0.8-30 μg mL(-1) atorvastatin and 0.5-30 μg mL(-1) clopedogrel. In the quotient method, 0.8-40 μg mL(-1) aspirin, 0.8-30 μg mL(-1) atorvastatin and 1.0-30 μg mL(-1) clopedogrel were determine from spectral data at the wavelength pairs that show the same ratio of absorbance for other two species. Standard addition method was used for resolving ternary mixture of 1.0-40 μg mL(-1) aspirin, 0.8-30 μg mL(-1) atorvastatin and 2.0-30 μg mL(-1) clopedogrel. The proposed methods were validated. The reproducibility and repeatability were found satisfactory which evidence was by low values of relative standard deviation (<2%). Recovery was found to be in the range (99.6-100.8%). By adopting these methods, the time taken for analysis was reduced as these methods involve very limited steps. The developed methods were applied for simultaneous analysis of aspirin, atorvastatin and clopedogrel in capsule dosage forms and results were in good concordance with alternative liquid chromatography.

Pyrrole alkaloids with potential cancer chemopreventive activity isolated from a goji berry-contaminated commercial sample of African mango

Bioassay-guided fractionation of a commercial sample of African mango (Irvingia gabonensis) that was later shown to be contaminated with goji berry (Lycium sp.) led to the isolation of a new pyrrole alkaloid, methyl 2-[2-formyl-5-(hydroxymethyl)-1H-pyrrol-1-yl]propanoate, 1, along with seven known compounds, 2-8. The structures of the isolated compounds were established by analysis of their spectroscopic data. The new compound 1g showed hydroxyl radical-scavenging activity with an ED50 value of 16.7 μM, whereas 4-[formyl-5-(methoxymethyl)-1H-pyrrol-1-yl]butanoic acid (2) was active in both the hydroxyl radical-scavenging (ED50 11.9 μM) and quinone reductase-induction [CD (concentration required to double QR activity) 2.4 μM)] assays used. The isolated compounds were shown to be absent in a taxonomically authenticated African mango sample but present in three separate authentic samples of goji berry (Lycium barbarum) using LC-MS and (1)H NMR fingerprinting analysis, including one sample that previously showed inhibitory activity in vivo in a rat esophageal cancer model induced with N-nitrosomethylbenzylamine. Additionally, microscopic features characteristic of goji berry were observed in the commercial African mango sample.

A novel method for beef potentiator preparation and identification of its characteristic aroma compounds

BACKGROUND

Beef potentiator (BP) is the most popular savoury flavour and regarded as the soul of the modern food industry. In this work, BP was prepared by a novel method with Aspergillus oryzae and Aspergillus niger (BPSF). Three other BPs prepared using commercial enzymes (Protamex, Flavourzyme and papain; BPCEs) were used as controls to investigate its aroma characteristics and related compounds.

RESULTS

Sensory evaluation showed that BPSF possessed more favourable and distinctive sauce-like, meat-like, roast and alcoholic attributes when compared with BPCEs. Significantly higher contents (peak areas) and proportions of pyrazines, pyrroles, sulfurous compounds and alcohols in BPSF were responsible for its sensory characteristics, and most of these aroma compounds were derived from microbial metabolism during beef koji preparation and the Maillard reaction.

CONCLUSION

BP prepared by synergistic fermentation with A. oryzae and A. niger is a potential alternative for BP preparation.

Tomato Paste Fraction Inhibiting the Formation of Advanced Glycation End-products

A water-soluble and low-molecular-weight fraction (SB) was obtained from tomato paste. The effects of SB on the formation of advanced glycation end-products (AGE) in protein glycation were studied by the methods of specific fluorescence, ELISA and a Western blot analysis, using the anti-AGE antibody after incubating protein with sugar. The results suggest that SB had strong inhibitory activity, in comparison with aminoguanidine as a positive control, and that the inhibitory mechanism of SB differed from that of aminoguanidine to involve trapping of reactive dicarbonyl intermediates in the early stage of glycation. SB contained an antioxidant, rutin, which showed potent inhibitory activity. The results also suggest that rutin chiefly contributed to inhibiting the formation of AGE, and that other compounds in SB may also have been related to the activity.

In-package nonthermal plasma degradation of pesticides on fresh produce

In-package nonthermal plasma (NTP) technology is a novel technology for the decontamination of foods and biological materials. This study presents the first report on the potential of the technology for the degradation of pesticide residues on fresh produce. A cocktail of pesticides, namely azoxystrobin, cyprodinil, fludioxonil and pyriproxyfen was tested on strawberries. The concentrations of these pesticides were monitored in priori and post-plasma treatment using GC-MS/MS. An applied voltage and time dependent degradation of the pesticides was observed for treatment voltages of 60, 70 and 80 kV and treatment durations ranging from 1 to 5 min, followed by 24h in-pack storage. The electrical characterisation revealed the operation of the discharge in a stable filamentary regime. The discharge was found to generate reactive oxygen and excited nitrogen species as observed by optical emission spectroscopy.

Immunoreagents and competitive assays to fludioxonil

Fludioxonil is a new-generation fungicide widely used for postharvest fruit protection. The aim of this study was to produce hitherto unreported immunoreagents for Fludioxonil analysis by immunoassay. Derivatives of this agrochemical were synthesized with different linker tethering sites. Those functionalized haptens were activated, and the purified active esters were efficiently conjugated to different carrier proteins for immunogen and assay antigen preparation. Antibodies to Fludioxonil were raised in rabbits, and their selectivity and affinity were characterized, revealing the significance of the linker. Those antibodies were evaluated using homologous and heterologous conjugates by direct and indirect competitive ELISA formats. Finally, a pair of immunoreagents was identified showing an IC50 value for Fludioxonil of 5.7 μg/L.

Aroma-active components of yeast extract pastes with a basic and characteristic meaty flavour

BACKGROUND

Aroma-active compounds, together with sugars, amino acids, fat and nucleotides, are the main chemical species determining the characteristic aroma and taste of food. For selecting yeast extract pastes products with a less undesirable aroma, the aroma-active compounds that affect the overall consumer acceptance of yeast extract pastes products were analysed in this work.

RESULTS

The aroma-active compounds of yeast extract pastes were extracted by using dynamic headspace extraction or simultaneous distillation extraction, and were detected by gas chromatography-olfactrometry-mass spectrometry in conjunction with dynamic headspace dilution analysis or aroma extract dilution analysis. Sensory results revealed that a meaty, roasted aroma was the dominant of overall aroma. The important aroma-active compounds referred in this work were mainly aldehydes, acids, ketones, furan derivatives, pyrazines, and sulfur-containing compounds. Of these, six volatile compounds such as 3-methylbutanal, 2,3-butanedione, 2,3,5-trimethyl-pyrazin, acetic acid ethenyl ester, 2-acetyl-1-pyrroline and (E,E)-2,4-decadienal had never been reported before as key aroma-active compounds of yeast extract pastes.

CONCLUSIONS

The key aroma-active compounds were identified in basic and characteristic meaty flavour yeast extract pastes, and their characterisation was determined.

Preclinical Pharmacology of the Pyrrolobenzodiazepine (PBD) Monomer DRH-417 (NSC 709119)

The pyrrolobenzodiazepine monomer DRH-417 is a member of the anthramycin group of anti-tumor antibiotics that bind covalently to the N2 of guanine within the minor groove of DNA. DRH-417 emerged from the EORTC-Drug Discovery Committee and NCI 60 cell line in vitro screening programs as a potent antiproliferative agent with differential sensitivity towards certain cancer types such as melanoma, breast and renal cell carcinoma (mean IC(50) = 3 nM). DRH-417 was therefore tested for in vivo activity. The maximum tolerated dose (MTD) was established as 0.5 mg/kg given i.p. Marked anti-tumor activity was seen in two human renal cell cancers, one breast cancer and a murine colon tumor model (p<0.01). A selective HPLC (LC/MS) analytical method was developed and plasma pharmacokinetics determined. At a dose of 0.5 mg kg(-1), the plasma AUC was 540 nM h (197.1 ng h ml(-1)) and the peak plasma concentration (171 nM [62.4 ng ml(-1)]) occurred at 30 min., reaching doses levels well above those needed for in vitro antiproliferative activity. Genomic profiling of in vivo sensitive tumors revealed that the latter have an activated insulin-like growth factor signaling pathway.

Comparative analysis of Tunisian wild Crataegus azarolus (yellow azarole) and Crataegus monogyna (red azarole) leaf, fruit, and traditionally derived syrup: phenolic profiles and antioxidant and antimicrobial activities of the aqueous-acetone extracts

Quantitative and qualitative analyses of the yellow and red azarole phenolic extracts prepared from leaf, fruit peel/pulp, and syrup were comparatively investigated. The yellow azarole was found significantly richer in polyphenols than the red-fruit species. Hyperoside was the main phenolic in both yellow and red azarole leaves and only in yellow fruits, whereas procyanidin B2 was the major compound in red fruits. Yellow azarole leaf and fruit peel extracts exhibited the strongest antioxidant activities using DPPH (≈168 and 79 μmol TEAC/g fw, respectively) and FRAP (≈378 and 161 μmol Fe(2+)/g fw, respectively) assays. The highest antibacterial activities were recorded for the yellow azarole leaf and fruit peel extracts, especially against Staphylococcus aureus and Streptococcus faecalis . The low phenolic content of the syrups contrasted with their significant antioxidant and antimicrobial potentials, which were correlated to their hydroxymethylfurfural (HMF) (furan derivative amounts) content.

Characterization of odor-active compounds in sweet-type Chinese rice wine by aroma extract dilution analysis with special emphasis on sotolon

The aroma characteristics of sweet-type Chinese rice wine were studied by sensory analysis, aroma extract dilution analysis (AEDA), and quantitative analysis. Sensory evaluation demonstrated that a caramel-like note was the most distinctive characteristic for sweet-type Chinese rice wine. AEDA was carried out on the extract of a typical sweet-type Chinese rice wine sample. Thirty-nine odor-active regions were detected in the sample with a flavor dilution (FD) factor ≥8, and 37 of these were further identified. Among them, sotolon and 2- and 3-methylbutanol showed the highest FD factor of 1024, followed by 2-acetyl-1-pyrroline (tentatively identified), dimethyl trisulfide, 2-phenylethanol, and vanillin with a FD factor of 512. Sotolon was identified as a key aroma compound in Chinese rice wine for the first time. AEDA results indicated that sotolon (caramel-like/seasoning-like) was the potentially key contributor to the caramel-like descriptor of sweet-type Chinese rice wine. The concentration of sotolon in Chinese rice wine was further quantitated by Lichrolut-EN solid-phase extraction coupled with microvial insert large volume injection method. The content of sotolon ranged from 35.93 to 526.17 μg/L, which was above its odor threshold (9 μg/L) for all Chinese rice wine samples. The highest concentration of sotolon was found in the sweet-type Chinese rice wine, which highlighted the important aroma role of sotolon for this particular type of Chinese rice wine.

Discovery and widespread occurrence of polyhalogenated 1,1'-dimethyl-2,2'-bipyrroles (PDBPs) in marine biota

Polyhalogenated 1,1'-dimethyl-2,2'-bipyrroles (PDBPs) are halogenated natural products (HNPs) previously shown to bioaccumulate in marine mammals and birds. Since their discovery in 1999, six hexahalogenated and a few lesser halogenated congeners have been identified in diverse marine mammal samples. Here we report the identification of 17 additional hexahalogenated PDBPs in the blubber extract of a humpback dolphin (Sousa chinensis) from Queensland, Australia. Thirteen of these new PDBPs were also detected in an Australian sea cucumber (Holothuria sp.). Additional samples were also tested positive on several new PDBPs, including an Australian venus tuskfish (Choerodon venustus) as well as a white whale (Delphinapterus leucas) and a sperm whale (Physeter macrocephalus) from the Northern Hemisphere. GC/ECNI-MS-SIM quantification of the molecular ions was carried out with the help of synthesized standards. The sum concentration of PDBPs was 1.1 mg/kg lipid in the humpback dolphin and 0.48 mg/kg lipid in the sea cucumber.

Preparation and characterization of sodium dodecyl sulfate doped polypyrrole solid phase micro extraction fiber and its application to endocrine disruptor pesticide analysis

A robust in house solid-phase micro extraction (SPME) surface has been developed for the headspace (HS)-SPME determination of endocrine disruptor pesticides, namely, Chlorpyrifos, Penconazole, Procymidone, Bromopropylate and Lambda-Cyhalothrin in wine sample by using sodium dodecylsulfate doped polypyrrole SPME fiber. Pyrrole monomer was electrochemically polymerized on a stainless steel wire in laboratory conditions in virtue of diminishing the cost and enhancing the analyte retention on its surface to exert better selectivity and hence the developed polymerized surface could offer to analyst to exploit it as a fiber in headspace SPME analysis. The parameters, mainly, adsorption temperature and time, desorption temperature, stirring rate and salt amount were optimized to be as 70°C and 45min, 200°C, 600rpm and 10gL(-1), respectively. Limit of detection was estimated in the range of 0.073-1.659ngmL(-1) for the pesticides studied. The developed method was applied in to red wine sample with acceptable recovery values (92-107%) which were obtained for these selected pesticides.

Sensomics analysis of key hazelnut odorants (Corylus avellana L. 'Tonda Gentile') using comprehensive two-dimensional gas chromatography in combination with time-of-flight mass spectrometry (GC×GC-TOF-MS)

Comprehensive two-dimensional gas chromatography-mass spectrometry (GC×GC-MS) has been used a few times to identify and quantitate single aroma-active compounds, but the capability of this technique to monitor a complete set of key odorants evoking the aroma of a given food in one run has not been exploited so far. A fast, multiodorant analysis using GC×GC-TOF-MS in combination with stable isotope dilution assays (SIDA) was developed to quantitate the entire set of aroma compounds, the sensometabolome, of raw and roasted hazelnuts ( Corylus avellana L. 'Tonda Gentile') previously established by GC-olfactometry. The capability of the method to evaluate the aroma contribution of each sensometabolite was evaluated by introducing a new term, the limit of odor activity value (LOAV), indicating whether a given aroma compound can be determined down to an odor activity value (OAV) of 1 (odor activity value = ratio of concentration to odor threshold). The advantage of the new method was proven by comparing the performance parameters with a traditional one-dimensional approach using GC-ion trap mass-spectrometry (GC-IT-MS). The results showed that the detector linearity and sensitivity of GC×GC-TOF-MS was on average higher by a factor of 10 compared to GC-IT-MS, thus enabling the quantitation of the aroma relevant amounts of 22 key odorants of hazelnuts in one run of the 30 aroma-active compounds. Seven novel isotopically labeled internal standards were synthesized to meet the analytical requirements defined by electron impact ionization in TOF-MS, that is, to keep the label. On the basis of the quantitative results obtained, it was possible to closely mimic the aroma of raw and roasted 'Tonda Gentile' hazelnuts by preparing an aroma recombinate containing the key odorants at their natural concentrations occurring in the nuts.