Rare isotachin-derived from the Dasymaschalon rostratum fungus Penicillium tanzanicum ZY-5.

Four rare isotachin-derived, isotachins E-H (1-4), together with two known biogenetically related isotachin derivatives (5 and 6) were isolated from the solid rice fermentation of a fungus Penicillium tanzanicum ZY-5 obtained from a medicinal plant Dasymaschalon rostratum collected from the Changjiang County, Hainan Province, China. Their structures were elucidated using comprehensive spectroscopic methods. The single-crystal X-ray diffraction of compound 5 was determined. Compounds 1-4 have a trans-3-(methylthio)-acrylic acid fragment, which are rare in nature. The inhibitory activities of all compounds against the nitric oxide (NO) production induced by lipopolysaccharide in mouse macrophage RAW 264.7 cells in vitro were evaluated.

Highly substituted decoupled gelatin methacrylamide free of hydrolabile methacrylate impurities: An optimum choice for long-term stability and cytocompatibility.

Gelatin methacryloyl (GelMA; GM) contains impurities, including hydrolabile photosensitive methacrylate groups or soluble methacrylic acid (MA), which could be potentially detrimental to its in vitro and in vivo applications. To date, the influence of GM photocurable side chains on the cytotoxicity and ambient structural stability has remained to be investigated. Here, we successfully separated highly substituted decoupled gelatin methacrylamide (DGM) from GM via removing methacrylate impurities in order to evaluate its stability, cell viability, and cell toxicity, compared to GM, DGM plus soluble MA, and soluble MA. The photocurable methacrylate groups in GM were hydrolytically labile in neutral solutions, changing into soluble MA over time; on the other hand, the photocurable methacrylamide groups in DGM remained intact under the same conditions. Soluble MA was found to decrease cell viability in a dose dependent manner and caused severe cell toxicity at above 10 mg/mL. DGM plus MA started to impair cell viability at a 25 mg/mL concentration. DGM exhibited excellent cell viability and little cell toxicity across the treated concentrations (0.1-25 mg/mL). DGM without hydrolabile methacrylate and cytotoxic MA impurities could be a better choice for long term stability and good cell compatibility for bioapplications including bioprinting and cell encapsulation.

Novel Methoxymethacrylate Natural Products Uncovered by Statistics-Based Mining of the Myxococcus fulvus Secondary Metabolome.

This study reports the uncovering of new myxobacterial natural products through comprehensive analysis of the Myxococcus fulvus secondary metabolome. Statistics-based mining of mass spectrometry data paved the way for full structure elucidation of two new secondary metabolites named fulvuthiacene A and B, and investigation of the underlying biosynthetic pathway revealed an evolutionary link between the fulvuthiacene hybrid polyketide synthase (PKS) and nonribosomal peptide synthetase (NRPS) gene cluster and the related myxothiazol and melithiazol assembly lines. Detailed characterization of the post-PKS modification enzyme cascade responsible for the fulvuthiacenes' terminal ß-methoxy-methyl acrylate moiety was pursued by heterologous expression of these enzymes in the myxothiazol producer Stigmatella aurantiaca DW4/3-1. The discovery of fulvuthiacenes provides new insights into the overall structure-activity relationship picture for the ß-methoxyacrylate class of respiratory chain inhibitors and might thus serve as starting point for the development of next-generation ß-methoxymethacrylate fungicides.

Poly[(2-(acryloyloxy) ethyl]trimethylammonium chloride-co-ethylene dimethacrylate monolith on-line solid-phase extraction coupled with liquid chromatography and tandem mass spectrometry for the fast determination of salicylic acid in foodstuffs.

We report the fabrication of an anion-exchange monolithic column in a stainless-steel chromatographic column (10 mm × 2.1 mm i.d.) using [2-(acryloyloxy) ethyl]trimethylammonium chloride as the monomer and ethylene dimethacrylate as the crosslinker. The prepared monolith was developed as the adsorbent for the on-line solid-phase extraction of salicylic acid in various animal-origin foodstuffs combined with liquid chromatography and tandem mass spectrometry. The monolith was characterized by using Fourier transform infrared spectroscopy, scanning electron microscopy, nitrogen adsorption analysis, and elemental analysis. Potential factors affecting the on-line solid-phase extraction and liquid chromatography with tandem mass spectrometry analysis were studied in detail. Under the optimized conditions, the total analysis time including cleanup and liquid chromatography with tandem mass spectrometry separation was 17 min. The developed method gave the linear range of 15-750 µg/kg, detection limits (S/N = 3) of 5 µg/kg, and quantification limits (S/N = 10) of 15 µg/kg. The recoveries obtained by spiking 10, 20, and 100 µg/kg of salicylic acid in the animal-origin food samples were in the range of 85.2-98.4%. In addition, the monolith was stable enough for 550 extraction cycles with the precision of peak area ≤11.6%.

[Determination of glycidyl methacrylate in the air of workplace captured adsorbent tube by gas chromatography].

Objective: To develop a new solid sorbent tube for capturing glycidyl methacrylate (GMA) in workplace air, and establish a complete set of method. Methods: GMA in workplace air was captured by the new solid sorbent tube filled with carbon aerogel adsorbent, desorbed with solution of 50% (V/V) dimethylformamide-carbon disulfide, separated through capillary chromatographic column, and then analyzed by gas chromatography-flame ionization detector. Results: The linear range of GMA was 0.38-604.80 mg/L, and the related coefficient was 0.999 82. The within-run and the between-run precision were 1.11%-2.80% and 2.53%-4.84% respectively. The average desorption efficiency was 93.20%-94.97%. The minimum quantification concentration and The minimum quantification concentration were 0.02 and 0.07 mg/m(3) respectively (3.00 L sample) . Samples could be stored for at least 8 days at room temperature. Conclusion: The newly developed solid sorbent tube and its complete set of gas chromatography method is simple, and has high sensitivity and precision, so it can be used for sampling and quantitative detection of GMA in workplace air.

Fundamental study of the separation of homopolymers from block copolymers by liquid chromatography with preloaded adsorption promoting barriers.

A fundamental study of the separation of homopolymers from polystyrene-block-polymethylmethacrylate (PS-b-PMMA) by liquid chromatography with preloaded discrete and continuous adsorption promoting barriers was performed. The impact of barrier composition on the separation of block copolymers (BCP) was studied by a dual detection (ultraviolet (UV) and evaporated light scattering (ELSD) detectors) system that enabled monitoring both barrier composition and BCP separation simultaneously. The separation of homopolymers from BCP by preloaded discrete adsorption promoting barriers was validated via a series of control experiments by blending known amounts of homopolymers PS or PMMA with PS-b-PMMA, and the resulting chromatograms were free from co-elution of homopolymers and BCP. Quantitation of homopolymers and BCP by ELSD was also demonstrated. The influence of BCP chemical composition on the separation by preloaded discrete adsorption promoting barriers was investigated. Results showed a PS-b-PMMA having 90wt% PMMA co-eluted with homopolymer PMMA, whereas PS-b-PMMA samples having lower amounts of PMMA block could be separated from homopolymer PMMA, successfully. Attempts at using a preloaded solvent gradient for separating homopolymers from block copolymers were unsuccessful. UV detection of the solvent gradient revealed significant deviation in solvent composition compared to the nominally loaded gradient. This deviation was due to the interaction of strong desorption solvent with column stationary phase. As such, the barrier composition in the preloaded gradient method was not as expected. Therefore, one can obtain undesired separation results by preloaded solvent gradients.

Monochlorinated calocerins A-D and 9-oxostrobilurin derivatives from the basidiomycete Favolaschia calocera.

Eight previously undescribed compounds were isolated and characterised from the supernatant and mycelium of a culture of the basidiomycete Favolaschia calocera originating from Kakamega equatorial rainforest in Kenya. These were: 9- oxostrobilurins A, G, K and I and the four monochlorinated calocerins A, B, C and D. The calocerins extend our knowledge of halogenated compounds obtained from natural sources. Four further known compounds were also identified: strobilurin G, favolon, pterulinic acid and 2,3 -dihydro-1-benzoxepin derivative. The four oxostrobilurins exhibited prominent antifungal and cytotoxic activities while the four calocerins only showed cytotoxic activity.

Simultaneous Determination of Seven Kinds of Fungicides in Citrus Fruits by Gas Chromatograghy/Mass Spectrometry.

A simple and accurate procedure was developed for the determination of seven fungicides, azoxystrobin (AZO), diphenyl (DP), fludioxonil (FLUDI), imazalil (IMZ), o-phenylphenol (OPP), pyrimethanil (PYRI) and thiabendazole (TBZ), in citrus fruits. The citrus fruit sample was extracted with acetonitrile and cleaned up with a graphite carbon/aminopropyl silanized silica gel solid-phase extraction cartridge using acetonitrile-toluene (3 : 1, v/v) as the eluent. Triphenylene was used as an internal standard (I.S.) at the concentration of 0.5 µg/mL. The sample solution was subjected to GC-MS utilizing the matrix-matched standard solution method. The recoveries of AZO, FLUDI, IMZ, OPP, PYRI and TBZ spiked in domestic citrus fruits (Satsuma mandarin) at the level of 0.01-10.0 µg/g were 72.8-104% and the limits of quantification were 0.01 µg/g. The recoveries of DP spiked in domestic citrus fruits at the level of 0.01-70.0 µg/g were 70.8-80.4% and the limit of quantification was 0.01 µg/g. The proposed method was applied to the determination of fungicides in citrus fruits purchased in various markets.

Assessment of strobilurin fungicides' content in soya-based drinks by liquid micro-extraction and liquid chromatography with tandem mass spectrometry.

Seven strobilurin fungicides were pre-concentrated from soya-based drinks using dispersive liquid-liquid micro-extraction (DLLME) with a prior protein precipitation step in acid medium. The enriched phase was analysed by liquid chromatography (LC) with dual detection, using diode array detection (DAD) and electrospray-ion trap tandem mass spectrometry (ESI-IT-MS/MS). After selecting 1-undecanol and methanol as the extractant and disperser solvents, respectively, for DLLME, the Taguchi experimental method, an orthogonal array design, was applied to select the optimal solvent volumes and salt concentration in the aqueous phase. The matrix effect was evaluated and quantification was carried out using external aqueous calibration for DAD and matrix-matched calibration method for MS/MS. Detection limits in the 4-130 and 0.8-4.5 ng g(-1) ranges were obtained for DAD and MS/MS, respectively. The DLLME-LC-DAD-MS method was applied to the analysis of 10 different samples, none of which was found to contain residues of the studied fungicides.

Multidetector thermal field-flow fractionation as a unique tool for the tacticity-based separation of poly(methyl methacrylate)-polystyrene block copolymer micelles.

Poly(methyl methacrylate)-polystyrene (PMMA-PS) micelles with isotactic and syndiotactic coronas are prepared in acetonitrile and subjected to thermal field-flow fractionation (ThFFF) analysis at various conditions of increasing temperature gradients. It is shown for the first time that multidetector ThFFF provides comprehensive information on important micelle characteristics such as size (Dh), shape (Rg/Rh), aggregation number (Z), thermal diffusion (DT) and Soret coefficients (ST) as a function of temperature from a single injection. Moreover, it is found that micelles exhibit a unique decreasing trend in DT as a function of temperature which is independent of the tacticity of the corona and the micelle preparation method used. It is also demonstrated that ThFFF can monitor micelle to vesicle transitions as a function of temperature. In addition to ThFFF, it is found from DLS analysis that the tacticity of the corona influences the critical micelle concentration and the magnitude to which micelles expand/contract with temperature. The tacticity does not, however, influence the critical micelle temperature. Furthermore, the separation of micelles based on the tacticity of the corona highlight the unique capabilities of ThFFF.

Controllable Assembly and Separation of Colloidal Nanoparticles through a One-Tube Synthesis Based on Density Gradient Centrifugation.

Self-assembly of gold nanoparticles into one-dimensional (1D) nanostructures with finite primary units was achieved by introducing a thin salt (NaCl) solution layer into density gradient before centrifugation. The electrostatic interactions between Au nanoparticles would be affected and cause 1D assembly upon passing through the salt layer. A negatively charged polymer such as poly(acrylic acid) was used as an encapsulation/stabilization layer to help the formation of 1D Au assemblies, which were subsequently sorted according to unit numbers at succeeding separation zones. A centrifugal field was introduced as the external field to overcome the random Brownian motion of NPs and benefit the assembly effect. Such a facile "one-tube synthesis" approach couples assembly and separation in one centrifuge tube by centrifuging once. The method can be tuned by changing the concentration of interference salt layer, encapsulation layer, and centrifugation rate. Furthermore, positively charged fluorescent polymers such as perylenediimide-poly(N,N-diethylaminoethyl methacrylate) could encapsulate the assemblies to give tunable fluorescence properties.

Simultaneous determination of tebuconazole, trifloxystrobin, and its metabolite trifloxystrobin acid residues in gherkin under field conditions.

A rapid, simple, and selective analytical method for the simultaneous determination of tebuconazole, trifloxystrobin, and its metabolite trifloxystrobin acid residues in gherkin and soil was developed and validated by gas chromatography coupled with mass spectrometry. The samples were extracted with acetonitrile and cleaned up by dispersive solid-phase extraction with primary secondary amine sorbent. The limit of quantification of the method was 0.05 mg/kg for all three compounds. The method was validated using blank samples spiked at three levels and recoveries ranged from 83.5 to 103.8% with a relative standard deviation of 1.2 to 4.8%. The developed method was validated and applied for the analysis of a degradation study sample. The residues of trifloxystrobin and tebuconazole were found to dissipate following first-order kinetics with half-life ranging between 3.31-3.38 and 3.0-3.04 days, respectively, for two different dosages. Pesticide residues were below the European Union maximum residue level after seven days for trifloxystrobin (0.2 mg/kg) and ten days for tebuconazole (0.05 mg/kg), which suggested the use of this fungicide mixture to be safe to humans. These results can be utilized in formulating the spray schedule and safety evaluation on trifloxystrobin and tebuconazole in gherkin crop.

Encapsulation of porcine pancreatic islets within an immunoprotective capsule comprising methacrylated glycol chitosan and alginate.

Encapsulation of cells in biocompatible polymer matrices represents a powerful tool for cell-based therapies and therapeutic delivery systems. This technology has successfully been used to deliver pancreatic islets to humans for the treatment of Type 1 diabetes. However, the clinical impact of this technology may be improved by reducing the inflammatory response brought on after implantation of capsules in vivo. Within this study a biocompatible polymeric delivery system combining alginate and photo-crosslinked methacrylated glycol chitosan (MGC) was developed. This approach involved encapsulating cells in calcium-alginate beads, coating with MGC and photo-polymerizing using UVA in the presence of photo-initiator (VA-086), resulting in the formation of capsules ∼600 µm in size. Crosslinking of the MGC outer wall allowed control over capsule swelling and improved the capsules overall properties. Capsule characterization demonstrated the stabilizing influence of polymerization and fluorescence imaging showed that the distribution of glycol chitosan is dependent on molecular weight. Good islet viability and insulin release was demonstrated in vitro over the course of a month, and in vivo transplantation of the capsules demonstrated good biocompatibility, particularly when compared with standard alginate/poly-l-ornithine/alginate capsules.

Sensitive monoclonal antibody-based immunoassays for kresoxim-methyl analysis in QuEChERS-based food extracts.

Kresoxim-methyl is nowadays widely used to combat a diversity of common diseases affecting high-value crops. In this article, we report the development and characterization of two novel immunoassays for the analysis of this pioneer strobilurin fungicide, and for the first time, a validation study with food samples was performed. A direct and an indirect competitive immunoassay based on a new anti-kresoxim-methyl monoclonal antibody were developed for sensitive and specific chemical analysis. Optimized assays showed limits of detection of 0.1 µg/L. Fruit and vegetable samples were extracted with acetonitrile by the QuEChERS procedure and analyzed by the developed immunoassays after a simple dilution in buffer, affording limits of quantification below US and European maximum residue limits. Immunochemical results of samples from kresoxim-methyl-sprayed strawberry fields demonstrated good statistical agreement with gas chromatography coupled to mass spectrometry as reference technique.

Simultaneous detection and degradation patterns of kresoxim-methyl and trifloxystrobin residues in citrus fruits by HPLC combined with QuEChERS.

This study aimed to investigate the residues, kinetics and dissipation patterns of kresoxim-methyl, (E)-methoxyimino[α-(o-tolyloxy)-o-tolyl]acetate, and trifloxystrobin, methyl(E)-methoxyimino-{(E)-α[1-(α,α,α-trifluoro-m-tolyl)ethylideneaminooxy]-o-tolyl}acetate". A simple and sensitive liquid chromatography-ultraviolet detection (LC-UV) method combined with the 'Quick Easy Cheap Effective Rugged and Safe' (QuEChERS) protocol was developed to quantify the levels of kresoxim-methyl and trifloxystrobin residues in citrus. More than 97% of the kresoxim-methyl and trifloxystrobin deposists gradually dissipated from the citrus peels within 15 days. The half-lives of kresoxim-methyl and trifloxystrobin in the peels were in the ranges of 2.63-2.66 d and 3.12-3.15 d, respectively, and the pattern of decline in the peels followed first-order kinetics. The kresoxim-methyl and trifloxystrobin residues in the pulp dissipated below the detectable level of 0.01 mg kg(-1) after 9 days. Kresoxim-methyl and trifloxystrobin were easily decomposed (T1/2 < 30 d), and the observed dissipation patterns could support the application of these two fungicides in the postharvest storage of citrus fruits.

Convenient solid phase extraction of cephalosporins in milk using a molecularly imprinted polymer.

In this paper, a molecularly imprinted polymer (MIP) for cephalosporin molecules (cephalexin (CFL) and cephapirin (CFP)), was prepared by non covalent molecular imprinting approach and applied to solid phase extraction (SPE). For MIP synthesis, a tributylammonium cefadroxil salt (TBA-CFD) was used as template with methacrylic acid and ethylene glycol dimethacrylate as monomer and cross-linker, respectively, in acetone-methanol 92/8 (v/v) mixture. The selectivity of MIP versus non imprinted polymer (NIP) was confirmed for CFL, CFD and CFP in standard solutions as well as in milk samples. The efficiency of the synthesized MIP was evaluated by means of the application of the proposed MIP-SPE procedure to spiked milk samples previous to the HPLC method for the detection of cephalosporins. The MIP-SPE recoveries were higher than 60% for the three target analytes in spiked milk.

Antiproliferative activity and apoptosis induction of Eucalyptus Citriodora resin and its major bioactive compound in melanoma B16F10 cells.

Antiproliferative activity and apoptosis induction of ethyl acetate of Eucalyptus citriodora resin (EAEER), and its major bioactive compound in melanoma B16F10 cells were investigated. 6-[1-(p-Hydroxy-phenyl)ethyl]-7-O-methyl aromadendrin (HEMA), a flavanol derivative, was isolated from EAEER and identified on the basis of its mass and NMR spectra. The results from MTT assay showed high antiproliferative effects of EAEER and HEMA on B16F10 cells. Moreover, EAEER- and HEMA-induced cell apoptosis was association with the decrease in the mitochondrial transmembrane potentials (Δψ(m)), increase in Bax/Bcl-2 ratio, and activation of caspase-3. Cells treated with EAEER and HEMA generated intracellular reactive oxygen species (ROS) and nitric oxide (NO), indicating that ROS and RNS play important roles in the induction of apoptosis in B16F10 cells. Taken together, EAEER and its major bioactive compound, HEMA, inhibited the proliferation of B16F10 cells via apoptosis and may be a potential antimelanoma agent.

Synthesis of poly (2-hydroxyethyl methacrylate) (PHEMA) based nanoparticles for biomedical and pharmaceutical applications.

The performance of polymeric nanomaterials relies greatly upon their properties which are intimately related to the methods of fabrication of the materials. Among various synthetic polymers, the polymers of 2-hydroxyetyhyl methacrylate (PHEMA) maintain a prime position in biomedical field due to their useful physicochemical properties and suitability for controlled drug delivery applications. Here we focus on three methods of preparation of PHEMA nanoparticles, by suspension polymerization, emulsion polymerization and dispersion polymerization without the use of any surfactants.

Determination of famoxadone, fenamidone, fenhexamid and iprodione residues in greenhouse tomatoes.

BACKGROUND: Greenhouse tomato production is intended exclusively for fresh consumption. Typical greenhouse conditions provide a conducive environment for the development of different fungi, principally late blight and grey mould, that can destroy plants and fruits. For this reason, different fungicides with different sites of action are used in integrated pest management strategies. Famoxadone, fenamidone, fenhexamid and iprodione (fig. 1) are fungicides of difference classes with different actions that could be used to control tomato pests. RESULTS: The QuEChERS method showed good recoveries, and the analytical method allowed good separation of the fungicides selected. Good results were obtained in terms of repeatability and intermediate precision, with a coefficient of variation of < 9.8%. The limits of determination and quantification of the method were far below the maximum residual levels (MRLs) set by the EU for these fungicides in tomatoes. The analysis of fungicide residues showed that cv. Shiren accounted for higher residue levels than cv. Caramba. The dissipation curves were similar in the two cultivars, indicating that the decrease in pesticides was not related to the tomato type. CONCLUSIONS: Care should be taken when using pesticides in greenhouse conditions, because degradation mainly affects fruit growth. The size of the tomato, in particular its surface/weight ratio, is very important for defining pesticide residues. All fungicides used showed residue levels below the MRLs at the preharvest interval.