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Type III-B rotaxane dendrimers (T3B-RDs) are hyperbranched macromolecules with mechanical bonds on every branching unit. Here we demonstrate the design, synthesis, and characterization of first to third (G1–G3), and up to the fourth (G4) generation (MW > 22,000 Da) of pure organic T3B-RDs and dendrons through the copper-catalyzed alkyne–azide cycloaddition (CuAAC) reaction. By utilizing multiple molecular shuttling of the mechanical bonds within the sphere-like macromolecule, a collective three-dimensional contract-extend molecular motion is demonstrated by diffusion ordered spectroscopy (DOSY) and atomic force microscopy (AFM). The discrete T3B-RDs are further observed and characterized by AFM, dynamic light scattering (DLS), and mass spectrometry (MS). The binding of chlorambucil and pH-triggered switching of the T3B-RDs are also characterized by ¹H-NMR spectroscopy. [ABSTRACT FROM AUTHOR]

Prolonged intake of aristolochic acid (AA) has been shown to be associated with the development of certain renal disorders. Renal tubular atrophy and interstitial fibrosis are the early symptoms of AA nephropathy. The symptoms were observed in rats that were dosed with AA at a dosage of 10 mg/kg/day for 1 month. Apart from the renal tubular atrophy and interstitial fibrosis, AA-DNA adducts were detected in the rat kidney tissue. Differentiated proteins were identified in the kidney tissues from proteomics investigations. The upregulated proteins identified included ornithine aminotransferase, sorbitol dehydrogenase, actin, aspartoacylase, 3-hydroxyisobutyrate dehydrogenase, and peroxiredoxin-1. Downregulated proteins such as ATP synthase subunit β, glutamate dehydrogenase 1, regucalcin, glutamate-cysteine ligase regulatory subunit, dihydropteridine reductase, hydroxyacyl-coenzyme A dehydrogenase, voltage-dependent anion-selective channel protein 1, prohibitin, and adenylate kinase isoenzyme 4 were also identified. Several identified protein markers were found to have biological and medical significance. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

We conducted a 3-month reciprocal transplant of the neogastropod Thais clavigera in cages between a site heavily contaminated with tributyltin and a relatively clean site to compare the sensitivity of its reproductive and physiological responses to accumulation and depuration of butyltins. Transplanting T. clavigera from the relatively clean site to the contaminated site resulted in a higher butyltin tissue concentration, higher relative penis size index (RPSI), as well as lower scope for growth (SFG) and lower Oxygen : Nitrogen (O:N) ratio. Nevertheless, growth and vas deferens sequence index (VDSI) were unaffected. Transplanting T. clavigera from the contaminated site to the relatively clean site resulted in a significant decline in tissue burden of butyltins and an elevation of scope for growth (SFG) and O:N ratio; however, there were no marked changes in growth, RPSI or VDSI. Our results thus indicated that growth is not sensitive enough for use in short-term transplant study, SFG and O:N ratio can be used as sensitive biomarkers of both accumulation and depuration of butyltins, whereas RPSI can be used only as a biomarker of accumulation of butyltins. [ABSTRACT FROM AUTHOR]

Spectrofluorometric titration, electrospray ionization time-of-flight mass spectrometric and UV melting methods were employed to study the binding of chelerythrine and sanguinarine to bulged DNA. The results showed that both alkaloids bind specifically to single pyrimidine (C, T) bulge sites. The ability of sanguinarine to bind to both regular and bulged hairpins was found to be stronger than that of chelerythrine, but the binding selectivity of chelerythrine toward single-base bulges was much larger than that of sanguinarine. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

A method involving solid-phase extraction (SPE) and reversed-phase liquid chromatography–mass spectrometry (LC–MS) has been developed for determination, in groundwater, of nitrobenzoic acids associated with 2,4,6-trinitrotoluene production. Pre-concentration on a co-polymer-based SPE cartridge enabled quantitative extraction of the analytes from water. Investigation of negative ion electrospray and atmospheric-pressure chemical ionization mass spectrometry indicated the sensitivity of APCI was more than twice that of ESI. An 15N-labeled internal standard was used to achieve more accurate quantitation and mass assignment. Recovery was better than 80% when 10 mL water was extracted with the SPE cartridge. Combination of SPE with LC–MS analysis resulted in method detection limits of less than 5 μg L−1. The method has been used for analysis of groundwater samples collected from a site of a former ammunition plant. Contamination with nitrobenzoic acids was determined at μg L−1 levels. [ABSTRACT FROM AUTHOR]

A reversed-phase HPLC method has been developed for determination of twelve intact glucosinolates—glucoiberin, glucocheirolin, progoitrin, sinigrin, epiprogoitrin, glucoraphenin, sinalbin, gluconapin, glucosibarin, glucotropaeolin, glucoerucin, and gluconasturtiin—in ten traditional Chinese plants. The samples were extracted with methanol and the extracts were cleaned on an activated Florisil column. A mobile phase gradient prepared from methanol and 30 mmol L−1 ammonium acetate at pH 5.0 enabled baseline separation of the glucosinolates. Glucosinolate detection was confirmed by quadrupole time-of-flight tandem mass spectrometric analysis in negative-ionization mode. Detection limits ranged from 0.06 to 0.36 μg g−1 when 5 g of dried plant was analyzed. Recoveries of the glucosinolates were better than 85% and precision (relative standard derivation, n = 3) ranged from 5.3 to 14.6%. Analysis of the glucosinolates provided scientific evidence enabling differentiation of three pairs of easily confused plants. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

A reversed-phase LC–MS method with quadrupole-time of flight (QTOF) detection has been developed for the determination of four dinitro-toluenesulfonic acids and two amino-nitro-toluenesulfonic acids in groundwater. The analytes were separated by HPLC with 0.1% (v/v) formic acid as mobile phase modifier compatible with mass spectrometric detection. QTOF-MS analysis with negative ion electrospray ionization afforded good selectivity and sensitivity for analysis of the dinitro- and amino-nitro-toluenesulfonic acids. Structure elucidation and confirmation were accomplished by tandem mass spectrometry. Characteristic ions resulting from the loss of NO, NO2, and SO2 from the [M-H]- ions were detected. An intense fragment ion at m/z 80 representing the [SO3]- ion was detected for all dinitro- and amino-nitro-toluenesulfonic acids. Solid-phase extraction using a co-polymer cartridge was developed for preconcentration of the analytes from water. Good recovery (>85%) was achieved when 0.1% formic acid was added into the water samples before extraction. Method detection limits ranged from 10 to 76 ng L-1 for the targeted compounds when 10 mL water was analyzed. Groundwater samples collected from wells close to a former ammunition plant in Stadtallendorf, Germany, were analyzed for the dinitro- and amino-nitro-toluenesulfonic acids. [ABSTRACT FROM AUTHOR]

A reversed-phase HPLC method was developed for analyzing sinigrin and gluconasturtiin in six vegetable and two Chinese herb samples. A gradient program and mobile phases using methanol and 0.05% trifluoroacetic acid containing 20 mM ammonium acetate allowed sufficient retention and separation of the glucosinolates in the sample extracts. Quadrupole time-of-flight tandem mass spectrometry in negative ion electrospray ionization was used to analyze the fractions collected from the HPLC elution to confirm the identification of the glucosinolates. The levels of sinigrin and gluconasturtiin in the vegetables and Chinese herbs were determined by using an external calibration method. Concentrations of gluconasturtiin in the Chinese herbs were more than 15 times higher than those of sinigrin. Detection limits were 18 nmol g-1 for sinigrin and 4 nmol g-1 for gluconasturtiin when 50 g of fresh vegetable was analyzed. [ABSTRACT FROM AUTHOR]

From the liver of fish Dasyatis akajei, ferritin has been isolated by thermal denaturation and ammonium sulfate fractionation and then further purified by anion exchange chromatography and gel exclusion chromatography. The molecular weight of the liver ferritin of D. akajei (DALF) was measured to be 400 kDa by PAGE. Moreover, SDS-PAGE experimentation indicates that protein shell of DALF consists of the H and L subunits with molecular weight of 18 and 13 kDa, respectively. Using isoelectric focusing with pH ranging from 5.0 to 6.0, the ferritin purified by the PAGE exhibited three bands with different pI values in the gel slab. Diameters of the protein shell and iron core were also investigated by transmission electron microscope and determined to be 10-12 nm and 5-8 nm, respectively. A kinetic study of DALF reveals that the rate of self-regulation of the protein shell rather than the complex surface of the iron core plays an important role in forming a process for iron release with mixed orders. [ABSTRACT FROM AUTHOR]