An efficient method was developed for the simultaneous determination of 10 industrial dyes (basic orange 2, basic orange 21, basic orange 22, acid orange II, auramine, basic rhodamine B and Sudan I-IV) in the foodstuffs using high-performance liquid chromatography coupled with diode array detector. Samples were extracted with acetonitrile and cleaned up on a solid phase extraction cartridge using HLB. The chromatographic separation was achieved on a C18 column using a mobile phase consisting of methanol and 10 mmol/L ammonium acetate with 0.1% formic acid by gradient elution. Good linearity (r ≥ 0.9993) was observed between 0.050 and 5.0 μg/mL. The limits of detection were in the range of 0.007-0.01 mg/kg, high recoveries (80.6-104%) and good reproducibility (1.1-5.7%) were obtained. Such method is simple, feasible and accurate, which can be applied to the quantification of 10 dyes in food samples.

A comprehensive method was developed for the simultaneous trace analysis of ten hormone antagonist pharmaceuticals (raloxifene, exemestane, letrozole, anastrozole, mifepristone, finastride, tamoxifen, N-desmethyltamoxifen, clomiphene, and toremifene) in municipal sewage and hospital wastewater samples. The target compounds were firstly extracted using an Oasis HLB cartridge, followed by purification by an aminopropyl cartridge, and were then analyzed by liquid chromatography electrospray ionization tandem mass spectrometry in positive ion mode. The recoveries for the analytes based on internal standard calibration in different test matrices ranged from 67.6 to 118.6% (with the exception of mifepristone in clinical wastewater samples), with relative standard deviations less than 20%. The method quantification limits of the ten pharmaceuticals were in the range 0.10-2.0 ng/L. Excluding exemestane and N-desmethyltamoxifen, eight drugs were detected at 0.20-195.0 ng/L in hospital wastewater and municipal wastewater samples from Beijing.

Tamoxifen and letrozole are two of the most effective pharmaceuticals mainly used in hormonal dependent breast cancer therapy. A trace analytical method using ultra performance liquid chromatography/tandem mass spectrometry (UPLC-MS/MS) was developed to simultaneously detect these two drugs in both influent and effluent of municipal sewage treatment plant. Sewage samples were passed through an Oasis HLB cartridge, then an amino solid phase extraction cartridge was connected with Oasis HLB cartridge. Target compounds was firstly eluted with 6 mL methanol and then 3 mL methanol was used to elute the amino solid phase extraction cartridge, collected and pooled the elutants. After concentration, target compounds were separated on a BEH C-18 column using a gradient elution profile with a mobile phase consisting of 0.1% formic acid aqueous solution and acetonitrile and detected by an electro spray ionization tandem mass spectrometry with multiple reactions monitoring(MRM). Satisfactory linearity(R-2 > 0.997) was obtained over the range of 1.0 - 100 mu g/L and 0.1 - 100 mu g/L for tamoxifen and letrozole, respectively, with limits of quantification (LOQ) of 1.0 and 0.1 ng/L. Mean recoveries of two target compounds(spiked in sewage samples at three concentration levels) ranged from 68.8% to 103.0%, with relative standard deviations(RSD) less than 15%. This method can be applied for the analysis of target drugs sewage samples.

Febrifugine is an alkaloid isolated from Dichroa febrifuga as the active component against Plasmodium falciparum. Adverse side effects have precluded febrifugine as a potential clinical drug. As part of an ongoing malaria chemotherapy project, novel febrifugine analogues were designed and synthesized. Lower toxicity of these newly designed compounds was achieved by reducing or eliminating the tendency to form chemically reactive and toxic intermediates. New compounds possess excellent in vivo antimalarial activity and most of them become less toxic than the natural product febrifugine. Some of the compounds possess a therapeutic index over ten times superior to that of febrifugine and the commonly used antimalarial drug chloroquine. These compounds, as well as the underlying design rationale, may find usefulness in the discovery and development of new antimalarial drugs.

The experiments of the ferrite warm deformation of ultra-low carbon (ULC) Ti-IF steel were carried out on a hot simulator and the influences of deformation temperature, strain, and strain rate on the flow stress were analyzed. New flow stress models suitable to ferrite warm forming of Ti-IF steel were given on the basis of analyzing the influence of deformation technology parameters on the flow stress.

Elucidation of the molecular forces governing small molecule-RNA binding is paramount to the progress of rational design strategies. The extensive characterization of the aminoglycoside-16S rRNA A-site interaction has deepened our understanding of how aminoglycosides bind to their target and exert their antimicrobial effects. However, to date no other RNA binding compounds have undergone such rigorous evaluation, and in general the origins of small molecule-RNA binding remain a mystery. We recently reported the identification of small molecules, dimers of 2-deoxystreptamine, which are able to bind selectively to RNA tetraloops and octaloops, respectively [Thomas, Liu, and Hergenrother (2005) J. Am. Chem. Soc. 127, 12434-12435]. Described herein is the biochemical and biophysical characterization of the RNA binding properties of the most selective compound, B-12, as well as closely related analogues. These studies further substantiate that B-12 is indeed selective for RNA octaloop sequences and indicate that the origin of this selectivity may lie in B-12's unusual binding mode, in which entropic factors are major contributors to the overall binding energy. In fact, isothermal titration calorimetry (ITC) experiments indicate that the binding of B-12 and most of its analogues is associated with a strong entropic contribution to the total binding energy. This is in stark contrast to the aminoglycosides, for which favorable enthalpy typically provides the driving force for binding. These studies are the first to examine small molecule-RNA hairpin loop binding in detail and are a necessary step toward the design of compounds that are specific binders for a given RNA sequence.

The targeting of one mRNA in the transcriptome requires small molecules that bind with substantial affinity and specificity. As such, compounds with specificity for individual RNA secondary structural motifs could be useful for targeting RNA. Described herein is the synthesis of a combinatorial library of 105 dimers of deoxystreptamine and the subsequent identification of compounds with specificity for specific RNA hairpin loop sizes, including tetraloops and octaloops. Such compounds will be useful for the perturbation of RNA function in vivo.

RNA is known to have multiple roles in critical cellular functions. Thus, there is great potential for RNA-binding small molecules as both therapeutic agents and cellular probes. Unfortunately, the multiple secondary structures that RNA can adopt have caused difficulty in the development of a general paradigm for RNA-small molecule binding. In particular, the standard RNA-binding compounds such as aminoglycosides do not generally bind RNA hairpin loops, a widespread and vitally important secondary structural motif. In this manuscript we report that dimers of deoxystreptamine bind to RNA hairpin loops with affinities rivaling that of RNA-aminoglycoside interactions.

Nat. Struct. Biol. 10, 781–788 (2003). Two mistakes are found in the final version of this manuscript. The first is on page 784 (second column, line 19 from the bottom); the correct sentence should read: “... in which the base U33 forms hydrogen bonds with the main chain amide and carbonyl groups ofGly263.

ABSTRACT An expedient synthesis of neutral [1,2,4]triazolo[3,2-d][1,5]-benzoxazepines 6a–e and their chalcogen analogues 6f–i was accomplished via cycloaddition of the heterocumulene cations (3a,b), generated sequentially by action of chroman-4-one as well as thiochroman-4-one ethoxy carbonylhydrazones (1a,b) with t-BuOCl and SbCl5, to the triple bond of nitriles and concurring ring enlargement and hydrolytic removal of the N(1)-ethoxycarbonyl group. The oily final products were characterized as their picrates.

α-Benzoylhemithioacetal (1) reacted with alkylamines under mild conditions to give 2-alkylamino-2-thiomethyl acetophenones (3) in good yields.

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The title compound 4, i.e. 9-chloro-4,5-dihydro-2-ethyl-1-(2,4,6-trichlorophenyl)-1H-1,2,4-triazolo[3,2-d]- [1,5]benzoxazepinium hexachloroantimonate, is a novel 6-7-5 tricyclic heterocycle. C18H14Cl4N3O . SbCl6, M = 764.61, P2(1)/c(#14), a = 13.457(4), b = 11.583(2), c = 18.992(3) Angstrom; alpha = 90, beta = 110.11(1)degrees, Z = 4, V = 2780(1) Angstrom(3), D-c = 1.827 g/cc, mu (MoK alpha) = 19.69 cm(-1), F(000) = 1488.00, T = 293 K, R-int = 0.055 for 3094 independent reflections with I>3.00 sigma(I). The five-membered heterocyclic ring is nearly planar, with the trichlorophenyl ring at N(2) almost perpendicular to it. However, the seven-membered ring is not planar, but adopts a twist-boat conformation.

Ethyl (1,1,1-trifluoro-2-propylidene)carbazate is converted with tert-butyl hypochlorite to the 2-chloro-1,1,1-trifluoro-2-propyl azo compound 2, which reacts with antimony pentachloride to produce the trifluoromethylated 1-aza-2-azoniaallene salt 3 as a highly reactive intermediate. The cation 3 is employed as a CF3-containing synthon for the preparation of the 5-trifluoromethylated 1H-1,2,4-triazolium picrates 6a-e.

Hydrazones of trifluoromethyl ketones I are converted with tert-butyl hypochlorite to 1-chloro-1-(trifluoromethyl)azo compounds 2, which at -10 degrees C react with antimony pentachloride to produce the trifluoromethylated 1-aza-2-azoniaallene salts 3 as reactive intermediates. The cations 3 are applied as synthetic blocks for the preparation of the 3-trifluoromethylated 1,2,4-triazolium heterocycles 5a-k. An X-ray structural analysis was carried out for 5f and the results compete well with the data obtained by AM1 calculation.