bluuebunny/crossref_metadata_2025_split huggingface dataset:
Structural studies of 2‐methyl‐7‐substituted pyrazolo[1,5‐a]pyrimidines
Authors: Frizzo Clarissa P. , Martins Marcos A.P. , Marzari Mara R. B. , Campos Patrick T. , Claramunt Rosa M. , García M. Ángeles , Sanz Dionisia , Alkorta Ibon , Elguero José 
Published: August 2010

Abstract
magnified image Six pyrazolo[1,5‐a]pyrimidines bearing a 7‐trifluoromethyl (three compounds), a 7‐trichloromethyl (two compounds), and a 7‐ethoxycarbonyl (one compound) have been structurally characterized. The new X‐ray structures of 2‐methyl‐5‐(p‐bromophenyl)‐7‐trifluoromethylpyrazolo[1,5‐a]pyrimidine (3) and 2‐methyl‐7‐trichloromethylpyrazolo[1,5‐a]pyrimidine (4) are reported. The combined use of GIAO/B3LYP/6‐311++G(d,p) calculations with NMR spectroscopy in solution and in the solid state allows to establish some general rules that can be useful for characterizing related compounds. Compounds 3 and 4 present in the solid‐state interesting intra‐ and intermolecular halogen bonds. J. Heterocyclic Chem., (2010).
Synthesis and anti‐Helicobacter pylori activity of 4‐(coumarin‐3‐yl)thiazol‐2‐ylhydrazone derivatives
Authors: Chimenti Franco , Bizzarri Bruna , Bolasco Adriana , Secci Daniela , Chimenti Paola , Granese Arianna , Carradori Simone , D'Ascenzio Melissa , Scaltrito M. Maddalena , Sisto Francesca 
Published: August 2010

Abstractmagnified image A novel class of coumarin‐thiazole conjugated systems (1‐31) were synthesized by Hantzsch condensation between α‐bromo‐3‐acetyl coumarin and several thiosemicarbazone intermediates. This scaffold was also evaluated for selective antibacterial activity against 20 isolates of H. pylori clinical strains, including four metronidazole resistant ones. J. Heterocyclic Chem., (2010).
An efficient and clean synthesis of indeno[1,2‐b]pyrazolo[4,3‐e] pyridin‐5(1H)‐one derivatives under microwave irradiation in water
Authors: Wang Shuliang , Ma Ning , Zhang Ge , Shi Feng , Jiang Bo , Lu Han , Gao Yuan , Tu Shujiang 
Published: August 2010

Abstractmagnified imageA series of new indeno[1,2‐b]pyrazolo[4,3‐e]pyridin‐5(1H)‐one derivatives were synthesized by three‐component reactions of 1,3‐indandione, 3‐methyl‐1H‐pyrazol‐5‐amine, and aldehyde in water under microwave irradiation without any catalyst. J. Heterocyclic Chem., (2010).
Synthesis of 2,3‐dihydroimidazo[2,1‐b]thiazole derivatives viacyclization of N‐allylimidazoline‐2‐thiones
Authors: Jasiński Marcin , Mlostoń Grzegorz , Heimgartner Heinz 
Published: August 2010

Abstract
magnified image A novel method for the preparation of 2,3‐dihydroimidazo[2,1‐b]thiazole 9 by iodination and subsequent cyclization of the easily available N‐allylimidazoline‐2‐thiones 5, is described. Selected transformations of the iodomethyl derivatives 9, leading to methylidene compounds 10 or the sulfide 11 (Nu = RS), via elimination with a base or via substitution with an enolizable imidazoline‐2‐thione (the term “1,3‐dihydroimidazole‐2‐thione” will be used alternatively), respectively, are presented. J. Heterocyclic Chem., (2010).
Intramolecular cyclization of Mannich reaction for synthesis of pyrimido[2,1‐b]‐1,3,5‐tiadiazines
Authors: El‐Sherief Hassan A. H. , Hozien Zeinab A. , El‐Mahdy Ahmed F. M. , Sarhan Abdelwarth A. O. 
Published: August 2010

Abstract
magnified image Reaction of 6‐aryl‐5‐cyano‐2‐mercapto‐3,4‐dihydropyrimidin‐4‐ones with formaldehyde and primary amines in suitable solvent via a double Mannich reaction gave the corresponding 8‐aryl‐7‐cyano‐3‐N‐substituted‐pyrimido[2,1‐b]‐1,3,5‐thiadiazin‐6‐ones rather than the isomeric products 6‐aryl‐7‐cyano‐3‐N‐substituted‐pyrimido[2,1‐b]‐1,3,5‐thiadiazin‐8‐ones. The cyclization method was found to be the most favored for the formation of the linear products rather than the angular isomers. This was confirmed not only by using spectral analysis and molecular mechanical calculations but also by X‐ray single crystal structure determination. J. Heterocyclic Chem., (2010).
First synthesis of 2‐(2,4,4‐trimethyl‐3,4‐dihydro‐2H‐benzo[h]chromen‐2‐yl)‐1‐naphthol and 3‐(2,4,4‐trimethyl‐3,4‐dihydro‐2H‐benzo[g]chromen‐2‐yl)‐2‐naphthol from 1‐ and 2‐naphthol derivatives
Authors: Menezes Jose C. J. M. D. S. , Srinivasan Bikshandarkoil R. , Raghavaiah Pallepogu , Paknikar Shashikumar K. , Kamat Shrivallabh P. 
Published: August 2010

AbstractTwo new structurally isomeric, 2‐(2,4,4‐trimethyl‐3,4‐dihydro‐2H‐benzo[h]chromen‐2‐yl)‐1‐naphthol (1) and 3‐(2,4,4‐trimethyl‐3,4‐dihydro‐2H‐benzo[g]chromen‐2‐yl)‐2‐naphthol (3) have been synthesized from 2‐acetyl‐1‐naphthol and ethyl‐3‐hydroxy‐2‐naphthoate, respectively, involving Grignard reaction, dehydration of the corresponding tertiary alcohols, and hetero Diels–Alder dimerization. The two benzochromenes (1 and 3) have been fully characterized by IR, NMR, and HRESIMS data. Their structures are further supported by crystallography of their corresponding acetates (2 and 4). J. Heterocyclic Chem., (2011).
Solvent‐free microwave extraction coupled with headspace single‐drop microextraction of essential oils from flower of Eugenia caryophyllata Thunb.
Authors: Jiang Chunzhu , Sun Ying , Zhu Xiaonan , Gao Yan , Wang Liying , Wang Jian , Wu Liwei , Song Daqian 
Published: August 2010

AbstractSolvent‐free microwave extraction coupled with headspace single‐drop microextraction was developed for extracting the essential oils from Eugenia caryophyllata Thunb. Carbonyl iron powders were mixed with the sample to extract essential oils from the dried plant materials and single‐drop solvent was used to simultaneously extract essential oils from the headspace. The single‐drop of decane was suspended from the tip of a microsyringe and exposed to the headspace above the sample. After the extraction was finished, the single‐drop was injected into gas chromatographic system and analyzed by GC‐MS. The effects of the experimental parameters, including microwave power, microwave irradiation time, the ratio of carbonyl iron powder to sample, extraction solvent, single‐drop volume and extraction time, were investigated. Sixteen compounds in the essential oils of E. caryophyllata T. were obtained and identified. The constituents of essential oils obtained by hydro‐distillation and solvent‐free microwave extraction–headspace single‐drop microextraction were not obviously different. Compared with hydro‐distillation, the proposed method required shorter extraction time and less amount of the sample.
Sorbent‐packed needle microextraction trap for benzene, toluene, ethylbenzene, and xylenes determination in aqueous samples
Authors: De Crom Jorn , Claeys Sara , Godayol Anna , Alonso Monica , Anticó Enriqueta , Sanchez Juan M. 
Published: August 2010

AbstractA needle trap (NT) device filled with Carbopack X as a sorbent material is evaluated for the static headspace analysis of benzene, toluene, ethylbenzene, and xylene (BTEX) compounds in aqueous samples. Injection parameters used with the NT device (e.g. volume of carrier gas and time to open the split valve) are evaluated to determine the mechanism involved during the desorption and transferring of the target compounds into the GC column. Furthermore, different parameters affecting the adsorption capacity of the sorbent are studied (e.g. sampling time and temperature, headspace/sample volume ratio, salting‐out, and stirring). The evaluation of the method with aqueous samples shows that repeatability and recoveries with the NT device are equivalent to those obtained using solid‐phase microextraction with a carboxen/PDMS (CAR/PDMS) coating. LODs obtained with flame ionization detection are in the range of 10–25 μg/L, and in the range of hundredths of μg/L with MS detection. The method developed is satisfactorily applied to the analysis of aqueous samples obtained from wastewater treatment plants.
Rapid and refined separation of human IgG2 disulfide isomers using superficially porous particles
Authors: Wang Qian , Lacher Nathan A. , Muralidhara Bilikallahalli K. , Schlittler Michael R. , Aykent Serdar , Demarest Charles W. 
Published: August 2010

AbstractA rapid reversed‐phase HPLC separation of recombinant human immunoglobulin gamma 2 (IgG2) disulfide isomers using columns packed with superficially porous particles is reported. Under optimal conditions, a separation of monoclonal IgG2 disulfide isomers was achieved in 10 min using a Poroshell™ 300SB‐C8 column via a combination of high column temperature (85°C), mobile phases with high eluotropic strength (e.g. isopropanol) and high flow rate (1.5 mL/min). Thermodynamic stability analyses of chromatographically enriched IgG2 disulfide isomers revealed differences in their individual denaturation temperatures, which correlate with the observed temperature‐dependent refinement of peak profiles by reversed‐phase HPLC. This reversed‐phase HPLC method in conjunction with other orthogonal analytical techniques (e.g. capillary gel electrophoresis, peptide mapping, ion exchange chromatography, etc.) is being used to characterize disulfide isomers in the development of therapeutic IgG2 antibodies.
Infrared‐assisted extraction coupled with high‐performance liquid chromatography for simultaneous determination of eight active compounds in Radix Salviae miltiorrhizae
Authors: Chen Yile , Duan Gengli , Xie Meifen , Chen Bin , Li Yan 
Published: August 2010

AbstractIn this study, a novel infrared‐assisted extraction (IRAE) method, in which infrared radiation was employed to extract the active compounds from plant, was developed and coupled with HPLC for simultaneous determination of four phenolic acids and four diterpenoids in Radix Salviae miltiorrhizae (Chinese name Danshen). The extraction conditions of IRAE were optimized and the optimal conditions were as follows: extraction time of 15 min; extraction solvent of 70% v/v methanol in water solution, and solid/liquid ratio of 0.1:15 (g/mL). Chromatography was performed on a 200 mm×4.6 mm id, 5‐μm particle size, C18 column. Good linearity (r>0.9994) was observed over the concentration ranges investigated, and intra‐day and inter‐day precision were high. Recoveries of the eight compounds were from 96.90 to 104.30% and RSD was below 2.5%. By using this novel IRAE method, with a shorter extraction time, the determined amounts of the eight active components in Danshen were comparable with or even higher than those extracted with conventional heat‐reflux extraction and ultrasound‐assisted extraction methods and microwave‐assisted extraction. The developed IRAE method is simple, low‐cost and efficient, offering a great promise for quick determination of active compounds in natural plants.
Development of the fingerprint for the quality of Radix Linderae through ultra‐pressure liquid chromatography‐photodiode array detection/electrospray ionization mass spectrometry
Authors: Wu Yong‐jiang , Zheng Yun‐liang , Luan Lian‐jun , Liu Xue‐song , Han Zheng , Ren Yi‐ping , Gan Li‐she , Zhou Chang‐xin 
Published: August 2010

AbstractAn ultra‐pressure LC (UPLC) method has been developed and validated for the quality evaluation of a traditional Chinese medicine (Radix Linderae) by chemical fingerprint analysis with chromatograms collected at two wavelengths (260 and 320 nm). Eleven characteristic peaks in the fingerprints were identified by comparing their retention times, UV spectra and ESI‐MS/MS data with those of the reference substances or the data in the literatures. Both correlation coefficient of similarities in chromatograms and relative peak areas of common peaks were calculated for quality expression of the Radix Linderae samples collected from different areas in China. The results showed high variation of relative peak area and correlation coefficients among the samples collected from various habitats, which indicated that the quality consistency of Radix Linderae is still a problem worthy of serious concern.
Rapid analysis of procyanidins and anthocyanins in plasma by microelution SPE and ultra‐HPLC
Authors: Martí Maria‐Pilar , Pantaleón Albert , Rozek Aleksandra , Soler Aranzazu , Valls Josep , Macià Alba , Romero Maria‐Paz , Motilva Maria‐José 
Published: August 2010

AbstractIn the analysis of biological samples, such as plasma or serum, the quantity of sample available is a critical parameter in most cases. A good approach is the use of the microelution SPE (μSPE) plates as sample pre‐treatment technique in which the loaded sample volume is low. An off‐line μSPE and ultra‐performance LC‐ESI‐MS/MS (UPLC‐ESI‐MS/MS) method was developed and validated to determine procyanidins and anthocyanins in spiked plasma samples. The sample pre‐treatment μSPE allowed the simultaneous determination of procyanidins and anthocyanins from plasma by using a small sample volume (350 μL) and without an evaporation step previous to the chromatographic analysis. Moreover, the use of UPLC technique allowed to determine the studied compounds at low concentration levels in a short analysis time (12.5 min approximately). Then, the developed method was applied to determine the studied compounds, procyanidins and anthocyanins, and their metabolites in rat plasma samples. Previously, the rats had consumed 5000 mg/kg of a grape pomace extract and the plasma was extracted 4 h after administration. The procyanidins catechin and epicatechin glucuronide, methyl catechin and epicatechin glucuronide, and methyl catechin and epicatechin sulphate were detected at μM concentration level, and the parent anthocyanins at nM.
High‐performance liquid chromatographic determination and pharmacokinetic study of cefepime in goat plasma and milk after pre‐column derivatization with Hg(I)
Authors: El‐Rabbat Nawal A. , Abdel‐Wadood Hanaa M. , Sayed Mohammed , Mousa Heba S. 
Published: August 2010

AbstractA highly sensitive and selective HPLC method with UV detection was developed for the determination of cefepime in goat plasma and milk. The proposed method was based on the complexation of cefepime with Hg(I) ions that imparts the high selectivity of the proposed method with enhancement of the sensitivity which enabled the analysis of cefepime in complex matrices such as plasma and milk. Detection was performed at 263 nm, using cefuroxime sodium as an internal standard. Chromatographic separation of cefepime and the internal standard was achieved with Aqua RP‐C18column using methanol/triethylamine‐acetate buffer, pH 3.5 (18:82, v/v) as mobile phase at a flow rate of 1 mL/min. Linear detector responses were observed spanning the range of 1.3–20 μg/mL. The LOD for standard cefepime was 0.43 μg/mL, whereas the LOD for cefepime in goat plasma was 0.84 μg/mL and the corresponding value in goat milk was 1.1 μg/mL. No interference from endogenous substances in plasma and milk was observed. The developed HPLC method has been successfully applied for the pharmacokinetic study of cefepime in goat plasma and milk, for the first time, after a single intramuscular injection of 50 mg cefepime/kg body weight.
Solvent gradient elution for comprehensive separation of constituents with wide range of polarity in Apocynum venetum leaves by high‐speed counter‐current chromatography
Authors: Zhang Yuchi , Liu Chunming , Zhang Zhengkun , Qi Yanjuan , Wu Guimei , Li Sainan 
Published: August 2010

AbstractA novel gradient elution was efficiently utilized for the separation of the chemical components with a wide range of polarity from the mixed extract of the Chinese medicinal herb Apocynum venetum or mixed standards by high‐speed counter‐current chromatography. Three sets of solvent systems, n‐hexane–ethyl acetate–methanol–water (1.5:3.5:2:4.5 v/v/v/v), ethyl acetate–methanol–water (5:2:5 v/v/v) and n‐butanol–methanol–water (5:1:5 v/v/v) were used for the one‐step elution. The separation was initiated by filling the column with the lower phase of n‐hexane–ethyl acetate–methanol–water (1.5:3.5:2:4.5 v/v/v/v) as a stationary phase followed by elution with the upper phase of n‐hexane–ethyl acetate–methanol–water (1.5:3.5:2:4.5 v/v/v/v) to separate the hydrophobic compounds (tail to head). Then the mobile phase was switched to the upper phase of ethyl acetate–methanol–water (5:2:5 v/v/v) to elute the moderate hydrophobic compounds, and finally the hydrophilic compounds still retained in the column were fractionated by eluting the column with the upper phase of n‐butanol–methanol–water (5:1:5 v/v/v). A total of 13 compounds including adhyperforin, hyperforin, amentoflavone, biapigenin, quercetin, astragalin, trifolin, isoquercetin, hyperside, acetyled hyperside, rutin, chlorogenic acid and quercetin‐3‐O‐β‐D‐glucosyl‐β‐D‐glucopyranoside were successfully separated via the three sets of solvent systems in one‐step operation for 90 min.
Toward high‐throughput drug screening on a chip‐based parallel affinity separation platform
Authors: Ohlson Sten , Duong‐Thi Minh‐Dao , Bergström Maria , Fex Tomas , Hansson Lennart , Pedersen Lennart , Guazotti Sergio , Isaksson Roland 
Published: August 2010

AbstractHigh‐throughput screening of compound libraries, including the study of fragments, has become one of the cornerstones in modern drug discovery research. During this process hits are defined that may be developed into valuable leads and eventually into possible drug candidates. In this paper, we have demonstrated that parallel zonal weak affinity chromatography in microcolumns on a chip offers a possible screening format for weakly binding ligands toward a protein target. We used albumin as a model system because this transport protein is well established as a binder (both weak and strong) for drug substances. Bovine serum albumin was immobilized on microparticulate diolsilica particles and then packed into a 24‐channel cartridge, which served as the separation platform. Analysis of the obtained chromatograms yielded information about affinity even in the millimolar range. Employing this approach, thousands of substances can be screened in just a day. We feel confident that zonal affinity chromatography will provide a useful technology in the future for performing high‐throughput screening.
Pressurized liquid extraction followed by LC‐ESI/MS for analysis of four chromones in Radix Saposhnikoviae
Authors: Li Wei , Wang Zi , Chen Li , Zhang Jing , Han Likun , Hou Jingang , Zheng Yinan 
Published: August 2010

AbstractAn efficient pressurized liquid extraction (PLE) technique was employed in extracting chromones from the roots of Saposhnikovia divaricata (Radix Saposhnikoviae). Chromones were quantified and analyzed by LC‐ESI/MS. The PLE procedure was optimized, validated and compared with the other conventional extraction techniques. PLE gained the best result due to the highest extraction efficiency within the shortest extraction time. The optimal conditions of PLE were employing 50% ethanol as the extraction solvent at a temperature of 140°C and an extraction pressure of 1500 psi, using one extraction cycle with a static extraction time of 8 min. A good LC separation was achieved using a Hypersil ODS2 column and methanol/water as the mobile phase at a flow rate of 0.8 mL/min. MS coupling with an ESI interface in the positive ion mode was used as the detection technique. This is the first report on combining PLE with LC‐ESI/MS for the extraction and quantification of chromones in Radix Saposhnikoviae. The elaborated PLE method also provided a good alternative for the chromone extraction from other plant substances.
Characterization of stationary phases by a linear solvation energy relationship utilizing supercritical fluid chromatography
Authors: Mitchell Clifford R. , Benz Nancy J. , Zhang Shuhong 
Published: August 2010

AbstractSupercritical fluid chromatography was utilized in combination with the Abraham model of linear solvation energy relationship to characterize 11 different HPLC stationary phases. System constants were determined at one supercritical fluid chromatography condition for each stationary phase. The results indicate that several types of silica columns, including type B silica, type C silica, and fused core silica, are very similar in their retention behavior. Several aromatic stationary phases were characterized and it was found that, in contrast to the other phases studied, all of the aromatic stationary phases had positive contributions from the dispersion/cavity (v) term of the linear solvation energy relationship. Several aliphatic phases were characterized and there were several linear solvation energy relationship constants that differentiated the phases from each other, mainly the polar terms (dipolarity and hydrogen bonding). One stationary phase, a fused core pentafluorophenyl (PFP) phase, had very poor regression quality. The column volume of this phase was lower than the others in the study, which may have had some impact on the results of the regression.
Plasma metabolomics reveals biomarkers of the atherosclerosis
Authors: Chen Xi , Liu Lian , Palacios Gustavo , Gao Jie , Zhang Ning , Li Guang , Lu Juan , Song Ting , Zhang Yingzhi , Lv Haitao 
Published: August 2010

AbstractAtherosclerotic cardiovascular disease remains the leading cause of morbidity and mortality in industrialized societies. The lack of metabolite biomarkers has impeded the clinical diagnosis of atherosclerosis so far. In this study, stable atherosclerosis patients (n=16) and age‐ and sex‐matched non‐atherosclerosis healthy subjects (n=28) were recruited from the local community (Harbin, P. R. China). The plasma was collected from each study subject and was subjected to metabolomics analysis by GC/MS. Pattern recognition analyses (principal components analysis, orthogonal partial least‐squares discriminate analysis, and hierarchical clustering analysis) commonly demonstrated plasma metabolome, which was significantly different from atherosclerotic and non‐atherosclerotic subjects. The development of atherosclerosis‐induced metabolic perturbations of fatty acids, such as palmitate, stearate, and 1‐monolinoleoylglycerol, was confirmed consistent with previous publication, showing that palmitate significantly contributes to atherosclerosis development via targeting apoptosis and inflammation pathways. Altogether, this study demonstrated that the development of atherosclerosis directly perturbed fatty acid metabolism, especially that of palmitate, which was confirmed as a phenotypic biomarker for clinical diagnosis of atherosclerosis.
A reliable isotope dilution method for simultaneous determination of fumonisins B1, B2 and B3 in traditional Chinese medicines by ultra‐high‐performance liquid chromatography‐tandem mass spectrometry
Authors: Han Zheng , Ren Yiping , Liu Xuesong , Luan Lianjun , Wu Yongjiang 
Published: August 2010

AbstractA reliable isotope dilution method for simultaneous determination of fumonisin B1, fumonisin B2 and fumonisin B3 in traditional Chinese medicines by ultra‐high‐performance LC‐MS/MS was developed, and a special focus was placed on the optimization of extraction, cleanup, ultra‐high‐performance LC separation and MS/MS conditions. Homogenized samples were extracted by 50% acetonitrile aqueous solution and purified with MultiSep 211 Fum columns. A linear gradient mobile phase, consisting of water containing 0.2% formic acid and acetonitrile/methanol (50:50 v/v) and an Acquity UPLC HSS T3 column (100 mm×2.1 mm, 1.8 μm) were employed to obtain the best resolution of the analytes for the positive ESI+ analysis. The established method was validated by determining the linearity (R2≥0.9991), sensitivity (LOQ, 0.08–0.16 ng/mL), recovery (88.2–113.3%) and precision (RSD≤12.3%). Finally, the validated method was successfully applied to the determination of fumonisins in different traditional Chinese medicines. Of 35 samples, 18 were contaminated with fumonisins. The mean levels (incidence) of fumonisin B1, fumonisin B1 and fumonisin B1 in positive samples were 8.55 (94.4%), 4.88 (77.8%) and 0.52 μg/kg (33.3%), respectively. Based on the contaminant situations, a possible association between the contamination levels and the selected herbs was clarified in this study.