Fischer's base-triggered formal (3+2) cycloadditions with 3-isothiocyanato oxindoles as acceptor-donor synthons.

Herein, previously unreported Fischer's base reactants serving as useful 2C building blocks in (3+2) cycloaddition reactions to build a library of bispiro[Fischer's base-oxindole] hybrids are described. These structurally intriguing products containing three adjacent quaternary stereocentres were smoothly afforded in up to 82% yield and >20 : 1 dr under catalyst-free conditions. Notably, the present protocol firstly employs 3-isothiocyanato oxindole serving as an acceptor and then as a donor in the formal (3+2) cycloadditions, allowing practical, straightforward access to structurally diverse cycloadducts. This work expands the applicability scope of 3-isothiocyanato oxindoles, which have been limited to behaving as donor/acceptor-based synthons in cycloadditions in previous work.

Up-regulated small-conductance calcium-activated potassium currents contribute to atrial arrhythmogenesis in high-fat feeding mice.

AIMS: Metabolic syndrome (MetS) is associated with arrhythmias and cardiovascular mortality. Arrhythmogenesis in MetS results from atrial structural and electrical remodelling. The small-conductance Ca2+-activated K+ (SK) currents modulate atrial repolarization and may influence atrial arrhythmogenicity. This study investigated the regulation of SK current perturbed by a high-fat diet (HFD) to mimic MetS. METHODS AND RESULTS: Thirty mice were divided into two groups that were fed with normal chow (CTL) and HFD for 4 months. Electrocardiography and echocardiography were used to detect cardiac electrical and structure remodelling. Atrial action potential duration (APD) and calcium transient duration (CaTD) were measured by optical mapping of Langendorff-perfused mice hearts. Atrial fibrillation (AF) inducibility and duration were assessed by burst pacing. Whole-cell patch clamp was performed in primarily isolated atrial myocytes for SK current density. The SK current density is higher in atrial myocytes from HFD than in CTL mice (P ≤ 0.037). The RNA and protein expression of SK channels are increased in HFD mice (P ≤ 0.041 and P ≤ 0.011, respectively). Action potential duration is shortened in HFD compared with CTL (P ≤ 0.015). The shortening of the atrial APD in HFD is reversed by the application of 100 nM apamin (P ≤ 0.043). Compared with CTL, CaTD is greater in HFD atria (P ≤ 0.029). Calcium transient decay (Tau) is significantly higher in HFD than in CTL (P = 0.001). Both APD and CaTD alternans thresholds were higher in HFD (P ≤ 0.043), along with higher inducibility and longer duration of AF in HFD (P ≤ 0.023). CONCLUSION: Up-regulation of apamin-sensitive SK currents plays a partial role in the atrial arrhythmogenicity of HFD mice.

Catalytic asymmetric Michael/cyclization reaction of 3-isothiocyanato thiobutyrolactone: an approach to the construction of a library of bispiro[pyrazolone-thiobutyrolactone] skeletons.

Here, we demonstrate the first example of 3-isothiocyanato thiobutyrolactone serving as a useful building block in the Michael/cyclization reaction with alkylidene pyrazolones for the enantioselective construction of optically active structural bispiro[pyrazolone-thiobutyrolactone] skeletons containing three contiguous stereocenters with two spiroquaternary stereocenters. These products were smoothly afforded in up to 90% yield, >20 : 1 dr and >99% ee with chiral squaramide as the catalyst under mild conditions. Notably, this is also the first example of the merger of a spirocyclic pyrazolone scaffold with a spirocyclic thiobutyrolactone scaffold, potentially useful in medicinal chemistry.

Ring opening and skeletal reconstruction of 3-vinyl benzofuranone-chromone synthons: catalyst-free access to skeletally-diverse 2-pyridone and optically active imidazoline derivatives.

Herein is reported the first example of ring opening and skeletal reconstruction of 3-vinyl benzofuranone-chromones 1 as versatile synthons, which can react with ammonia or primary aliphatic amines as binucleophiles, for the eco-friendly and atom-economical synthesis of diverse and functionalized 2-pyridones 3 with potential biological activity in good to excellent yields (77-93%). When using optically active 1,2-diphenylethylenediamine 2 as the binucleophile, the in situ generated 2-pyridone intermediates are successfully transformed to novel optically active functionalized imidazoline derivatives 4 with high efficiency (up to 87% yield). In particular, this is the first report on the catalyst-free intramolecular cyclization occurring between an amide and a primary aliphatic amine for the construction of imidazoline molecules.

[NIR-SERS Spectra Detection of Cytidine on Nano-Silver Films].

The polyvinyl alcohol (PVA) protected silver glass-like nanostructure (PVA-Ag-GNS) with high surface-enhanced Raman scattering (SERS) activity was prepared and employed to detect the near-infrared surface enhanced Raman scattering (NIR-SERS) spectra of cytidine aqueous solution (10(-2)-10(-8) mol x L(-1)). In the work, the near-infrared laser beam (785 nm) was used as the excitation light source. The experiment results show that high-quality NIR-SERS spectra were obtained in the ranges of 300 to 2 000 cm(-1) and the detection limit of cytidine aqueous solution was down to 10(-7) mol x L(-1). Meanwhile, the PVA-Ag-GNS shows a high enhancement factor (EF) of -10(8). In order to test the optical reproducibility of PVA-Ag-GNS, ten samples of cytidine aqueous solution (10(-2)-10(-5) mol x L(-1)) had been dropped onto the surface of PVA-Ag-GNS respectively. Meanwhile, these samples were measured by the portable Raman spectrometer. As a result, the PVA-Ag-GNS demonstrated good optical reproducibility in the detection of cytidine aqueous solution. In addition, to explain the reason of enhancement effect, the ultraviolet-visible (UV-Vis) extinction spectrum and scanning electron microscope (SEM) of cytidine molecules adsorbed on the surface of PVA-Ag-GNS were measured. There is plasmon resonance band at 800 nm in the UV-Vis extinction Spectrum of the compound system. Therefore, when the near-infrared laser beam (785 nm) was used as excitation light source, the compound system may produce strongly surface plasmon resonance (SPR). According to the SEM of PVA-Ag-GNS, there are much interstitial between the silver nanoparticles. So NIR-SERS is mainly attributed to electromagnetic (EM) fields associated with strong surface plasmon resonance. At last, the geometry optimization and pre-Raman spectrum of cytidine for the ground states were performed with DFT, B3LYP functional and the 6-311G basis set, and the near-infrared laser with wavelength of 785 nm was employed in the pre-Raman spectrum calculation process. The calculation results without imaginary frequency and the results match pretty well with the experimental Raman spectrum. At the same time, the assignations of Raman bands and adsorption behaviors of cytidine molecules on the surface of PVA-Ag-GNS are also discussed. According to our experiment and calculations, cytidine molecules mainly adsorbed on silver nanoparticles via the ribose moiety and amino group may get close to the local electromagnetic field.

[Study of volatile organic compounds of fresh allium species using headspace combined with surface-enhanced Raman scattering].

In order to identify volatile organic compounds of fresh plants at room temperature and avoid sample pretreatment and extractions which can be labor intensive, garlic, Chinese chives and scallion were chopped into pieces. Then some of them were placed in the headspace vial and sealed. The gases were drawn from the vial with a syringe and were injected very slowly into Ag colloids for test using R-3000 portable Raman spectrometer. The spectra of volatile organic compounds of allium species, fresh garlic, Chinese chive and shallot plants were successfully.recorded for the first time. For garlic high intensity bands are present at 307, 399, 569, 711, 1,182, 1,287, 1,397 and 1,622 cm(-1). For Chinese chives the high intensity band is present at 672 cm(-1). Low intensity bands are present at 274, 412, 575, 1,185, 1,289, 1,396, 1,618 cm(-1). For shallot high intensity bands are present at 693 cm(-1). Lower intensity bands are present at 372, 888, 1,023 cm(-1). Low intensity bands are present at 1,088, 1,211 and 1,322 cm(-1). The SERS of diallyl disulfide, allyl methyl sulfide and 1-propanethiol in liquid state and gas state were also obtained. The main volatile organic compound of fresh garlic, Chinese chive and shallot are diallyl disulfide, allyl methyl sulfide and 1-propanethiol respectively, and the volatile organic compound of fresh onion, scallion, shallot and chive are all 1-propanethiol. The presented results illustrate that combining headspace and SERS is a powerful tool for volatile organic compound analysis in fresh plants. The volatile organic compound can be detected in fresh plant samples directly and quickly without extraction.

[Study on DNA Fourier infrared spectroscopy of three kinds of Nicotiana tabacum L].

The aim is analyzing genetic reLationship and identifying varieties by detecting DNA differences of three kinds of Nicotiana tabacum L. using Fourier infrared spectrum (FTIR). Results show that DNA FTIR of three kinds of Nicotiana tabacum L. is relatively similar. They all have four obvious characteristic peaks. 1 105 cm(-1) beLongs to symmetrical stretching vibration of phosphodiester bond, 1 250 cm(-1) is unsymmetrical stretching vibration of phosphodiester bond, 1 400 cm(-1) is contributed to glucosidic bond, and 1 622 cm(-1) belongs to C4-C5=C6 stretching vibration of cytosine. DNA FTIR data was handled by smoothing, standardizing, second derivative, principal component analysis and Hierarchical cluster analysis. The standard model of Hierarchical cluster combined with principal component of the second derivative was set up. The correct rate of identification is 100%. Yunyan 87 and K326 were clustered into one by using the model. The distance coefficient is 0.003, and DNA similarity is 99.7%, Hongda was clustered into one by itself. The correct rate of cluster is 100%. The study provides a reference for Nicotiana tabacum L. variety identification and genetic breeding.

[Analysis of leave FTIR of nine kinds of plants from Rosaceae with genetic relationship].

Leaves of nine kinds of plants from three subfamily of Rosaceae were used as materials. Genetic relationship was analyzed and species were identified through studying FTIR of nine kinds of plants. Leaves mainly contain large amounts of carbohydrates, proteins, lipids, nucleic acids and other substances. The peaks of carbohydrates are mainly between 1440 and 775 cm(-1). The vibration peaks of the cellulose and lignin are between 1440 and 1337 cm(-1). The peaks between 1000 and 775 cm(-1) are stretching vibration of ribose. The vibration peaks of protein are between 1620 and 1235 cm(-1). The peak at 1620 cm(-1) is sensitive to C=O stretching vibration of protein amide I. The peak at 1523 cm(-1) is assigned to N-H and C-N stretching vibration of protein amide II. Peaks of lipids mainly appeared between 2930 and 1380 cm(-1). The peak at 2922 cm(-1) is CH2 stretching vibration of fat. The peak at 1732 cm(-1) is C=O stretching vibration of fatty acids. The mark peak of the nucleic acid appears in the region between 1250 and 1000 cm(-1). The peak at 1068 cm(-1) is due to the symmetric stretching vibration of PO(2-) group of the phosphodiester-deoxyribose backbone, and the peak at 1246 cm(-1) is associated to the asymmetric stretch vibration of PO(2-) group. The results showed that the cluster model is established by smoothing, standardizing, the second derivative, principal component analysis and Hierarchical cluster analysis. It is accordant with the traditional classification. The result of cluster shows that Prunus armeniaca L. and Prunus seudocerasus Lindl. were clustered into one (Prunoideae). Potentilla fulgens Wall. Rosa chinensis Jacd and Fragaria ananassa Duchesne var. were clustered into the second (Rosoideae). Pyracantha fortuneana Li, Malus pumila Mill. Eriobotrya bengalensis Hook. f. and Malus hallianna Koehne were clustered into the third (Pomoideae). The correct rate of cluster at subfamily is 100%. The correct rate of cluster at genus is 55.56%. The correct rate of identification is 100% when unknown species waiting for determined were laid into the model of Hierarchical cluster to identify. This study provides a new thought and method for genetic relationship analysis of planst.

[Elementary SERS spectroscopy studies of three kinds of pathogens in Ag colloids prepared by microwave method].

The normal Raman (NR) and surface enhanced Raman spectroscopy (SERS) for Alternaria alternate, Colletotrichum musae, and fusarium suspensions were measured by a portable Raman spectrometer (785 nm). The result indicates that the silver colloid prepared by microwave method shows high enhancement of Raman scattering for the three kinds of pathogens. Comparing SERS spectrums of the three kinds of pathogens, there are some similarities. In these SERS spectrums, the peaks in the range of 500-1 000 cm(-1) are very weak. Additionally, the peaks in the range of 1 000-1 600 cm(-1) are strong. Meanwhile, the peak at 481 cm(-1) is the strongest. Although these spectrums are similar, there are some differences such as the distribution and shape of peaks. Therefore, the three kinds of pathogens can be discriminated quickly.

[Analysis of surface enhanced Raman scattering spectra of oxyhemoglobin for liver cancer with combined multivariate statistics].

Investigation of surface-enhanced Raman spectra of oxyhemoglobin for 30 liver cancers and 30 normal persons based on the silver nanofilm was reported. Principal components analysis (PCA) and independent variable T test were employed to develop effective diagnostic algorithms for distinguishing liver cancer form normal. Discriminant analysis was used to evaluate the diagnostic efficiency and the result indicates that SERS spectra of the oxyhemoglobin are obviously different between normal persons and liver cancers. PCA and independent variable T test were employed to get a three-dimensional scatter plot of PC scores for the healthy and cancer groups, and it can be learned that they are distributed in separate areas. By using the method of discriminate analysis, it was fount that the diagnostic algorithm separates the two groups with sensitivity of 96.7% and diagnostic specificity of 90%, the overall diagnostic accuracy was 93.3%. By analyzing the assignations of the SERS bands, it was found that the content of asparagine, tyrosine and phenylalanine in the hemoglobin are significantly lower than healthy people. The results from this exploratory study demonstrate that SERS detection of oxyhemoglobin for liver cancers based on the method of PCA combined with independent variable T test is expected to develop into a new type of liver cancer diagnostic tool.

[Preparation and SERS activity studies on substrate of nano-silver film with broad plasma absorption band].

A highly reproducible and broad plasma absorption band nano-silver film was prepared by electrostatic self-assembly technology. The size of nano-silver particles on the surface of silver film, in the scanning electron microscopy (SEM) micrograph, is in a wide distribution from 18 to 200 nm. At the same time, the ultraviolet-visible spectrophotometer was employed to detect the nano-silver film. There is a broad plasma absorption band in the UV-Vis spectrum. To test the SERS activity of the nano-silver film, crystal violet and serum of healthy person were used as probe molecules and the high quality SERS spectra were obtained.

[SERS spectroscopy study of three pathogenic bacteria].

The SERS spectra of staphylococcus aureus, proteus, and Escherichia coli was obtained on colloidal Ag nanoparticles prepared by the microwave method with the portable Raman spectrometer. Staphylococcus aureus have obvious Raman vibrating peak at 725, 1 330 and 1 450 cm(-1), proteus have obvious Raman vibrating peaks at 650,725,950, 1 325 and 1 463 cm(-1), while E. coli have obvious Raman vibrating peaks at 650, 950, 1 125, 1 242,1 320 and 1 457 cm(-1). Each peak was assigned preliminarily. Not only the position of Raman vibration peaks but also the intensity of the three bacteria is obviously different, so SERS can be used for identification and distinction of E. coli, staphylococcus aureus and proteus.

[Investigation of typical melamine urinary stones using infrared spectra].

A typical melamine kidney stone confirmed by some medicine expert was collected from the first people's hospital of Yunnan. The kidney stone was adequately determined by PE corporation spectra 100(with resolution of 1 cm(-1)). The stone samples for FTIR analysis were prepared using the KBr pellet technique, where 2 mg of the pretreated stone powder was mixed with 200 mg of analytical grade KBr using an agate pestle and mortar. The digital spectrum was then scanned in the mid-infrared region from 4 000 to 400 cm(-1) at room temperature. The appearing bands between 4 000 and 2 000 cm(-1) were 3 487, 3 325, 3 162 and 2 788 cm(-1), those between 1 700 and 1 000 cm(-1) were 1 694, 1 555, 1 383, 1 340, 1 189 and 1 122 cm(-1), and those between 1 000 and 400 cm(-1) were 993, 782, 748, 709, 624, 585, 565 and 476 cm(-1). It was found that the main constituent of calculi showed few comparability with cat kidney stone, which was from cats that died after consuming the contaminated food, and confirmed that these deposits were primarily composed of melamine and cyanuric acid compared to the IR spectra of calculi in literature. It was also found that the main constituent of calculi showed few comparability with popular kidney stone by comparison with the IR spectra of calculi in literature. The spectrum of calculi was 50% respectively similar with melamine and uric acid as compared with the IR spectrum. It was found that the main constituent of calculi was melamine itself and uric acid as compared with the IR spectra of calculi and melamine: (1 : 1), because the spectrum of calculi was 83. 3% similar to melamine and uric acid (1 : 1). The appearing bands of melamine and uric acid (1 : 1) between 4 000 and 2 000 cm(-1) were 3 469, 3 419, 3 333, 3 132, 3 026, 2 827 cm(-1), those between 1 700 and 1 000 cm(-1) were 1 696, 1 656, 1 555, 1 489, 1 439, 1 350, 1 311, 1 198, 1 124 and 1 028 cm(-1), and those between 1 000 and 400 cm(-1) were 993, 878, 814, 784, 745, 708, 619, 577 and 475 cm(-1).

[SERS spectra of Xanthomonas oryzae pv. Oryzae (Xoo) on nano silver film prepared by electrolysis method].

The nano silver film was prepared by electrolysis method using silver nitrate and polyvinyl alcohol (PVA) in deionized water as the electrolyte, with four glass slides put in the electrolyte and two silver rods dipped into the electrolyte as the anode and cathode. A direct current was applied to the rods, then the four glass slides stayed in the silver colloids. Thus the authors got the nano silver film. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) were employed to detect the silver particles in the silver colloids and on the nano silver film. From the SEM we can see that the silver particles on the film formed different layers. In one layer, the distance between two particles was about 100 nm. The samples of Xanthomonas oryzae pv. Oryzae (Xoo) were 7 different kinds of bacterial blight, namely 1-YN1, 2-YN7, 3-YN11, 4-GD414, 5-SCYC6, 6-HEN11 and 7-FWJ. Because the silver particles in the colloids were aggregated on the film, there was large electromagnetic potentiation. So the SERS spectra of Xoo were perfect. The authors used the area analytical method to distinguish the different kinds of Xoo. The silver film prepared by electrolysis was cheap and active, the preparation time of the samples was short, and any normal chemistry lab can make it, which can find excellent application to detecting the Xoo in agriculture. On the other hand, this film is active on biomolecules and bioorganism, which may be a new kind of SERS fundus to explain the creation of the SERS. Further study was under way.

[The study of fermentation liquid's absorption spectra in elastase fermentation].

The present article studied the fermentation liquid's absorption spectra, bacteria growth period and elastase' production in elastase fermentation, and compared and analyzed the their relation. The results show that the changes in the absorption spectra were closely related with bacteria growth and elastase' production. The UV spectroscopic technique is helpful for detecting the change of the organic nitrogen base and enzyme. The study offers a new method to detect fermentation process and is basic for detecting fermentation process on line by UV spectroscopic technique.

[Study on absorption spectra of cell substrate for Hep-2 cell after being radiated by X-ray].

UV-absorption spectra of the Hep-2 cell's culture medium RPMI1640 (10% Foetal Calf Serum) were collected by UV-3101 spectrophotometer after the Hep-2 cell was radiated by X-ray and cultivated for 24, 48 and 72 h, and the absorbability of the proteins in the substrate was analyzed. From these results it was found that there were visible differences among these absorption spectra. In particular, the absorption peaks of the RPMI1640 culture medium during the cultivation shifted from 233 to 235 nm, while the absorption peak at 278 nm became more and more smooth and even finally disappeared with the cultivation time. On the other hand, the absorption intensity of the different-dose groups rose greatly with the time, and were all lower than the control group until the cells were cultivated for 72 h after being radiated by X-ray. It was showed that the content of each amino acid has already changed. That is, during the growing course of the cancer cells, the tryptophan and casein were not depleted equivalently. And there were some important relations between the absorption spectra and the cells' apoptosis and necrosis induced by X-ray. This will be a foundation for the study of the best X-ray dose for the larynx carcinoma.