Copper-catalyzed oxidative cyclization of glycine derivatives toward 2-substituted benzoxazoles.

A novel and straightforward intramolecular cyclization of glycine derivatives to 2-substituted benzoxazoles through copper-catalyzed oxidative C-H/O-H cross-coupling was described. A variety of glycine derivatives involving short peptides underwent cross-dehydrogenative-coupling readily to afford diverse 2-substituted benzoxazoles. The synthetic method has the advantages of simple operation, broad substrate scope and mild reaction conditions, thus providing an alternative effective approach for benzoxazole construction.

Efficient biocatalytic strategy for one-pot Biginelli reaction via enhanced specific effects of microwave in a circulating reactor.

A one-pot efficient biocatalytic strategy for the synthesis of 3,4-dihydropyrimidin-2-(1H)-ones was developed in a circulating microwave reactor selecting α-chymotrypsin as the promiscuous biocatalyst. In the circulating reaction system, the combination of microwave heating and external cooling could avoid the denaturation and inactivation of enzyme, and greatly improved the radiation power of microwave, thus improving the specific effects of microwave. During the reaction process, the microwave radiation power was automatically adjusted by adjusting the speed of the reaction mixture circulation. When the microwave power was maintained at 110 W, the best results could be obtained with the highest yield of 96% at 55 °C in 50 min, and the reaction had a wide range of substrates. But no obvious product was detected in a tank microwave reactor at 55 °C for 100 min, under this condition, the microwave power was maintained at about 3 W. As a contrast, the reaction only obtained 63% yield in 55 °C oil bath for 96 h.

Additional New Cytotoxic Triquinane-Type Sesquiterpenoids Chondrosterins K-M from the Marine Fungus Chondrostereum sp.

By the method of ¹H NMR prescreening and tracing the diagnostic proton signals of the methyl groups, three additional new triquinane-type sesquiterpenoids-chondrosterins K-M (1-3) and the known sesquiterpenoid anhydroarthrosporone (4)-were isolated from the marine fungus Chondrostereum sp. Their structures were elucidated on the basis of MS, 1D, and 2D NMR data. Chondrosterin K is a rare hirsutane sesquiterpenoid, in which a methyl group was migrated from C-2 to C-6 and has a double bond between C-2 and C-3. Compounds 1-3 showed significant cytotoxicities against various cancer cell lines in vitro.

Four new citrinin derivatives from a marine-derived Penicillium sp. fungal strain.

Four new citrinin derivatives, including two citrinin dimers and two citrinin monomer derivatives, were isolated and identified from a marine-derived fungal strain Penicillium sp. ML226 along with six known related compounds. Their structures were elucidated by spectroscopic and chemical methods. The new compounds showed modest cytotoxic activity against HepG-2 cell line and weak antimicrobial activity against Staphylococcus aureus.

[Analysis of software for identifying spectral line of laser-induced breakdown spectroscopy based on LabVIEW].

Self-designed identifying software for LIBS spectral line was introduced. Being integrated with LabVIEW, the soft ware can smooth spectral lines and pick peaks. The second difference and threshold methods were employed. Characteristic spectrum of several elements matches the NIST database, and realizes automatic spectral line identification and qualitative analysis of the basic composition of sample. This software can analyze spectrum handily and rapidly. It will be a useful tool for LIBS.

Three new oblongolides from Phomopsis sp. XZ-01, an endophytic fungus from Camptotheca acuminate.

Four new metabolites, including three new oblongolides named C1, P1, and X1 (1-3) and 6-hydroxyphomodiol (10), along with eight known compounds--oblongolides B (4), C (5), D (6), O (7), P (8) and U (9), (3R,4aR,5S,6R)-6-hydroxy-5-methylramulosin (11), and (3R)-5-methylmellein (12)--were isolated from the endophytic fungal strain Phomopsis sp. XZ-01 of Camptotheca acuminate. Their structures were elucidated by spectroscopic analyses, including 1H- and 13C-NMR, 2D NMR (HSQC, HMBC, 1H-1H COSY and NOESY) and HR-FT-MS. Cytotoxic activities of these compounds were evaluated. Some of them showed weak selective activities.

3'-(3-Hy-droxy-phen-yl)-4-methyl-spiro-[benzo[e][1,4]diazepine-3,2'-oxirane]-2,5(1H,4H)-dione.

In the title compound, C(17)H(14)N(2)O(4), the seven-membered ring adopts a boat conformation, and the two benzene rings make a dihedral angle of 45.22 (5)°. The crystal packing is stabilized by inter-molecular N-H⋯O and O-H⋯O hydrogen bonds.

[Research on parameters optimization of laser-induced breakdown spectroscopy based experimental device].

For a better application of laser-induced breakdown spectroscopy (LIBS) to coal quality analysis, it is necessary to optimize the key parameters of the experimental LIBS-based device. The relationships between the key parameters and the signal-to-noise ratios (S/N) of the elemental emission lines in the plasma spectrum of the pulverized coal were studied, according to which the optimal parameters can be selected. Experimental results indicate that the optimal settings for our LIBS-based device are laser pulse energy = 120 mJ x Pulse(-1), delay time of spectrometer = 200 ns, laser focal point be located 3-5 mm underneath the sample surface, rotation speed of sample cell = 2.7 rev x min(-1), a narrow-band filter with center frequency of 1 064 nm and a diaphragm with center hole diameter of 1.5 mm be placed in the path of the laser beam. Quantitative analysis results of pulverized coal show that, by using the optimal LIBS-based device, the standard deviation (SD) of C has been reduced from 6.7% to 1.6%, while the relative standard deviation (RSD) of other trace elements has been reduced from 28% to 10%. As a result, th accuracy has been improved greatly.

Cluster Size and Quinary Structure Determine the Rheological Effects of Antibody Self-Association at High Concentrations.

The question of how nonspecific reversible intermolecular protein interactions affect solution rheology at high concentrations is fundamentally rooted in the translation of nanometer-scale interactions into macroscopic properties. Well-defined solutions of purified monoclonal antibodies (mAbs) provide a useful system with which to investigate the manifold intricacies of weak protein interactions at high concentrations. Recently, characterization of self-associating IgG1 antibody (mAb2) solutions has established the direct role of protein clusters on concentrated mAb rheology. Expanding on our earlier work with three additional mAbs (mAb1, mAb3, and mAb4), the observed concentration-dependent static light scattering and rheological data present a substantially more complex relationship between protein interactions and solution viscosity at high concentrations. The four mAb systems exhibited divergent correlations between cluster formation (size) and concentrated solution viscosities dependent on mAb primary sequence and solution conditions. To address this challenge, well-established features of colloidal cluster phenomena could be applied as a framework for interpreting our observations. The initial stages of mAb cluster formation were investigated with small-angle X-ray scattering (SAXS) and ensemble-optimized fit methods, to uncover shifts in the dimer structure populations which are produced by changes in mAb interaction modes and association valence under the different solution conditions. Analysis of mAb average cluster number and effective hydrodynamic radii at high concentrations revealed cluster architectures can have a wide range of fractal dimensions. Collectively, the static light scattering, SAXS, and rheological characterization demonstrate that nonspecific and anisotropic attractive intermolecular interactions produce antibody clusters with different quinary structures to regulate the rheological properties of concentrated mAb solutions.

Two new cyclopeptides and one new nonenolide from Xylaria sp. 101.

Two novel cyclopeptides, xylarotides A (1), and B (2), and one novel nonenolide, xylarolide (3), along with two known compounds, coriloxin (4), and 2-hydroxy-3-methoxy-5-methyl-p-benzoquinone (5) were isolated from the fungal strain Xylaria sp. 101. This strain was isolated from the fruiting body of Xylaria sp. collected in Gaoligong Mountain, Yunnan Province. The chemical structures were elucidated by spectroscopic analyses, including 1D- and 2D-NMR spectroscopic experiments, and on the basis of HR-Q-TOF mass spectrometry. Antibacterial assays of 1 - 3 were carried out; no effects on the growth of the tested bacteria and yeast were observed.