Synthesis of Highly Luminescent Chiral Nanographene.

Chiral nanographenes with both high fluorescence quantum yields (ΦF ) and large dissymmetry factors (glum ) are essential to the development of circularly polarized luminescence (CPL) materials. However, most studies have been focused on the improvement of glum , whereas how to design highly emissive chiral nanographenes is still unclear. In this work, we propose a new design strategy to achieve chiral nanographenes with high ΦF by helical π-extension of strongly luminescent chromophores while maintaining the frontier molecular orbital (FMO) distribution pattern. Chiral nanographene with perylene as the core and two dibenzo[6]helicene fragments as the wings has been synthesized, which exhibits a record high ΦF of 93 % among the reported chiral nanographenes and excellent CPL brightness (BCPL ) of 32 M-1 cm-1 .

Evaluation of storage period of fresh ginseng for quality improvement of dried and red processed varieties.

Background: Dried and red ginseng are well-known types of processed ginseng and are widely used as healthy food. The dried and red ginseng quality may vary with the storage period of raw ginseng. Therefore, herein, the effect of the storage period of fresh ginseng on processed ginseng quality was evaluated through multicomponent quantification with statistical analysis. Methods: A method based on ultrahigh performance liquid chromatography coupled to triple quadrupole mass spectrometry in multiple-reaction monitoring mode (UPLC-MRM-MS) was developed for quantitation of ginsenosides and oligosaccharides in dried and red ginseng. Principal component analysis and partial least squares discriminant analysis were conducted to evaluate the dynamic distributions of ginsenosides and oligosaccharides after different storage periods. Results: Eighteen PPD, PPT and OLE ginsenosides and nine reducing and nonreducing oligosaccharides were identified and quantified. With storage period extension, the ginsenoside content in the processed ginseng increased slightly in the first 2 weeks and decreased gradually in the following 9 weeks. The content of reducing oligosaccharides decreased continuously as storage time extending, while that of the nonreducing oligosaccharides increased. Chemical conversions occurred during storage, based on which potential chemical markers for the storage period evaluation of fresh ginseng were screened. Conclusion: According to ginsenoside and oligosaccharide distributions, it was found that the optimal storage period was 2 weeks and that the storage period of fresh ginseng should not exceed 4 weeks at 0 °C. This study provides deep insights into the quality control of processed ginseng and comprehensive factors for storage of raw ginseng.

B,N-Embedded Double Hetero[7]helicenes with Strong Chiroptical Responses in the Visible Light Region.

The development of helicene molecules with significant chiroptical responses covering a broad range of the visible spectrum is highly desirable for chiral optoelectronic applications; however, their absorption dissymmetry factors (gabs) have been mostly lower than 0.01. In this work, we report unprecedented B,N-embedded double hetero[7]helicenes with nonbonded B and N atoms, which exhibit excellent chiroptical properties, such as strong chiroptical activities from 300 to 700 nm, record high gabs up to 0.033 in the visible spectral range, and tunable circularly polarized luminescence (CPL) from red to near-infrared regions (600-800 nm) with high photoluminescence quantum yields (PLQYs) up to 100%. As revealed by theoretical analyses, the high gabs values are related to the separate molecular orbital distributions owing to the incorporation of nonbonded B and N atoms. The new type of B,N-embedded double heterohelicenes opens up an appealing avenue to the future exploitation of high-performance chiroptical materials.

Chemical Comparison of White Ginseng before and after Extrusion by UHPLC-Q-Orbitrap-MS/MS and Multivariate Statistical Analysis.

Ultrahigh-performance liquid chromatography Quadrupole-Orbitrap tandem mass spectrometry (UHPLC-Q-Orbitrap-MS/MS) was used to compare the composition of ginsenosides in white ginseng (WG) and extruded white ginseng (EWG). A total of 45 saponins, including original neutral ginsenosides, malonyl-ginsenosides, and chemical transformation of ginsenosides, were successfully identified in both WG and EWG. Multivariate statistical analyses including supervised orthogonal partial least squared discrimination analysis (OPLS-DA) and hierarchical clustering analysis (HCA) were used to analyze components of white ginseng before and after extrusion. As a result, three ginsenosides (malonyl (M)-Rb1, M-Rb2, and M-Rc) were found to be increased in WG, while three ginsenosides (Rb2, Rc, and Rg1) were elevated in EWG. In the OPLS-DA S-plot, the different compositions of ginsenoside that were distinguished between WG and EWG were screened out. Experimental results indicate that the UHPLC-Q-Orbitrap-MS/MS is a useful tool to characterize variations of ginsenosides in WG and EWG.

Highly Selective Bioconversion of Ginsenoside Rb1 to Compound K by the Mycelium of Cordyceps sinensis under Optimized Conditions.

Compound K (CK), a highly active and bioavailable derivative obtained from protopanaxadiol ginsenosides, displays a wide variety of pharmacological properties, especially antitumor activity. However, the inadequacy of natural sources limits its application in the pharmaceutical industry. In this study, we firstly discovered that Cordyceps sinensis was a potent biocatalyst for the biotransformation of ginsenoside Rb1 into CK. After a series of investigations on the biotransformation parameters, an optimal composition of the biotransformation culture was found to be lactose, soybean powder and MgSO4 without controlling the pH. Also, an optimum temperature of 30 °C for the biotransformation process was suggested in a range of 25 °C-50 °C. Then, a biotransformation pathway of Rb1→Rd→F2→CK was established using high performance liquid chromatography/quadrupole time-of-flight mass spectrometry (HPLC-Q-TOF-MS). Our results demonstrated that the molar bioconversion rate of Rb1 to CK was more than 82% and the purity of CK produced by C. sinensis under the optimized conditions was more than 91%. In conclusion, the combination of C. sinensis and the optimized conditions is applicable for the industrial preparation of CK for medicinal purposes.

MicroRNA-328 inhibits proliferation of human melanoma cells by targeting TGFß2.

Some microRNAs (miRNAs) have been shown to act as oncogenes or tumor suppressor genes in human melanomas. miR-328 is upregulated in blood cells of melanoma patients compared to in healthy controls. This suggests a role for miR-328 in melanoma that warrants investigation. In this study, we demonstrated miR-328 levels to be dramatically decreased in human melanoma cell lines. Moreover, forced expression of miR-328 inhibited proliferation and induced G1-phase arrest of the SK-MEL-1 melanoma cell line. We identified TGFß2 as a direct target gene for miR-328 using a fluorescent reporter assay and western blotting. Levels of TGFß2 were dramatically increased in human melanoma cell lines and were inversely correlated with the miR-328 expression level. Our findings provide new insights into the mechanisms of human melanoma development, indicating that miR-328 has therapeutic potential for this disease.

Production of graphite chloride and bromide using microwave sparks.

Chemically modified graphite is an economical material with promising applications in its own right or as an intermediate in the synthesis of graphene. However, because of its extreme chemical inertness, to date only two methods-oxidation and fluorination-have been found which can modify graphite with high yield and large throughput. Herein, we describe a third chemical approach for the synthesis of large quantities of highly modified graphite which uses a microwave-sparks-assisted halogenation reaction. The resulting graphite halide can easily be exfoliated into monolayer graphene in organic solvents. The structure and electronic properties of the original graphene can be recovered after thermal annealing of the graphene halide. Furthermore, the graphene halide can be further modified by a variety of organic functional groups. Solution-processed field-effect transistors based on the graphene halides resulted in device performances were comparable to, or even better than, that of graphene oxide.

Direct asymmetric vinylogous Mannich reaction of 3,4-dihalofuran-2(5H)-one with aldimine catalyzed by quinine.

The direct asymmetric vinylogous Mannich reaction of 3,4-dihalofuran-2(5H)-one with aldimine catalyzed by quinine was first reported, and γ-butenolides have been obtained in excellent yield (up to 98%) and enantioselectivities (up to 95% ee). The synthetic applications of this protocol are demonstrated in the preparations of γ-substituted amino butyrolactones and vicinal amino alcohols.

Organocatalytic stereocontrolled synthesis of 3,3'-pyrrolidinyl spirooxindoles by [3+2] annulation of isocyanoesters with methyleneindolinones.

A stereoselective [3+2] cycloaddition of isocyanoesters to methyleneindolinones catalyzed by a quinine-based thiourea-tertiary amine has been successfully developed. Just by tuning the protecting groups on substrates, a variety of optically enriched 3,3'-pyrrolidinyl spirooxindole diastereomers could be obtained in excellent enantioselectivities (up to 99% ee).

Asymmetric Michael addition of α-substituted isocyanoacetates with maleimides catalyzed by chiral tertiary amine thiourea.

A highly diastereoselective and enantioselective Michael addition of α-substituted isocyanoacetates with maleimides catalyzed by bifunctional tertiary amine thioureas has been developed. Various chiral succinimide derivatives bearing adjacent quaternary and tertiary stereocenters were prepared in excellent yields (up to 98%), diastereoselectivities (up to 99:1), and enantioselectivities (up to 98% ee). The synthetic utility of chiral succinimide derivatives is also demonstrated in the preparation of h5-HT(1d) receptor agonist motifs.

Highly enantioselective aldol reaction of acetone with ß,γ-unsaturated α-keto esters promoted by simple chiral primary-tertiary diamine catalysts.

A series of primary-tertiary diamine catalysts were successfully applied to promote the enantioselective aldol reaction of acetone with ß,γ-unsaturated α-keto esters in excellent yields (up to 99%) and enantioselectivities (up to 96% ee).