Xinmiao Liang

Effects of dye additives on the ozonation process and oxidation by-products: a comparative study using hydrolyzed C.I. Reactive Red 120

Decolorization of azo reactive dyes by ozone has been described by several authors. However, the efficiency of ozonation and the by-products produced by dye additives/impurities such as synthetic precursors, by-products, salts and dispersing agents in commercial azo dyes during the oxidative treatment have not been reported. To investigate the effects of such impurities on the ozonation process and on the formation of oxidation by-products, a commercially available azo reactive dye C.I. Reactive Red 120 was chosen as a model compound. Experiments were conducted in aqueous solutions of hydrolyzed C.I. Reactive Red 120 (200 mg/l) either with or without purification. Treatment efficiencies of purified and unpurified dye were evaluated in terms of COD, BOD28, absorbance and initial decolorization rates. Additionally, organic and inorganic anions were analyzed by HPIC. After 28 days of incubation the BOD28/COD ratio increased from 0.22 to 0.48 and from 0.05 to 0.26 for purified and unpurified C.I. Reactive Red 120, respectively, indicating an enhancement of biodegradable compounds in the ozonated solutions. The results also illustrate that the dye additives/impurities in commercial dyes affect the microbial activity as well as the biodegradability. It is therefore recommended that dyes should be purified before ozonation, if detailed information on the degradation processes and the resulting oxidation by-products are required.

TEMPO/HCl/NaNO2 catalyst: a transition-metal-free approach to efficient aerobic oxidation of alcohols to aldehydes and ketones under mild conditions.

Hydrochloric acid, a very inexpensive and readily available inorganic acid, has been found to cooperate exquisitely with NaNO(2)/TEMPO in catalyzing the molecular-oxygen-driven oxidation of a broad range of alcohol substrates to the corresponding aldehydes and ketones. This transition-metal-free catalytic oxidative conversion is novel and represents an interesting alternative route to the corresponding carbonyl compounds to the metal-catalyzed aerobic oxidation of alcohols. The reaction is highly selective with respect to the desired product when carried out at room temperature in air at atmospheric pressure. Notably, the use of very inexpensive NaNO(2) and HCl in combination with TEMPO for this highly selective aerobic oxidation of alcohols in air at ambient temperature makes the reaction operationally and economically very attractive. The results of mechanistic studies, performed with the aid of electrospray ionization mass spectrometry (ESI-MS), are presented and discussed. TEMPO, TEMPOH, and TEMPO(+) were observed in the redox cycle by means of ESI-MS. On the basis of these observations, a mechanism is proposed that may provide an insight into the newly developed aerobic alcohol oxidation.

Study on the retention equation in hydrophilic interaction liquid chromatography.

Hydrophilic interaction liquid chromatography (HILIC) is an effective technique for separating polar compounds. But its retention equation has not been studied systematically yet. In this study, an appropriate retention equation was established by using eight nucleosides as model analytes and by comparing four retention models on six different HILIC columns. As a result, retention equation Ink = a + b x InC(B) + cxC(B) could be quantitatively described the retention factors with good accuracy in HILIC mode. Based on this equation, the retention times of eight nucleosides under the conditions by other mobile phase can be predicted on each column. All of the predicted relative errors of retention times were smaller than 5%. The established retention model was also successfully applied to predict retention times of the real Traditional Chinese Medicine-Carthaus tinctorius L. sample.

Novel two-dimensional reversed-phase liquid chromatography/hydrophilic interaction chromatography, an excellent orthogonal system for practical analysis

A novel two-dimensional reversed-phase liquid chromatography/hydrophilic interaction chromatography (2D-RPLC/HILIC) system is developed with the introduction of the click beta-cyclodextrin (beta-CD) stationary phase. The offline system shows excellent abilities for the separation of polar and medium-polarity components in traditional Chinese medicine (TCM). It facilitates us not only to separate components that cannot be resolved by uni-dimensional chromatography, but also to achieve much more efficient detection of components with low abundance. The orthogonality of this new system is excellent. A simple geometric approach is developed to characterize the practical orthogonality of 2D-LC in the analysis of complex unknown samples. The mathematical characterization results are in good accordance with the experimental findings, and both demonstrate that the proposed 2D-RPLC/HILIC system is a powerful tool for the separation of polar and medium-polarity complex samples. This system may have a great potential for the separation of peptides and metabolomic compounds with similar polarity.

Enantioselective Organocatalytic Michael Addition of Malonates to α,β-Unsaturated Ketones

A novel type of primary amine thiourea organocatalysts derived from 1,2-diaminocyclohexane and 9-amino (9-deoxy) cinchona alkaloid was developed into asymmetric Michael addition of malonates to enones. A series of cyclic and acyclic enones could react very well with different malonates in the presence of 4 with 0.5-10 mol % catalyst loading affording chiral Michael adducts with excellent yields and ee values.

Centrifugation Assisted Microreactor Enables Facile Integration of Trypsin Digestion, Hydrophilic Interaction Chromatography Enrichment, and On-Column Deglycosylation for Rapid and Sensitive N-Glycoproteome Analysis

Sample handling procedures including protein digestion, glycopeptide enrichment, and deglycosylation have significant impact on the performance of glycoproteome analysis. Several glycoproteomic analysis systems were developed to integrate some of these sample preparation procedures. However, no microsystem integrates all of above three procedures together. In this work, we developed a glycoproteomic microreactor enabling seamless integration of all these procedures. In this reactor, trypsin digestion was accelerated by adding acetonitrile to 80%, and after acidification of protein digest by trifluoroacetic acid (TFA), the following hydrophilic interaction chromatography (HILIC) enrichment and deglycosylation were sequentially performed without any desalting, lyophilization, or buffer exchange steps. The total processing time could be as short as 1.5 h. The detection limit of human IgG as low as 30 fmol was also achieved. When applied to human serum glycoproteome analysis, a total number of 92, 178, and 221 unique N-glycosylation sites were identified from three replicate analyses of 10 nL, 100 nL, and 1 μL of human serum, respectively. It was demonstrated that the glycoproteomic microreactor based method had very high sensitivity and was well suited for glycoproteome analysis of minute protein samples.

Systematic screening and characterization of tertiary and quaternary alkaloids from corydalis yanhusuo W.T. Wang using ultra-performance liquid chromatography-quadrupole-time-of-flight mass spectrometry

Ultra-performance liquid chromatography-quadrupole-time-of-flight mass spectrometry (UPLC-Q-TOF-MS) is an effective technique for analysis of complex samples with offering rapid, efficient separation in combination with accurate mass measurement and tandem mass spectrometry (MS/MS). This paper exploits this technique to identify the alkaloids in corydalis yanhusuo, an important antalgic Traditional Chinese Medicine (TCM). The mass spectral fragmentation behavior of one tertiary alkaloid and two quaternary alkaloids was studied in detail. Low-abundance product ions of tertiary and quaternary alkaloids were investigated and compared between each other. Sixteen alkaloids were screened out by using a systematic screening method developed in our laboratory; structures of eight therein were identified by characteristic UV absorption spectrum and positive ion mode of Q-TOF-MS/MS; and two of them were discovered for the first time in corydalis yanhusuo to our knowledge. This research demonstrates the potential of UPLC-Q-TOF-MS in structural characterization and identification of components in traditional Chinese herbal medicines.

Highly Diastereo‐ and Enantioselective Synthesis of 5‐Substituted 3‐Pyrrolidin‐2‐ones: Vinylogous Michael Addition under Multifunctional Catalysis

molecules display marvelous biological properties including antiviral, pesticidal, and antitumor activity, as well as other pharmacological properties, which undoubtably contribute greatly to their importance in the field of organic chemistry both in terms of their chemical synthesis and in the development of synthetic methodologies. As one of the efficient chemical precursors to 5-substituted 3-pyrrolidin-2-one derivatives, a,b-unsaturated g-butyrolactam has recently appeared as one of the most attractive reactants in various chemical reactions including Mannich, Aldol, Michael, and other simple transformations of either direct or Mukaiyama-type reactions. Even more attractive are the diastereoor enantioenriched products that could be further utilized as versatile building blocks towards more functionalized pyrrolidin-2-ones. However, stereoselective transformations involving this interesting molecule still remain rare, both in the field of organocatalytic synthesis and organometallic catalysis, compared with other important nucleophilic reagents. The scarcity of reactions is partially due to the difficulties in the chemoselective activation of the a, b-unsaturated vinylogous system either as a donor or as an acceptor in chemical reactions, and the challenges in the enantioand diastereoselectivity during those processes. Satisfactory results were achieved in the recent report of Shibasaki and co-workers in the asymmetric vinylogous Mannich and Michael reaction of this a,b-unsaturated g-butyrolactam with N-Boc imines and nitroolefins involving a dinuclear nickel catalytic system. Furthermore, Chen and co-workers have presented an asymmetric Michael addition with a,b-unsaturated aldehydes under the well-established iminium activation using the catalyst developed by Jørgensen and Hayashi. However, to the best of our knowledge, the vinylogous Michael additions of this a,b-unsaturated g-butyrolactam to a,bunsaturated ketones has never been reported and still represents a challenging task regarding the reactivity and stereoselectivity of the two relatively inert reactants. Herein, we report our investigations on this transformation under a multifunctional catalytic system, as well as some explorations into the use of the resulting products to demonstrate the potential utility of this strategy in the pharmaceutical and organic synthesis fields. Our initial investigations were carried out using a series of catalysts (1–3) for the model reaction of benzalacetone 4a and a,b-unsaturated g-butyrolactam 5a in CH2Cl2 at room temperature (Table 1, entries 1–11). Experimental data showed that the cyclohexane-1,2-diamine catalysts 1a and 1b could promote the reaction more effectively than other types of catalysts, with conversions of up to 93% after 72 hours, but with low stereoselectivity (entries 1 and 2). The 9-amino-epiquinine 2 a and its derivative 2b afforded the products with slightly increased ee values, but still with unsatisfactory reaction conversions or stereoselectivity (entries 3 and 4). Then our attention turned to another type of iminium-activation catalyst bearing a chiral 1,2-diphenylethane-1,2-diamine fragment with the hope that it would provide an improvement in this transformation. Attractive ee values were attained using the simple (R,R)-1,2-diphenylScheme 1. Several natural products that contain the fragments of 5-substituted 3-pyrrolidin-2-one derivatives.

Enantioselective organocatalytic phospha-Michael reaction of α,β-unsaturated ketones

Enantioselective organocatalytic phospha-Michael reaction of alpha,beta-unsaturated ketones and diaryl phosphine oxides has been developed for the first time employing multifunctional organocatalysts. Optically active products bearing quaternary chiral carbon stereocenters were obtained in high yields with good to excellent enantioselectivities (up to 98% ee).

Lysophosphatidylcholine profiling of plasma: discrimination of isomers and discovery of lung cancer biomarkers

Lysophosphatidylcholines (lysoPCs) are a class of compounds that have a constant polar head, and fatty acyls of different chain lengths, position, degrees of saturation, and double bond location in human plasma. LysoPCs levels can be a clinical diagnostic indicator that reveals pathophysiological changes. In this work, a method was developed to discriminate between different types of lysoPCs using reversed phase ultra-performance liquid chromatography coupled to quadrupole time-of-flight mass spectrometry, using mass spectrometry MSE. Isomeric lysoPCs were distinguished based on retention time and the peak intensity ratio of product ions, and 14 pairs of lysoPCs regioisomers were identified in human plasma. The plasma samples of 12 lung cancer patients and 12 healthy persons were collected and analyzed by principal component analysis to generate metabolic profiles of the identified lysoPCs. Both electrospray ionization ESI+ and ESI− results showed that all lung cancer patients had the same five lysoPC metabolic abnormalities, specifically in sn-1 lyso16:0, sn-2 lysoPC 16:0, sn-1 lysoPC 18:0, sn-1 lysoPC 18:1 and sn-1 lysoPC 18:2. Thus, the function of isomers with different fatty acyl positions may be related to lung cancer, and this may help elucidate the mechanism of the disease.