Glucosamine sulfoforms: Solid-phase synthesis, mass spectrometry analysis and biological profiling

Sulfated α-glucosamine derivatives (GlcN sulfoforms) bearing hydroxyethyl linkers were prepared by solid-phase synthesis, establishing the feasibility of generating sulfate esters on resin-immobilized carbohydrates. An orthogonally protected GlcN scaffold was loaded onto a trityl-PS resin and subjected to regioselective deprotection and sulfation conditions, which was optimized with the aid of on-resin IR and Raman analysis. The sulfoforms were cleaved from the resin using mild Lewis acid conditions without affecting the O- or N-sulfate esters, and purified by reversed-phase high-performance liquid chromatography (HPLC) with retention of Bu4N+ as the sulfate counterion. The α-GlcN sulfoforms and their 4-O-benzyl ethers were examined by electrospray ionization tandem mass spectrometry (ESI-MS/MS) with daughter ions produced by collision-induced dissociation (CID). The benzylated α-GlcN sulfoforms were suitable models of internal glucosamines within heparan sulfate, and had significant differences in parent ion stabilities and fragmentation rates as a function of sulfate position. Mass fragmentation spectra of GlcN sulfoforms showed characteristic patterns with strong correlation to the position of both free hydroxyl groups and sulfate esters. Fragmentation analysis could readily distinguish GlcN sulfoforms bearing the relative rare 3-O -sulfate from isomers with the more common 6-O-sulfate. The solid-phase synthesis strategy was also optimized for the preparation of mono- and disaccharide GlcN sulfoforms bearing an aminoethyl linker, to facilitate the formation of glycoconjugates for biological studies. This second-generation solid-phase synthesis included an optimized cleavage condition from the trityl-PS resin and eliminated redundant ion exchange operations, which improved the efficiency and yields of GlcN derivatives with multiple-sulfates. GlcN and GlcN(1→4)Glc sulfoforms were prepared by second-generation solid-phase synthesis, converted to amine-terminated hexaethyleneglycol conjugates, and tested for their binding affinity to FGF2 and L-selectin using microarray-based screening. Our results indicate that even monosaccharide GlcN sulfoforms can exhibit significant differences in binding affinity. The affinities of sulfoforms linked in 1,4-linked fashion to β-glucoside were not significantly higher than that of monosaccharides, but GlcN sulfoforms linked to a 6-O -sulfo-β-glucoside appeared to have higher affinity for L-selectin and FGF2. Lastly, a GlcN(α1→4)Glc disaccharide scaffold bearing 5 orthogonal protecting groups was synthesized for generating GlcN(α1→4)Glc-6S sulfoforms, for screening against L-selectin, FGF2, and other heparin-binding proteins

Green Governance and International Business Strategies of Emerging Economies’ Multinational Enterprises: A Multiple-Case Study of Chinese Firms in Pollution-Intensive Industries

With the global consensus on the need for sustainability practices, green governance has attracted increasing attention from international business (IB) scholars and multinational enterprise (MNE) managers. In this study, we propose a more fine-grained framework of the green governance context along two dimensions: foreign direct investment (FDI) policy and environmental regulation. Then, we examine the framework using cluster analysis. On the basis of a multiple-case study comprising 11 Chinese MNEs in pollution-intensive industries operating in four different green governance contexts, we conclude that (1) the green governance context is a significant factor in MNEs’ global location choices and is an important driving force behind MNEs’ response patterns; (2) environmental capabilities enable MNEs to surmount a host country’s environmental entry barrier and facilitate wider global business deployment; (3) technological capabilities increase MNEs’ competitive edge and allow them to better harness a host country’s growth opportunities; (4) there are four types of green governance response patterns, and the details of the proposed classification structure and its validation are presented; and (5) both strict environmental regulation and friendly FDI policy can positively influence MNEs’ adoption of more active response patterns, and greater availability of environmental and technological capabilities does not affect MNEs’ environmental commitment. This study contributes to the international strategy-capability-environment alignment of emerging economies’ multinational enterprises (EMNEs) in different green governance contexts

A survey on coronary heart disease related signal pathways, drug targets and pharmacological interventions

Coronary heart disease (CHD), the most common form of cardiovascular disease, is a chronic, multifactorial disease. With significant advances in our understanding of the pathophysiological process of CHD in recent years, more and more drug targets have been identified and adopted in drug discovery for CHD. Purpose and methods: In this review, a comprehensive perspective of pathological and pharmacological development of CHD was introduced through searching in multiple bibliographic sources. Results: CHD related signal pathways (including 412 proteins), drug targets (including 101 proteins) and pharmacological interventions were summarized and visualized. Conclusions: The knowledge of these signal pathways and drug targets may facilitate new drug discovery and medicine intervention for CHD in the future

Indirectly measuring the displacements of tension structures under dominant design loads by exerting simple testing loads

Structural stiffness of a real tension structure may degrade due to many factors, so the stiffness monitoring is very important. If the displacements under the dominant design loads are obtained, the stiffness state of the real structure can be intuitively assessed by a deformation checking process. However, exerting design loads on a real structure is neither efficient nor economical, because they usually have too many loading points. A method is hence proposed to indirectly measure the displacements under the design loads by merely exerting several simple testing loads. By utilizing the linear combination of several contributing eigenvectors to express the displacements, the problem of measuring displacements is transformed to that of measuring combinational coefficients of these contributing eigenvectors. The relationship between the combinational coefficients of the mutual contributing eigenvector of the design load and the testing load is set up firstly, with two basic conditions established. To satisfy the basic conditions, a strategy to decompose the design load and an algorithm to find proper testing loads are suggested. The numerical example of a cable net with two typical design loads is finally analyzed. Results illustrate that the proposed indirect method is effective, with three simple testing loads (no more than 3 loading points) found to replace the two design loads (181 loading points) in the on-site static testing. Besides, the proposed indirect method is more robust to resist the influence of measurement noise than the traditional direct method. The reason why the proposed indirect method has better robustness is also discussed.</p

Structural Characterization and Identification of Major Constituents in Jitai Tablets by High-Performance Liquid Chromatography/Diode-Array Detection Coupled with Electrospray Ionization Tandem Mass Spectrometry

In the present study a universally applicable HPLC-DAD/ESI-MS/MS method was developed for carrying out the comprehensive characterization of Jitai tablets (JTT). Based on the ESI-MSn fragmentation patterns of the reference standards, a total of 101 components were identified or tentatively characterized by comparing their retention times, UV and MS spectra with those of reference standards or through the matching of empirical information with those of published components in the in-house library. The characteristic fragmentation pattern of alkaloids, phenolic acids, tanshinones, flavonoid glycosides, cyanogenic glycosides, ginsenosides, 2-(2-phenylethyl) chromones, phthalides and gingerol-related compounds were tentatively elucidated using structurally-relevant product ions. It was observed that neutral losses of C9H10O3 and C9H8O2 were the characteristic product ions of scopola alkaloids. Neutral fragment mandelonitrile was the characteristic ion of cyanogenic glycosides. To our knowledge, tropylium ion and C4H2O unit were the characteristic ions of 2-(2-phenylethyl) chromone, which resulted from the Retro-Diels-Alder (RDA) cleavage of the C ring. The results indicated that the developed analysis method could be employed as a rapid, effective technique for structural characterization of chemical constituents in TCM. This work is expected to provide comprehensive information for the quality evaluation and pharmacokinetic studies of JTT

Structural Characterization and Identification of Major Constituents in Jitai Tablets by High-Performance Liquid Chromatography/Diode-Array Detection Coupled with Electrospray Ionization Tandem Mass Spectrometry

In the present study a universally applicable HPLC-DAD/ESI-MS/MS method was developed for carrying out the comprehensive characterization of Jitai tablets (JTT). Based on the ESI-MS&lt;sup&gt;n&lt;/sup&gt; fragmentation patterns of the reference standards, a total of 101 components were identified or tentatively characterized by comparing their retention times, UV and MS spectra with those of reference standards or through the matching of empirical information with those of published components in the in-house library. The characteristic fragmentation pattern of alkaloids, phenolic acids, tanshinones, flavonoid glycosides, cyanogenic glycosides, ginsenosides, 2-(2-phenylethyl) chromones, phthalides and gingerol-related compounds were tentatively elucidated using structurally-relevant product ions. It was observed that neutral losses of C&lt;sub&gt;9&lt;/sub&gt;H&lt;sub&gt;10&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt; and C&lt;sub&gt;9&lt;/sub&gt;H&lt;sub&gt;8&lt;/sub&gt;O&lt;sub&gt;2&lt;/sub&gt; were the characteristic product ions of scopola alkaloids. Neutral fragment mandelonitrile was the characteristic ion of cyanogenic glycosides. To our knowledge, tropylium ion&lt;sub&gt; &lt;/sub&gt;and C&lt;sub&gt;4&lt;/sub&gt;H&lt;sub&gt;2&lt;/sub&gt;O unit were the characteristic ions of 2-(2-phenylethyl) chromone, which resulted from the Retro-Diels-Alder (RDA) cleavage of the C ring. The results indicated that the developed analysis method could be employed as a rapid, effective technique for structural characterization of chemical constituents in TCM. This work is expected to provide comprehensive information for the quality evaluation and pharmacokinetic studies of JTT.&lt;strong&gt;&lt;/strong&gt