Analysis of sialic acid levels in Chinese intravenous immunoglobulins by high‐performance liquid chromatography with fluorescence detection

Intravenous immunoglobulin (IVIg) is increasingly used for the treatment of autoimmune and systemic inflammatory diseases with both licensed and off‐label indications. Recent studies indicated that IVIg‐mediated immunomodulation and anti‐inflammation are closely associated with the IgG sialylation, especially with IgG crystallizable fragment (Fc) sialylation. The sialic acid levels of the IgG molecules and Fc fragments in 12 IVIg preparations from six Chinese manufacturers were evaluated. The Fc fragments were derived from the papain digestion of IVIg, followed by affinity and size exclusion chromatography. The sialic acid levels in Fc fragments and IVIg preparations were determined by high‐performance liquid chromatography with fluorescence detection, after the sialic acid residues were released from the proteins. The results showed that the sialic acid levels in Chinese IVIg preparations ranged from 0.875 (mol/mol IgG) to 1.085 (mol/mol IgG), and the sialic acid levels in Fc fragments were from 0.321 (mol/mol Fc) to 0.361 (mol/mol Fc). Furthermore, the sialic acid levels of IVIg preparations and Fc fragments from different Chinese manufactures were significantly different. These findings will contribute to an increased understanding of Chinese IVIg preparations and the relationship between the sialic acid levels in IVIg preparations and their clinical efficacy in future clinical studies.     

Potential influence on drug efficacy from interaction of tartrazine and trypsin

The extent to which drugs combine with trypsin is influenced by the interaction of tartrazine and trypsin, which may cause overdose or underdose of drugs. Therefore, the interaction of tartrazine and trypsin is investigated by methods of spectrometry in this paper. The binding rate of tartrazine to trypsin is 80.95–95.71% at 310?K, and Hill’s coefficients are almost 1. The effect of tartrazine on trypsin structure was studied by synchronous and circular dichroism. The results showed that the binding of tartrazine and trypsin induced the conformational change of trypsin, and quenched the endogenous fluorescence in trypsin. The results of molecular docking revealed that tartrazine is located in the catalytic active site of trypsin, and is consistent with that of experimental calculation.     

Study on the reduction roasting of spent LiNixCoyMnzO2 lithium-ion battery cathode materials

Journal of Thermal Analysis and Calorimetry - Simple and environment-friendly recovery of valuable metals from spent LIBs was explored. The experimental method, which included reduction roasting...     

Sulfonylation from sodium dithionite or thiourea dioxide

The cheap and easily available sodium dithionite and thiourea dioxide have been used as the source of sulfonyl group in the synthesis of sulfones and sulfonamides recently.Compared with other methods for the sulfonylation reactions,the strategies using sodium dithionite or thiourea dioxide provide an alternative and complementary route to diverse sulfonyl compounds.During the reaction process,sulfur dioxide anion radical is the key intermediate,which is usually generated from a single electron transfer under suitable conditions.The advantages using sodium dithionite or thiourea dioxide in the sulfonylation reactions include mild conditions and broad substrate scope with excellent functional group compatibility.Further applications by using sodium dithionite and thiourea dioxide in organic transformations will be anticipated.     

Synthesis of Tadalafil Analogues

Five novel compounds as potential phosphodiesterase type 5 (PDE‐5) inhibitors were synthesized from D‐tryptophan methyl ester via the Pictet–Spengler reaction and cyclization reaction. The structures of those compounds were confirmed by elemental analyses, IR, ¹H NMR, and ESI‐MS spectra.     

A Benzylation Study of 2,3-Dichloronaphthazarin

Depending on different reaction time and temperature employed, benzylation of 2,3-dichloronaphthazarin (I) using silver oxide as the catalyst can form either exclusively 5,8-dibenzyloxy-6,7-dichloronaphthalene-1,4-dione (II), or exclusively 5-benzyloxy-2,3-dichloro-8-hydroxynaphthalene-1,4-dione (IV); or a mixture of II and 5,8-dibenzyloxy-2,3-dichloronaphthalene-1,4-dione (III). Structures of these compounds were identified by nmr analysis.     

STUDIES ON CYCLOADDITION REACTIONS OF VINYLPHOSPHONATES WITH NITRONES

Cycloaddition reactions of vinylphosphonates with nitrones were studied. A series of 4-phosphonyl-3-aryl-N-arylisoxazolidines were synthesized by the reaction of vinylphosphonates with nitrones. The structure of 3a was confirmed by X-ray single-crystal diffraction.     

Synthesis of fluorine-substituted [2.2]paracyclophane-based carbene precursors for copper-catalyzed enantioselective boration of α,β-unsaturated ketones

Fluorine-substituted [2.2]paracyclophane-based carbene precursors have been successfully synthesized and applied to copper-catalyzed asymmetric β-boration of α,β-unsaturated ketones. Fluorination of the planar chiral carbenes has a beneficial impact on the catalytic performance of the relevant complexes. A variety of chiral β-boryl ketones were obtained in excellent yields (up to 99%) and with high enantioselectivities (up to 99% ee).