Publications by authors named "Niusheng Xu"

Characterizing major bovine milk proteins, including whey and casein, is of significant interest in the dairy industry. The diverse array of protein proteoforms can be different in terms of genetic variation, breed ways, lactation stage, and animal nutritional status. Current routine methods for bovine milk protein profiling are typically based on immunological techniques, infrared spectroscopy, slab gel isoelectric focusing, capillary electrophoresis, and high-performance liquid chromatography.

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The presence of veterinary drug and pesticide residues in food products pose considerable threats to human health. Monitoring of these residues in food is mainly carried out using targeted analysis by triple quadrupole mass spectrometry. However, these methods are not suitable for suspect screening and untargeted analysis of unknowns.

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Synthetic cannabinoids (SCs) are new psychoactive substances that function as endocannabinoid CB1 and CB2 receptor agonists. Abuse of SCs can lead to symptoms such as confusion, dizziness, and even death. At present, Synthetic cannabinoids constitute one of the largest groups of new psychoactive substances and become popular recreational drugs of abuse for their psychoactive properties.

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Xiaokewan is a typical Traditional Chinese medicine (TCM) for diabetes and contains various natural chemicals, such as lignans, flavonoids, saponins, polysaccharides, and western medicine glibenclamide. In the current study, a highly efficient system for screening hypoglycemic efficacy constituents of Xiaokewan has been developed with the integration of intelligent data acquisition, data mining, network pharmacology, and computer assisted target fishing. With the combination of background exclusion data dependent acquisition (BE-DDA) and non-targeted precise-and-thorough background-subtraction (PATBS) techniques, a novel workflow has been established for the non-targeted recognition and identification of TCM constituents in vivo, and has been applied to the exposure study of Xiaokewan in rat.

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Conventional strategies for the screening of DNA triplex binders cannot be used for complicated samples, such as ligand libraries created by combinatorial chemistry or from natural product extracts. In the current study, an ultra-high-performance liquid chromatography coupled with an Orbitrap mass spectrometry (UHPLC-Orbitrap-MS)-based approach, which we call peak area-fading (PAF) UHPLC-Orbitrap-MS and was designed for just such a purpose, is reported. The triplex DNA modified 96-well plate and the single stranded oligonucleotide modified 96-well plate (as control) were incubated with ligand libraries, and the unbound ligands were directly determined via UHPLC-ESI-MS.

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Notoginsenoside Fc (NGFc) is a protopanaxadiol-type (PPD-type) saponin from Panax notoginseng, which has perfect anti-platelet aggregatory effect. However, its pharmacokinetics and metabolism in vivo remain unknown. In this study, a simple and sensitive liquid chromatography/electrospray ionization tandem mass spectrometry (LC-MS/MS) method was first developed for the determination of NGFc in rat plasma.

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A new method using TurboFlow on-line cleanup liquid chromatography combined with tandem mass spectrometry (MS/MS) has been developed for simultaneous determination of six progesterones including 19-norethindrone, 17alpha-hydroxyprogesterone, medroxyprogesterone, megestrol acetate, progesterone and melengestrol acetate in milk. Samples were extracted by acetonitrile. The analytes in extract were on-line purified directly on Cyclone-P purification column where the sample matrices were washed away.

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In this study, electrospray ionization mass spectrometry (ESI-MS) was used to investigate the binding interaction of six alkaloids with parallel intermolecular G-quadruplex [d(TGGGGT)](4), and five alkaloids including berberine, jatrorrhizine, palmatine, tetrandrine, and fangchinoline showed complexation with the target DNA. Relative binding affinities were estimated on the basis of mass spectrometric data. The slight differences in chemical structures of berberine, jatrorrhizine, and palmatine had little influence on their binding affinities to [d(TGGGGT)](4).

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A novel ligand fishing assay was established to screen triplex DNA binders from complicated samples by a combination of immobilization of triplex DNA on agarose beads and high-performance liquid chromatography-electrospray ionization-mass spectrometry (HPLC-ESI-MS). The biotinylated oligodeoxynucleotides were first bound to the streptavidin agarose beads and then incubated with the duplex DNA as the baits for ligand fishing. This assay was validated by the testing ligand library consisting of coralyne, ethidium bromide, vitexin, and formononetin.

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