Hydroxyl groups introducing NMR strategy for structural elucidation of a heptasaccharide isolated from Trillium tschonoskii.

A heptasaccharide was isolated from an active fraction of Trillium tschonoskii using HILIC and high-temperature PGC chromatography methods. UHPLC-Q/TOF-MS analysis gave this oligosaccharide a degree of polymerization (DP) of 7 and MS/MS showed that it has a six-carbon aldehyde glucan structure with the possible chain 1 → 4 connected. The structure was determined by series 1D and 2D NMR in two solvents DO and DMSO‑d.

Abundance of Modifications in Mature miRNAs Revealed by LC-MS/MS Method Coupled with a Two-Step Hybridization Purification Strategy.

Accurate detection of endogenous miRNA modifications, such as N6-methyladenosine (mA), 7-methylguanosine (mG), and 5-methylcytidine (mC), poses significant challenges, resulting in considerable uncertainty regarding their presence in mature miRNAs. In this study, we demonstrate for the first time that liquid chromatography coupled with a tandem mass spectrometry (LC-MS/MS) nucleoside analysis method is a practical tool for quantitatively analyzing human miRNA modifications. The newly designed liquid-solid two-step hybridization (LSTH) strategy enhances specificity for miRNA purification, while LC-MS/MS offers robust capability in recognizing modifications and sufficient sensitivity with detection limits ranging from attomoles to low femtomoles.

Structure characterization and immunomodulatory activity of a polysaccharide from Saposhnikoviae Radix.

A new polysaccharide, named SP800201 with Mw of 2.17 × 10 g/mol, was isolated from Saposhnikoviae Radix. The monosaccharide composition of SP800201 mainly contained Gal, GalA, Ara, and Rha.

Quantification of alcohols, diols and glycerol in fermentation with an instantaneous derivatization using trichloroacetyl isocyanante via liquid chromatography-massspectrometry.

A sensitive LC-MS/MS method was established to quantify diols and glycerol in fermentation broth using trichloroacetyl isocyanate as instantaneous derivatization reagent for monitoring the production of 1,3-propanediol and 2,3-butanediol from the biodiesel biorefinery process. Due to the derivatization reaction was very quickly at room temperature, only 1 min was needed for the reaction process. In addition, both extraction of analytes and evaporation of water were not employed in the analytical procedure.

Synthesis and evaluation of panaxatriol derivatives as Na, K-ATPase inhibitors.

Panaxatriol, a triterpene bearing a steroid-like structure similar to cardiac glycosides, was presumed to share the same bioactivity with cardiac glycosides, and may be a potential Na, K-ATPase inhibitor. In this paper, a series of panaxatriol derivatives were synthesized and evaluated for Na, K-ATPase inhibitory activities. The results of biological tests showed that more than half of the synthesized derivatives presented increased inhibitory activities compared with panaxatriol.

Structurally Diverse Cytotoxic Dimeric Chalcones from Oxytropis chiliophylla.

Ten isomeric cyclobutane- and cyclohexene-containing chalcone dimers, oxyfadichalcones A-G, were isolated from the aerial parts of Oxytropis chiliophylla. These included six new compounds and three pairs of enantiomers that are being reported from natural sources for the first time. The relative configurations were elucidated by spectroscopic data analysis, while the absolute configurations were determined by comparing the experimental and calculated electronic circular dichroism spectra.

A potential mechanism for degradation of 4,5-dichloro-2-(n-octyl)-3[2H]-isothiazolone (DCOIT) by brown-rot fungus Gloeophyllum trabeum.

This study aims to investigate the biodegradation of 4,5-dichloro-2-(n-octyl)-3[2H]-isothiazolone (DCOIT) by a brown-rot fungus Gloeophyllum trabeum as well as the involved mechanism. In the present study, the retentions of DCOIT in treated Masson pine (Pinus massoniana) (MP) chips were determined periodically after incubation with G. trabeum.

Selective elimination of the free fatty acid fraction from esterified fatty acids in rat plasma through chemical derivatization and immobilization on amino functionalized silica nano-particles.

A high throughput and low cost approach to separate free fatty acids (FFAs) from phospholipid and acylglycerols (esterified fatty acids, EFAs) has been demonstrated, which may be widely used as a sample preparation method in the metabolomics and lipid research. The optimal conditions for FFAs reacting with N-hydroxysuccinimide (NHS) only need 10min at room temperature to obtain a 93.5% yield of FFAs-NHS ester.

Pd-loaded magnetic mesoporous nanocomposites: A magnetically recoverable catalyst with effective enrichment and high activity for DDT and DDE removal under mild conditions.

1,1,1-Trichloro-2,2-bis(4-chlorophenyl) ethane (DDT), an organochlorine pollutant, is highly persistent in environment and responsible for many ecological and health damages. Although remediation and degradation of DDT and its metabolites in soil and water by microorganisms and abiotic techniques can be accomplished, success is often accompanied by rigorous reaction conditions, such as anaerobic system, explosive gases, high pressure or temperature, and illumination. Here a triple-functional nanocomposite was prepared by integrating superparamagnetic Fe3O4 and palladium (Pd) nanoparticles onto mesoporous Fe3O4@nSiO2@mSiO2 nanospheres.

New Lignans and Iridoid Glycosides from Dipsacus asper Wall.

Six new compounds, including four new lignans, dipsalignan A (1), B-D (3-5), and two new bis-iridoid glycoside dimmers, dipsanosides M (7) and N (8), together with two known compounds (2) and (6), have been isolated from the roots of Dipsacus asper Wall. Their structures were established on the basis of spectroscopic data (MS, 1D, 2D NMR, and CD) and chemical methods. All the isolated compounds were tested against human immunodeficiency virus-1 (HIV-1) integrase inhibition activities, and only compounds 1, 2, 7, and 8 displayed weak activities.

A novel matrix additive, MCM-41-type mesoporous silica nanoparticles, used for analysis of peptides by MALDI-FT/ICRMS.

Matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) was thought to be unsuitable for the analysis of low-molecular-weight species since matrix peak noise made it difficult to identify analyte ions. In this study, MCM-41-type mesoporous silica nanoparticles (MSNs) were used as a matrix additive with saturated 2,5-dihydroxybenzoic acid (DHB) or α-cyano-4-hydroxycinnannic acid (CHCA) solution for the analysis of six peptides of a wide range molecular weight, Leu-Val, Phe-Val, Lue-Phe, bradykinin fragment 1-7, angiotensin II and ACTH fragment 18-39. It was shown that MSNs were capable of reducing matrix peaks with laser power lower than 34% of saturated DHB especially for low polarity analyte or CHCA especially for high polarity analyte with molecular weight less than 500 regardless of the analyte-to-matrix ratio.

[IR search through Internet].

In our laboratories, we have almost had the complete Sadtler IR database, about 133,000 spectra. Based on Sadtler IR Search Master software, off-line spectrum search through internet has been set up in this work. Customers e-mail their unknown spectra as attached files to ftir2000@sina.

HPLC and MS Studies of Orientation of Melittin on Phospholipid Membrane.

The orientation of melittin binding to liposomes with or without transmembrane potential was investigated. With a combination of high performance liquid chromatography and mass spectrometry, the membrane association state of melittin was detected by analyzing its trypsin-digested products. It was found that the enzyme could access all the proteolytic sites on protein binding to the liposome without membrane potential, while one proteolytic site on the N-terminal of the protein was blocked after it binding to the liposome with negative transmembrane potential.

NMR determination of the structure of Julibroside J1.

Julibroside J1 is a new triterpenoid saponin which contains one triterpene, two monoterpenes and nine sugar residues. The structure has been determined almost exclusively by high-resolution NMR methods. The 1H and 13C NMR spectra of Julibroside J1 C5D5N have been assigned by homonuclear and heteronuclear correlation experiments, such as COSY, CH-COSY, TOCSY, HMBC, HMQC-COSY, HMQC-TOCSY and NOESY.