Acetonitrile extraction coupled with UHPLC-MS/MS for the accurate quantification of 17 heterocyclic aromatic amines in meat products.

This study proposed a simple and accurate acetonitrile extraction pretreatment method coupled with ultrahigh-performance liquid chromatography with tandem mass spectrometry for the simultaneous determination of 17 heterocyclic aromatic amines (HAAs) in meat products. With this new method, all 17 HAAs, including 11 polar and 6 nonpolarHAAs, were simultaneously extracted by acetonitrile and purified by one-step Oasis MCX cartridge purification. Compared with two different improved reference methods, the acetonitrile method could obtain higher recoveries (in the range of 42.

Investigating the inhibitory activity and mechanism differences between norartocarpetin and luteolin for tyrosinase: A combinatory kinetic study and computational simulation analysis.

Flavonoids are an important type of natural tyrosinase inhibitor, but their inhibitory activity and mechanism against tyrosinase are very different because of their different structures. In this study, the inhibitory activity and mechanism differences between norartocarpetin and luteolin for tyrosinase were investigated by a combination of kinetic studies and computational simulations. The kinetic analysis showed that norartocarpetin reversibly inhibited tyrosinase in a competitive manner, whereas luteolin caused reversible noncompetitive inhibition.

A novel isoflavone profiling method based on UPLC-PDA-ESI-MS.

A novel non-targeted isoflavone profiling method was developed using the diagnostic fragment-ion-based extension strategy, based on ultra-high performance liquid chromatography coupled with photo-diode array detector and electrospray ionization-mass spectrometry (UPLC-PDA-ESI-MS). 16 types of isoflavones were obtained in positive mode, but only 12 were obtained in negative mode due to the absence of precursor ions. Malonyldaidzin and malonylgenistin glycosylated at the 4'-O position or malonylated at the 4″-O position of glucose were indicated by their retention behavior and fragmentation pattern.

Simultaneous analysis of PhIP, 4'-OH-PhIP, and their precursors using UHPLC-MS/MS.

A novel method allowing simultaneous analysis of PhIP, 4'-OH-PhIP, and their precursors (phenylalanine, tyrosine, creatine, creatinine, glucose) has been developed as a robust kinetic study tool by using ultra high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). A direct hydrochloric acid (HCl) extraction was applied to achieve the simultaneous extraction of all seven analytes, with the mean recoveries ranging from 60% to 120% at two concentration levels. Then, an Atlantis dC18 column selected from four different chromatographic columns was ultimately used to separate these compounds within 15 min.

Preparation of human milk fat substitutes from palm stearin with arachidonic and docosahexaenoic acid: combination of enzymatic and physical methods.

Human milk fat substitutes (HMFSs) were prepared by a two-step process, namely, Lipozyme RM IM-catalyzed acidolysis of interesterified high-melting palm stearin with fatty acids from rapeseed oil and blending of the enzymatic product with the selected oils on the basis of the calculation model. The optimum conditions for the enzymatic reaction were a mole ratio of palm stearin/fatty acids 1:10, 60 °C, 8% enzyme load (wt % of substrates), 4 h, and 3.5% water content (wt % of enzyme); the enzymatic product contained 39.

Detoxification and degradation of microcystin-LR and -RR by ozonation.

In the present study, two Microsystins (MCs) of Microcystin-LR and Microcystin-RR were degraded with different dosages of ozone (O(3)). The possible degradation pathways were elucidated by analyzing their intermediates and end-products with liquid chromatography-mass spectrometry (LC-MS) method. The toxicity of the MCs ozonation products was also evaluated by assaying the protein phosphatase inhibition in vitro and acute toxicity in vivo.

A myxobacterium strain Sorangium cellulosum AHB125 producing epothilone B and other anticancer substances.

A myxobacterium strain AHB125 belonging to genus Sorangium cellulosum was isolated from Anhui area in China and identified with morphological analysis by electron microscopy and phase contrast microscope according to Bergey's manual of systematic bacteriology (8th Ed.). Its high-antitumor bioactivity metabolites was evaluated by bioassay-directed screening technique with B16 tumor cell line etc.

[Analysis of mannoligosaccharides by liquid chromatography-electrospray ionization mass spectrometry].

Oligosaccharide characterization has been of utmost interest in various areas such as medicine, biochemistry, and food chemistry. These biologically relevant molecules are ideally suited for mass spectrometric investigation, because of the capability of this technique in offering structure and relative molecular mass information. Therefore, liquid chromatography-electrospray ionization mass spectrometry (LC-ESI-MS) was applied to characterize the acetolysis of mannan from Saccharomyces cerevisiae.