Magnetic conjugated microporous polymer for rapid extraction and sensitive analysis of environmental endocrine disruptors in environmental waters and dairy products.

Background: Environmental endocrine disruptors (EEDs) are a class of new pollutants that are diffusely used in the medical industry and animal husbandry. In view of toxicity concerns, elevated levels of EEDs in the environment and food, which cause potential harm to human beings and ecosystems, must be monitored. Determination of EEDs contaminants to ensure environment and food safety has became a major concern worldwide, it is also a challenging task because of their trace level and probable matrices interference.

Application of magnetic N-doped carbon nanotubes in solid-phase extraction of trace bisphenols from fruit juices.

Magnetic N-doped carbon nanotubes were firstly applied as adsorbent in food analysis for pre-concentration of bisphenols in fruit juices followed by ultra-high performance liquid chromatography-tandem mass spectrometry determination. The magnetic nanoparticles were characterized by X-ray diffraction, infrared spectroscopy, scanning electron microscopy and vibrating sample magnetometer. The adsorption conditions were further optimized by response surface methodology.

Three novel indole alkaloids from Kopsia officinalis.

Three new indole alkaloids, named kopsioffines A-C (1-3), possessing relatively novel ten-membered lactam ring, and one known compound (11,12-demethoxy-16-deoxypauciflorine, 4) were isolated from the leaves and stems of Kopsia officinalis. Their structures were elucidated by means of spectroscopic methods. The absolute configuration of 1 was determined by calculated electronic circular dichroism data.

Melaxillines A and B, monoterpenoid indole alkaloids from Melodinus axillaris.

Two new monoterpenoid indole alkaloids, melaxillines A (1) and B (2), together with four known alkaloids (3-6), were isolated from the roots of Melodinus axillaris. The structures were determined by extensive spectroscopic methods, including 1D and 2D-NMR spectroscopy, high resolution mass spectrometric data, and by comparison to literature data. New compounds 1-2 might be derived from a common precursor (3) by proposing their biogenetic route, and compound 1 represents the first Melodinus alkaloid featuring an ethyl acetate group skeleton at C-18.

Large-scale separation of alkaloids from Gelsemium elegans by pH-zone-refining counter-current chromatography with a new solvent system screening method.

A rapid and simple solvent system screening method was developed for pH-zone-refining counter-current chromatography (CCC) separation, which was much easier to find a suitable solvent system than the traditional method. Using this method, an optimal solvent system composed of hexane-ethyl acetate-methanol-water (3:7:1:9, v/v) was selected for pH-zone-refining CCC separation of alkaloids from the stems of Gelsemium elegans, where 10mM triethylamine (TEA) was added to the upper organic stationary phase as a retainer and 10mM hydrochloric acid (HCl) to the aqueous mobile phase as an eluter. As a result, six oxindole alkaloids, 420mg 19-xo-gelsenicine, 456mg gelsemine, 723mg koumine, 379mg 11-methoxygelsemamide, 342mg gelsenicine and 318mg humantenine were successfully purified in one step from 4.