Isolation and bioactive evaluation of flavonoid glycosides from Lobelia chinensis Lour using two-dimensional liquid chromatography combined with label-free cell phenotypic assays.

Flavonoid glycosides are widespread in herbs and often used as medicines and nutraceuticals because of good bioactivities and low toxicities. However, due to their structural complexity and diversity, isolation of flavonoid glycosides and evaluation of their bioactivities are still highly challenging. To solve this problem, a new method for separation and preparation of novel flavonoid glycosides from Lobelia chinensis Lour (L.

[Preparation of macroporous silica and its application on polysaccharide derivative based chiral stationary phase].

In order to prepare 100-nm macroporous silica, spherical silica (5 μm in particle size, 10 nm in pore diameter) was treated by hydrothermal or baking methods. During hydrothermal treatment, 22 g/L NaF was added, which efficiently promoted the enlargement of pore diameters. By this method, the average pore diameter of silica reached 100 nm after heating for 48 h at 160℃ in an autoclave, but showed a poor size distribution.

Qualitative and quantitative analysis of an alkaloid fraction from Piper longum L. using ultra-high performance liquid chromatography-diode array detector-electrospray ionization mass spectrometry.

In a previous research, an alkaloid fraction and 18 alkaloid compounds were prepared from Piper longum L. by series of purification process. In this paper, a qualitative and quantitative analysis method using ultra-high performance liquid chromatography-diode array detector-mass spectrometry (UHPLC-DAD-MS) was developed to evaluate the alkaloid fraction.

[Fast analysis of indole alkaloids from Evodiae fructus by supercritical fluid chromatography].

A fast chromatographic separation of indole alkaloids from Evodiae fructus was developed by supercritical fluid chromatography (SFC). The initial screening of four stationary phases was investigated with a standard mixture of evodiamine and rutaecarpine, and a complex sample of indole alkaloids prepared from Evodiae fructus as probes. Later, the effects of chromatographic parameters on separation were studied including injection volume, organic modifier, additive, temperature and back pressure.

Alkaloids analysis using off-line two-dimensional supercritical fluid chromatography × ultra-high performance liquid chromatography.

In this study, an off-line two-dimensional (2-D) supercritical fluid chromatography (SFC) × ultra-high performance liquid chromatography (UHPLC) method with high orthogonality was developed for the analysis of the practical amide alkaloids fraction from P. longum L. The effects of SFC parameters such as column type, organic modifier, temperature and back-pressure on separation were systematically evaluated.

A novel ionic-bonded cellulose stationary phase for saccharide separation.

A hydrophilic interaction liquid chromatography (HILIC) stationary phase of cellulose-coated silica was synthesized as a novel saccharide separation material. The material, prepared with a method based on ionic interaction, was demonstrated to be efficient for immobilization of saccharides on silica supports. The method is more efficient than traditional immobilized saccharide stationary phase synthesis methods.

Purification of amide alkaloids from Piper longum L. using preparative two-dimensional normal-phase liquid chromatography × reversed-phase liquid chromatography.

A comprehensive off-line two-dimensional liquid chromatography (2D-LC) method coupling normal phase liquid chromatography (NPLC) and reversed phase liquid chromatography (RPLC) was developed for separation and purification of amide alkaloids from Piper longum L. In the first dimension, the crude alkaloid fractions were separated in NPLC mode and 20 fractions were collected. Then fractions 5-20 were selected for further purification in RPLC mode in the second dimension.

Investigation of peptoid chiral stationary phases varied in absolute configuration.

Based on chiral N-(1-phenylethyl) glycines, a series of peptoid chiral stationary phases (CSPs) terminated with achiral alkyl group (diisopropyl, t-butyl or n-butyl) and varied in absolute configuration of selector were investigated with nine axially chiral analytes. It is very interesting to observe that selectors with heterogeneous configuration form, such as S-R-R, S-R-S, S-S-R, generally performed better than S-S-S selectors. Moreover, longer S-R-S-R-S selector did not outperform the S-R-S one obviously, with several separations declined.

Improvement of peptoid chiral stationary phases by modifying the terminal group of selector.

The role of a terminal group of a peptoid selector in a chiral separation was investigated. Six chiral stationary phases (CSPs) with the terminal groups replaced by achiral alkyl groups (n-butyl, t-butyl and diisopropyl) and chiral groups ((1R, 2R)-2-aminocyclohexyl phenylcarbamate, N'-phenyl-L-proline amide and N'-phenyl-L-leucine amide) were synthesized. Achiral terminal groups with different steric hindrances did not broaden the enantioselectivity, but improved the separation factors for some analytes, probably due to the improvement of interactions between the analytes and peptoid chain.

Preparation of a stationary phase with quaternary ammonium embedded group for selective separation of alkaloids based on ion-exclusion interaction.

A stationary phase (named QA C10) with quaternary ammonium embedded between a propyl and a decyl chain was synthesized by immobilization of N,N-dimethyldecylamine on chloropropyl-silica surface. A set of representative neutral, basic, and acidic compounds was employed to evaluate its chromatographic properties. The results illustrated that QA C10 was a mixed-mode stationary phase possessing both hydrophobic and ionic characteristics.

Combination of off-line two-dimensional hydrophilic interaction liquid chromatography for polar fraction and two-dimensional hydrophilic interaction liquid chromatography×reversed-phase liquid chromatography for medium-polar fraction in a traditional Chinese medicine.

Two-dimensional liquid chromatography (2-D LC) has been widely used for the analysis of complex samples owing to its great improvement in separation selectivity and peak capacity. However, one 2-D LC system may not be enough to meet the separation requirements due to the complexity of certain samples and respective limitations of two separation modes. In this work, water extract of Scutellaria barbata D.