Separation of alkamides from Echinacea purpurea extracts by cyclodextrin-modified micellar electrokinetic chromatography

Dodeca-2(E),4(E)-dienoic acid isobutylamide enhances glucose uptake in 3T3-L1 cells via activation of Akt signaling

Dodeca-2(E),4(E)-dienoic acid isobutylamide (DDI), an alkamide derived from the plant Echinacea purpurea, promotes adipocyte differentiation and activates peroxisome proliferator-activated receptor γ, which is associated with enhanced insulin sensitivity. In the present study, we investigated whether DDI may increase glucose uptake through activation of the insulin signaling pathway in 3T3-L1 adipocytes. DDI increased insulin-stimulated glucose uptake, and expression and translocation of glucose transporter 4 in adipocytes treated with sub-optimal levels of insulin. Additionally, DDI enhanced Akt phosphorylation, whereas phosphoinositide 3-kinase/Akt inhibitors suppressed DDI-induced glucose uptake. These results suggest that DDI may improve insulin sensitivity through the activation of Akt signaling, which leads to enhanced glucose uptake.

Echinacea purpurea root extract enhances the adipocyte differentiation of 3T3-L1 cells

Echinacea purpurea has been shown to have anti-diabetic activities; for example, it activates peroxisome proliferator-activated receptor γ (PPARγ) and increases insulin-stimulated glucose uptake. Adipogenesis has been used to study the insulin signaling pathway and to screen anti-diabetic compounds. The present study was conducted to investigate the effects of an ethanol extract of E. purpurea (EEEP) and its constituents on the insulin-induced adipocyte differentiation of 3T3-L1 preadipocytes. When adipocyte differentiation was induced with insulin plus 3-isobutyl-1-methylxanthine and dexamethasone, the accumulation of lipid droplets and the cellular triglyceride content were significantly increased by EEEP. The expressions of PPARγ and C/EBPα in adipocytes treated with EEEP were gradually increased as compared with control cells. Fat accumulation and triglyceride content of adipocytes treated with dodeca-2(E),4(E)-dienoic acid isobutylamide were significantly increased as compared with control cells. The expressions of PPARγ and C/EBPα in adipocytes treated with dodeca-2(E),4(E)-dienoic acid isobutylamide were significantly higher than in control cells. These results suggest EEEP promotes the adipogenesis that is partially induced by insulin and that dodeca-2(E),4(E)-dienoic acid isobutylamide appears to be responsible for EEEP-enhanced adipocyte differentiation.

Separation of very hydrophobic analytes by micellar electrokinetic chromatography. III. Characterization and optimization of the composition of the separation electrolyte using carbon number equivalents

Four coefficients are suggested to characterize the separation properties of separation electrolytes in MEKC. These coefficients are the electrophoretic mobility of the pseudostationary phase (PSP), the electroosmotic mobility, and two parameters which can be obtained via the Martin equation using the retention data of the members of a suitable homologous series. These four coefficients are used for the characterization of separation electrolytes applicable to the separation of very hydrophobic analytes (log P(OW) = 3-4) with SDS as PSP and to quantitatively describe the influence of the buffer additives ACN and urea for the fine-tuning of retention factors and the additive calcium chloride for the fine-tuning of the width of the migration time window. Together with carbon number equivalents (N*(C)) as analyte descriptors the suggested coefficients provide a tool for the fast optimization of the composition of the separation electrolyte. The proposed method optimization scheme is applied to the separation of ingredients of essential oils. Predicted resolutions are compared to experimental results.

Study on separation of aristolochic acid I and II by micellar electrokinetic capillary chromatography and competition mechanism between SDS and β-cyclodextrin

In this study, a rapid MEKC method using 40 mM sodium borate buffer containing 50 mM SDS as surfactant was developed for the analysis of aristolochic acid (AA) in Aristolochia plants. Baseline separation of AA-I and AA-II was achieved within 3 min with high separation efficiency, satisfactory sensitivity, repeatability, and recovery. Resolution between AA-I and AA-II is above 5 and great performance with higher than 200,000 theoretical plate numbers was obtained. The detection limits (based on 3 S/N) were both 1.0 microg/mL. Two kinds of AA in 35 herbal samples of Aristolochia plants were successfully determined. The competition mechanism between beta-CD and SDS was also investigated by changing the content ratio of beta-CD and SDS.

Rapid separation and determination of resibufogenin and cinobufagin in toad venom and Liushen tablet by beta-cyclodextrin modified micellar electrokinetic chromatography

A rapid cyclodextrin modified micellar electrokinetic chromatography (CD-MEKC) method was proposed for the determination of resibufogenin and cinobufagin in the Chinese herbal extracts from toad venom and its medicinal preparation (Liushen tablet). The two components have the close structural similarity and similar hydrophobicity, which result in poor resolution in normal MEKC. The addition of neutral beta-CD to the MEKC system was found to improve the separation of the studied compounds. The effects of several CD-MEKC parameters on the resolutions were evaluated systematically. Based on the investigation, a background electrolyte solution consisting of 10 mM borate buffer adjusted to pH 8.5, 40 mM sodium dodecyl sulfate (SDS), 12 mM beta-CD and 10% (v/v) of methanol was found to be optimal conditions for the fast separation. The contents of resibufogenin and cinobufagin were successfully determined within 5 min, with satisfactory repeatability and recovery.

High-resolution method for regulatory control of Echinacea species in Nutraceuticals by CD-MEKC

One problem in the international regulatory control of Echinacea, a therapeutic Nutraceutical, is recognition of caffeoyl solutes and alkamides in different products. Cyclodextrin-modified micellar electrokinetic chromatography (CD-MEKC) has been applied to Echinacea spp. in combination with pattern recognition of some caffeoyl solutes. A novel metric based on relative migration time (RMT) data has been developed in CE to address the problem of variable reported migration time. The CD-MEKC method of Gotti's group using hydroxypropyl-beta-cyclodexrin (HP-beta-CD; 100 mM) with sodium dodecyl sulphate (SDS; 110 mM), in a triacid background electrolyte (10 mM, pH 8) under 19 kV was adapted to identify two key hydrophilic solutes: chlorogenic acid and cichoric acid present in all commercial products. Two internal markers were taken as reference points to calculate the RMT of any target peak: RMT=t(m (target))/t(m (marker)). The RMT method was robust to temperature change from 20 to 40 degrees C, but sensitive to pH. The lateral shift and reproducibility of the target peak t(m (target)) were significantly reduced by this novel transformation. In the worst cases migration time variability ranged up to 12% (n=6); the RMT algorithm reduced this to less than 1%. In general, the RMT transformation reduced the variability of migration time data by a factor of 2-5. For systematic comparison of electrophoretic profiles for test sample and standard, a new pattern recognition algorithm permits sequential peak-by-peak comparison using specified segments of the electropherograms for comparison of test and Echinacea purpurea (root product) as a standard. This algorithm was capable of rapidly characterising the similarity of target peaks in a test sample relative to those in the reference standard. Combination of the RMT algorithm and pattern recognition in CE is expected to offer a robust approach to international regulatory characterisation and control of Nutraceuticals.