Xue-Hong Zhang

A novel molecularly imprinted polymer of the specific ionic liquid monomer for selective separation of synephrine from methanol-water media

A novel molecularly imprinted polymer (MIP) using the specific ionic liquid (i.e. 1-vinyl-3-carboxymethylimidazolium bromide, 1-vinyl-3-carboxyethylimidazolium bromide, 1-viny-3-carboxybutylimidazolium bromide, or 1-vinyl-3-carboxypentylimidazolium bromide) as functional monomer was prepared via precipitation polymerization, which can be used to selectively separate synephrine (SYN) from methanol-water media. Ionic liquids are facile to be designed with varying the cation or anion, which enables the specific ionic liquid to be effectively designed to be a functional monomer for the preparation of MIP. The MIP showed a good selectivity and high adsorption capacity for SYN in methanol-water media. The adsorption process could be described by the pseudo-first-order model, which meant that the adsorption kinetics described a diffusion-controlled process. The equilibrium data fitted well to the Freundlich model, indicating multilayer adsorption. Finally, the MIP were successfully applied as sorbent to selectively enrich and separate SYN from the extracts of Aurantii Fructus Immaturus with a relatively high recovery (80-90%).

Optimization of ionic liquid based ultrasonic assisted extraction of puerarin from Radix Puerariae Lobatae by response surface methodology

Ionic liquid (IL) based ultrasonic assisted extraction (ILUAE) was developed for the effective extraction of puerarin from Radix Puerariae Lobatae (RPL). The ILUAE parameters including the type of ILs, IL concentration, RPL amount, ultrasonic power and time were optimized by single-factor experiment and response surface methodology. Under the optimized experimental conditions, the best results were obtained using RPL amount 0.43 g in 10 mL 1.06 molL(-1) 1-butyl-3-methylimidazolium bromide aqueous solution, ultrasonic time 27.43 min and ultrasonic power 480 W. Scanning electron microscope images of RPL samples were obtained to provide visual evidence of the sonication effect. Compared with the conventional ultrasonic assisted extraction and refluent extraction, the proposed ILUAE offered shorter extraction time and remarkable higher efficiencies due to the higher penetration ability and solubility of IL and the cavitation phenomenon produced in the solvent by the passage of an ultrasonic wave, which further supported the suitability of the proposed approach.

Molecularly imprinted polymers for selective extraction of synephrine from Aurantii Fructus Immaturus

AbstractIn this work, molecularly imprinted solid-phase extraction (MISPE) has been used to selectively enrich, purify, or remove synephrine from Aurantii Fructus Immaturus. To this end, a molecularly imprinted polymer (MIP) was prepared by self-assembly from the template synephrine, the functional monomer methacrylic acid, and the crosslinker ethylene glycol dimethacrylate in 1:4:20 molar ratio. Subsequent molecular interrogation of the MIP binding sites revealed preferential structural selectivity for synephrine relative to other structurally related naturally occurring compounds (i.e. octopamine and tyramine ). This selectivity was subsequently exploited to achieve substantial sample clean-up of extracts of crude Aurantii Fructus Immaturus and Aurantii Fructus Immaturus stir-baked with bran. The purity of synephrine in the extracts after MISPE represented approximately 24.21-fold enrichment of the synephrine in the untreated extracts of Aurantii Fructus Immaturus stir-baked with bran. High recoveries (85–90%) from the samples proved that the method was valid for selective enrichment, purification, or removal of synephrine from Aurantii Fructus Immaturus. FigureThe Molecularly imprinted polymers for the selective extraction of synephrine

Extraction of Puerarin using Ionic Liquid Based Aqueous Two-Phase Systems

Various ionic liquid-based aqueous two-phase systems (IL-ATPS) were evaluated to extract puerarin. The results indicated that the nature of ILs, the salting-out ability of salt, and the acidity and basicity of the salt-rich solution had important influence on the extraction efficiency. Various factors were optimized systematically, that is, the amount of IL, salt, puerarin, and short-chain alcohol. Under the optimal experimental conditions (the amount of K2HPO4 0.30–0.42 g/mL, [Bmim]Br 0.30–0.36 g/mL and 1.0 mL puerarin stock solution), the extraction efficiency of puerarin was over 99% by a single-step extraction, which indicated that the evaluated IL-ATPS was a prospective extraction medium. Finally, the IL-ATPS was successfully used to extract puerarin from Radix Puerariae Lobatae extracts.

SEPARATION OF THREE TRITERPENE ACIDS IN LEAVES OF DIOSPYROS KAKI BY HIGH PERFORMANCE LIQUID CHROMATOGRAPHY USING HYDROXYPROPYL-β-CYCLODEXTRIN AS MOBILE PHASE MODIFIER

An improved high-performance liquid chromatography method for the separation and determination of rotungenic acid and two isomeric triterpene acids (oleanolic acid and ursolic acid) was developed. Results proved that these triterpene acids can be separated with high resolution by adding hydroxypropyl-β-cyclodextrin (HP-β-CD) into the mobile phase; the resolution of the triterpene acids increased and their retention time in the column decreased with HP-β-CD concentrations increasing due to the formation of inclusion complexes between triterpene acids and HP-β-CD. The formation of 1:1 inclusion complexes was assumed and apparent formation constants of triterpene acids with HP-β-CD were determined experimentally at 20°C and 35°C. At last, the method was used to determine rotungenic acid, oleanolic acid, and ursolic acid in the leaves of Diospyros kaki and proved to be sensitive, rapid, accurate, and suitable.

Ultrasonic assisted extraction of ursolic acid from apple pomace: A novel and facile technique

ABSTRACT Substantial amount of apple pomace (AP) is produced in apple processing industries and is often discarded as waste which becomes a source of polluting the environment. However, the by-product constitutes a promising bioresource of ursolic acid with various biological activities. Therefore, this particular research study was aimed to develop a novel and facile method to separate ursolic acid from AP. First, AP was extracted with ultrasound assistance using methanol as extraction solvent, 2.86% with 10:1 (mL g−1) of liquid–solid ratio, 300 W of ultrasonic power, 50°C of extraction temperature, and 90 min of ultrasonic time. Meanwhile, the disruption effect of ultrasound on AP was observed by scanning electron microscope. Second, a novel and facile method was applied to separation of ursolic acid, then a perfect colorless needle crystal of ursolic acid was obtained with the yield of about 1.34% of dry AP.

Synthesis and Evaluation of Uniformly Sized Synephrine-Imprinted Microparticles Prepared by Precipitation Polymerization

Uniformly sized synephrine molecularly imprinted polymer (MIP) microparticles were prepared via precipitation polymerization. The presence of the template, the amount of monomer, crosslinker, and porogenic solvent could affect the size distribution and morphology of the polymers. The pseudo-second-order kinetic model could provide a better correlation for the adsorption than the pseudo-first-order model. The intraparticle diffusion study showed that the sorption involved intraparticle diffusion, but that was not the only rate-controlling step. The equilibrium data better fit the Freundlich model than the Langmuir model. The Scatchard plot of MIPs revealed MIPs had two groups of sites with different affinities. Subsequent recognition selectivity experiments demonstrated preferential structural selectivity for synephrine with respect to other structurally similar compounds (i.e., octopamine and tyramine). Compared with the bulk MIP of SYN, the SYN MIP microparticles in this work had higher adsorption selectivity and capacity due to their smaller particle sizes; moreover, the precipitation polymerization was time-saving due to not using a crash-and-sieve process.

Optimization of ultrasonic-assisted extraction of three main taxoids in the twigs of Taxus × media using multi-objective response surface methodology

ABSTRACT A multi-objective response surface methodology (RSM) based on a desirability function analysis (DFA) was used to model and optimize the operational parameters of ultrasonic-assisted extraction of three main taxoids in the twigs of Taxus × media. Liquid–solid ratio, extraction temperature, extraction time, and ultrasonic power were chosen as four independent variables, with three objective variables considered: the extraction yields of 10-deacetylbaccatin III (10-DAB III), cephalomannine and paclitaxel. Under the predicted conditions with the highest “desirability’’, compared with the predicted value, the goodness of fit for the experiment extraction yields of 10-DAB III, cephalomannine and paclitaxel was 97.36, 100.81, and 97.46%, respectively. Analysis of variance (ANOVA), regression analysis, and verification test indicated a satisfactory correlation between the experimental data and predicted values. These results showed that RSM and DFA were good methods to solve the problem of multi-objective optimization. GRAPHICAL ABSTRACT