Extraction and Purification of Depigmenting Agents from Chinese Plants

Introduction Melaninisaheterogeneousbiopolymerproduced bytheskincells,melanocytes,whichdetermine,mostly,thecoloroftheskin.Excessiveproductionof melaninanditsaccumulationintheskincancausepig mentingdisordersincludingmelasma,solarlentigoand postinflammatory…     

Adsorption Isotherms of Quercetin and Catechin Compounds on Quercetin-MIP

A molecular imprinted polymer(MIP)was prepared with quercetin as the template and methacrylic acid(MAA)as the functional monomer.Acetonitrile and methanol were used as the porogen with ethylene glycol dimethacrylate(EGDMA)as the crosslinker and 2,2'-azobis(isobutyronitrile)(AIBN)as the initiator.The experimental parameters of the equilibrium isotherms were estimated via linear and nonlinear regression analyses.The linear equation as the functions of the adsorption concentration of the single compound in its solution and the competitive adsorption of the single compound in its mixed compounds solution was then expressed,and the adsorption equilibrium data were correlated to Langmuir and Freundlich isotherm models.The mixture compounds show competitive adsorption on the specific binding sites of quercetin-MIP.Furthermore,the competitive Langmuir isotherms were applied to the mixture compounds.The adsorption concentrations of quercetin,( )catechin( C),and(-)epicatechin(EC)on the quercetin molecular imprinted polymer were compared.The quercetin-imprinted polymer shows extraordinarily higher adsorption ability for quercetin than for the two catechin compounds that were also assessed.     

Preparation of a Hybrid Organic-inorganic Monolith for Extraction and Purification of Quercetin and Myricetin from Chamaecyparis obtusa

A new hybrid organic-inorganic monolithic cartridge was synthesized and used as the selective sorbent for the extraction and purification of quercetin and myricetin from Chamaecyparis obtusa via a solid-phase extraction method.The morphology of the monolithic material was examined by field emission-scanning electron microscopy and a Brunauer-Emmett-Teller（BET） test.The adsorption capacity of the obtained material for quercetin and myricetin was investigated by fitting the adsorption data to four different adsorption equations,of which the LangmuirFreundlich isotherm was selected as the most suitable model.Under optimized conditions,good calibration curves were observed at nine concentrations ranged from 0.5 μg/mL to 100.0 μg/mL of quercetin and myricetin.The extraction recovery ranged from 74.5％ to 84.6％ and the inter-and intra-day relative standard deviations were ＜6％.This type of hybrid monolith has potential for the separation and purification of bioactive compounds from natural plant extracts.     

Determination of Three Tanshinones from Radix Salvia Miltiorrhiza by Molecularly Imprinted Solid-phase Extraction

A selective molecularly imprinted solid‐phase extraction procedure was developed for the selective separation of tanshinone I, tanshinone IIA, and cryptotanshinone from Radix Salvia Miltiorrhiza samples. Tanshinone IIA imprinted polymers (MIP) synthesized in ethanol‐dodecanol system show high affinity to tanshinone IIA and its structure analogs in aqueous environment and the affinity can be controlled by adjusting the intensity of the eluents. By using 60% water‐40% methanol (volume ratio) and 99.5% methanol‐0.5% trifluoroacetic acid (volume ratio) as washing and eluting solvents, most interferences originating from the salvia matrix were eliminated. The extracts were sufficiently clean enough to be directly injected into HPLC for further chromatographic analysis. Good linearity was obtained from 0.4 to 500.0 mg·L^?1 (r²=0.999) with the relative standard deviations less than 4.2%. The mean recoveries of tanshinone IIA in Radix Salvia Miltiorrhiza were more than 85.6% at three different concentrations and the limits of detection were 0.06–0.09 mg·L^?1. This method is a viable alternative tool to the existing HPLC methods for analyzing the content of the three tanshinones in Radix Salvia Miltiorrhiza samples.     

Effect of Ionic Liquid on Retention of Solutes on C_(18) Column Based on Linear Solvation Energy Relationships

Several chromatography systems with ionic liquids and a mixture of water with the modifier as mobile phase were characterized via the linear solvation energy relationships(LSER) model. The effects of the ionic liquids and modifier(methanol) concentrations on the retention of 10 solutes(caffeine,pyridine,aniline,phenol,methylparaben,acetopenone,m-cresol,p-cresol,o-cresol,and benzene) were discussed. The LSER model demonstrated high potential to predict retention factors with high squared correlation coeffici...     

Purification of Astaxanthin from Laminaria japonica by Ionic Liquid-based Monolithic Cartridge

An effective and accurate method was developed for the extraction of astaxanthin from Laminaria japonica with subsequent separation by ionic liquid-based monolithic cartridge. The optimized extraction conditions including extraction solvent(ethanol), extraction time(90 min) and ultrasonic power(75 W) were obtained by systematical investigation. Chromatographic analysis was performed on a C₁₈ column with ultraviolet(UV) detection at 476 nm, and a solution consisting of methanol/acetonitrile/H₂O/dichloromethane(83:6:6:5, volume ratio) was used as the mobile phase at a flow rate of 0.7 mL/min. After ionic liquid-based monolithic solid phase extraction, 17.82 μg/g astaxanthin was obtained from Laminaria japonica. This ionic liquid-based monolithic cartridge exhibits high affinity and selectivity for astaxanthin, and it can be potentially used as the stationary phase of high performance liquid chromatography(HPLC).     

Evaluation of Retention Factors for Nine Solutes with Ionic Liquid Additives via Linear Solvation Energy Relationships

<正>A linear solvation energy relationships(LSERs) model was used to examine the fundamental chemical interactions governing the retention of 9 organic compounds on a C_(18) column by means of reversed-phase high performance liquid chromatography(RP-HPLC).Three ionic liquids,1-hexyl-3-methylimidazolium tetrafluoroborate ([Hmin][BF_4]),1-butyl-3-methylimidazolium tetrafluoroborate([Bmin][BF_4]) and 1-octyl-3-methylimidazolium tetrafluoroborate([OMIm][BF_4]) as additives,were added to a methanol-water mobile phase.The effects of these three ionic liquids additives on the retention of nine organic compounds were investigated,and a comparison between the predicted and experimental retention factors was made via the LSERs model,which indicated that the LSERs model could be used to reproduce the experimental retention factors of the solutes under different mobile phase conditions. It is also a useful tool for modeling the interactions of the solutes between the stationary and mobile phases and evaluating the retention characteristics of HPLC.     

Production of ceramide with Saccharomyces cerevisiae

The possibility of producing the biologically active material of the skin, ceramide, was studied using yeasts. The yeast strain that produced the most ceramide, Saccharomyces cerevisiae (KCCM 50515), was selected, and the optimal conditions for ceramide production were determined using shakeflask culture and batch fermentation. By measuring the production rate of ceramide at various pH values and temperatures, the optimal conditions for ceramide production were found to be pH 6.0 and 30°C. When heat shock was applied to the cells for 1 h by increasing the culture temperature from 30 to 40°C after cell growth, the amount of ceramide produced was increased 5.9-fold. A cell growth and ceramide production model was developed with Monod kinetics and the Leudecking-Piret model. It showed that ceramide production was increased when the cells were in the stationary phase.     

Selective Solid-phase Extraction of Aloe Emodin from Aloe by Molecularly Imprinted Polymers

The extraction and separation of aloe emodin were optimized via selective molecularly imprinted solid-phase extraction. Molecularly imprinted polymer was prepared from the functional monomer, methacrylic acid and a mixture of ethanol/dodecanol(90/10, volume ratio) as porogen. It overcomes the common problems of imprin-ting biological polar compounds and shows high selectivity compared favorably with those of non-imprinted polymer and commercially available C₁₈ and silica cartridges in similar aloe emodin tests. Good linearity was obtained between 0.002 and 2.5 mg/mL(r²=0.998) with relative standard deviations below 3.3%.     

Comparison of Adsorption Isotherms of Methylxanthines on C18 Column

A comparison of the adsorption isotherms of caffeine, theophylline and theobromine and the competitive adsorption of the three compounds on a C 18 column were investigated. The experimental parameters of the equilibrium isotherms were estimated by linear and nonlinear regression analyses. The linear equation as a function of the adsorption concentration of the single compound in its solution and the competitive adsorption of a single compound in a mixed solution were then determined. The adsorption equilibrium data were then correlated to the linear, Langmuir, Freundlich, Langmuir-Freundlich and stoichiometric displacement theory for adsorption(SDT-A) isotherm models. The mixed compounds of the three compounds were competitively adsorbed on the C 18 particles. The expression of stoichiometric displacement theory for adsorption was found to be more suitable for adsorption of methylxanthines on a C 18 column.