Synthesis and protective effect of scutellarein on focal cerebral ischemia/reperfusion in rats

Scutellarein, the main metabolite of scutellarin in vivo, has relatively better solubility, bioavailability and bio-activity than scutellarin. However, compared with scutellarin, it is very difficult to obtain scutellarein from Nature. Therefore, the present study focused on establishing an efficient route for the synthesis of scutellarein by hydrolyzing scutellarin. Neurological deficit score and cerebral infarction volume with the administration of scutellarein were then used to compare its neuroprotective effects on focal cerebral ischemia/reperfusion in rats induced by middle cerebral artery occlusion (MCAO) with those of scutellarin. The results showed that scutellarein had better protective effect on focal cerebral ischemia/reperfusion than scutellarin, which laid the foundation for further research and development of scutellarein as a promising candidate for ischemic cerebro-vascular disease.     

Synthesis and physiochemical property evaluation of carbamate derivatives of scutellarin methyl ester

A series of carbamate prodrugs of scutellarin methyl ester (4a-4e) were prepared in the presence of bis(trichloromethyl) carbonate (BTC) with scutellarin methyl esters and L-amino acid tert-butyl ester hydrochloride as starting materials. In vitro stability and aqueous solubility of target compounds were evaluated. The results indicated that compounds 4d and 4e have higher solubility and in vitro stability than scutellarin respectively.     

Calculation of the Density and Activity of Water in ATPS Systems for Separation of Biomolecules

In this study, the perturbed hard sphere chain equation of state is utilized to calculate the activity of water in binary and ternary solutions of polyethylene glycol (PEG), salt and water. The liquid density of the binary and ternary solutions is also predicted. To estimate the water activity in PEG–water binary systems, a linear correlation is obtained for the binary interaction parameter between water and PEG. Then, using this correlation and without introducing any additional binary parameters, the water activities are predicted in ternary solutions of water, salt and PEG with different molecular weights (MW). Our results show that the mean absolute average relative deviation (AARD %) of water activity for binary PEG–water solutions in 298 K is 0.73 %. In addition, the water activity in ternary solutions of water and two PEGs with different MW is predicted within 0.31 % AARD %. Furthermore, the AARD % for prediction of water activities in binary PEG–water solutions over the temperature range 308–338 K is 0.41 %. Also, the water activities of aqueous two-phase systems are predicted with AARD % = 0.64 %. In this regard, no adjustable parameters were correlated between salt and PEG. Finally, liquid densities were predicted in binary solutions of water–PEG and ternary solutions of water–PEG–salt.     

Application of the Reversed-phase Liquid Chromatography Coupled to Ion Trap Mass Spectrometry with Principal Components Analysis for Metabonomics Studies of Scutellarin in Rat Urine

Recently, much attention has been paid to metabonomics and great growth in it as a novel systemic approach to study metabolic profile accelerate the process of drug development1-5. Traditional Chinese Medicine (TCM) is an emerging field for medical and ph…     

Microwave‐assisted extraction coupled with countercurrent chromatography for the rapid preparation of flavonoids from Scutellaria barbata D. Don

As a famous Chinese herb having good inhibitory effects on numerous human cancers both in vitro and in vivo, Scutellaria barbata D. Don attracts extensive attention worldwide. In this work, four flavonoids named scutellarin, baicalin, luteolin, and apigenin were simply and rapidly prepared from S. barbata by microwave‐assisted extraction coupled to countercurrent chromatography. Extraction conditions including irradiation time, extraction temperature, liquid/solid ratio, and microwave power were optimized using an orthogonal array design method. The extract of S. barbata was separated and purified with a two‐phase solvent system composed of hexane/ethyl acetate/methanol/acetic acid/water (1:5:1.5:1:4, v/v/v/v/v) and 4.5 mg of scutellarin, 4.6 mg of baicalin, 1.1 mg of luteolin, 2.1 mg of apigenin were obtained from 2.0 g original sample in a single run. The purities of scutellarin, baicalin, luteolin, and apigenin determined by HPLC were 93.6, 97.3, 97.6, and 98.4%, respectively. The targeted compounds were identified by LC with MS and ¹H NMR spectroscopy. The total time including extraction, separation, and purification was <300 min. Compared to traditional methods, microwave‐assisted extraction coupled to countercurrent chromatography method is more simple and rapid for the extraction, separation, and purification of flavonoid compounds from natural products.     

Microwave-assisted extraction of scutellarin from Erigeron breviscapus Hand-Mazz and its determination by high-performance liquid chromatography

An efficient microwave-assisted extraction (MAE) technique has been developed to extract scutellarin from Erigeron breviscapus for rapid determination by high-performance liquid chromatography (HPLC). The maximum yield of scutellarin reached 1.02% in 40 min under the optimal MAE conditions with 80 °C of extraction temperature and 1:10 (w/v) of the solid/liquid ratio. The MAE showed obvious advantages in terms of short duration and high efficiency to extract scutellarin in comparison with heat-flux extraction. The mechanism of the enhanced extraction by microwave assistance was discussed by detecting particle size and specific surface area of plant materials and observing cell destruction of plant material by light microscopy and scanning electron microscopy. The results showed that the plant materials were significantly destroyed due to the cell rupture after MAE treatment. Afterward, the method validation for HPLC-UV analysis was developed. Calibration range was 0.1-100 μg mL⁻¹ for scutellarin, and correlation coefficient R was 0.9993. Limit of detection was less than 0.01 μg mL⁻¹. The intra- and inter-day relative standard deviation (R.S.D.) of scutellarin detection ranged from 1.58% to 2.96% and from 3.32% to 4.19%, respectively. The recovery of the method for scutellarin ranged from 96.7% to 101.9%.     

Effect of guest hydrophobicity on water sorption behavior of oligomer/alpha-cyclodextrin inclusion complexes

Cyclomaltohexaose (alpha-cyclodextrin, alpha-CD) can form inclusion complexes (ICs) with polymer molecules in the columnar crystal structure in which alpha-CD molecules stack to form a molecular tube. Complementary water vapor sorption and wide-angle X-ray diffractomery (WAXD) were performed on oligomer/alpha-CD ICs to determine their structures and stabilities. To discern the effect of guest molecule hydrophobicity on water adsorption isotherms, polyethylene glycol (PEG, MW = 600 g/mol) and hexatriacontane (HTC) guests were used. Sorption isotherms for PEG/alpha-CD IC are similar to those obtained for pure alpha-CD and PEG, suggesting the presence of dethreaded PEG in the sample. WAXD collected before and after water vapor sorption of PEG/alpha-CD IC indicated a partial conversion from columnar to cage crystal structure, the thermodynamically preferred structure for pure alpha-CD, due to dethreading of PEG. This behavior does not occur for HTC/alpha-CD IC. Sorption isotherms collected at 20, 30, 40, and 50 degrees C allowed the calculation of the isosteric heats of adsorption and the integral entropies of adsorbed water which are characterized by minima that indicate the monolayer concentration of water in the ICs.     

Nanosphere formation in copolymerization of methyl methacrylate with poly(ethylene glycol) macromonomers

Polymeric nanospheres consisting of poly(methyl methacrylate) (PMMA) cores and poly(ethylene glycol) (PEG) branches on their surfaces were prepared by free radical copolymerization of methyl methacrylate (MMA) with PEG macromonomers in ethanol/water mixed solvents. PEG macromonomers having a methacryloyl (MMA‐PEG) and p‐vinylbenzyl (St‐PEG) end group were used. It has become clear that the obtained polymer dispersions form three kinds of states, particle dispersion (milky solution), clear solution, and gel/precipitation. It was found that the reaction parameters such as MMA concentration, molecular weight, and concentration of PEG macromonomers, and water content can affect nanosphere formation in a copolymerization system. The water volume fraction of mixed ethanol/water solvents affected the particle size of the nanospheres. These differences in the formation of nanospheres were due to the solvophilic/solvophobic balance between the copolymers and solvents during the self‐assembling process of the copolymers. The sizes of nanospheres can be controlled by varying concentration of PEG macromonomer and water content in solvents. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 1811–1817, 2000     

反相高效液相色谱法测定肾复康胶囊中的野黄芩苷和芦丁

建立了肾复康胶囊中野黄芩苷和芦丁的反相高效液相色谱测定方法。以甲醇-水为提取溶剂,采用超声提取法对样品进行前处理。以0.02 mol/L磷酸二氢钾缓冲溶液(含1.0％（体积分数）冰醋酸)-甲醇（体积比为63∶37）为流动相,于330 nm波长下检测,肾复康提取液中野黄芩苷和芦丁可达基线分离,分析时间在20 min内。野黄芩苷和芦丁在10 ~300 mg/L内,其峰面积与浓度之间线性关系良好,目标物的加标回收率大于98％。该方法适用于肾复康胶囊及相关药材中野黄芩苷和芦丁黄酮类化合物的测定和质量控制。     

Zeta potentials of PDMS surfaces modified with poly(ethylene glycol) by physisorption

Controlling zeta potential of PDMS surface coated with a layer of PEG is important for electroosmosis and electrophoresis in PDMS made microfluidic chips. Here, zeta potentials of PDMS surfaces modified by simple physisorption of PEG of different concentrations in phosphate buffer solutions, pure water, and PEG solution were reported. Coating PEG on PDMS surfaces was achieved by immersing a PDMS layer into the PEG solution for 10 min and then taking it out and placing it in an oven at 80℃ for 10 h. To avoid damaging the PEG layer on the PDMS surface, an induction current method was employed for zeta potential measurement. Zeta potentials of PEG modified PDMS in electrolyte solutions were measured. The results show that 2.5% PEG can effectively modify PDMS surface with positive zeta potential value in phosphate buffer solutions, pure water and 10% PEG solution. Further increase in PEG solution beyond 5% for surface modification has no obvious effect on zeta potential change.     

PEG-catalytic water splitting in the interface of a bipolar membrane

This paper investigates the effect of polyethylene glycol (PEG) on the water dissociation of bipolar membranes. To do this, bipolar membranes were prepared by immersing anion exchange membranes in different-concentration solutions of different-molecular-weight PEGs and then casting the solutions of sulfonated polyphenylene oxide (SPPO) on the anion exchange membranes. All the bipolar membranes with PEG in the interface are evaluated by current-voltage curves. The experimental results prove that PEG has excellent catalytic function for water dissociation. Furthermore, this function is enhanced by both PEG amount (PEG concentration) and PEG molecular weight in the interface of a bipolar membrane.     

Metabolism profile of scutellarin in urine following oral administration to rats by ultra performance liquid chromatography coupled to time-of-flight mass spectrometry

Scutellarin, a flavone glucuronide of 5,6,4′-trihydroxyflavone-7-O-glucoronide, is the main active component of the traditional Chinese botanic drug Erigeron breviscapus (Vant.) Hand.-Mazz. In this study, a method based on ultra performance liquid chromatography coupled with a time-of-flight mass spectrometer (UPLC/TOF MS) was established and validated to profile the metabolites of scutellarin in Sprague-Dawley rat urine following oral administration of single dose of scutellarin at 80.8 mg/kg. The column utilized was an Acquity BEH C18 (150 mm × 2.1 mm, 1.7 μm). The mobile phase was 0.2% formic acid and acetonitrile with gradient condition. Two standard curves of scutellarin were obtained for the concentration range of 1.065-10.65 μg/mL and 10.65-63.92 μg/mL, respectively. By automating the data processing of the software Masslynx developed by Waters Ltd., 17 metabolites of scutellarin were found and determined in rat urine, with the corresponding reactions in vivo such as isomerism, reduction, methylation, glucuronide conjugation, hydroxylation, hydroxylation and methylation, etc., most of which were discovered for the first time. For most metabolites, the time (T_p) of peak excretion was 8-12 h. Calculated as scutellarin, the cumulative urine excretion rate of the metabolites was 1.93%.     

Structural Properties of Water–PEG–LiOH,NaOH, and KOH Solutions,According to Viscometry and Densimetry Data

Russian Journal of Physical Chemistry A - The dynamic viscosity and density of water–PEG, water–PEG–LiOH, water–PEG–NaOH, and water–PEG–KOH systems are...     

Aqueous Suspensions of Poly(ethylene Glycol)/Pyrocarbon/Fumed Silica

Aqueous suspensions of fumed silica and pyrocarbon/silica (CS) in the presence of dissolved poly(ethylene glycol) (PEG) were studied using (1)H NMR spectroscopy with freezing-out of bulk water and quantum chemical computations of the chemical shifts. The freezing effect for PEG/water is akin to that for low-molecular organics, as formation of solid phases of water (ice) and PEG occurs, and their mixture forms at the eutectic temperature. In the aqueous suspensions of fumed silica or CS, PEG molecules are localized at the solid-liquid interfaces and do not form the bulk solution even at large concentrations; however, the amount of bulk undisturbed water rises due to formation of the immobilized PEG layer. For such suspensions of silica or CS at a low amount of pyrocarbon (C(C)=4 wt%), there is a portion of the graph of the surface free energy (gamma(S)) increasing nearly linearly with the PEG concentration (C(PEG)); however, in the case of large C(C)=40 wt% in CS, a similar effect is not observed, as gamma(S) is maximal at low C(PEG)=0.1 wt%. Copyright 2001 Academic Press.     

Determination of scutellarin in Erigeron breviscapus extract by liquid chromatography-tandem mass spectrometry.

A quantitative assay for scutellarin by LC-MS-MS (negative ion mode) was developed. The scutellarin was extracted from dry Erigeron breviscapus. Significant ion suppression was observed, which could be eliminated by increasing the turboionspray interface temperature to 350 degrees C and by 1000-fold dilution of the extract with solvent. The calibration curve of scutellarin showed excellent linearity over a wide concentration range (0.01-100 microg/ml) (r=0.998), and the limit of detection was 15 pg/ml using a 10-microl injection volume. The analysis time was 4 min/sample.     

THE INFLUENCE OF PEG MOLECULAR WEIGHT ON MORPHOLOGIES AND PROPERTIES OF PVDF ASYMMETRIC MEMBRANES

The preparation and properties of asymmetric poly(vinyldiene fluoride)(PVDF)membranes are described in this study.Membranes were prepared from a casting solution of PVDF,N,N-dimethylacetamide(DMAc)solvent and water- soluble poly(ethylene glycol)(PEG)additives by immersing them in water as coagulant medium.Experiments showed that when PEG molecular weight increased,the changes in the resultant membranes' morphologies and properties showed a transition point at PEG6000.This indicated that PEG with a relati...     

Ideal tetrafunctional amphiphilic PEG/PDMS conetworks by a dual‐purpose extender/crosslinker. II. Characterization and properties of water‐swollen membranes

Select characteristics and properties of a series of ideal tetrafunctional amphiphilic conetworks consisting of random poly(ethylene glycol) (PEG) and polydimethylsiloxane (PDMS) segments crosslinked by a novel dual‐purpose crosslinker/extender were determined. The overall composition of the conetworks was varied in the 16–40% PEG range, and membranes were prepared by polymerizing/crosslinking charges in molds. Membranes were characterized by equilibrium swelling (both in water and n‐heptane) and by determining their oxygen permeabilities and select mechanical properties. Swelling in water increases, whereas in heptane it decreases with increasing PEG content. Significant swelling in both solvents indicates bicontinuous (bipercolating) PEG and PDMS phases. Bicontinuity is reached with ～13% PEG in the conetworks. The oxygen permeabilities of optically clear water‐swollen membranes containing 24, 32, and 40 wt % PEG are ～350, ～245 and ～185 barrers, respectively, i.e., oxygen permeability decreases by increasing the hydrophilic constituent. These oxygen permeabilities are far superior to those of contemporary soft contact lenses. The tensile strengths and moduli of water‐swollen membranes decrease, while elongations increase, with increasing PEG content. Dry membranes exhibit first order transitions at ?52 and ～46 °C indicating phase‐separated crystalline PDMS and PEG domains, respectively. Both dry and water‐swollen membranes are optically clear, indicating the presence of PEG and PDMS domains with dimensions well below the wavelength of visible light. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 4965–4971, 2005     

Vinyl polymerization-412: Polymerization of methyl methacrylate initiated by the system of polyethyleneglycol,copper(II) chloride and water

The polymerization of methyl methacrylate (MMA) was carried out with the system polyethyleneglycol (PEG), copper(II) chloride and water at 85°. The effects of the amount of each component on the conversion of MMA were studied. Some polymerization occurred even if copper(II) ion was not present. It is suggested that there were three reactions: (1) polymerization initiated by the complex of PEG, copper(II) ion and water, (2) polymerization by PEG in water, (3) in the water phase, inhibition by copper(II) ion. The polymerization proceeded through a radical mechanism.     

Effect of PEG additive on membrane formation by phase inversion

This study investigates the effect of PEG additive as a pore-former on the structure formation of membranes and their permeation properties connected with the changes of thermodynamic and kinetic properties in phase inversion process. The membranes were prepared by using polysulfone (PSf)/N-methyl-2-pyrrolidone (NMP)/poly(ethylene glycol) (PEG) casting solution and water coagulant. The resulting membranes prepared by changing the molecular weight of PEG additive and the ratio of PEG to NMP were characterized by scanning electron microscope observations, measurements of water flux and PEG rejection. The thermodynamic and kinetic properties of membrane-forming system were studied through coagulation value, light transmittance and viscosity. The correlations between the final membrane structure/permeation properties and thermodynamic/kinetic properties of membrane forming system are discussed extensively.     

Poly (caprolactone)/poly (ethylene glycol) pervaporation blend membranes: Synthesis,characterization, and performance

Poly (caprolactone) membranes with addition of different poly (ethylene glycol) concentrations were prepared for separation of water/isopropanol azeotropic mixture by pervaporation process. Different characterization tests including Fourier transform infrared, scanning electron microscopy, water contact angle, and thermogravimetric analysis were carried out on the prepared membranes. In addition, the effect of poly (ethylene glycol) PEG content on the swelling degree and the performance of the prepared membranes in pervaporation process were investigated. According to the obtained results, all the membranes were water selective and the blend membrane containing 3 wt% PEG exhibited the best pervaporation performance with a water flux of 0.517 kg/m² hour and separation factor of 1642 at the ambient temperature. Hydrophilicity improvement of the blend membranes was confirmed by constant decrease in water contact angle of the membranes as PEG content increased in the casting solution. Scanning electron microscopy cross‐sectional images indicated that the blend membranes containing PEG had a closed cellular structure. Furthermore, mechanical and thermal properties of the membranes decreased by adding PEG.