Biomedical subjects

Zhide Hu

Publications and source records attributed to Zhide Hu.

At least 19 recordsLinked to original sources

PubMed2007

Combination of flow injection with electrophoresis using capillaries and chips.

The technique of combined flow injection CE (FI-CE) integrates the essential favorable merits of FI and CE and can significantly expand the application of CE by utilizing the various on-line sample pretreatments and preconcentration of FI. The basic principles, instrumental developments, and applications of the FI-CE system from 2004 to 2006 are reviewed. The recent developments and applications of FI-CE are outlined.

Calibration↗

PubMed2006

Prediction of milk/plasma drug concentration (M/P) ratio using support vector machine (SVM) method.

PURPOSE: Development of reliable computational models to predict/classify milk-to-plasma (M/P) drug concentration ratio remains a challenging object. Support vector machine (SVM) method, as a new algorithm, was constructed to distinguish the potential risk of drugs to nursing infants. METHODS: Each drug was represented by a large pool of descriptors, of which five were found to be most important for constructing the predictive models. Next, two classification models, linear discriminant analysis (LDA) and SVM, were developed with bootstrapping validation based on the selected molecular descriptors. RESULTS AND CONCLUSIONS: The classification accuracy of training set and test set for SVM was 90.63 and 90.00%, respectively. The total accuracy for SVM was 90.48%, which was higher than that of LDA (77.78%). Comparison of the two methods shows that the performance of SVM was better than that of LDA, which implies that the SVM method is an effective tool in evaluating the risk of drugs when experimental M/P ratios have not been investigated.

Algorithms↗

PubMed2006

Interaction of rhein with human serum albumin investigation by optical spectroscopic technique and modeling studies.

The binding of rhein with human serum albumin (HSA) has been studied in detail by spectroscopic method including circular dichroism (CD), Fourier transformation infrared spectra (FT-IR), fluorescence spectra. The binding parameters for the reaction have been calculated according to Scatchard equation at different temperatures. The plots indicated that the binding of HSA to rhein at 303, 310 and 318 K is characterized by one binding site with the affinity constant K at (4.93+/-0.16)x10(5), (4.02+/-0.16)x10(5) and (2.69+/-0.16)x10(5) M-1, respectively. The secondary structure compositions of free HSA and its rhein complexes were estimated by the FT-IR spectra. FT-IR and curve-fitted results of amide I band are in good agreement with the analyses of CD spectra. Molecular Modeling method was used to calculate the interaction modes between the drug and HSA.

Anthraquinones↗

PubMed2006

Enantioseparation of palonosetron hydrochloride by micellar electrokinetic chromatography with sodium cholate as chiral selector.

The enantioseparation of four stereoisomers of palonosetron hydrochloride by micellar electrokinetic chromatography using sodium cholate as chiral surfactant was described. Sodium cholate was shown to be effective in separating palonosetron hydrochloride stereoisomers. For method optimization, several parameters such as sodium cholate concentration, buffer pH and concentration, the types and concentration of organic modifiers and applied voltage, on the enantioseparation were evaluated and the optimum conditions were obtained as follows: 30 mM borate buffer (pH 9.40) containing 70 mM sodium cholate and 20% (v/v) methanol with an applied voltage of 20 kV. Under these conditions, baseline separation of palonosetron hydrochloride stereoisomers was achieved within 18 min.

Chromatography, Micellar Electrokinetic Capillary↗

PubMed2006

Accurate quantitative structure-property relationship model of mobilities of peptides in capillary zone electrophoresis.

The aim of this work was to predict electrophoretic mobilities of peptides in capillary zone electrophoresis (CZE) using the linear heuristic method (HM) and a nonlinear radial basis function neural network (RBFNN). Two data sets, consisting of 125 peptides ranging in size between 2 and 14 amino acids and 58 peptides ranging in size between 2 and 39 amino acids, are researched to test applicability of the QSPR methods. In this study, the root mean squared (RMS) errors of the training set, the test set and the whole set of data set 1 are 1.3766, 1.5608 and 1.4157 and the correlation coefficients (R2) are 0.9740, 0.9671 and 0.9724 predicted by RBFNN, respectively. While the RMS errors of the training set, the test set and the whole set of data set 2 are 0.6279, 0.8145 and 0.6673 and the correlation coefficients (R2) are 0.9773, 0.9489 and 0.9732, respectively. So the Offord charge-over-mass term (Q/M(2/3)) combined with descriptors calculated by CODESSA represents the structural features of the peptides appropriately. The electrophoretic mobilities of peptides can be accurately predicted by the linear and nonlinear model. Furthermore, the results of nonlinear model are closer to the experimental data than those of linear model.

Electrophoresis, Capillary↗

PubMed2006

Analysis of baicalein, baicalin and wogonin in Scutellariae radix and its preparation by microemulsion electrokinetic chromatography with 1-butyl-3-methylimizolium tetrafluoborate ionic liquid as additive.

Microemulsion electrokinetic chromatography (MEEKC) using 1-butyl-3-methylimidazolium tetrafluoroborate (BMIM-BF4) ionic liquid (IL) as additive was developed for the analysis of baicalin, wogonin and baicalein in Scutellariae radix and its preparation. After conducting a series of optimizations, baseline separation was obtained for the analytes within 5min under the optimum conditions (sodium dodecyl sulfate (SDS) 0.88% (m/v) ethyl acetate 0.8% (v/v) butan-1-ol 0.2% (v/v) and the buffer composition were 25% acetonitrile (v/v), 7.5 mM BMIM-BF4 and 10 mM NaH2PO4, pH 8.2, applied voltage 17.5 kV and detection at 254 nm), the method has been successfully applied to the determination and quantification of the analytes in the extracts of S. radix (cooked), S. radix (raw) and Qingfeiyihuowan which was the preparation including S. radix.

Borates↗

PubMed2006

The accurate QSPR models for the prediction of nonionic surfactant cloud point.

Quantitative structure-property relationship models were developed to predict cloud points and study the cloud phenomena of nonionic surfactants in aqueous solution. Four descriptors were selected by the heuristic method as the inputs of multiplier linear regression and support vector machine (SVM) models. Very satisfactory results were obtained. SVM models performed better both in fitness and in prediction capacity. For the test set, they gave a predictive correlation coefficient (R) of 0.9882, root mean squared error of 4.2727, and absolute average relative deviation of 9.5490, respectively. The proposed models can identify and provide some insight into what structural features are related to the cloud points of compounds, i.e., the molecular size, structure, and isomerism of the hydrocarbon moiety and the degree of oxyethylation. They can also help to understand the cloud phenomena of nonionic surfactants in aqueous solution. Additionally, this paper provides two simple, practical, and effective methods for analytical chemists to predict the cloud points of nonionic surfactants in aqueous solution.

Journal Article↗

PubMed2006

Comparison of the characterization on binding of alpinetin and cardamonin to lysozyme by spectroscopic methods.

Studies on the binding affinity of protein to the active components of herbs are novel in biochemistry and are valuable for the information about speciation of drugs and exchange in biological systems. Alpinetin and cardamonin, two of the main constituents from the seeds of Alpinia katsumadai Hayata, have been used in traditional herbs as antibacterial, anti-inflammatory, and other important therapeutic activities of significant potency and low systemic toxicity. The interactions between two flavonoids analogs and lysozyme have been studied for the first time by spectroscopic method including Fourier transform infrared (FT-IR) spectroscopy, circular dichroism (CD) and UV-absorption spectroscopy in combination with Fluorescence quenching study. Both molecules showed high affinities to lysozyme under the experimental condition with drug concentrations from 3.33 x 10(-6) to 2.67 x 10(-5)molL(-1) for alpinetin and 1.67 x 10(-6) to 13.33 x 10(-6)molL(-1) for cardamonin. The alterations of protein secondary structure in the presence of drugs in aqueous solution were quantitatively estimated by the evidences from CD and FT-IR spectroscopy. The thermodynamic parameters obtained and the results of spectroscopic measurements suggest that hydrophobic and electrostatic interactions are the predominant intermolecular forces stabilizing two coordination compounds. The quenching mechanism and the number of binding site (n approximately 1) were obtained by fluorescence titration data. The efficiency of energy transfer provided the binding distances of 4.04 and 5.90 nm for alpinetin-LYSO and cardamonin-LYSO systems, respectively.

Alpinia↗

PubMed2006

Determination of five anthraquinones in medicinal plants by capillary zone electrophoresis with beta-cyclodextrin addition.

A simple and rapid method for the simultaneous determination of five anthraquinone derivatives including aloe-emodin, emodin, chrysophanol, physcoin and rhein in Rheum species and Polygonum cuspidatum was established by capillary zone electrophoresis (CZE) using beta-cyclodextrin (CD) as modifier and urea to enhance its solubility. The apparent binding constants of these derivatives with beta-CD were evaluated. After an optimization study, the best conditions were selected using 35 mM phosphate buffer (pH 11.0) containing 20 mM beta-CD and 2 M urea, applied voltage 20 kV and detection at 254 nm. Under such conditions, all of the five anthraquinones were baseline-separated within a short analysis time of 12 min with symmetrical peaks and high theoretical plate numbers (189,000-314,000). The RSD values of the migration times and peak areas were 0.6-1.1, 1.3-1.9% (intra-day) and 0.6-1.5, 1.3-2.8% (inter-day, for a 5-day period), respectively. The limits of detection for the analytes (S/N = 3) were 0.33-0.62 microg/ml. The recoveries were ranged from 93.37 to 107.69%. The proposed method was successfully applied to the determination of anthraquinones in ethanol extracts of two kinds of Rheum plants (R. palmatum and R. hotaoense) and P. cuspidatum.

Anthraquinones↗

PubMed2006

Separation and determination of honokiol and magnolol in herbal medicines by flow injection-capillary electrophoresis.

A simple, rapid, and accurate method for the separation and determination of honokiol and magnolol in Magnolia officinalis and related herbal medicines was developed by combination of flow injection (FI) and capillary zone electrophoresis (CZE). The analysis was carried out using an unmodified fused-silica capillary (50-microm I.D.; total length 7.5 cm; effective length 4.5 cm). A series of optimization steps afforded the following conditions: the sample solvent consisted of 150 mM NaOH and a running buffer composed of 10 mM sodium tetraborate/10 mM sodium dihydrogenphosphate (NaH2PO4) at pH 12 was applied for the separation of the analytes. The separation could be achieved within 5 min with a sample throughput rate of up to 28 h(-1). The repeatability (defined as the relative standard deviation, RSD) for honokiol and magnolol was 2.0% and 1.6% with peak area evaluation, 3.6% and 2.0% with peak height evaluation, and 2.0% and 1.4% with migration time evaluation, respectively. Regression equations revealed linear relationships (r = 0.9991-0.9998) between the peak area of each analyte and the concentration.

Biphenyl Compounds↗

PubMed2006

Flow injection analysis-Rayleigh light scattering detection for online determination of protein in human serum sample.

A flow injection analysis (FIA) system combined with Rayleigh light scattering (RLS) detection is developed for the sensitive and rapid determination of protein concentration in human serum sample. This method is based on the weak intensity of RLS of Eriochrome Black T (EBT, 2-hydroxy-1-(1-hydroxy-2-naphthylazo)-6-nitronaphthalene-4-sulfonic acid sodium salt), which can be enhanced by the addition of protein in weakly acidic solution. The effects of pH and interfering species on the determination of protein were examined. Calibrations for protein, based on RLS intensity, were linear in the concentration ranges of 7-36 microg/ml for human serum album (HSA) and 8-44 microg/ml for bovine serum album (BSA). The detection limits of the method were found to be 0.882 and 2.507 microg/ml for HSA and BSA, respectively. A relative standard deviation of 0.76% (n=5) was obtained with 20 microg/ml HSA standard solution. The FIA-RLS method was more stable than the general RLS method, and the average RSD value of FIA-RLS was less than that of the general RLS. The sample rate was determined to be 90 samples per hour.

Animals↗

PubMed2006

Quantitative structure-property relationships for pesticides in biopartitioning micellar chromatography.

The retention factor (log k) in the biopartitioning micellar chromatography (BMC) of 79 heterogeneous pesticides was studied by quantitative structure-property relationships (QSPR) method. Heuristic method (HM) and support vector machine (SVM) method were used to build linear and nonlinear models, respectively. Compared the results of these two methods, those obtained by the SVM model are much better. For the test set, a predictive correlation coefficient (R) of 0.9755 and root-mean-square (RMS) error of 0.1403 were obtained. The proposed QSPR models, both by HM and SVM, contain the same descriptors that agree with the classical Abraham parameters of well-known linear solvation energy relationships (LSER).

Chromatography↗

PubMed2006

Simultaneous determination of bioactive flavone derivatives in Chinese herb extraction by capillary electrophoresis used different electrolyte systems--borate and ionic liquids.

In this paper, novel capillary electrophoresis (CE) methods, which used ionic liquids (1-ethyl-3-methylimidazoium tetrafluoroborate, 1-butyl-3-methylimidazoium tetrafluoroborate), were established to separate and determine some bioactive flavone derivatives in Chinese herb Seriphidium santolinum (Schrenk) Poljak. In order to investigate the traits of ionic liquids in CE, borate was also used as electrolyte to compare with. And the excellence of CE, which used ionic liquids as main running electrolyte and beta-cyclodextrin (beta-CD) as modifier, was illuminated as well. As a result of the study, the difference of ionic liquids and borate in CE was discussed and the advantage of CE, which used ionic liquids as electrolytes for separation, was shown. The analysis was obtained within short time (5-6 min). From the result, it was found that the system, which used ionic liquids, was robust because the joule heating was small. The method of CE, which used ionic liquids, has lower detection limits (0.137-0.642 microg/mL) than that of borate (0.762-1.036 microg/mL). And the CE, which used ionic liquids method, has lower limit of linear range (1.100-2.656 microg/mL), while that of CE, which used borate method, was 2.188-5.313 microg/mL.

Asteraceae↗

PubMed2006

Separation and determination of strychnine and brucine in Strychnos nux-vomica L. and its preparation by nonaqueous capillary electrophoresis.

An easy, rapid method for simultaneous determination of strychnine and brucine in Strychnos nux-vomica L. and its preparation was developed by nonaqueous capillary electrophoresis (NACE) without pretreatment for the first time. Optimum separation was achieved with a fused-silica capillary column (50 cmx75 microm i.d.) and a running buffer containing 30 mM ammonium acetate, 1.0% acetic acid and 15% acetonitrile (ACN) in methanol medium. The applied voltage was 30.0 kV. The analytes were detected by UV at 214 nm. The effects of concentration of ammonium acetate, acetic acid and organic modifier on electrophoretic behavior of the analytes were studied. The established method with sophoridine as internal standard was linear in the range of 5-1000 mg/mL for both strychnine and brucine. The extracts of Strychnos nux-vomica and its preparation could be directly injected for determination with recoveries ranging from 94.5 to 104%.

Acetates↗

PubMed2006

Rapid separation and determination of aconitine alkaloids in traditional Chinese herbs by capillary electrophoresis using 1-butyl-3-methylimidazoium-based ionic liquid as running electrolyte.

A novel and very simple capillary electrophoretic method for analyzing aconitine components in Aconitum plants was developed using 1-butyl-3-methylimidazoium tetrafluoroborate (1B-3MI-TFB)-based ionic liquid as running electrolyte solution for the first time. The optimum conditions were 35 mM 1B-3MI-TFB solution (pH 8.50) and 15 kV applied voltage. The detection was performed at 254 nm. Aconitine, meaconitine and hypaconitine in Aconitum plants were separated and identified within 5 min. The recoveries were 91.0-103.0% for hypaconitine, 92.8-96.2% for aconitine and 96.0-106.6% for mesaconitine, respectively. Compared with other methods, the analytical time was decreased 4-8-fold and the effect of Joule heating was weaker because the current was smaller.

Aconitine↗

PubMed2006

Determination of active components in Cynanchum chinense R. Br. by capillary electrophoresis.

A method for the determination of 7-O-alpha-l-rhamnopyranosyl-kaempferol-3-O-beta-d-glucopyranoside (GL) and 7-O-alpha-l-rhamnopyranosyl-kaempferol-3-O-alpha-l-rhamnopyranoside (RH) in the traditional Chinese herb Cynanchum chinense R. Br. by capillary electrophoresis has been developed. With botate buffer (30 mmol/L, pH 9.50) as running buffer and an applied voltage of 20 kV, the compounds were completely separated within 6 min and detected at UV 254 nm. The correlation coefficients of the calibration curves for GL and RH were 0.9990 and 0.9992, respectively, over the concentration ranges (15.0-1000.0 and 12.0-1000.0 microg/mL), and the recoveries were from 91.4 to 107.1%.

Cynanchum↗

PubMed2006

Method for derivatization of ephedrine and pseudoephedrine in nonaqueous media and determination by nonaqueous capillary electrophoresis with laser induced fluorescence detection.

A nonaqueous capillary electrophoresis with laser-induced fluorescence detection method was developed for the quantification of ephedrine and pseudoephedrine after derivatization with 4-chloro-7-nitrobenzo-2-oxa-1, 3-diazol in nonaqueous media. The derivatization was made in off-line mode. By a series of optimizations, a derivatization buffer composed of 40 mm ammonium acetate and 20% acetonitrile and a running buffer composed of 80 mm ammonium acetate and 3% acetic acid were applied for the derivatization and separation of ephedrine and pseudoephedrine, respectively. Linear relationships for ephedrine and pseudoephedrine were obtained in the range 1.23-19.60 mg/L (correlation coefficients 0.9970 for ephedrine and 0.9994 for pseudoephedrine), and the detection limits for ephedrine and pseudoephedrine were 0.014 and 0.011 mg/L, respectively. The method was applied to the analysis of ephedrine and pseudoephedrine in four preparations with recoveries in the range 93.9-105.1%.

Acetic Acid↗

PubMed2006

Separation and determination of epinephrine and dopamine in traditional Chinese medicines by micellar electrokinetic capillary chromatography with laser induced fluorescence detection.

A micellar electrokinetic capillary chromatography method with laser-induced fluorescence detection was developed for the analysis of epinephrine and dopamine after derivatization with 4-chloro-7-nitrobenzo-2-oxa-1,3-diazole. The optimum derivatization conditions were: 30 mM sodium borate (pH adjusted to 8.0 with 1.0 M HCl), reaction time 30 min at 60 degrees C. Baseline separation was achieved within 14 min with a running buffer composed of 10 mM sodium borate + 25 mM sodium dodecyl sulfate (pH adjusted to 9.5 with 0.1 M NaOH) and an applied voltage of 15 kV. Good linearity relationships (correlation coefficients: 0.9991 for epinephrine and 0.9985 for dopamine) between peak areas and concentrations of the analytes were obtained. The detection limits and quantification limits for epinephrine and dopamine were 0.0038 mg/L and 0.013 mg/L, and 0.065 mg/L and 0.020 mg/L, respectively. The method was applied to the analysis of the two compounds in two Chinese medicines with recoveries in the range of 92.6-108.7%.

Amphibian Venoms↗