PubMed Health⌕ Search

Biomedical subjects

Yizeng Liang

Publications and source records attributed to Yizeng Liang.

14 recordsLinked to original sources
PubMed2007

Screening and analysis of the multiple absorbed bioactive components and metabolites of Dangguibuxue decoction by the metabolic fingerprinting technique and liquid chromatography/diode-array detection mass spectrometry.

Based on the metabolic fingerprinting technique and liquid chromatography/diode array detection mass spectrometry (LC/DAD-MS), a method for rapid screening and analysis of the multiple absorbed bioactive components and metabolites of an oral solution of Dangguibuxue decoction (ODD) in rabbit plasma after oral administration of ODD was developed. The results obtained from a comprehensive comparative analysis of the fingerprints of the ODD and its metabolic fingerprints in rabbit plasma indicated that 46 components in the ODD were absorbed into the rabbit's body. Of them, ten components were tentatively identified from their MS and UV spectra and retention behaviors by comparing the results with the reported literature. They were calycosin-7-O-beta-D-glycoside, (6aR,-11aR)-hydroxy-9,10-dimethoxypterocarpan-3-O-beta-D-glycoside, ononin, L-3-hydroxy-9,10-dimethoxypterocarpan, formononetin, (3R)-7,2'-dihydroxy-3',4'-dimethoxyisoflavan, sedanenolide, E-ligustilide, Z-ligustilide, and Z-butylidenephthalide. In addition, 21 components were only found in the metabolic fingerprints, which suggested that they might be metabolites of some components in the ODD. The findings demonstrated that the proposed method could be used to rapidly and simultaneously analyze and screen the multiple absorbed bioactive constituents and metabolites in a formula of traditional Chinese medicines (TCMs) by comparing and contrasting the chromatographic fingerprints with its metabolic fingerprints. This is very important not only for the pharmaceutical discovery process and the quality control of crude drugs, but also to explain the curative mechanism of TCMs.

Administration, Oral↗
PubMed2006

Toward automated biochemotype annotation for large compound libraries.

Combinatorial chemistry allows scientists to probe large synthetically accessible chemical space. However, identifying the sub-space which is selectively associated with an interested biological target, is crucial to drug discovery and life sciences. This paper describes a process to automatically annotate biochemotypes of compounds in a library and thus to identify bioactivity related chemotypes (biochemotypes) from a large library of compounds. The process consists of two steps: (1) predicting all possible bioactivities for each compound in a library, and (2) deriving possible biochemotypes based on predictions. The Prediction of Activity Spectra for Substances program (PASS) was used in the first step. In second step, structural similarity and scaffold-hopping technologies are employed. These technologies are used to derive biochemotypes from bioactivity predictions and the corresponding annotated biochemotypes from MDL Drug Data Report (MDDR) database. About a one million (982,889) commercially available compound library (CACL) has been tested using this process. This paper demonstrates the feasibility of automatically annotating biochemotypes for large libraries of compounds. Nevertheless, some issues need to be considered in order to improve the process. First, the prediction accuracy of PASS program has no significant correlation with the number of compounds in a training set. Larger training sets do not necessarily increase the maximal error of prediction (MEP), nor do they increase the hit structural diversity. Smaller training sets do not necessarily decrease MEP, nor do they decrease the hit structural diversity. Second, the success of systematic bioactivity prediction relies on modeling, training data, and the definition of bioactivities (biochemotype ontology). Unfortunately, the biochemotype ontology was not well developed in the PASS program. Consequently, "ill-defined" bioactivities can reduce the quality of predictions. This paper suggests the ways in which the systematic bioactivities prediction program should be improved.

Chemistry, Pharmaceutical↗
PubMed2006

Use of sodium lauroyl sarcosinate in a high-sensitivity protein assay by resonance light scattering technique.

A simple and high-sensitivity method has been developed for the determination of proteins in aqueous solutions by resonance light scattering (RLS) technique. At pH 3.4 and ionic strength 1.2 x 10(-3), the weak RLS intensity of sodium lauroyl sarcosinate was greatly enhanced by the addition of proteins with the maximum peak located at 391 nm. Under the optimum conditions, the enhanced RLS intensities were in proportion to the concentrations of proteins in the range of 0.04 to 2.1 microg/mL for lysozyme, 0.0025 to 1.2 microg/mL for bovine serum albumin, 0.0075 to 0.9 microg/mL for human serum albumin, 0.02 to 1.4 microg/mL for gamma-globulin, 0.02 to 0.8 microg/mL for egg albumin, and 0.01 to 0.6 microg/mL for hemoglobin. Low detection limits ranging from 0.8 ng/mL to 4.3 ng/mL depending on the kind of proteins that have been achieved. The protein concentrations in synthetic samples and real biochemical samples were determined with satisfactory results. This method presented here is not only sensitive and simple but also reliable and suitable for practical bioassay applications.

Animals↗
PubMed2006

Variation in chemical composition and antibacterial activities of essential oils from two species of Houttuynia THUNB.

Houttuynia THUNB. (Saururaceae) has been used for dozens of years in China for the treatment of cough, leucorrhea and ureteritis. The essential oils from the two species: Houttuynia emeiensis and Houttuynia cordata sold in China under one trade name 'Yuxingcao', obtained by hydrodistillation, were analyzed by GC-MS. The results show that fifty-five components were identified and methyl nonyl ketone (2.10-40.36%), bornyl acetate (0.4-8.61%) and beta-myrcene (2.58-18.47%) were the most abundant components in oil, but the percentage of most of compounds in different species and parts varied greatly. The two fold broth dilution and agar dilution method were used to study essential oil of two Houttuynia THUNB. species for their antibacterial properties against microorganisms, Staphylococcus aureus and Sarcina ureae. The two fold dilution method was allowed to determine the minimum inhibitory concentration (MIC) of essential oil from different parts and species. Results showed that all essential oils possessed antibacterial effect, with MIC values in the range of 0.0625 x 10(-3) to 4.0 x 10(-3) ml/ml. However, essential oil from different parts and species differed clearly in their antibacterial activities. The essential oil from the aboveground part of the cultivated Houttuynia emeiensis exhibited higher activity than both parts of the wild and cultivated Houttuynia cordata when used on Staphylococcus aureus (MIC = 0.25 x 10(-3) ml/ml) and Sarcina ureae (MIC = 0.0625 x 10(-3) ml/ml), and had the same activity as the positive control ampicillin sodium.

Anti-Bacterial Agents↗
PubMed2006

Exploring time-dependent structural changes during the cold crystallization process of isotactic polystyrene by infrared spectroscopy and multivariate curve resolution.

The present study attempts an application of Fourier transform infrared (FT-IR) spectroscopy in conjunction with multivariate curve resolution (MCR) techniques to explore the structural evolution of isotactic polystyrene (iPS) during the cold crystallization process. The focus of the present study is placed on the performance of MCR techniques, e.g., orthogonal projection (OP), alternating least squares (ALS), and fixed-size moving window evolving factor analysis (FSMWEFA), and the interpretability of spectral changes in the investigated chemical process. As a result, valuable information and conclusions about the structural evolution of iPS during the crystallization process can be extracted: when the amorphous phase of iPS changes, the ordering of the phenyl rings takes place first, and then the polymer chains adjust their local conformations to form short 3(1) helix structures. Furthermore, according to intensity profiles of the spectral variations, the ordering of the phenyl rings proceeds more intensely than the formation of ordered local chains, and the structural evolution of iPS occurs even during the induction period. The spectral variations resulting from the conformational changes in the 3(1) helical structures depend on the sequence length of the helical chains: the longer the polymer chain is, the smaller the corresponding band variations are. It has been demonstrated that the combination of FTIR spectroscopy and chemometric MCR techniques is very promising for the analysis of the crystallization process of polymers. MCR is a powerful tool for analyzing and visualizing spectral data and integrating them with other information, making spectral intensity variations more amenable to interpretation in order to explore the molecular dynamics of polymers.

Algorithms↗
PubMed2005

[Determination of carotenoids in foods by high performance liquid chromatography].

Recent research on the types and contents of carotenoids in food emphasis has been increasingly placed on obtaining more accurate data. The analysis of carotenoids, however, is challenging because of the diversity and the presence of cis-trans isomers, in addition to the characteristic conjugated double bond system of carotenoids causing their particular instability, especially under light, heat, oxygen and acids. The determination of carotenoids and carotenoid ester in foods using high performance liquid chromatographic methods are reviewed. In addition, the sample extraction, treatment and some methods for chromatographic separation and analysis are briefly commented on.

Carotenoids↗
PubMed2005

[Relativity study of the topological index of methylalkane structures and chromatographic retention index].

Quantitative structure-property relationships (QSPR) have been demonstrated to be a powerful tool in chromatography. QSPR have been used to obtain simple models to explain and predict the chromatographic behavior of various classes of compounds. The study of quantitative structure and retention index relationship (QSRR) is an important subject in chromatographic field. One hundred twenty-seven topological descriptors of 207 methylalkane structures are calculated. GAPLS method, which is a variable selection method combining with genetic algorithms (GA), back stepwise and partial least squares (PLS), is introduced in the variable selection of quantitative structure gas chromatographic (GC) retention index relationship. Seven topological descriptors are selected from 127 topological descriptors by GAPLS method to build QSRR model with high regression quality: squared correlation coefficient (R2) of 0.99998, standard deviation (S) of 2.88. The error of the model is similar to the experimental error. The validation of the model is checked by leave-one-out cross-validation technique. The result of leave-one-out cross-validation indicates that the built model is reliable and stable with high prediction quality, such as squared correlation coefficient of leave-one-out (R2cv) of 0.99997 and standard deviation of leave-one-out predictions (Scv) of 2.95. A successful interpretation of the complex relationship between GC retention indexes of methylalkanes and the chemical structure is achieved using QSPR method. The seven variables in the model are also rationally interpreted, which indicates methylalkane retention index are precisely represented by topological descriptors.

Alkanes↗
PubMed2004

Identification of structures of nitrogen-containing compounds in crude oils in conjunction with chemometric resolution.

A universal method was established for the systematically structural identification of nitrogen-containing compounds in crude oils. Pre-fractionation of the non-hydrocarbons in a crude oil sample into 7 fractions was performed by di-adsorption column chromatography using neutral aluminum oxide and silica gel; subsequent high-resolution separation of individual components was achieved by using capillary column gas chromatography, and compound types were detected by mass spectrometer. The two-dimensional data from the compounds in the fractions were further resolved by a chemometric method to obtained the deconvoluted chromatogram and mass spectrum of every compound, and then, the nitrogen-containing compounds were identified in combination with the retention indices. This method could relieve the difficulty of classical analysis in identifying those species with very low contents or incompletely separation, particularly in the cases where the authentic standards were not available for addition into the unknown samples in order to reveal what indeed existed in them. The structures of 168 nitrogen-containing compounds in a crude oil sample were determined by this method with satisfactory results.

Aluminum Oxide↗
PubMed2004

Systemic analysis of structures and contents of nitrogen-containing compounds and other non-hydrocarbons in crude oils in conjunction with chemometric resolution technique.

A method is described for the systemic identification and quantitative analysis of nitrogen-containing compounds and other non-hydrocarbons in crude oils. The pre-fractionation of a crude oil sample into 7 fractions was performed by di-adsorption column chromatography using neutral aluminum oxide and silica gel. A subsequent high-resolution separation of individual components was achieved by using capillary column gas chromatography, and compound types were detected by a mass spectrometer. In conjunction with a chemometric method, the compounds in the fractions were further resolved or separated, which made it possible to identify some nitrogen-containing compounds and other non-hydrocarbons in crude oils. To a certain extent, this method could relieve the difficulty of classical analysis in identifying those species with very low contents or incompletely separation, particularly in the cases where authentic standards were not available for addition into the unknown samples in order to reveal what indeed existed in them. The structures and contents of 168 nitrogen-containing compounds in one crude sample and 60 non-nitrogen-containing compounds in one of non-hydrocarbon fractions of this oil sample were determined, and the addition-recovery examination of some standard compounds showed that the analytical veracity was satisfactory.

Journal Article↗
PubMed2003

Data mining for seeking accurate quantitative relationship between molecular structure and GC retention indices of alkanes by projection pursuit.

Primary data mining on alkanes for seeking accurate quantitative relationship between molecular structure and retention indices of gas chromatography is developed in this paper. Based on the results obtained from projection pursuit (PP), a new variable named class distance variable, which essentially describes the branching structure of the alkanes, is proposed. With the help of the new variable, both fitting and prediction accuracy of the regression model can be dramatically improved. The results obtained in this work show that the technique of PP developed in statistics is a quite promising tool for seeking accurate quantitative structure-activity relationship (QSAR) and/or quantitative structure-property relationship (QSPR) researches.

Journal Article↗
PubMed2003

Chemometric resolution of ATR-IR spectra data for polycondensation reaction of bis(hydroxyethylterephthalate) with a combination of self-modeling curve resolution (SMCR) and local rank analysis.

Self-modeling curve resolution (SMCR) methods, simple-to-use interactive self-modeling mixture analysis (SIMPLISMA) and alternating least squares (ALS) were used to calculate pure concentration profiles and pure spectra for the two-way spectral data collected during the on-line polycondensation reaction of bis(hydroxyethylterephthalate) with an ATR-FT-IR spectrometer. In order to improve the resolution results, SIMPLISMA was combined with local rank analysis method, fixed size moving window evolving factor analysis (FSMWEFA) to search for selective regions of various components and then look for the purest wavenumber variables in the selective regions. Such combination allows more accurate determination of the number of chemical components in the reaction system and the calculations of more accurate concentration profiles and spectra.

Journal Article↗
PubMedDate not supplied

Orthogonalization of block variables by subspace-projection for quantitative structure property relationship (QSPR) research.

A subspace-projection method is developed to construct orthogonal block variable, which is originally from some kinds of series of topological indices or quantum chemical parameters. With the help of canonical correlation analysis, the orthogonal block variables were used to establish the structure-retention index correlation model. The regression of only few new orthogonal variables obtained by canonical correlation analysis against retention index shows significant improvement both in fitting and prediction ability of the correlation model. Moreover, the quantitative intercorrelation between the different block variables of topological indices can also be evaluated with the help of the subspace-projection technique proposed in this work.

Journal Article↗
PubMedDate not supplied

Data mining for seeking an accurate quantitative relationship between molecular structure and GC retention indices of alkenes by projection pursuit.

Primary data mining on alkenes for seeking an accurate quantitative relationship between the molecular structure and retention indices of gas chromatography is developed in this paper. Based on the results obtained from projection pursuit, all alkenes investigated show an interesting classification. Thus, a new variable named class distance variable of alkenes, which essentially describes information about the branch, position of the double bonds, the number of double bonds, and so on for alkenes, is proposed. With the help of the new variable, both fitting and prediction accuracy of the regression model can be dramatically improved. The results obtained in this work show that the technique of projection pursuit developed in statistics is a quite promising tool for seeking an accurate quantitative structure-retention relationship (QSRR).

Journal Article↗