Biomedical subjects

Lie Li

Publications and source records attributed to Lie Li.

13 recordsLinked to original sources

PubMed2006

Simultaneous determination of 12 major constituents in Forsythia suspensa by high performance liquid chromatography--DAD method.

A high performance liquid chromatographic method was developed to simultaneously determine the 12 major constituents of Forsythia suspensa, namely R-suspensaside, S-suspensaside, S-suspensaside methyl ether, (+)-pinoresinol-beta-d-glucoside, forsythiaside, (+)-epipinoresinol-4'-O-glucoside, suspensaside A, rutin, phillyrin, (+)-pinoresinol, (+)-epipinoresinol and phillygenin. The HPLC assay was performed on a Zorbax XDB C(18) column with gradient elution of methanol and 0.3% aqueous acetic acid within 55 min. The detection wavelength was 280 nm. All the compounds showed good linearity (r(2)>0.9998). The method was reproducible with intra- and inter-day variation less than 3%. The recovery of the assay was in the range of 91.2-104.9%. The method was successfully applied to the quantification of 12 constituents in 33 F. suspensa samples. The results indicated that the developed assay could be considered as a suitable quality control method for F. suspensa.

Calibration↗

PubMed2006

Gib2, a novel Gbeta-like/RACK1 homolog, functions as a Gbeta subunit in cAMP signaling and is essential in Cryptococcus neoformans.

Canonical G proteins are heterotrimeric, consisting of alpha, beta, and gamma subunits. Despite multiple Galpha subunits functioning in fungi, only a single Gbeta subunit per species has been identified, suggesting that non-conventional G protein signaling exists in this diverse group of eukaryotic organisms. Using the Galpha subunit Gpa1 that functions in cAMP signaling as bait in a two-hybrid screen, we have identified a novel Gbeta-like/RACK1 protein homolog, Gib2, from the human pathogenic fungus Cryptococcus neoformans. Gib2 contains a seven WD-40 repeat motif and is predicted to form a seven-bladed beta propeller structure characteristic of beta transducins. Gib2 is also shown to interact, respectively, with two Ggamma subunit homologs, Gpg1 and Gpg2, similar to the conventional Gbeta subunit Gpb1. In contrast to Gpb1 whose overexpression promotes mating response, overproduction of Gib2 suppresses defects of gpa1 mutation in both melanization and capsule formation, the phenotypes regulated by cAMP signaling and associated with virulence. Furthermore, depletion of Gib2 by antisense suppression results in a severe growth defect, suggesting that Gib2 is essential. Finally, Gib2 is shown to also physically interact with a downstream target of Gpa1-cAMP signaling, Smg1, and the protein kinase C homolog Pkc1, indicating that Gib2 is also a multifunctional RACK1-like protein.

Amino Acid Sequence↗

PubMed2006

High-performance liquid chromatographic assay for the active saponins from Panax notoginseng in rat tissues.

A reversed-phase liquid chromatographic method was used to determine the ginsenosides Rg1, Rb1 and Rd of Panax notoginseng in rat tissues (kidney, liver, heart, spleen and lung) after the administration of total saponins of P. notoginseng. The tissue samples were treated with solid-phase extraction prior to HPLC. The calibration curves for the three saponins were linear in the given concentration ranges. The intra-day and inter-day assay coefficients in tissues were between 76 and 120% respectively. The recoveries of all the tissues were higher than 70%. This method was applied to evaluate the distribution of the three major saponins of P. notoginseng in rat tissues.

Animals↗

PubMed2005

Simultaneous quantification of six major phenolic acids in the roots of Salvia miltiorrhiza and four related traditional Chinese medicinal preparations by HPLC-DAD method.

A high-performance liquid chromatographic method was applied to the determination of danshensu, protocatechuic aldehyde, rosmarinic acid, lithospermic acid, salvianolic acid B and salvianolic acid A in the roots of Salvia miltiorrhiza and four related traditional Chinese medicinal preparations. The six phenolic acids were simultaneously analyzed with a Zorbax Extend C18 column by gradient elution using 0.026% (v/v) phosphoric acid and acetonitrile as the mobile phase. The flow rate was 1 ml min(-1), and detection wavelength was set at 288 nm. The recovery of the method was in the range of 95.1-104.8%, and all the compounds showed good linearity (r > 0.9997) in a relatively wide concentration range. This assay was successfully applied to the determination of six major phenolic acids in 32 samples. The results indicated that the developed HPLC assay could be readily utilized as a quality control method for S. miltiorrhiza and its related traditional Chinese medicinal preparations.

Calibration↗

PubMed2005

Simultaneous quantification of six major active saponins of Panax notoginseng by high-performance liquid chromatography-UV method.

A simple, sensitive and specific high-performance liquid chromatography-UV (HPLC-UV) method has been developed for the first time to simultaneously quantify the six major active saponins of Panax notoginseng, namely notoginsenoside R1, ginsenoside Rg1, Rb1, Rg2, Rh1 and Rd. Astragaloside IV is used as the internal standard. This HPLC assay was performed on a reversed-phase C18 column with gradient elution of acetonitrile and 0.01% formic acid in 30 min. The method provided good reproducibility and sensitivity for the quantification of six saponins with overall intra- and inter-day precision and accuracy of less than 4.0% and higher than 90%, respectively. This assay is successfully applied to the determination of the six saponins in 23 notoginseng samples. The results indicated that the developed HPLC assay can be readily utilized as a quality control method for P. notoginseng.

Calibration↗

PubMed2005

Simultaneous determination of gallic acid, albiflorin, paeoniflorin, ferulic acid and benzoic acid in Si-Wu decoction by high-performance liquid chromatography DAD method.

A high-performance liquid chromatographic method was applied to the determination of gallic acid, albiflorin, paeoniflorin, ferulic acid and benzoic acid in Si-Wu decoction and other 13 combinations of the formula. These five compounds were analyzed simultaneously with a Zorbox SB C-18 column by gradient elution using 0.01% (v/v) phosphoric acid-acetonitrile as the mobile phase. The flow rate was 1 ml min(-1), and detection was set at 230 nm. The recovery of the method was in the range of 94.8-103.1%, and all the compounds showed good linearity (r>0.9995) in a relatively wide concentration range. The result indicated that the content of these five compounds changed after decocting process. The contents of paeoniflorin, albiflorin, ferulic acid and gallic acid increased and that of benzoic acid decreased significantly.

Calibration↗

PubMed2005

HPLC determination and pharmacokinetic studies of salvianolic acid B in rat plasma after oral administration of Radix Salviae Miltiorrhizae extract.

A precise and reproducible HPLC method has been established and validated for determination of salvianolic acid B (SalB) in rat plasma after oral administration of Radix Salviae Miltiorrhizae extract. Liquid-liquid extraction was adopted for the sample preparation. Separation was accomplished on a C(18) column with a linear gradient elution consisting of acetonitrile and aqueous phosphoric acid. Ultraviolet detection was at 280 nm. The method was validated over the concentration range 10.8-259.4 microg/mL using 1 mL of plasma. The assay was linear over this concentration range with a coefficient of variation less than 7%. The extraction recovery of SalB was within the range 71-83% with RSD 11%. The mean recovery of the internal standard was 84% (n = 6) with RSD of 5.6%. This method is suitable to determine SalB in plasma and to investigate the pharmacokinetics of SalB.

Acetonitriles↗

PubMed2005

Metabolic studies on the total phenolic acids from the roots of Salvia miltiorrhiza in rats.

Phenolic acids are the main active constituents of Salvia miltiorrhiza Bunge. The metabolism of total phenolic acids from the roots of Salvia miltiorrhiza in rats was investigated. A sample preparation method combining the solid-phase extraction with liquid-liquid extraction was established to separate metabolites from the biological matrix. HPLC-UV and HPLC-MS methods were employed to analyze the metabolites. Five metabolites (M1-M5) were identified by HPLC-MS analysis and comparison with those of the reference standards. The fi ve metabolites were characterized as danshensu (M1), caffeic acid (M2), ferulic acid (M3), isoferulic acid (M4) and methylized ferulic acid (M5), respectively. The possible metabolic pathway of the phenolic acids is proposed.

Animals↗

PubMed2005

Determination of four active saponins of Panax notoginseng in rat feces by high-performance liquid chromatography.

A method is developed for the determination of ginsenoside Rg1, Rb1, Rd, and notoginsenoside R1 of Panax notoginseng (PNS) in rat feces after oral and intravenous administration of total saponins of PNS. The fecal samples are treated with organic extraction and solid-phase extraction prior to high-performance liquid chromatography. The calibration curves for the four saponins are linear in the given concentration ranges. The precision of the method is in the range of 1.0-10.0% (relative standard deviation), and the accuracy is between 80.0% and 110%. The recoveries of this method are all over 75%. This method is successfully applied to the analyses of fecal samples of rats treated with PNS.

Animals↗

PubMed2004

Liquid chromatographic method for determination of four active saponins from Panax notoginseng in rat urine using solid-phase extraction.

Four major active saponins (ginsenosides Rg1, Rb1, Rd and notoginsenoside R1) in Panax notoginseng were determined in rat urine after oral and intravenous administration of total saponins of P. notoginseng (PNS), and the urine samples were treated with solid-phase extraction (SPE) prior to liquid chromatography. A reversed-phase liquid chromatography system with ultraviolet detection and a Zorbax SB-C18 column was used. The within-day and between-day assay coefficients of variation for the four saponins in urine were less than 7% and the recovery of this method was higher than 85%. Using this method, the excretion profile of the drug in rat urine after administration of PNS was revealed for the first time.

Animals↗

PubMed2004

Solid-phase extraction-liquid chromatographic method for the determination and pharmacokinetic studies of albiflorin and paeoniflorin in rat serum after oral administration of Si-Wu decoction.

A sensitive and rapid high-performance liquid chromatography (HPLC) method with solid-phase extraction (SPE) to simultaneously determine albiflorin and paeoniflorin in rat serum was described. Serum samples were pretreated with solid-phase extraction using Extract-Clean cartridges, and the extracts were analyzed by HPLC on a reversed-phase C(18) column and a mobile phase of acetonitrile-0.03% formic acid (17:83 (v/v)) with ultraviolet detection at 230 nm. Pentoxifylline was used as the internal standard (IS). The linear ranges of the calibration curves were 29-1450 ng/ml for albiflorin and 10-2000 ng/ml for paeoniflorin. The intra- and inter-day precisions (R.S.D.) were <or=10.49% for albiflorin and <or=11.29% for paeoniflorin, respectively. Mean recovery was determined to be 89.75% for albiflorin and 85.82% for paeoniflorin. The limit of quantification was 29 ng/ml for albiflorin and 10 ng/ml for paeoniflorin, respectively. The validated method was applicable to pharmacokinetic studies of albiflorin and paeoniflorin from rat serum after oral administration of Si-Wu decoction. The pharmacokinetic study indicated that albiflorin and paeoniflorin had poor absorption and rapid elimination. This assay result was necessary for the pharmacokinetic evaluation of Si-Wu decoction.

Administration, Oral↗

PubMed2004

Simultaneous determination of albiflorin and paeoniflorin in rat urine by solid-phase extraction and high-performance liquid chromatography following oral administration of Si-Wu decoction.

A high performance liquid chromatographic method (HPLC), together with solid phase extraction (SPE), was developed for simultaneous determination of albiflorin and paeoniflorin in rat urine after oral administration of Si-Wu decoction. The samples were pretreated with solid phase extraction using Extract-Cleantrade mark cartridges. Analysis of the extract was performed on a reversed-phase C18 column and a mobile phase made up of acetonitrile and 0.03% formic acid (17:83, v/v). UV detection was set at 230 nm. The assay was linear over the range 2.625-52.50 mg/mL for albiflorin and 3.875-77.50 microg/mL for paeoniflorin. The average percentage recoveries of three spiked urines were 97.01 +/- 3.32 and 102.32 +/- 6.97 for albiflorin and paeoniflorin, respectively. The intra-day precision (RSD) ranged from 0.21 to 1.79% at concentrations of 4.20, 10.50, 26.25 and 39.375 microg/mL of albiflorin and 0.12 to 2.92% at concentrations of 3.875, 10.85, 23.25 and 58.125 microg/mL of paeoniflorin, and inter-day precision (RSD) was from 1.02 to 1.86% for albiflorin and 0.94 to 3.30% for paeoniflorin, at the same four concentrations. This method was applied in order to analyze albiflorin and paeoniflorin in rat urine following oral administration of traditional Chinese medicinal preparation of Si-Wu decoction.

Animals↗

PubMed2004

HPLC determination of four active saponins from Panax notoginseng in rat serum and its application to pharmacokinetic studies.

Four main active saponins (ginsenosides Rg1, Rb1, Rd and notoginsenoside R1) in Panax notoginseng in rat serum after oral and intravenous administration of total saponins of P. notoginseng (PNS) to rats were determined using a simple and sensitive high-performance chromatographic method. The serum samples were pretreated with solid-phase extraction before analysis. The calibration curves for the four saponins were linear in the given concentration ranges. The intra-day and inter-day assay coefficients in serum were less than 10.0% and the recoveries of the method were higher than 80.0% in the high, middle and low concentrations. This method was applied to study the pharmacokinetics following oral and intravenous administration of PNS.

Animals↗