[HPLC determination of the related substances in erdosteine].

An HPLC method was established for the determination of the related substance in erdosteine. Waters ODS-SunFire (250 mm x 4.6 mm ID, 5 microm) column was used, the mobile phase was composed of methanol-acetonitrile-0.

Analysis of species-dependent hydrolysis and protein binding of esmolol enantiomers.

The stereoselective hydrolysis of esmolol in whole blood and in its separated components from rat, rabbit and human was investigated. Blood esterase activities were variable in different species in the order of rat>rabbit>human. Rat plasma showed the high esterase activity and had no stereoselectivity to enantiomers.

Study on the metabolic mechanism of chiral inversion of S-mandelic acid in vitro.

Mandelic acid (MA) is generally used as a biological indicator of occupational exposure to styrene, which is classified as a class of hazardous environmental pollutants. It was found to undergo one-directional chiral inversion (S-MA to R-MA) in Wistar and Sprague-Dawley rats in vivo. This study was aimed to explore the metabolic mechanism of chiral inversion of S-MA in vitro.

[Determination of residual solvents in 7-amino-3-chloro cephalosporanic acid by gas chromatography].

Objective: To develop a gas chromatography method for determination of residual solvents in 7-amino-3-chloro cephalosporanic acid (7-ACCA).

Methods: The residual levels of acetone, methanol, dichloromethane, ethyl acetate, isobutanol, pyridine and toluene in 7-ACCA were measured by gas chromatography using Agilent INNOWAX capillary column (30 m × 0.32 mm,0.

Pharmacokinetics and plasma protein binding of rutin deca (H-) sulfate sodium.

Rutin deca (H-) sulfate sodium (RDS) possesses very good activity as an inhibitor of the complement system of warm-blooded animals and HIV. An ion-pair coupled with solid-phase extraction technique (IP-SPE) was developed to extract RDS from rat plasma, urine, bile and protein solution samples. The assay was applied to pharmacokinetics of RDS, including plasma pharmacokinetics, excretion and protein binding studies.

Simultaneous determination of notoginsenoside R1, ginsenoside Rg1, Re, Rb1 and icariin in rat plasma by ultra-performance liquid chromatography-tandem mass spectrometry.

An ultra-high pressure liquid chromatography-tandem mass spectrometry method has been developed and validated for identification and quantification of five major bioactive components in rat plasma after oral administration of Qihuotongqiao tablets. The analysis was performed on an Acquity UPLC HSS T3 column (100 mm x 2.1mm, 1.

[Absorption and distribution of extracts of Elsholtzia blanda in rats].

The study is aimed to establish a RP-HPLC method for determination of luteolin from the extracts of Elsholtzia blanda (EEB) in rats' biological specimen. A RP-HPLC method was established for determination of free and total luteolin in SD rats' plasma and gastrointestinal tract and total luteolin in SD rats' heart, liver, lung and kidney at 0.17, 0.

[Pharmacokinetics of luteolin from Elsholtzia blanda extracts in rats].

An RP-HPLC method for determination of luteolin from Elsholtzia blanda Benth. extracts in rats' plasma was established and the pharmacokinetics of luteolin in rats was studied. Drug blood samples from caudal vein were gotten after oral administration of luteolin.

[Research progress on interactions between luteolin (glucosides) and drug-metabolizing enzyme].

The paper summarizes the interactions between luteolin (glucosides) and drug-metabolizing enzyme from the literature of recent years and our research work. The metabolism of luteolin is chiefly mediated by phase II metabolic enzyme. Its glucosides are firstly hydrolyzed into aglycone in intestinal tract, and then absorbed and metabolized.

[Determination of dimethyl sulphate residual in granisetron hydrochloride by headspace gas chromatography].

Objective: To develop a headspace gas chromatography method for determining dimethyl sulphate residual in granisetron hydrochloride.

Methods: An Angilent INNOWAX capillary column with nitrogen gas as carrier and FID as detector was applied in this study. Dimethyl sulphate was tested under a constant column temperature.

[Metabolism-based interaction of diphenytriazol and flavone compounds].

Objective: To observe the metabolism-based interaction of diphenytriazol and flavone compounds.

Methods: Flavone compounds kaempferol, isoharmnten and Elsholtzia blanda benth extract were chosen as the substrate of glucuronidation in the phase II metabolism. The metabolism was investigated in different rat liver microsome incubates pretreated with beta-naphthoflavone (BNF), diphenytriazol and tea oil (control).

[Luteolin excretion after oral administration of Elsholtzia blanda benth extracts in rats].

Objective: To observe the excretion of luteolin after oral administration of Elsholtzia blanda benth extracts in rats.

Methods: Samples of urine, feces and bile were collected after oral administration of Elsholtzia blanda benth extracts in rate. After deconjugation with beta-glucuronidase/sulfatase, the levels of luteolin in urine, feces and bile were measured by RP-HPLC.

[Expression of human CYP2E1 in insect cells using bac-to-bac expression system].

Objective: To obtain recombinant human CYP2E1 and to determine its activity by using the specific probe substrate.

Methods: CYP2E1 cDNA was obtained by RT-PCR using human liver RNA as template. The cloned CYP2E1 cDNA was ligated with pFastBac vector to generate recombinant pFastBac-CYP2E1, which was then transformed into E.

[Interaction between (E)-2-(4-(diethylamino methyl) benzylidene)-5,6-dimethoxy-2,3-dihydroinden-one and P-glycoprotein].

Cell lines of Bcap37 and Bcap37/MDR1 (the high P-glycoprotein (P-gp) expressing cell line) were used as model to investigate the different accumulations of (E)-2-(4-(diethylamino methyl) benzylidene)-5,6-dimethoxy-2,3-dihydroinden-one (BYZX) in the two kinds of cells. It was authenticated that whether BYZX was the substrate of P-gp. Meanwhile, the inhibitive effects of BYZX on the P-gp were investigated by determining the fluorescence intensity of rhodamine 123 in the model cells, with and without BYZX.

[Determination of residual organic solvents in Panax notoginseng extracts by capillary gas chromatography with headspace sampling].

Objective: To develop a headspace gas chromatography method for the determination of residual organic solvents in Panax notoginseng extracts.

Methods: The samples were injected into HP-INNOWAX capillary column by headspace sampler and analyzed with FID detector using standard addition method.

Results: There was a good linearity in the experimental concentration (r=0.

In vitro metabolism of BYZX in human liver microsomes and the structural elucidation of metabolite by liquid chromatography-mass spectrometry method.

In vitro phase I metabolism of BYZX, a novel central-acting cholinesterase inhibitor for the treatment of the symptoms of Alzheimer's disease, was studied in human liver microsomes (HLM) and the metabolite formation pathways were investigated by chemical inhibition experiments and correlation analysis. The residual concentration of substrate and the metabolite formed in incubate were determined by HPLC method. The calibration curves of BYZX were linear over the concentration range from 5.

[In vitro metabolic interaction between diphenytriazol and steroid hormone drugs].

Aim: To observe the metabolic interaction between diphenytriazol and steroid hormone drugs, and provide some useful information for clinical medication.

Methods: The steroid hormone drugs which may be co-administrated with diphenytriazol were selected, such as mifepriston, estradiol, medroxyprogesterone acetate, progesterone, norethisterone and so on. Diphenytriazol was incubated with each drug in rat liver microsome.

Determination of rutin deca(H-) sulfate sodium in rat plasma using ion-pairing liquid chromatography after ion-pairing solid-phase extraction.

Rutin deca(H-) sulfate sodium (RDS) is one of the most important drug candidates, which possesses very good activity as inhibitor of the complement system of warm-blooded animals and human immunodeficiency virus (HIV). In order to understand RDS metabolism and disposition, an ion-pairing coupled with solid-phase extraction technique (IP-SPE) was developed to extract RDS from rat plasma sample. Tetrabutyl ammonium bromide (TBAB) buffer (0.

Stereoselective RP-HPLC determination of esmolol enantiomers in human plasma after pre-column derivatization.

A stereoselective reversed-phase HPLC assay to determine S-(-) and R-(+) enantiomers of esmolol in human plasma was developed. The method involved liquid-liquid extraction of esmolol from human plasma, using S-(-)-propranolol as the internal standard, and employed 2,3,4,6-tetra-O-acetyl-beta-d-glucopyranosyl isothiocyanate as a pre-column chiral derivatization reagent. The derivatized products were separated on a 5-microm reversed-phase C18 column with a mixture of acetonitrile/0.

Separation of rutin nona(H-) and deca(H-) sulfonate sodium by ion-pairing reversed-phase liquid chromatography.

Ion-pairing reversed-phase liquid chromatography (RPLC) was used to separate two polysulfonates, rutin nona(H-) sulfonate sodium and rutin deca(H-) sulfonate sodium, which have very similar chemical structures. The final product always contained both of them when one of the compounds was synthesized. Baseline separation was achieved on a C8-bonded silica column at ambient temperature.

Simultaneous determination of the enantiomers of esmolol and its acid metabolite in human plasma by reversed phase liquid chromatography with solid-phase extraction.

A stereoselective RP-high performance liquid chromatography (HPLC) assay to determine simultaneously the enantiomers of esmolol and its acid metabolite in human plasma was developed. The method involved a solid-phase extraction and a reversed-phase chromatographic separation with UV detection (lambda = 224 nm) after chiral derivatization. 2,3,4,6-tetra-O-acetyl-beta-d-glucopyranosyl isothiocyanate (GITC) was employed as a pre-column chiral derivatization reagent.

Induction of diphenytriazol on cytochrome CYP1A.

Aim: To study the effects of diphenytriazol on cytochrome P-450 (CYP) enzymes.

Methods: SD rats were pretreated with diphenytriazol. The catalytic activities of rat liver microsomes were determined by assaying ethoxyresorufin-O-deethylase (EROD) and pentoxyresorufin-O-dealkylase.

[Ginkgo flavones in in vitro metabolism and its clinical application].

Aim: To develop a method for assaying Ginkgo flavones in rat hepatical microsome.

Methods: Quercetin, isorhamnetin and keampferol were added to microsome incubate and incubated for a given time then extracted with ether-acetone. After evaporated, the residue was reconstituted with 100 microL of phosphate buffer solution (pH 2.

In vitro metabolism and inductive or inhibitive effect of DL111 on rat cytochrome P4501A enzyme.

In vitro metabolism and the inductive or inhibitive effect of DL111, a non-hormonal early pregnancy-terminating agent, toward cytochrome P450 (CYP) enzymes in rat liver microsomes were studied. In vitro metabolism of DL111 was performed in different rat liver microsomes (pretreated with phenobarbital (PB), dexamethasone (Dex), beta-naphthoflavone (BNF), DL111, respectively) and the catalytic abilities of these microsomes for DL111 were compared with control group. DL111 was well metabolized in microsomes pretreated with beta-naphthoflavone and itself.

[HPLC determination of zolmitriptan and its related substances].

Objective: To develop an analytical method and quality control for determination of zolmitriptan and related substances.

Methods: Zolmitriptan and related substances were separated and determined on a shimadzu CLC-C(8) column (150 mm x 6 mm, 10 microm) with a mobile phase of acetonitrile-10 mmol/L phosphate buffer (25:75 pH 7.5) and a flow-rate of 1 ml/min; the UV-VIS detector was operated at 229 nm.