Structural and functional biomimetics of [Fe]-hydrogenase featuring a mono-, di- or tetrasubstituted pyridine ligand with a -C, N, and S ligation.

The combined structural and functional modeling study of [Fe]-Hase has remained a great challenge, to date. Now, we report a series of new structural and functional [Fe]-Hase models (1-6) that contain a mono-, di- or tetrasubstituted pyridine ligand with a biomimetic -C, N, and S ligation. While models 1-3, 5 and 6 are conveniently prepared by a novel flexible pyridine ligand (FPL)-based method, model 4 is prepared simply by an intramolecular CO replacement reaction of model 3.

Biomimetic models of [Fe]-hydrogenase featuring a 2-acylphenylthiomethyl-6-R-pyridine (R = H or OMe) ligand.

Despite a variety of [Fe]-Hase models prepared so far, the structural and functional modeling study of the enzyme has remained a great challenge. Now, we report a new type of flexible pyridine ligand (FPL)-based synthetic method by which two novel [Fe]-Hase models have been prepared. Notably, the two models contain not only a biomimetic -acyl C, pyridyl N, thioether S coordination mode but also possess the enzyme-like H/D activation functions.

Weighted Gene Coexpression Network Analysis Reveals Essential Genes and Pathways in Bipolar Disorder.

Bipolar disorder (BD) is a major and highly heritable mental illness with severe psychosocial impairment, but its etiology and pathogenesis remains unclear. This study aimed to identify the essential pathways and genes involved in BD using weighted gene coexpression network analysis (WGCNA), a bioinformatic method studying the relationships between genes and phenotypes. Using two available BD gene expression datasets (GSE5388, GSE5389), we constructed a gene coexpression network and identified modules related to BD.

Purification, structure characterization and antioxidant activity of polysaccharides from Saposhnikovia divaricata.

Polysaccharide from traditional Chinese herb, Saposhnikovia divaricata (Turcz.) Schischk. (SD) was extracted, fractionated and characterized in this work.

Purification and characterization of a novel anti-coagulant from the leech Hirudinaria manillensis.

Protease inhibitors have been reported rarely from the leech . In this study, we purified a novel protease inhibitor (bdellin-HM-2) with anticoagulant properties from . With a molecular weight of 1.

In vitro and in vivo evaluation of hypothermia on pharmacokinetics and pharmacodynamics of nimodipine in rabbits.

Objective To investigate the effect of hypothermia on the pharmacokinetics and pharmacodynamics of nimodipine in rabbits using in vivo and in vitro methods. Methods Five healthy New Zealand rabbits received a single dose of nimodipine (0.5 mg/kg) intravenously under normothermic and hypothermic conditions.

Auto-Induction Effect of Chloroxoquinoline on the Cytochrome P450 Enzymes of Rats Associated with CYP 3A and 1A.

To investigate the auto-induction of cytochrome P450 (CYP450) by Chloroxoquinoline (CXL), a novel anticancer drug. Three experiments related to the induction of CYP450 were performed: a) In vitro use of the rat fresh hepatocytes model; b) In vivo 'cocktail' of CYP450 probe model; c) Pharmacokinetic (PK) study of the single and multiple doses. Some typical CYP enzyme probes and inducers were used in these experiments and were all determined by HPLC-MS/MS.

[Determination of morroniside concentration in rat plasma by high performance liquid chromatography-tandem mass spectrometry].

Morroniside, an iridoid glycoside extracted from Cornus officinalis, has multiple pharmacological effects such as neuroprotection. This study took the lead in establishing a method for determining morroniside concentration in rat plasma by high performance liquid chromatography-tandem mass spectrometry. Plasma samples were processed with protein precipitation method, with hyperoside as the internal standard.

In vitro evaluation of 9-(2-phosphonylmethoxyethyl)adenine ester analogues, a series of anti-HBV structures with improved plasma stability and liver release.

Chronic hepatitis B virus (HBV) infection may lead to liver cirrhosis and hepatocellular carcinoma, but few drugs are available for its treatment. Acyclic nucleoside phosphonates (ANPs) have remarkable antivirus activities but are not easily absorbed from the gastrointestinal tract and accumulate in the kidneys, resulting in nephrotoxicity. Therefore, there is a need to find effective liver site-specific prodrugs.

Simultaneous determination of triptolide and its prodrug MC002 in dog blood by LC-MS/MS and its application in pharmacokinetic studies.

Ethnopharmacological Relevance: Tripterygium wilfordii HOOK F (TWHF) is a traditional Chinese medicine used in the treatment of various autoimmune diseases and inflammatory disorders including rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), and skin diseases. Triptolide (TP) is one of the main active ingredients of this traditional Chinese medicine. MC002 is a novel semi-synthetic derivate of TP which is highly water soluble, acts as a prodrug and is converted to TP in vivo.

Rapid screening of drug-protein binding using high-performance affinity chromatography with columns containing immobilized human serum albumin.

For drug candidates, a plasma protein binding (PPB) more than 90% is more meaningful and deserves further investigation in development. In the study, a high-performance liquid chromatography method employing column containing immobilized human serum albumin (HSA) to screen in vitro PPB of leading compounds was established and successfully applied to tested compounds. Good correlation (a coefficient correlation of 0.

[Research progress of enhancing quantitative sensitivity by using LC-MS(n) with derivatization method in bio-matrices].

Liquid chromatography/mass spectrometry (LC-MS(n)) has been essential to a large number of quantitative analytical applications in drug research, and especially in the drug PK/PD research, due to its high sensitivity and high specificity. But following the appearance of drugs with high activity and low dosage and the especial structural compounds, a number of limitations of LC-MS(n) have been noted. Derivatization changes the structure of drugs and therefore changes their physical and chemical properties, resulting in high ionization efficiency, low matrix effect and low disturbance by inorganic salts and endogenous compounds in LC-MS(n).

Plasma membrane as the target site of cholic acid analogs.

Although the mechanism is unknown, Calculus Bovis and its active components, cholic acid analogs (CAAs), have been used in China to treat a wide range of diseases. Based on the previous finding that the potency of CAA is strongly dependent on the intrinsic surface activity, this paper aimed to investigate the role of the plasma membrane in the pharmacological activity of CAAs. First, CAAs (0.

Pharmacokinetic properties of albiflorin and paeoniflorin after oral administration of pure compound, Radix Paeoniae alba extract and danggui-shaoyao-san extract to rats.

This study compared the pharmacokinetics of albiflorin (ALB) and paeoniflorin (PAE), respectively, after oral administration of ALB, PAE, Radix Paeoniae alba (RPA) extract, and Danggui-Shaoyao-San (DSS) extract to rats on separate occasions. Analytes were detected simultaneously with liquid chromatography-tandem mass spectrometry. Noncompartmental pharmacokinetic parameters were calculated.

Liquid chromatography-tandem mass spectrometry for the determination of paclitaxel in rat plasma after intravenous administration of poly(L-glutamic acid)-alanine-paclitaxel conjugate.

A specific and sensitive liquid chromatography-tandem mass spectrometric method for quantitative determination of paclitaxel in rat plasma was developed and validated using docetaxel as an internal standard. Liquid-liquid extraction using tert-butyl methyl ether was used to extract the drug and the internal standard from plasma. The separation of paclitaxel was performed on a C(18) column with a mobile phase of acetonitrile:water:formic acid (65:35:0.

Metabolic stability of human parathyroid hormone peptide hPTH (1-34) in rat tissue homogenates: kinetics and products of proteolytic degradation.

The present study aim to investigate the metabolic stability and degradation of cleavage sites of human parathyroid hormone peptide, hPTH (1-34), in rat tissue homogenate, and to identify the types of proteases involved in hPTH (1-34) processing degradation. The stability of hPTH (1-34) in rat kidney, lung and liver homogenates was evaluated by LC-ESI-MS, and the structures of the major degradation products were identified by MALDI-TOF MS and LC-ESI-MS/MS. The ability of protease inhibitors to inhibit hPTH (1-34) degradation was used to identify the class of proteases involved in the metabolism of hPTH (1-34).

[Determination of decapeptide LXT-101 in plasma by HPLC-MS/MS and its pharmacokinetics in Beagle dogs].

This paper developed a sensitive and specific liquid chromatography-electrospray ionization mass spectrometry (HPLC-MS/MS) method for the determination of decapeptide LXT-101 in Beagle dog plasma. Plasma samples spiked with internal standard (IS) were treated with acetonitrile to precipitate the protein. Selected reaction monitoring (SRM) using the precursor --> product ion combinations of m/z 472.

Determination of 4-dimethylaminophenol concentrations in dog blood using LC-ESI/MS/MS combined with precolumn derivatization.

A sensitive and reproducible LC-ESI/MS/MS method, which was combined with the precolumn dansyl chloride derivatization to enhance the signal intensity of analytes, was developed to determine blood 4-dimethylaminophenol (DMAP) concentrations. The linearity of the method was observed within the concentration range of 2-2000 ng/mL. The precision, accuracy, stability, recovery and matrix effect of the method were also investigated and found to meet the requirements for pharmacokinetic studies of the drug.

Degradation of salmon calcitonin in rat kidney and liver homogenates.

Salmon calcitonin (sCT), a 32-amino-acid peptide, is the active component in many pharmaceuticals used for the management of bone diseases. In this study, the stability of sCT in rat kidney and liver homogenates were evaluated by LC-ESI-MS, and the structures of the major degradation products were identified by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). The results show that the half life of sCT was 13.

Simultaneous determination of harpagoside and cinnamic acid in rat plasma by liquid chromatography electrospray ionization mass spectrometry and its application to pharmacokinetic studies.

A simple and sensitive method was developed for the simultaneous quantification of harpagoside and cinnamic acid in rat plasma using high-performance liquid chromatography system coupled to a negative ion electrospray mass spectrometric analysis. The plasma sample preparation was a simple deproteinization by the addition of two volumes of acetonitrile. The analytes were separated on an Intersil C8-3 column (2.

Simultaneous quantification of chlorogenic acid and caffeic acid in rat plasma after an intravenous administration of mailuoning injection using liquid chromatography/mass spectrometry.

A simple, rapid and sensitive method was developed for the simultaneous quantification of chlorogenic acid (CGA) and caffeic acid (CA) in rat plasma using a high-performance liquid chromatography system coupled to a negative ion electrospray mass spectrometric analysis. The plasma sample preparation was a simple deproteinization by the addition of two volumes of acetonitrile followed by centrifugation. The analytes and internal standard ferulic acid were separated on an Intersil C8-3 column (5 mm; 250 x 2.

A simplified model to predict P-glycoprotein interacting drugs from 3D molecular interaction field.

A new two components partial least squares discriminant analysis (PLS) model for the prediction of P-glycoprotein-associated ATPase activity of drugs by using VolSurf compute theoretical molecular descriptors derived from 3D molecular interaction field was reported in the present study. By using 27 diverse drugs from literature, two models were constructed (R(2)=0.9003, 0.

Identification of rat faecal, urinary and biliary metabolites of thionorphine, a novel mixed agonist-antagonist analgesic, using liquid chromatography/electrospray ionization tandem mass spectrometry.

The biotransformation of thionorphine (N-cyclopropylmethyl-7alpha-[(s)-1-hydroxy-1-methyl-3-(2thiophene)-propyl]-6,14-endo-ethano tetrahydrooripavine), a new analgesic, was in-vestigated in rats. The results of metabolite analysis by liquid chromatography/electrospray ionization tandem mass spectrometry with positive ion mode, in which a mobile phase of 10 mM ammonium acetate (pH 3.0)/acetonitrile (25/75) was used, suggested that thionorphine is biotransformed to two potentially active metabolites, the N-dealkylated thionorphine (M-I) and the oxidized thionorphine (M-II), and subsequently form conjugates with glucuronic acid of both thionorphine and the metabolites.

[Stability studies of sulfated polyguluronic acid ester].

Aim: To test the stability of marine polysaccharide drug sulfated polyguluronic acid ester.

Methods: Four methods including high performance gel chromatography (HPGC), poly-acrylamide gel electrophoresis (PAGE), UV scan of absorbance between 200 and 800 nm and gelatin nephelometry were established. Samples were tested in high temperature, high humidity, strong light and accelerated test conditions.