Structural-Based Optimizations of the Marine-Originated Meridianin C as Glucose Uptake Agents by Inhibiting GSK-3β

Glycogen synthase kinase 3β (GSK-3β) is a widely investigated molecular target for numerous diseases, and inhibition of GSK-3β activity has become an attractive approach for the treatment of diabetes. Meridianin C, an indole-based natural product isolated from marine Aplidium meridianum, has been reported as a potent GSK-3β inhibitor. In the present study, applying the structural-based optimization strategy, the pyrimidine group of meridianin C was modified by introducing different substituents based on the 2-aminopyrimidines-substituted pyrazolo pyridazine scaffold. Among them, compounds B29 and B30 showed a much higher glucose uptake than meridianin C (<5%) and the positive compound 4-benzyl-2-methyl-1,2,4-thiadiazolidine-3,5-dione (TDZD-8, 16%), with no significant toxicity against HepG2 cells at the same time. Furthermore, they displayed good GSK-3β inhibitory activities (IC₅₀ = 5.85; 24.4 μM). These results suggest that these meridianin C analogues represent novel lead compounds with therapeutic potential for diabetes.

Sulfadiazine Masquerading as a Natural Product from Scilla madeirensis (Scilloideae)

The structure of 2,4-(4'-aminobenzenamine)pyrimidine (1), a pyrimidine alkaloid previously isolated from the bulbs of Scilla madeirensis (Asparagaceae, synonym Autonoë madeirensis), has been revised. These conclusions were met via comparison of reported NMR and EIMS data with those obtained from synthetic standards. The corrected structure is the antibiotic sulfadiazine (2), which has likely been isolated as a contaminant from the site of collection. The reported bioactivity of 1 as an α1-adrenoceptor antagonist should instead be ascribed to sulfadiazine. Our findings appear to show another example of an anthropogenic contaminant being identified as a natural product and emphasize the importance of considering the biosynthetic origins of isolated compounds within a phylogenetic context.

Kinetics and isotherm modeling of azoxystrobin and imidacloprid retention in biomixtures

The paper reports the kinetics and adsorption isotherm modeling for imidacloprid (IMIDA) and azoxystrobin (AZOXY) in rice straw (RS)/corn cob (CC) and peat (P)/compost (C) based biomixtures. The pseudo-first-order (PFO), pseudo-second-order (PSO), Elovich and intraparticle diffusion models were used to describe the kinetics. The adsorption data were subjected to the Langmuir and the Freundlich isotherms. Results (r²_Adj values) suggested that the modified Elovich model was the best suited to explain the kinetics of IMIDA sorption while different models explained AZOXY sorption kinetics in different biomixtures (PFO in RS + C and RS + P; PSO in CC + P and Elovich in CC + C). Biomixtures varied in their capacity to adsorb both pesticides and the adsorption coefficient (K_d) values were 116.8-369.24 (AZOXY) and 24.2-293.4 (IMIDA). The Freundlich isotherm better explained the sorption of both pesticides. Comparison analysis of linear and nonlinear method for estimating the Freundlich adsorption constants was made. In general, r²_Adj values were higher for the nonlinear fit (AZOXY = 0.938-0.982; IMIDA = 0.91-0.970) than the linear fit (AZOXY = 0.886-0.993; IMIDA = 0.870-0.974) suggesting that the nonlinear Freundlich equation better explained the sorption. The rice straw-based biomixtures performed better in adsorbing both the pesticides and can be used in bio-purification systems.

The Phytochemical and Biological Investigation of Jatropha pelargoniifolia Root Native to the Kingdom of Saudi Arabia

Extensive phytochemical analysis of different root fractions of Jatropha pelargoniifolia Courb. (Euphorbiaceae) has resulted in the isolation and identification of 22 secondary metabolites. 6-hydroxy-8-methoxycoumarin-7-O-β-d-glycopyranoside (15) and 2-hydroxymethyl N-methyltryptamine (18) were isolated and identified as new compounds along with the known diterpenoid (1, 3, 4, and 7), triterpenoid (2 and 6), flavonoid (5, 11, 13, 14, and 16), coumarinolignan (8⁻10), coumarin (15), pyrimidine (12), indole (17, 18), and tyramine-derived molecules (19⁻22). The anti-inflammatory, analgesic, and antipyretic activities were evaluated for fifteen of the adequately available isolated compounds (1⁻6, 8⁻11, 13, 14, 16, 21, and 22). Seven (4, 6, 10, 5, 13, 16, and 22) of the tested compounds showed a significant analgesic effect ranging from 40% to 80% at 10 mg/kg in two in vivo models. Compound 1 could also prove its analgesic property (67.21%) when it was evaluated on a third in vivo model at the same dose. The in vitro anti-inflammatory activity was also recorded where all compounds showed the ability to scavenge nitric oxide (NO) radical in a dose-dependent manner. However, eight compounds (1, 4, 5, 6, 10, 13, 16, and 22) out of the fifteen tested compounds exhibited considerable in vivo anti-inflammatory activity which reached 64.91% for compound 10 at a dose of 10 mg/kg. Moreover, the tested compounds exhibited an antipyretic effect in a yeast-induced hyperthermia in mice. The activity was found to be highly pronounced with compounds 1, 5, 6, 10, 13, and 16 which decreased the rectal temperature to about 37 °C after 2 h of the induced hyperthermia (~39 °C) at a dose of 10 mg/kg. This study could provide scientific evidence for the traditional use of J. pelargoniifolia as an anti-inflammatory, analgesic, and antipyretic.

Adsorption-desorption of dimethenamid and fenarimol onto three agricultural soils as affected by treated wastewater and fresh sewage sludge-derived dissolved organic carbon

The use of treated wastewaters (TWW) in agriculture is widening in areas suffering drought, such as southern Europe, to preserve freshwater supply for human consumption. The composition of TWW, especially concerning their organic carbon (OC) content, has been demonstrated to influence the processes governing the behavior of non-ionic pesticides in soils. Three OC-poor agricultural soils (SV, RM1 and RM3) from the province of Granada (Spain) were chosen for the assessment of the adsorption and desorption of the herbicide dimethenamid (DIM) and the fungicide fenarimol (FEN). TWW and sewage sludge extracts at different dissolved OC (DOC) concentrations (30, 90 and 300 mg L^-1) were considered to evaluate their effect on pesticide adsorption-desorption. As expected by their properties, DIM and FEN were weakly and moderately adsorbed to the soils, respectively. Soil OC seemed to be the major factor controlling FEN adsorption, whereas the mineral fraction played a key role in DIM adsorption, especially in RM1 with high clay:OC ratio. Although TWW did not significantly modify the adsorption of pesticides, it enhanced DIM desorption from the three soils. Adsorption of FEN to SV and RM3 was directly related to the concentration of DOC, possibly due to co-sorption phenomena. Hysteretic desorption was found in all cases, indicating partially reversible adsorption. While FEN desorption was not altered by the solutions, the use of sludge extracts at the highest DOC concentration (300 mg L^-1) enhanced DIM desorption as occurred with TWW. Interactions with DOC in solution seemed to predominate for this less hydrophobic compound, thus increasing the risk of natural waters contamination if TWW will be used.

Synthesis and application of selective adsorbent for pirimicarb pesticides in aqueous media using allyl-β-cyclodextrin based binary functional monomers

BACKGROUND

Binary functional monomers, allyl-β-cyclodextrin (allyl-β-CD) and methacrylic acid (MAA) or allyl-β-CD and acrylonitrile (AN), were exploited in a fabrication of molecularly imprinted polymers (MIPs) for selective recognition and large enrichment of pirimicarb from aqueous media.

RESULTS

Special attention was paid to the computational simulation of the imprinting molecular and functional monomers. The morphological characteristics of MIPs made of allyl-β-CD and MAA (M-MAA) were characterised by scanning electron microscopy. The effect of binding capacity of MAA-linked allyl-β-CD MIPs (M-MAA) demonstrated higher efficiency than that of AN-linked allyl-β-CD MIPs (M-AN) when tested in binding specificity. Finally, M-MAA was chosen to run through molecularly imprinted solid-phase extraction (MISPE) to analyse the spiked fresh leafy vegetables of pirimicarb.

CONCLUSION

The present proposed technique is a promising tool for the preparation of the receptors which could recognise pirimicarb pesticide in aqueous media. © 2017 Society of Chemical Industry.

Pesticide residue removal in classic domestic processing of tomato and its effects on product quality

This study was undertaken to evaluate the effectiveness of several household practices (washing with water or acidic, alkaline, and oxidizing solutions, and peeling) in minimizing pesticide residue contamination of tomatoes, as well as the impact on the quality of the treated fruit. Tests were performed using two systemic fungicides (azoxystrobin and difenoconazole) and one contact fungicide (chlorothalonil). Solid-liquid extraction with low temperature partition (SLE/LTP) and liquid-liquid extraction with low temperature partition (LLE/LTP) were used to prepare the samples for pesticides determination by gas chromatography. Washing the tomatoes with water removed approximately 44% of chlorothalonil, 26% of difenoconazole, and 17% of azoxystrobin. Sodium bicarbonate (5%) and acetic acid (5%) solutions were more efficient, removing between 32 and 83% of the residues, while peeling removed from 68 to 88% of the pesticides. The washing solutions altered some fruit quality parameters, including acidity and chroma, and also caused weight loss. Acetic acid (0.15 and 5%) and hypochlorite (1%) solutions had the greatest effect on these parameters.

Chloromethylhalicyclamine B, a Marine-Derived Protein Kinase CK1δ/ε Inhibitor

The halogenated alkaloid chloromethylhalicyclamine B (1), together with the known natural compound halicyclamine B (2), was isolated from the extract of the sponge Acanthostrongylophora ingens. The structure of compound 1 was determined by spectroscopic means, and it was shown that 1 is produced by reaction of 2 with CH₂Cl₂ used for extraction. Compound 1 was a selective CK1δ/ε inhibitor with an IC₅₀ of 6 μM, while the natural compound 2 was inactive. The absolute configuration of 1 was determined by quantum mechanical calculation of its ECD spectrum, and this also determined the previously unknown absolute configuration of the parent halicyclamine B (2). Computational studies, validated by NOESY data, showed that compound 1 can efficiently interact with the ATP-binding site of CK1δ in spite of its globular structure, very different from the planar structure of known inhibitors of CK1δ. This opens the way to the design of a new structural type of CK1δ/ε inhibitors.

Evaluation of Sulfadiazine Degradation in Three Newly Isolated Pure Bacterial Cultures

This study is aimed to assess the biodegradation of sulfadiazine (SDZ) and characterization of heavy metal resistance in three pure bacterial cultures and also their chemotactic response towards 2-aminopyrimidine. The bacterial cultures were isolated from pig manure, activated sludge and sediment samples, by enrichment technique on SDZ (6 mg L^-1). Based on the 16S rRNA gene sequence analysis, the microorganisms were identified within the genera of Paracoccus, Methylobacterium and Kribbella, which were further designated as SDZ-PM2-BSH30, SDZ-W2-SJ40 and SDZ-3S-SCL47. The three identified pure bacterial strains degraded up to 50.0, 55.2 and 60.0% of SDZ (5 mg L^-1), respectively within 290 h. On the basis of quadrupole time-of-flight mass spectrometry and high performance liquid chromatography, 2-aminopyrimidine and 4-hydroxy-2-aminopyrimidine were identified as the main intermediates of SDZ biodegradation. These bacteria were also able to degrade the metabolite, 2-aminopyrimidine, of the SDZ. Furthermore, SDZ-PM2-BSH30, SDZ-W2-SJ40 and SDZ-3S-SCL47 also showed resistance to various heavy metals like copper, cadmium, chromium, cobalt, lead, nickel and zinc. Additionally, all three bacteria exhibited positive chemotaxis towards 2-aminopyrimidine based on the drop plate method and capillary assay. The results of this study advanced our understanding about the microbial degradation of SDZ, which would be useful towards the future SDZ removal in the environment.

Fast Simultaneous Determination of 13 Nucleosides and Nucleobases in Cordyceps sinensis by UHPLC-ESI-MS/MS

A reliable ultra-high-performance liquid chromatography–electrospray ionization–tandem mass spectrometry (UHPLC–ESI–MS/MS) method for the fast simultaneous determination of 13 nucleosides and nucleobases in Cordyceps sinensis (C. sinensis) with 2-chloroadenosine as internal standard was developed and validated. Samples were ultrasonically extracted in an ice bath thrice, and the optimum analyte separation was performed on an ACQUITY UPLC^TM HSS C18 column (100 mm × 2.1 mm, 1.8 μm) with gradient elution. All targeted analytes were separated in 5.5 min. Furthermore, all calibration curves showed good linear regression (r > 0.9970) within the test ranges, and the limits of quantitation and detection of the 13 analytes were less than 150 and 75 ng/mL, respectively. The relative standard deviations (RSDs) of intra- and inter-day precisions were <6.23%. Recoveries of the quantified analytes ranged within 85.3%–117.3%, with RSD < 6.18%. The developed UHPLC–ESI–MS/MS method was successfully applied to determine nucleosides and nucleobases in 11 batches of C. sinensis samples from different regions in China. The range for the total content in the analyzed samples was 1329–2057 µg/g.

Anti-parasitic Guanidine and Pyrimidine Alkaloids from the Marine Sponge Monanchora arbuscula

HPLC-UV-ELSD-MS-guided fractionation of the anti-parasitic extract obtained from the marine sponge Monanchora arbuscula, collected off the southeastern coast of Brazil, led to the isolation of a series of guanidine and pyrimidine alkaloids. The pyrimidines monalidine A (1) and arbusculidine A (7), as well as the guanidine alkaloids batzellamide A (8) and hemibatzelladines 9-11, represent new minor constituents that were identified by analysis of spectroscopic data. The total synthesis of monalidine A confirmed its structure. Arbusculidine A (7), related to the ptilocaulin/mirabilin/netamine family of tricyclic guanidine alkaloids, is the first in this family to possess a benzene ring. Batzellamide A (8) and hemibatzelladines 9-11 represent new carbon skeletons that are related to the batzelladines. Evaluation of the anti-parasitic activity of the major known metabolites, batzelladines D (12), F (13), L (14), and nor-L (15), as well as of synthetic monalidine A (1), against Trypanosoma cruzi and Leishmania infantum is also reported, along with a detailed investigation of parasite cell-death pathways promoted by batzelladine L (14) and norbatzelladine L (15).

Enhanced Photocatalytic Activity of as-Prepared Sodium Titanates for m-Dinitrobenzene Reduction and Sulfosulfuron Oxidation

This paper demonstrates the preparation and photocatalytic activity of sodium titanate nanorods and nanotubes prepared by hydrothermal method using P25-TiO2 as the precursor. XRD results confirmed the monoclinic structure of sodium titanate nanorods obtained after calcinations of orthorhombic sodium titanate nanotubes at 800 °C for 2 h. The BET surface area of sodium titanate nanotubes (176 m2 g-1) was significantly reduced for sodium titanate nanorods (21 m2 g-1) formation because of the collapsing of the hollow interior of the former during its high temperature sintering. The selective formation of m-diaminobenzene by the photoreduction of the m-dinitrobenzene was found to be comparable by sodium titanate nanorods (89.5 ± 0.5%) and P25-TiO2 (98.2 ± 0.8%), whereas Au-deposition (0.5 and 2 wt%) onto sodium titanate nanorods notably altered the products (m-nitroaniline and m-diaminobenzene) distribution after 8 h of UV-light irradiation and which was confirmed later by GC-MS analysis. This high photoactivity of as-prepared nanorods could be credited to better delocalization and longer relaxation lifetime (68 µs) of photoexcited e-/h+ pairs along the length of crystalline sodium titanate nanorods than P25-TiO2 (45 µs) as measured from Time-resolved spectroscopy. The photooxidation of sulfosulfuron herbicide (1000 ppm) and corresponding CO2 formation was found to be highest with sodium titanate nanotubes due to the presence of more hydroxyl groups over the largest surface area that dominates over its least relaxation lifetime (41 µs).

Mass spectrometry detection of minor new meridianins from the Antarctic colonial ascidians Aplidium falklandicum and Aplidium meridianum

Taking into account the broad biological activities found in the meridianin indole alkaloids isolated to date, we have re-examined the organic extracts of an Antarctic collection of the tunicates Aplidium meridianum and A. falklandicum (Chordata: Ascidiacea) by HPLC in conjunction with a high-resolution mass spectrometer (HPLC-MS). A new set of analogs of meridianins A-G has been detected, and their structures are proposed on the basis of the molecular formulae identified by LC-HRMS analysis using a C18 column with a gradient of water/acetonitrile and an LTQ-FT-MS Orbitrap detector. Remarkably, dimers derived from meridianin A and from meridianin B or E were also detected. Our findings provide further evidence of the broad variability within the meridianin-like derivatives of this highly bioactive alkaloid family.

New Anti-Inflammatory Agents

The pyrrole derivatives 1a, b and 2a, b were used as precursors for the preparation of N-substituted pyrrole derivatives 3a, b-9a, b and pyrrolo[2,3-d]pyrimidines 13-16. Also, all the newly prepared products were tested for anti-inflammatory activity as analogues to fenamates, and some of them revealed moderate anti-inflammatory activity compared to the standard drug indomethacin.

Identification of potential HIV-1 integrase strand transfer inhibitors: in silico virtual screening and QM/MM docking studies

HIV-1 integrase (IN) is a retroviral enzyme that catalyses integration of the reverse-transcribed viral DNA into the host genome, which is necessary for efficient viral replication. In this study, we have performed an in silico virtual screening for the identification of potential HIV-1 IN strand transfer (ST) inhibitors. Pharmacophore modelling and atom-based 3D-QSAR studies were carried out for a series of compounds belonging to 3-Hydroxypyrimidine-2,4-diones. Based on the ligand-based pharmacophore model, we obtained a five-point pharmacophore with two hydrogen bond acceptors (A), one hydrogen bond donor (D), one hydrophobic group (H) and one aromatic ring (R) as pharmacophoric features. The pharmacophore hypothesis AADHR was used as a 3D query in a sequential virtual screening study to filter small molecule databases Maybridge, ChemBridge and Asinex. Hits matching with pharmacophore hypothesis AADHR were retrieved and passed progressively through Lipinski's rule of five filtering, molecular docking and hierarchical clustering. The five compounds with best hits with novel and diverse chemotypes were subjected to QM/MM docking, which showed improved docking accuracy. We further performed molecular dynamics simulation and found three compounds that form stable interactions with key residues. These compounds could be used as a leads for further drug development and rational design of HIV-1 IN inhibitors.

Isolation and structures of axistatins 1-3 from the Republic of Palau marine sponge Agelas axifera Hentschel

An investigation begun in 1979 directed at the Republic of Palau marine sponge Agelas axifera Hentschel for cancer cell growth inhibitory constituents subsequently led to the isolation of three new pyrimidine diterpenes designated axistatins 1 (1), 2 (2), and 3 (3), together with the previously reported formamides 4, 5, and agelasine F (6). The structures were elucidated by analysis of 2D-NMR spectra and by HRMS. All of the isolated compounds were found to be moderate inhibitors of cancer cell growth. Axistatins 1-3 (1-3), formamide 4, and agelasine F (6) also exhibited antimicrobial activity.

Persistence of pyrazosulfuron in rice-field and laboratory soil under Indian tropical conditions

BACKGROUND

Pyrazosulfuron ethyl, a new rice herbicide belonging to the sulfonylurea group, has recently been registered in India for weed control in rice crops. Many field experiments revealed the bioefficacy of this herbicide; however, no information is available on the persistence of this herbicide in paddy soil under Indian tropical conditions. Therefore, a field experiment was undertaken to investigate the fate of pyrazosulfuron ethyl in soil and water of rice fields. Persistence studies were also carried out under laboratory conditions in sterile and non-sterile soil to evaluate the microbial contribution to degradation.

RESULTS

High-performance liquid chromatography (HPLC) of pyrazosulfuron ethyl gave a single sharp peak at 3.41 min. The instrument detection limit (IDL) for pyrazosulfuron ethyl by HPLC was 0.1 µg mL(-1) , with a sensitivity of 2 ng. The estimated method detection limit (EMDL) was 0.001 µg mL(-1) and 0.002 µg g(-1) for water and soil respectively. Two applications at an interval of 10 days gave good weed control. The herbicide residues dissipated faster in water than in soil. In the present study, with a field-soil pH of 8.2 and an organic matter content of 0.5%, the pyrazosulfuron ethyl residues dissipated with a half-life of 5.4 and 0.9 days in soil and water respectively. Dissipation followed first-order kinetics. Under laboratory conditions, degradation of pyrazosulfuron ethyl was faster in non-sterile soil (t(1/2) = 9.7 days) than in sterile soil (t(1/2) = 16.9 days).

CONCLUSION

Pyrazosulfuron ethyl is a short-lived molecule, and it dissipated rapidly in field soil and water. The faster degradation of pyrazosulfuron in non-sterile soil than in sterile soil indicated microbial degradation of this herbicide.

Trypanocidal activity of oxoaporphine and pyrimidine-β-carboline alkaloids from the branches of Annona foetida Mart. (Annonaceae)

Phytochemical investigation of the branches of Annona foetida Mart. led to isolation from the CH₂Cl₂ extract of four alkaloids: Atherospermidine (1), described for the first time in this species, liriodenine (2), O-methylmoschatoline (3), and annomontine (4). Their chemical structures were established on the basis of spectroscopic data from IR, MS, NMR (1D and 2D), and comparison with the literature. Compounds 2–4 showed potent trypanocidal effect when evaluated against epimastigote and trypomastigote forms of Trypanosoma cruzi.

Heterogeneous photocatalytic oxidation of cyprodinil and fludioxonil in leaching water under solar irradiation

The efficiency of ZnO and TiO(2) suspensions in the photocatalytic degradation of two fungicides (cyprodinil and fludioxonil) in leaching water was investigated. The experiments were carried out at pilot plant scale using compound parabolic collectors under natural sunlight. The blank experiments for both irradiated compounds solutions showed that both oxides strongly enhanced the removal of the fungicides. The addition of an oxidant (Na(2)S(2)O(8)) to the ZnO or TiO(2) increased the rate of photooxidation. The degradation of cyprodinil and fludioxonil followed first order kinetics according to the Langmuir-Hinshelwood model. Complete degradation of both fungicides was achieved within 4 h (t(30W)=18 min) when treated with illuminated ZnO. The disappearance time (DT(75)), when referred to the normalized illumination time (t(30W)), was lower than 40 and 550 min (t(30W)=2 and 40 min) for both fungicides using ZnO or TiO(2), respectively. ZnO appeared to be more effective in cyprodinil and fludioxonil oxidation than TiO(2) probably due to its nonstoichiometry.

Remediation of fungicide residues on fresh produce by use of gaseous ozone

Ozone fumigation was explored as a means for degrading organic fungicide residues on fresh produce. Fungicides sorbed onto model abiotic glass surfaces or onto grape berries were fumigated separately in a flow-through chamber. Gaseous ozone at a constant concentration of 150 ± 10 ppmv (μL·L(-1)) selectively oxidized fungicides sorbed to model surfaces. Over 140 min, boscalid and iprodione levels did not change significantly based on a single-factor analysis of variance (ANOVA) at the 95% level of confidence (p = 0.05); however, pseudo-first-order losses resulted in observable rate constants of ozonolysis, k(ozonolysis) (min(-1)), of 0.0233 ± 0.0029 (t(1/2) ≈ 29.7 min), 0.0168 ± 0.0028 (t(1/2) ≈ 41.3 min), and 0.0127 ± 0.0010 (t(1/2) ≈ 54.6 min) for fenhexamid, cyprodinil, and pyrimethanil, respectively. The relative degradation of fungicides on berries at gaseous ozone concentrations of 900 ± 12 ppmv (μL·L(-1)) over 2 h was similar to that on glass; decreases in residue concentration were observed for only fenhexamid (∼ 64%), cyprodinil (∼ 38%), and pyrimethanil (∼ 35%) with corresponding k(ozonolysis) (min(-1)) of 0.0085 ± 0.0021 (t(1/2) ≈ 81.5 min), 0.0039 ± 0.0008 (t(1/2) ≈ 177.7 min), and 0.0036 ± 0.0007 (t(1/2) ≈ 192.5 min). Heterogeneous rate constants of gaseous ozone reacting with a sorbed fungicide, k(O(3)) (M(-1)·min(-1)), were calculated for both surfaces and indicate losses proceed ∼ 15-fold slower on grapes. The kinetics and mechanism of fungicide removal, supported by gas chromatography- and liquid chromatography-mass spectrometry product analyses, is discussed in the context of facilitating compliance with maximum residue level (MRL) tolerances for fresh produce.

Annomontine, an alkaloid isolated from Annona purpurea, has anxiolytic-like effects in the elevated plus-maze

The effects of annomontine, a pyrimidine- β-carboline alkaloid isolated from the root of ANNONA PURPUREA, on anxiety was studied in mice using the elevated plus-maze. The behavioral effects of this alkaloid on the pentobarbital-induced hypnosis, the locomotor activity in an open field, and the motor coordination in the rotarod test were also evaluated. The intraperitoneal injection of annomontine (1-30 mg/kg) increased in a dose-dependent way the number of visits to and the time spent in the open arms of the elevated plus-maze in comparison to the control animals. Such effects were blocked by the prior application of flumazenil (3 mg/kg; i. p.), a specific antagonist for the binding of benzodiazepines on the GABA (A) receptor. Under the same experimental conditions annomontine failed to affect the behavior of the animals in the pentobarbital-induced hypnosis test and had no effects on locomotion and motor coordination. These results suggest that annomontine possesses anxiolytic-like effects which may be mediated at the level of the benzodiazepine binding site on the GABA (A) receptor.

Occurrence and fate of rosuvastatin, rosuvastatin lactone, and atorvastatin in Canadian sewage and surface water samples

Rosuvastatin (RST) and atorvastatin (ATO) are prescription drugs and members in the statin family used for the treatment of elevated cholesterol levels. A method using solid-phase extraction and liquid chromatography-tandem mass spectrometry (LC-MS/MS) for the determination of ATO, RST and its metabolite rosuvastatin lactone (RSTL) in sewage and surface water samples has been developed. In the influent and effluent samples collected from 11 sewage treatment plants located in Ontario, Canada, ATO, RST, and RSTL were detected in all samples with median concentrations of 166 ng L(-1) (influent) and 77 ng L(-1) (effluent) for ATO, 448 ng L(-1) (influent) and 324 ng L(-1) (effluent) for RST, as well as 158 ng L(-1) (influent) and 41 ng L(-1) (effluent) for RSTL. Due to the inter-conversion between RST and RSTL, the total concentration of RST and RSTL in a sewage sample should be reported. The median removal rate by wastewater treatment was 66% for ATO and 22% for RST and RSTL combined. These statins were quite persistent in sewage. After a storage period of 21 and 62 days, there was only a slight decrease in ATO concentration and no change in the total RST concentrations. These three compounds were also detected in a number of surface water samples at low ng L(-1) concentrations. This is the first reported occurrence and fate of RST and RSTL in the Canadian aquatic environment.

Adsorption and desorption characteristics of monosulfuron in Chinese soils

Through batch equilibration experiments, the adsorption-desorption characteristics of monosulfuron, a new sulfonylurea herbicide widely used, were investigated in eight agricultural soil samples collected from China. The isotherms for monosulfuron adsorption were nonlinear (n ranged from 0.748 to 0.943) and well described by the revised Freundlich equation. Data obtained from adsorption experiments showed that monosulfuron had weak to moderate adsorption capability in different soils and might readily result in leaching problems, which was correlated significantly with soil properties. The content and chemical characteristic of the soil organic matter (SOM) was considered to be one of the important factors leading to differences in sorption capacity. Meanwhile, the extent of monosulfuron adsorption on soil was at rather high level under low pH value conditions and decreased with increasing pH value. Besides, desorption hysteresis of monosulfuron were observed in most of tested soils, and was demonstrated to be improved with increased concentration in initial solution and depended significantly on SOM.

Combining Synthetic and Analytical Strategies for Preparative HPLC Enantioseparation of Monastrol Racemic Mixture

Large-scale resolution of racemic monastrol has been carried out by normal-phase mode HPLC on an amylose-based chiral stationary phase. Because monastrol solubility, in media of proper compositions for normal-mode HPLC separations (in terms of retention factors and selectivity), was significantly low and impractical for preparative scopes, racemic monastrol was transformed into the corresponding O-tert-butyldimethylsilyl derivative. The tert-butyldimethylsilyl group was chosen as a suitable derivatizing agent because it induced approximatively a six-times higher solubility and allowed for an almost quantitative recovery of pure monastrol from the derivatization-deprotection sequence. The competitive isotherms of the O-tert-butyldimethylsilyl compounds, measured through frontal analysis, were fitted to competitive Langmuir and four-parameter bi-Langmuir models. The equilibrium dispersive model of chromatography was used for modeling the nonlinear separation of the racemate and to optimize the experimental conditions for collection of highly concentrated fractions of pure (R,S)-O-tert-butyldimethylsilyl compounds, from which significant amounts of the corresponding enantiomers of monastrol (about 100 mg of each enantiomer with 30 runs on an analytical-scale column) were obtained by quantitative back-derivatization.

Separation efficiencies in hydrophilic interaction chromatography

Hydrophilic interaction chromatography (HILIC) is important for the separation of highly polar substances including biologically active compounds, such as pharmaceutical drugs, neurotransmitters, nucleosides, nucleotides, amino acids, peptides, proteins, oligosaccharides, carbohydrates, etc. In the HILIC mode separation, aqueous organic solvents are used as mobile phases on more polar stationary phases that consist of bare silica, and silica phases modified with amino, amide, zwitterionic functional group, polyols including saccharides and other polar groups. This review discusses the column efficiency of HILIC materials in relation to solute and stationary phase structures, as well as comparisons between particle-packed and monolithic columns. In addition, a literature review consisting of 2006-2007 data is included, as a follow up to the excellent review by Hemström and Irgum.

Full NMR analysis of annomontine, methoxy- annomontine and N-hydroxyannomontine pyrimidine-beta-carboline alkaloids

Using modern NMR techniques, including 1H--13C and 1H--15N heteronuclear correlation experiments, the complete and unambiguous 1H, 13C, and 15N NMR chemical shift assignments of annomontine, methoxyannomontine, and N-hydroxyannomontine pyrimidine-beta-carboline alkaloids were performed. All 1H--1H scalar coupling constants and signal multiplicities were determined, and all nOe observations were also included.

Rapid identification of antibacterial agents effective against Staphylococcus aureus using small-molecule macroarrays

There is an urgent, global need for the development of new antibacterial agents. We have applied the small-molecule macroarray approach to the synthesis and screening of antibacterial compounds active against the Gram-positive pathogen Staphylococcus aureus. Several macroarrays of 1,3-diphenyl-2-propen-1-ones (chalcones), cyanopyridines, and pyrimidines were synthesized on a planar cellulose support system on the order of days. This support system was found to be highly compatible with antibacterial assay formats, including disk-diffusion and agar-overlay visualization methods. Further, sufficient compound was isolated from each spot of the macroarray for both compound characterization and minimum inhibitory concentration (MIC) estimation. Analysis of the small-molecule macroarrays in these assays uncovered a set of antibacterial agents with in vitro MIC values against methicillin-resistant S. aureus comparable to certain antibacterial drugs in use today.

Analytical and semipreparative enantioseparation of 9-hydroxyrisperidone, the main metabolite of risperidone, using high-performance liquid chromatography and capillary electrophoresis

The HPLC semipreparative enantioseparation of 9-hydroxyrisperidone (9-OHRisp) was studied by optimizing various experimental conditions: the nature of the chiral stationary phase (CSP), mobile phase composition, temperature and analyte loading. This semipreparative enantioseparation was successfully completed using the polysaccharide Chiralcel OJ chiral stationary phase and a n-hexane/ethanol/methanol (50/35/15, v/v/v) ternary mobile phase. To assess the enantiomeric purity of both isolated isomers, three analytical methods using UV detection were developed and validated: one CE method using dual cyclodextrin mode and two HPLC methods using either the Chiralcel OJ CSP in normal-phase mode or the alpha-acid glycoprotein (alpha-AGP) CSP in reversed-phase mode. The three methods make it possible to obtain excellent enantioseparations (R(s) >3) with analysis times lower than 15 min, and the calculated limits of detection allow for the determination of minor enantiomeric impurities (0.1%). Enantiomeric purity obtained for dextrorotatory and levorotatory enantiomers was superior to 99.9% and equal to 98.9%, respectively, which proved the success of the semipreparative enantioseparation. A brief comparison of the performances of the analytical methods completes this work.

[Isolation and structure identification of chemical constituents from Saposhnikovia divaricata (Turcz.) Schischk]

Fourteen compounds were isolated from the ethanol extraction of Saposhnikovia divaricata (Turcz.) Schischk using column chromatographic methods after enrichment by macroporous adsorptive resins. They were identified as fangfengalpyrimidine (1), clemiscosin A (2), 5-hydroxy-8-methoxypsoralen (3), sec-O-glucosylhamaudol (4), hamaudol (5), nodakenetin (6), prim-O-glucosylcimifugin (7), cimifugin (8), 4'-O-beta-D-glucosyl-5-O-methylvisamminol (9), 5-O-methylvisamminol (10), marmesin (11), adenosine (12), daucosterol (13) and beta-sitosterol (14) by physico-chemical properties and spectral data. Compound 1 is a new compound. Compounds 2 and 3 were isolated from umbelliferae plants and Saposhnikovia divaricata (Turcz.) Schischk for the first time respectively.

Rapid preparation of the mitotic kinesin Eg5 inhibitor monastrol using controlled microwave-assisted synthesis

We present here a protocol for the synthesis of the dihydropyrimidine (DHPM) derivative monastrol, which is known to be a specific mitotic kinesin Eg5 inhibitor. By applying controlled microwave heating under sealed-vessel conditions, the synthesis via the one-pot three-component Biginelli condensation can be performed in a shorter reaction time (30 min) compared with conventional heating methods that normally require several hours of reflux heating. For the purification of the crude target compound, two different methods are presented. The first protocol includes a simple precipitation/filtration step to provide monastrol in 76% isolated yield and high purity so that no recrystallization step is necessary. This can be ascribed to the microwave heating technology in which less side-product formation is typically one of the advantages. In an alternative purification step, column chromatography is performed, which provides the product in a slightly higher yield (86%). Monastrol synthesis can be conducted in approximately 2 h by employing the precipitation/filtration purification method.

c-Src protein kinase inhibitors block assembly and maturation of dengue virus

Dengue virus is a mosquito-borne flavivirus that represents an important emerging infectious disease and is an international health concern. Currently, there is no vaccine or effective antiviral therapy to prevent or to treat dengue virus infection. The slow progress in developing antiviral agents might be alleviated by the availability of efficient high-throughput anti-dengue virus screening assays. In this study, we report an immunofluorescence image-based assay suitable for identification of small molecule inhibitors of dengue virus infection and replication. Using this assay, we have discovered that inhibitors of the c-Src protein kinase exhibit a potent inhibitory effect on dengue virus (serotypes 1-4) and murine flavivirus Modoc. Mechanism of action studies demonstrated that the c-Src protein kinase inhibitor dasatinib prevents the assembly of dengue virions within the virus-induced membranous replication complex. These results demonstrate that this cell-based screen may provide a powerful means to identify new potential targets for anti-dengue drug development while simultaneously providing pharmacological probes to investigate dengue virus-host cell interactions at the biochemical level. Given the simplicity and excellent reproducibility of the assay, it should be useful in high-throughput screens of both small molecule and RNAi libraries when implemented on a robotic image-based high-throughput screen (HTS) platform. Given the reasonable clinical safety of inhibitors such as dasatinib and AZD0530, inhibitors of c-Src protein kinase may have the potential to become a new class of anti-dengue viral therapeutic agents.

HPLC separation of some purine and pyrimidine derivatives on Chromolith Performance Si monolithic column

The chromatographic behavior of some purines and pyrimidines on a monolithic Chromolith Performance Si column under normal-phase high-performance liquid chromatography mode has been studied. Column pressure, column efficiency and selectivity of Chromolith Performance Si column were compared to those of conventional spherical 5 microm silica packed columns Econosphere Silica and Zorbax Rx-SIL. The investigation has shown that application of Chromolith Performance Si column for analysis of polar solutes can reduce the separation time without sacrificing column efficiency and selectivity. Improvement of the monolithic silica column efficiency for polar solutes is observed when ternary mobile phases (mixtures of hexane-isopropanol with ethylene glycol, water or acetonitrile) are applied.

Hydroxyl-specific fluorescence labeling of ABP-deoxyguanosine, PhIP-deoxyguanosine, and AFB1-formamidopyrimidine with BODIPY-FL

Detection and analysis of DNA adducts resulting from endogenous or exogenous exposures to carcinogens are essential not only for quantifying biologically effective doses but also for establishing relationships between exposure and cancer risk. We have developed and validated a procedure of high sensitivity and specificity based on fluorescence labeling of DNA adducts combined with high-performance liquid chromatography-laser-induced fluorescence detection. The fluorescent dye 4,4-difluoro-5,7-dimethyl-4-bora-3a,4a-diaza-s-indacene-3-propionic acid (BODIPY FL) was used to label the deoxynucleoside adducts N-(2'-deoxyguanosine-8-yl)-4-aminobiphenyl and N-(2'-deoxyguanosine-8-yl)-2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine and the base adduct aflatoxin B(1)-formamidopyrimidine by acylation. The labeling reaction was carried out on adducts at 1pmol to 30nmol concentrations at 25 degrees C for 4h in dichloromethane with 200- to 5000-fold excess of BODIPY FL. BODIPY FL and its activating agents 1,3-dicyclohexylcarbodiimide and 4-dimethylaminopyridine were used at a molar ratio of 1:2:2. Under these conditions, all of the above adducts were quantitatively converted to bis-labeled products, as confirmed by mass spectrometry. Sites of derivatization of adduct deoxynucleosides were established primarily by nuclear magnetic resonance and by collision-induced dissociation mass spectrometric analysis, which indicated that the bis-BODIPY groups were located predominantely on the 3'- and 5'-hydroxyl groups of the deoxyribose ring.

Enhanced separation of purine and pyrimidine bases using carboxylic multiwalled carbon nanotubes as additive in capillary zone electrophoresis

This paper describes the enhanced separation of adenine (A), hypoxanthine (HX), 8-azaadenine (8-AA), thymine (T), cytosine (C), uracil (U) and guanine (G) by CZE dispersing carboxylic multiwalled carbon nanotubes (c-MWNTs) into the running buffer. The effect of important factors such as c-MWNT nanoparticle concentration, the acidity and concentration of running buffer, and separation voltage were investigated to acquire the optimum conditions. The seven purine and pyrimidine bases could be well separated within 16 min in a 35 cm effective length fused-silica capillary at a separation voltage of +8.0 kV in a 23 mM tetraborate buffer (pH 9.2) containing 8.0 x 10(-5) g/mL c-MWNTs. Under the optimal conditions, the linear ranges were of 2-250 microg/mL for A (R2 = 0.995), 3-200 microg/mL for U (R2 = 0.990) and G (R2 = 0.992), 3-250 microg/mL for T (R2 = 0.998), 2-200 microg/mL for C (R2 = 0.985) and 4-200 microg/mL for HX (R2 = 0.988) and 8-AA (R2 = 0.990). The detection limits were 0.9 microg/mL for A (S/N = 3), 2.4 microg/mL for U, 2.0 microg/mL for T, 1.5 microg/mL for C, 2.5 microg/mL for G and 3.0 microg/mL for HX and 8-AA. The proposed method was successfully applied for determining five purine and pyrimidine bases in yeast RNA.

Retention mechanism of l-glutamide-derived noncrystalline stationary phases in reversed-phase high-performance liquid chromatography and application for separation of nucleic acid constituents

Double alkylated L-glutamide-derived noncrystalline stationary phases Sil-DSG and Sil-DBG have been prepared by coupling N',N''-dioctadecyl-N-[4-carboxybutanoyl]-L-glutamide (DSG) and N',N'',-dibutyl-N-[4-carboxybutanoyl]-L-glutamide (DBG) with aminopropylated silica (Sil-APS). TEM observations of DSG and DBG showed that lipid DSG can aggregate in organic solvents (methanol, chloroform, toluene, etc.) and self-assembled nano fibers are observed while such fibrous aggregations are not observed for DBG. The resulting chromatographic data have been provided information about its selective interaction with guest molecules (PAHs) in RP-HPLC. We have observed that the carbonyl groups in Sil-DSG exist in ordered state by forming a condensing thin layer over silica surface while DBG cannot form such an ordered state due to its lower order of short alkyl chain. The ordered carbonyl groups present in Sil-DSG promotes multiple carbonyl pi-benzene pi interactions with guest PAHs isomers which enhance the selectivity for these compounds. The contribution of pi-pi interactions was also supported by the substantial effects on the selectivity of benzene and nitrobenzenes. The effect of pi-electron containing solvent on the retention behavior of the PAHs was also studied. The selectivity for nucleic acid constituents, i.e. nucleosides and its bases were also evaluated by Sil-DSG and the selectivity for these compounds on Sil-DSG was compared with the selectivity of conventional polymeric ODS phase. It has been found that Sil-DSG provided higher selectivity for nucleic acid constituents than polymeric ODS and that HPLC packing materials can be efficiently employed for routine analysis of these compounds. The effect of methanol content on the separation behavior of nucleosides was also studied.

Synthesis and HPLC evaluation of carboxylic acid phases on a hydride surface

Three organic moieties containing carboxylic acid functional groups are attached to a particulate silica surface through silanization/hydrosilation. Two compounds (undecylenic acid and 10-undecynoic acid) have 11 carbon chains and the other is a five-carbon acid (pentenoic acid). Bonding is confirmed through carbon elemental analysis, diffuse reflectance infrared fourier transform spectroscopy, and carbon-13 and silicon-29 CP-MAS NMR spectroscopy. The bonded phases are tested by HPLC using PTH amino acids, nucleic acids, theophylline-related compounds, anilines, benzoic acid compounds, choline, and tobramycin. The latter two compounds are used to investigate the aqueous normal phase properties of the three bonded materials.

A pyrimidine-beta-carboline and other alkaloids from Annona foetida with antileishmanial activity

Bioassay-guided fractionation of the bark extract of Annona foetida afforded a new antileishmanial pyrimidine-beta-carboline alkaloid, N-hydroxyannomontine (1), together with the previously reported annomontine (2), O-methylmoschatoline (3), and liriodenine (4). The structure of compound 1 was established on the basis of extensive 1D and 2D NMR and MS analyses. This is the third reported pyrimidine-beta-carboline-type alkaloid and is particularly important for Annona genus chemotaxonomy. In addition, all compounds exhibit in vitro antileishmanial activity against promastigote forms of Leishmania braziliensis. Compounds 2 and 4 showed better activity than compounds 1 and 3 against L. braziliensis. Compound 2 was not active against L. guyanensis.

Analysis of triazolopyrimidine herbicides in soils using field-enhanced sample injection-coelectroosmotic capillary electrophoresis combined with solid-phase extraction

In this work, a combined methodology using off-line solid-phase extraction (SPE), on-line field-enhanced sample injection (FESI) and coelectroosmotic capillary electrophoresis with UV detection (CE-UV) is developed for the trace analysis of five triazolopyrimidine sulfonanilide pesticides (i.e., flumetsulam, florasulam, cloransulam-methyl, diclosulam and metosulam). An adequate background electrolyte (BGE) was obtained for the separation of these pesticides using hexadimethrine bromide (HDB) as electroosmotic flow (EOF) modifier. This BGE consisted of 0.00042% HDB, 11 mM formic acid, 16 mM ammonium carbonate and 2.5 mM alpha-CD solution at pH 7.6. The use of this running buffer together with the FESI preconcentration method provided limits of detection (LODs) in the low microg/L range (i.e., between 13.0 and 31.5 microg/L). The optimized FESI-CE-UV method was combined with off-line SPE using C(18) cartridges and applied to the determination of the selected group of pesticides in soil samples. Recovery percentages ranged between 50 and 84% in these samples with LODs between 18 and 34 microg/kg. This work shows the great possibilities of the combined use of SPE-FESI-CE-UV to improve CE sensitivity allowing the achievement of LODs similar to other analytical techniques as GC or HPLC.

Two-dimensional separation system of coupling capillary liquid chromatography to capillary electrophoresis for analysis of Escherichia coli metabolites

A two-dimensional (2-D) separation system of coupling chromatography to electrophoresis was developed for profiling Escherichia coli metabolites. Capillary liquid chromatography (LC) with a monolithic silica-octadecyl silica column (500 x 0.2 mm ID) was used as the first dimension, from which the effluent fractions were further analyzed by capillary electrophoresis (CE) acting as the second dimension. Field-enhanced stacking was selectively employed as a concentration strategy to interface the two dimensions, which proved to be beneficial for the detection of metabolites. An artificial sample containing 118 standards, some of which lack chromophores or have weak UV absorbance, was used to optimize the 2-D separation system. Under the optimum conditions, 63 components in the artificial sample having absorbance at 254 nm could be well resolved and detected. The utility of the system was demonstrated by comprehensive analysis of E. coli metabolites. Comparing with the previous 2-D separation system we published in Anal. Chem. 2004, 76, 1419-1428, using a longer monolithic column in the first dimension improved the separation efficiency and offered the possibility of increasing the injection volume without compromising the separation efficiency. In the second dimension, field-enhanced stacking was used to improve the concentration sensitivity of the metabolites, and more metabolites in E. coli cell extract were detected and identified using the developed 2-D separation system. In addition, preliminary investigation for future CE-mass spectrometry coupling was also made in the study by using volatile buffers in the capillary LC and CE techniques.

Simultaneous high performance liquid chromatographic separation of purines, pyrimidines, N-acetylated amino acids, and dicarboxylic acids for the chemical diagnosis of inborn errors of metabolism

OBJECTIVES

To set up a novel simple, sensitive, and reliable ion-pairing HPLC method for the synchronous separation of several purines, pyrimidines, N-acetylated amino acids, and dicarboxylic acids for the chemical diagnosis and screening of inborn errors of metabolism (IEM).

DESIGN AND METHODS

The separation was set up using a Hypersil C-18, 5-microm particle size, 250 x 4.6 mm column, and a step gradient using two buffers and tetrabutylammonium hydroxide as the pairing reagent. A highly sensitive diode array UV detector was set up at a wavelength between 200 and 300 nm that revealed purines and pyrimidines at 260 nm and other compounds at 206 nm.

RESULTS

Compounds were determined in the plasma of 15 healthy adults, in the urine of 50 healthy subjects (1-3 years, 4-6 years, 8-10 years, 12-18 years, 25-35 years), and in 10 non-pathological amniotic fluid samples. To assess the validity of the chemical diagnosis of IEM, plasma and urine samples were analyzed in patients affected by Canavan disease (n = 10; mean age 4.6 +/- 2.3). Low plasma levels of N-acetylaspartate (16.96 +/- 19.57 micromol/L plasma; not detectable in healthy adults) and dramatically high urinary N-acetylaspartate concentrations (1872.03 +/- 631.86 micromol/mmol creatinine; 450 times higher than that which was observed in age-matched controls) were recorded. Neither N-acetylglutamate nor N-acetylaspartylglutamate could be detected in the plasma or urine of controls or patients with Canavan disease.

CONCLUSIONS

The results demonstrate the suitability of the present ion-pairing HPLC separation with UV detection of cytosine, cytidine, creatinine, uracil, uridine, beta-pseudouridine, adenine, 3-methyladenine, hypoxanthine, xanthine, xanthosine, inosine, guanosine, ascorbic acid, thymine, thymidine, uric acid, 1-methyluric acid, orotic acid, N-acetylaspartate, N-acetylglutamate, N-acetylaspartylglutamate, malonic acid, methylmalonic acid, GSH, and GSSG as a reliable method for the prenatal and neonatal chemical diagnosis and screening of IEM using biological fluids.

Separation of atropisomeric 1,4,5,6-tetrahydropyrimidinium salts by chiral HPLC and determination of their enantiomerization barriers

Chiral HPLC separation of a series of novel atropisomeric quaternary (1) and ternary (2) 1,2-disubstituted 1,4,5,6-tetrahydropyrimidinium salts bearing disymmetric aryl groups in positions 1 and/or 2 is described. A screening of different polysaccharide stationary phases (OD-R, OJ-R and AD-RH) and chromatographic conditions allowed for partial or baseline resolution of 16 over 26 compounds. When a semi-preparative separation was achieved, the corresponding enantiomerization barriers were determined employing the off-column method. The experimental data were compared inter se in order to establish the factors influencing the magnitude of the barriers and with those corresponding to the parent amidines.

Combining solid-phase microextraction and on-line preconcentration-capillary electrophoresis for sensitive analysis of pesticides in foods

The combined use of solid-phase microextraction (SPME) and different on-line preconcentration strategies for ultrasensitive capillary electrophoresis-ultraviolet (CE-UV) analysis of five pesticides in a single run is investigated. Normal stacking mode (NSM), field-enhanced sample injection (FESI), and stacking with matrix removal (SWMR) are explored to increase the sensitivity of the CE-UV analysis of a selected group of pesticides (cyprodinil, cyromazine, pyrifenox, pirimicarb, and pyrimethanil). It could be observed that reverse polarity-stacking with matrix removal (RP-SWMR) provided the best results in terms of sensitivity (enhancement was up to 272-fold compared with normal injection). The separation buffer consisted of 0.4 mM cetyltrimethylammonium chloride (CTAC), 0.4 M acetic acid at pH 4 containing 5% v / v 2-propanol. This approach was then combined with SPME to determine the pesticides in water, apple, and orange juice. The combination of both preconcentration procedures allowed the determination of these pesticides at concentrations down to 2.5 microg / L in water and 3.1 microg / L in juices (i.e., levels well below the maximum residue limits allowed for these compounds). To our knowledge, this is the first report showing the great possibilities of the combined use of SPME, on-line sample preconcentration, and CE for pesticide analysis.

Biliary Excretion of Imatinib Mesylate and Its Metabolite CGP 74588 in Humans

Imatinib mesylate, licensed to treat chronic myelogenous leukemia and gastrointestinal stromal tumors, is metabolized by cytochrome P450 3A and undergoes little renal excretion, but its biliary excretion by humans is uncharacterized. Liquid chromatography-mass spectrometry was used to quantitate imatinib and its metabolite CGP 74588 in the bile of two patients with biliary stents; the ratio of imatinib:CGP 74588 in each was approximately 9:1. In the first patient, who was receiving long-term therapy with imatinib 400 mg/day and had normal liver function tests, biliary imatinib accounted for 17.7% of the daily dose and CGP 74588 accounted for 2.1%. In the second patient, who had elevated liver function tests and was studied after his first dose of imatinib 300 mg, biliary imatinib accounted for only 1.8% of the daily dose and CGP 74588 accounted for 0.2%. These data show both the qualitative similarities and the quantitative variability in biliary excretion of imatinib and its principal metabolite.

Preparation and chiral recognition of a novel chiral stationary phase for high-performance liquid chromatography, based on mono(6A-N-allylamino-6A-deoxy)-perfunctionalized β-cyclodextrin and covalently bonded silica gel

A novel chiral stationary phase (CSP) was prepared by immobilizing mono(6A-N-allylamino-6A-deoxy)-perphenylcarbamoylated beta-cyclodextrin onto the surface of silica gel via hydrosilylation. The chromatographic properties of this column were tested with a wide range of structurally diverse racemic compounds and drugs under reverse phases. Separation mechanisms involved are also discussed.

Separation of purine and pyrimidine bases by capillary electrophoresis using β-cyclodextrin as an additive

Capillary electrophoresis was applied to separate purine and pyrimidine bases in the basis of their partial ionization in the alkaline buffer. The effects of buffer pH, buffer and beta-cylclodextrin concentration were systematically investigated using a commercial capillary electrophoresis instrument with UV detector at 254nm. We found that the resolutions of bases (especially for adenine and thymine) were significantly improved in the presence of beta-cylclodextrin. The satisfactory separation of five bases such as cytosine, thymine, adenine, guanine and uracil were achieved by capillary electrophoresis using beta-cylclodextrin as an additive. Under the optimal conditions, the linear range was from 2 to 200microg/ml for bases (R= 0,991-0,9977 ) and the detection limits were from 0.8 to 1.8microg/ml (S/N = 2). The detection limit of 0.05microg/ml ( S/N=2 ) for uracil was obtained by stacking injection mode. The assay was used to determine the deamination of cytosine to uracil by heating in the presence of sodium hydroxide. Our primarily results show that capillary electrophoresis is a very useful tool for determination of purine and pyrimidine bases and study on nucleic acids.

Residue analysis and dissipation of monosulfuron in soil and wheat

HPL-UV residue analytical method for monosulfuron [N-[(4'-methyl) pyrimidin-2'yl]-2-nitrophenylsulfonyl urea] in soil and wheat was developed. Monosulfuron residues were recovered by solvent extraction, followed by liquid-liquid partition, and C18 cartrige clean-up. Excellent method recoveries ranging from 95%-104% for both fortified soil and wheat grain were obtained with coefficients of variation 1.5%-11.8%. The minimum detectable quantities in soil and wheat were both 4 ng, the limit of detection was 0.02 mg/kg. When monosulfuron was applied according to double dosage of maximum recommended use direction(120 g ai/hm2 of 10% monosulfuron wettable powder sprayed for once during development of wheat) in field studies conducted in Shandong Province and near Beijing, monosulfuron residues was not detected in soil and wheat samples collected 75 d after application. Laboratory soil degradation studies showed that monosulfuron degraded faster in acidic soil and strong alkaline soil than in neutral or weak alkaline soil. Half lives in Jiangxi soil, Shijiazhuang soil, Jiangsu soil and Heilongjiang soil were 41, 48, 87 and 84 d respectively. Monosulfuron residues dissipated rapidly in Shandong and Beijing field test sites with half-lives of less than 14 d.