Novel Rivastigmine Derivatives as Promising Multi-Target Compounds for Potential Treatment of Alzheimer's Disease.

Alzheimer's disease (AD) is the most serious and prevalent neurodegenerative disorder still without cure. Since its aetiology is diverse, recent research on anti-AD drugs has been focused on multi-target compounds. In this work, seven novel hybrids (RIV-BIM) conjugating the active moiety of the drug rivastigmine (RIV) with 2 isomeric hydroxyphenylbenzimidazole (BIM) units were developed and studied. While RIV assures the inhibition of cholinesterases, BIM provides further appropriate properties, such as inhibition of amyloid ß-peptide (Aß) aggregation, antioxidation and metal chelation. The evaluated biological properties of these hybrids included antioxidant activity; inhibition of acetylcholinesterase (AChE), butyrylcholinesterase (BChE) and Aß42 aggregation; as well as promotion of cell viability and neuroprotection. All the compounds are better inhibitors of AChE than rivastigmine (IC50 = 32.1 µM), but compounds of series 5 are better inhibitors of BChE (IC50 = 0.9-1.7 µM) than those of series 4. Series 5 also showed good capacity to inhibit self- (42.1-58.7%) and Cu(II)-induced (40.3-60.8%) Aß aggregation and also to narrow (22.4-42.6%) amyloid fibrils, the relevant compounds being 5b and 5d. Some of these compounds can also prevent the toxicity induced in SH-SY5Y cells by Aß42 and oxidative stress. Therefore, RIV-BIM hybrids seem to be potential drug candidates for AD with multi-target abilities.

Determination of ibuprofen enantiomers in breast milk using vortex-assisted matrix solid-phase dispersion and direct chiral liquid chromatography.

A mixture of ß-cyclodextrin (ß-CD) and primary and secondary amine (PSA) sorbents was employed for the extraction and quantification of ibuprofen enantiomers from human breast milk, combining a vortex-assisted matrix solid-phase dispersion method (MSPD) and direct chiral liquid chromatography (CLC) with ultraviolet detection (UV). The MSPD sample preparation procedure was optimized focusing on both the type and amount of dispersion/sorption sorbents and the nature of the elution solvent, in order to obtain acceptable recoveries and avoiding enantiomer conversion. These MSPD parameters were optimized with the aid of an experimental design approach. Hence, a factorial design was used for identification of the main variables affecting the extraction process of ibuprofen enantiomers. Under optimum selected conditions, MSPD combined with direct CLC-UV was successfully applied for ibuprofen enantiomeric determination in breast milk at enantiomer levels between 0.15 and 6.0µgg-1. The proposed analytical method also provided good repeatability, with relative standard deviations of 6.4% and 8.3% for the intra-day and inter-day precision, respectively.

Determination of serotonin and its precursors in chocolate samples by capillary liquid chromatography with mass spectrometry detection.

A method for the analysis of serotonin (5-HT) and its precursors, 5-hydroxytryptophan (5-HTP) and l-tryptophan (TP) in chocolate samples by capillary liquid chromatography-mass spectrometry (cLC-MS) has been developed. Optimum chromatographic conditions were established by using a personalized multifactorial experimental design. Finally the cLC separation was achieved through a mixture of acetonitrile and 5mM ammonium formate at pH 4 (3:97, v/v) as mobile phase in gradient elution, setting the injection volume at 10 µL and using pure water as injection solvent for focusing purposes on the head of the capillary column. For extraction of targets in chocolate samples a new, fast and simple procedure based on the use of acidic extraction medium and sonication was developed. Working in selected ion mode (m/z 177 for 5-HT, m/z 205 for l-tryptophan and m/z 221 for 5-HTP) detection limits were between 0.01 and 0.11 µg g(-1) and linearity was in the concentration range of 0.5-25 µg g(-1). Recoveries higher than 76% with RSDs lower than 8% were obtained from spiked samples for all analytes, showing the effectiveness of the proposed method. Serotonin and its precursors were determined in 5 kinds of commonly consumed chocolates with different cocoa contents (70-100%). The highest serotonin content was found in chocolate with a cocoa content of 85% (2.93 µg g(-1)). Regarding l-tryptophan, the highest content of this amino acid (13.27-13.34 µg g(-1)) was found in chocolate samples with the lowest cocoa content (70-85%). 5-Hydroxytryptophan was not detected in any chocolate samples.

Síndrome de Panayiotopoulos: dificultades académicas y alteraciones comportamentales / Panayiotopoulos syndrome: academic difficulties and behavioural disorders

Introducción. El síndrome de Panayiotopoulos (SP) constituye una de las epilepsias benignas de la infancia. Existen artículos en los que se muestra que los pacientes pueden presentar trastornos del comportamiento y dificultad para el aprendizaje. Objetivos. Revisar a los pacientes con diagnóstico de SP de nuestro hospital y comprobar si evidencian dichas alteraciones y si existe alguna característica específica que permita identificar a pacientes con riesgo. Pacientes y métodos. Revisión retrospectiva de historias clínicas de pacientes con diagnóstico de SP. Se realizó electroencefalograma (EEG) o video-EEG-poligrafía de sueño a todos los pacientes. Para la valoración intelectual se utilizó la escala de inteligencia de Wechsler para niños.Resultados. Se recogieron 33 pacientes, 17 de ellos, niños. La mediana de edad al inicio fue de 3,2 años y el seguimiento fue de 4,9 años (rango: 1-12 años). En 31 pacientes se detectaron grafoelementos irritativos en regiones occipitales (67,7%), temporales (45,2%) o parietales (22,5%). El 72,7% de los pacientes presentó más de dos crisis. Veintitrés pacientes precisaron tratamiento antiepiléptico. A dos pacientes se les diagnosticó trastorno por déficit de atención/hiperactividad. El 30,3% refería una atención dispersa, y el 27,3%, temperamento impulsivo. El 51,1% tenía un rendimiento en los estudios bueno, el 26,5% regular y el 17,6% malo. El 39,4% precisó apoyos extraescolares. Se realizó una valoración del nivel intelectual a 11 pacientes. Conclusión. El SP es una entidad con un buen pronóstico, pero parece asociar trastornos del aprendizaje y conductuales (AU)

Introduction. Panayiotopoulos syndrome (PS) is one of the benign epilepsies found in childhood. Some papers have shown that patients can present behavioural disorders and learning difficulties. Aims. To review patients diagnosed with PS in our hospital and to check whether they display evidence of such disorders and if there is any specific feature that allows high-risk patients to be identified. Patients and methods. A retrospective review of the medical records of patients diagnosed with PS was carried out. An electroencephalogram (EEG) or video-EEG-polygraph recordings were performed on all patients during sleep. The Weschler Intelligence Scale for Children was used to evaluate intelligence. Results. Data were collected for 33 patients, 17 of whom were children. The mean age at onset was 3.2 years and the follow-up was 4.9 years (range: 1-12 years). Irritative EEG phenomena were detected in the occipital (67.7%), temporal (45.2%) or parietal regions (22.5%) in 31 patients. Furthermore, 72.7% of patients presented more than two seizures. Twenty-three patients required treatment with antiepileptic drugs. Two patients were diagnosed with attention deficit hyperactivity disorder. Additionally, 30.3% reported dispersed attention and 27.3% had an impulsive character. It was found that 51.1% had a good level of academic achievement, in 26.5% it was regular and in 17.6% poor. A total of 39.4%needed assistance in the form of after-school classes. The level of intelligence was evaluated in 11 patients. Conclusion. PS is a condition with a good prognosis, but seems to be associated to learning and behavioural disorders (AU)

Direct chiral liquid chromatography determination of aryloxyphenoxypropionic herbicides in soil: deconvolution tools for peak processing.

In this paper, the enantiomeric separation of two aryloxyphenoxypropionic esters (fluazifop-butyl and quizalofop-ethyl) and a safener herbicide (mefenpyr-diethyl), which is widely used for protecting crop plants, has been studied by direct liquid chromatography (LC) with UV detection on an α(1)-acid glycoprotein as chiral stationary phase. Optimization of separation conditions was done by factorial experimental design. Experimental factors and ranges selected were propanol (5-10%), phosphate buffer pH (6.5-7.0), and column temperature (15-25 °C). Responses were expressed in terms of enantioresolution (R(s)) and adjusted retention time of the second eluted enantiomer (t(r2)'). The chemometric method used to explore data was response surface analysis. Multiple response analyses were carried out to determine the combination of experimental factors which simultaneously optimize experimental responses. Under optimum conditions for enantioseparation of each herbicide, partially overlapped or fully resolved enantiomers were obtained. Deconvolution tools were employed as an integration method to fit chromatographic data and to achieve a more precise enantiomeric ratio (ER) and enantiomeric fraction (EF) values. Applicability of both direct chiral LC and peak deconvolution methods was evaluated in spiked soil samples at different R/S enantiomeric ratios. Acceptable and reproducible recoveries between 71% and 96% with precision in the range 1-6% were achieved for herbicide-spiked levels from 0.50 to 9.0 µg g(-1). In addition, parameters such as R(s), ER, and EF were calculated and compared with values obtained using the common valley drop integration method.

Large injection volumes in capillary liquid chromatography: Study of the effect of focusing on chromatographic performance.

This paper describes a multivariate approach to study the effect on chromatographic conditions and to optimize such conditions in capillary liquid chromatography when high injection volumes are required. Several separations have been evaluated by using isocratic and gradient solvent elution, as well as isocratic elution combined with temperature programming. In this study, easily ionisable organic compounds with low logP have been used as representative analytes. Injection volume and nature of the injection solution have been evaluated in order to increase the sensitivity (peak area) and column performance (N values). The equations obtained by multiple linear regressions and response surfaces allow achieving the optimum on-column focusing conditions for chlorophenoxy acids, carbamates and heterocyclic amines.

Capillary liquid chromatography with diode array and mass spectrometry detection for heterocyclic aromatic amine determination in ready-to-eat food treated with electron-beam irradiation.

In the present paper, we have developed a capillary liquid chromatography with MS detection for the determination at ngg⁻¹ levels of four heterocyclic aromatic amines (MeIQx, norharman, harman and harmine), a group of mutagenic and carcinogenic compounds that can potentially be produced in protein-rich food during processing operations. They have been determined in commercial ready-to-eat (RTE) smoked salmon and soft cheese treated with E-beam irradiation. On the basis of experimental design studies and operating conditions of MS detector, best chromatographic conditions were obtained using a Luna® C¹8 capillary column (150 mm × 0.3 mm I.D.) with a mixture of acetonitrile-ammonium formate 5 mM pH 3.6 buffer (13:87, v/v) as mobile phase. To improve sensitivity, large injection volumes (20 µL) and injection solutions of low elution strength were employed. Sample preparation procedure included a previous treatment with 1M NaOH, followed by two solid-phase extraction steps; firstly on diatomaceous earth and then on mixed-mode cartridges. Heterocyclic amines were detected neither in irradiated and in non-irradiated samples, indicating that they were not formed by the radiation effect even at doses higher than those indicated in the Food Safety Objective established by regulatory agencies. RTE food samples were spiked at concentration levels in the range 10-30 ngg⁻¹. Recoveries higher than 85% (n=3 for each spiked level) were obtained, showing the effectiveness of the proposed methodology.

New approach to optimize HPLC separations of acid-base compounds with elution order involved, by using combined three-band resolution maps.

Some of the optimization methods in reversed phase high-performance liquid chromatography (RP-HPLC) are based on resolution of the critical band pair. Mobile phase composition is changed systematically to establish those conditions giving an acceptable resolution for such a critical band pair, but sometimes the critical pair may change with the separation conditions, which obliges to identify it for each of those conditions. In the case of ionizable compounds, more than two bands may be involved in resolution, showing--in some cases--changes in the elution order when the mobile phase composition was modified. In this paper, an alternative way that does not identify the critical pair after changing experimental conditions is proposed. The relative separation of the three bands involved in two alternating critical band pairs is evaluated as a sort of conjugate or combined resolution, represented as contour maps vs. two variables (content of organic modifier and pH). These maps are obtained from data of chromatograms made under different separation conditions; these conditions were generated by experimental design and data was mathematically processed with a computer program. Analytes of three families that have acid-base properties, triazines, phenoxyacids, and phenols, were used for this purpose. The chromatographic behavior when elution order reversion of ionizable compounds exists is studied.

Multiresidue determination of chlorophenoxy acid herbicides in human urine samples by use of solid-phase extraction and capillary LC-UV detection.

Chlorophenoxy acid herbicides are intensively applied to get rid of unwanted plants because of their low cost and selectivity. Due to their toxicity, which depends on their chemical form, the European Community has established legal directives to restrict their use and to control their maximum residue levels in several matrices. Determination of chlorophenoxy acids-2,4-dichlorophenoxyacetic acid (2,4-D), 4-chloro-2-methylphenoxyacetic acid (MCPA), 2-(2,4-dichlorophenoxy)propanoic acid (2,4-DP), 2-(4-chloro-2-methylphenoxy)propanoic acid (MCPP), 4-(4-chloro-2-methylphenoxy)butanoic acid (MCPB) and 2-(2,4,5-trichlorophenoxy)propanoic acid (2,4,5-TP) in spiked human urine samples has been carried out by capillary LC, after solid-phase extraction on a column packed with silica C18 restricted-access material. Chromatographic analysis was performed in gradient-elution mode at 25 degrees C, with injection of 20 microL low-organic-solvent composition herbicide solutions for focusing purposes on the head of the capillary column, and diode array detection at 232 nm. Urine samples collected during 24 h from healthy and unexposed volunteers were spiked in the concentration range 25-150 microg L(-1); recoveries obtained were between 66 and 100% (n = 6 for each spiked level) and RSDs (relative standard deviations) were between 1 and 5%. Detection limits in the urine samples from volunteers were between 3.5 and 6.0 microg L(-1). The developed methodology has allowed the clean-up and preconcentration of low volumes of untreated human urine without previous treatment, showing the effectiveness of the employed SPE sorbent for extracting the target analytes and ultimately resulting in the reduction of the sample-preparation time.

Effect of temperature on the separation of chlorophenoxy acids and carbamates by capillary high-performance liquid chromatography and UV (or diode array) detection.

In this work, the effect of temperature in isothermal and programmed modes on several chromatographic parameters such as retention factor, selectivity, resolution and plate number has been discussed. A critical comparison of isocratic/isothermal, gradient/isothermal and isocratic/program temperature modes has been made. Two representative families of pesticides have been selected for this study. One includes ionisable chlorophenoxy acids and two of their esters, some of which show similar polarities. The other one contains several weakly polar carbamates. Analysis was carried out using a reversed-phase capillary high-performance liquid chromatography (HPLC) system and focusing technique with UV or diode array detection (DAD).

Capillary liquid chromatography of chlorophenoxy acid herbicides and their esters in apple juice samples after preconcentration on a cation exchanger based on polydivinylbenzene-N-vinylpyrrolidone.

A capillary liquid chromatography (cLC) method with gradient elution has been used to determine chlorophenoxy acid herbicides: 2,4-dichlorophenoxyacetic acid, 4-chloro-2-methylphenoxyacetic acid, 2-(2,4-dichlorophenoxy)propanoic acid, 2-(4-chloro-2-methylphenoxy)propanoic acid, 4-(2,4-dichlorophenoxy)butanoic acid, 4-(4-chloro-2-methylphenoxy)butanoic acid, 2-(2,4,5-trichlorophenoxy)propanoic acid, 2,4-dichlorophenoxyacetic-1-methyl ester and 2,4-dichlorophenoxyacetic-1-butyl ester in spiked apple juice samples with amounts between 0.025 and 0.150 mg kg(-1) of each herbicide. Clean-up and preconcentration of acid and esters were carried out in an Oasis MCX polymer. Detection limits obtained by cLC, between 0.005 and 0.018 mg kg(-1), allowed the determination of chlorophenoxy acids and their esters in apple juice samples around the levels permitted by the European Regulations, with recoveries in the range 84-99% and RSDs between 1 and 4%.

Rapid analysis of pyrethroids in whole urine by high-performance liquid chromatography using a monolithic column and off-line preconcentration in a restricted access material cartridge.

A rapid high-performance liquid chromatography (HPLC) method using a monolithic column with UV detection at 238 nm was developed for the determination of fenpropathrin, betacyfluthrin, deltamethrin, and permethrin (cis and trans isomers) in whole urine. The method is based on the use of a monolithic chromatographic column and a restricted access material (RAM) cartridge for sample preparation. The mobile phase was water/acetonitrile (42:58 v/v), the flow rate was 3 mL min(-1), and chromatographic separation was carried out in 10 min. The separation of cis and trans isomers of permethrin was also possible under the above-mentioned conditions. Detection limits in reconstituted whole urine samples were between 0.9 microg L(-1) for betacyfluthrin and 4.4 microg L(-1) for fenpropathrin and trans-permethrin. Recoveries for urine samples spiked with different amounts of pyrethroids (between 19 microg L(-1) and 75 microg L(-1)) were in the 70+/-6 to 90+/-7% range.

Enantiomeric separation of chlorophenoxy acid herbicides by nano liquid chromatography-UV detection on a vancomycin-based chiral stationary phase.

Enantiomeric separation of mecoprop, dichlorprop, and fenoprop herbicides in their acid form, commonly used to control the growth of broad-leaved weeds, was carried out by nano-liquid chromatography (nano-LC) at a flow rate of 60 nL/min, using a packed capillary column with vancomycin-modified silica particles of 5 microm. The length of chiral stationary phase was 21 cm, while the total and effective lengths were 43 and 33cm, respectively. Inner diameter was 0.075 mm. Separated peaks were detected at 195 nm. Several mixtures of methanol, water, and 500 mM ammonium acetate buffer at different pH's were tested as mobile phase, and experimental parameters such as resolution (Rs), capacity factor (k), efficiency (N/m), and enantioselectivity factor (alpha) were measured under all the test conditions. Baseline enantiomeric separation was obtained for the three studied herbicides with alpha in the range 1.6-1.9, using as the mobile phase aqueous solutions containing 85% methanol, 5% of 500mM ammonium acetate pH4.5 buffer, and 10% water. Experimental results show that the vancomycin stationary phase presents a great enantiorecognition capability towards chlorophenoxy acid herbicides on using nano-LC.

Determination of chlorine and bromine in automotive shredder residues by oxygen bomb and ion chromatography.

An analytical procedure, oxygen bomb combustion-ion chromatography (IC), has been developed for the determination of total chlorine in Automotive Shredder Residues (ASR). Samples of these residues are fired under elevated oxygen pressure (30 atm) and the combustion products are transferred into a Na2CO3/NaHCO3 absorbent solution containing 1% of H2O2; the chlorine contents are then evaluated by ion chromatography. The use of the non-suppressed IC determination with a conductivity detector provides a rapid, sensitive and selective method for chlorine determination in ASR, allowing determinations of this heteroatom at levels below 1% in the presence of bromine and sulfur. Moreover, the proposed method allows the simultaneous determination of chlorine, bromine and sulfur which are potential environmental hazards.

Antipyretic effects of dipyrone versus ibuprofen versus acetaminophen in children: results of a multinational, randomized, modified double-blind study.

This study compared the antipyretic effectiveness of acetaminophen, ibuprofen, and dipyrone in young children with fever. The results were based on a modified double-blind, randomized, multinational trial that evaluated 628 febrile children, aged 6 months to 6 years. All three drugs lowered temperature in the 555 patients completing the study. Temperature normalization rates in the ibuprofen and dipyrone groups (78% and 82%, respectively) were significantly higher than the acetaminophen group (68%, P = 0.004). After 4 to 6 hours, mean temperature in the dipyrone group was significantly lower than the other groups, demonstrating longer temperature normalization with dipyrone. All three drugs showed comparable tolerability profiles.

Chemically modified polymeric sorbents for sample preconcentration.

Solid-phase extraction is an attractive alternative in sample preparation because it overcomes many drawbacks of liquid-liquid extraction and makes on-line determination possible by hyphenation with chromatographic techniques. Driven by the need for more effective and more selective sorbents, advances in solid-phase extraction include the development of new materials. This paper describes different types of chemically modified sorbents for the solid-phase extraction of compounds from aqueous samples. Chemical introduction of different functional groups into a polymeric resin improves the efficiency of solid-phase extraction by providing better surface contact with the aqueous samples; also, these sorbents have a greater capacity than the typical solid-phase materials for polar compounds have. The most important new sorbents are the chemically modified resins based on styrene-divinylbenzene copolymers. Preparation of these new sorbents is described, and advantages and drawbacks of off-line procedures and on-line procedures are also discussed. Applications for off-line and on-line chromatographic determinations of polar compounds are presented.

Preconcentration of pentachlorophenol from sawdust using quinolin-8-ol immobilized on controlled-pore glass and determination by liquid chromatography.

A method for quantitative evaluation of pentachlorophenol (PCP) in sawdust has been developed. Pentachlorophenol is extracted from the solid matrix with 0.5 M sodium hydroxide and preconcentration was carried out using quinolin-8-ol immobilized on controlled pore glass. Determination was carried out by using liquid chromatography with detection at 240 nm. Recoveries were between 84 and 97% at 1-3 microg/g.