<Emphasis Type="Italic">N</Emphasis>-Arylamine derivatives of 3-hydroxy-4-pyridinones: solution studies and bioevaluation in view of Al-detoxification roles

A study of a series of bifunctional 3-hydroxy-4-pyridinone derivatives, containing side-chains with various alkyl-aryl-amine-amides as extra-functional groups, was conducted to assess the relevance of those groups to the Al-chelating affinity, the lipo–hydrophilic balance of the compounds, and ⁶⁷Ga biodistribution in mice, in view of their potential use as Al-decorporating agents; the results were compared with those for the drug Deferriprone. Their acid–base properties and Al-chelating affinity in aqueous solution were studied by potentiometric techniques. These ligands form very stable tris-chelated Al complexes and the non-chelating extra-groups are only responsible for small differences in the complex stability (pAl1.2). At physiological pH the major ligand/complex species have different charges, because of the different extent of protonation of the ligands. The introduction of the different groups induces a well-balanced stepwise-like lipo–hydrophilic character (–0.2<log D_oct./water<+1.1). The effect of each ligand on the biodistribution of ⁶⁷Ga in overloaded mice is rapid blood clearance for all of them, but with different biodistribution patterns, namely excretion pathways and brain uptake/clearance, thus suggesting potential different clinical use.     

Analysis of carbohydrates in Lupinus albus stems on imposition of water deficit, using porous graphitic carbon liquid chromatography-electrospray ionization mass spectrometry

This work reports the development and application of a negative ion mode online LC-ESI-MS method for studying the effect of water deficit on the carbohydrate content of Lupinus albus stems, using a porous graphitic carbon (PGC) stationary phase and an ion trap mass spectrometer. Using this method, separation and detection of several water soluble carbohydrates, ranging from mono-, di-, and oligosaccharides (raffinose, stachyose, and verbascose) to sugar alcohols was achieved in approximately 10 min. This on-line PGC-LC-ESI-MS method shows good linearity with correlation coefficients R(2)>0.99, selectivity, short analysis time, and limits of detection (LOD) ranging from 0.4 to 9 pmol for sugars and 4-20 pmol for sugar alcohols. This PGC-LC-ESI-MS method is sensitive and allowed us to detect even small alterations in carbohydrate levels in L. albus stems that resulted from a mild/early water deficit (nmol g(-1)DW). This paper describes details of our method and its application to the quantitative analysis of water soluble underivatised carbohydrates extracted from L. albus stem tissues that have been subjected to early and severe water deficit conditions, followed by a rewatering period.     

Natural lycopene from Blakeslea trispora: all-trans lycopene thermochemical and structural properties

Structural and thermal properties of all-trans lycopene are described in the present paper. Different crystalline lycopene samples obtained from fermentation process and recrystallized lycopene were analyzed. Structural properties (NMR, mass spectrometry and powder X-ray diffraction) of lycopene were clarified with recent techniques. High purity sample analysis by differential scanning calorimetry was used to study thermal behavior of pure lycopene and with traces of isomers. But also this was correlated with HPLC method for determine lycopene purity and isomers in low proportion.     

Biocompatible in-tube solid phase microextraction coupled with liquid chromatography-fluorescence detection for determination of interferon α in plasma samples

The present work demonstrates the successful application of automated biocompatible in-tube solid-phase microextraction coupled with liquid chromatography (in-tube SPME/LC) for determination of interferon alpha(2a) (IFN α(2a)) in plasma samples for therapeutic drug monitoring. A restricted access material (RAM, protein-coated silica) was employed for preparation of a lab-made biocompatible in-tube SPME capillary that enables the direct injection of biological fluids as well as the simultaneous exclusion of macromolecules by chemical diffusion barrier and drug pre-concentration. The in-tube SPME variables, such as sample volume, draw/eject volume, number of draw-eject cycles, and desorption mode were optimized, to improve the sensitivity of the proposed method. The IFN α(2a) analyses in plasma sample were carried out within 25min (sample preparation and LC analyses). The response of the proposed method was linear over a dynamic range, from 0.06 to 3.0MIUmL(-1), with correlation coefficient equal to 0.998. The interday precision of the method presented coefficient of variation lower than 8%. The proposed automated method has adequate analytical sensitivity and selectivity for determination of IFN α(2a) in plasma samples for therapeutic drug monitoring.     

An N‐Acetyl Cysteine Ruthenium Tricarbonyl Conjugate Enables Simultaneous Release of CO and Ablation of Reactive Oxygen Species

We have designed and synthesised a [Ru(CO)₃Cl₂(NAC)] pro‐drug that features an N‐acetyl cysteine (NAC) ligand. This NAC carbon monoxide releasing molecule (CORM) conjugate is able to simultaneously release biologically active CO and to ablate the concurrent formation of reactive oxygen species (ROS). Complexes of the general formulae [Ru(CO)₃(L)₃]²⁺, including [Ru(CO)₃Cl(glycinate)] (CORM‐3), have been shown to produce ROS through a water–gas shift reaction, which contributes significantly, for example, to their antibacterial activity. In contrast, NAC‐CORM conjugates do not produce ROS or possess antibacterial activity. In addition, we demonstrate the synergistic effect of CO and NAC both for the inhibition of nitric oxide (formation) and in the expression of tumour‐necrosis factor (TNF)‐α. This work highlights the advantages of combining a CO‐releasing scaffold with the anti‐oxidant and anti‐inflammatory drug NAC in a unique pro‐drug.     

Simultaneous Determination of Caffeine,Ibuprofen, and Paracetamol by Flow‐injection Analysis with Multiple‐pulse Amperometric Detection on Boron‐doped Diamond Electrode

This work presents a simple, fast and low‐cost method for the simultaneous determination of three drugs by flow‐injection analysis with multiple‐pulse amperometric (MPA) detection using a wall‐jet flow cell with a boron‐doped diamond electrode. The amperometric determination of caffeine (CF), ibuprofen (IB) and paracetamol (PC) was performed by the application of a four‐potential waveform using the MPA technique. PC is oxidized at E₁ (1.20 V/70 ms) and thus selectively detected; PC and CF are oxidized at E₂ (1.49 V/40 ms); PC, CF and IB are oxidized at E₃ (1.70 V/70 ms); and E₄ (1.80 V/100 ms) is applied for electrode cleaning. The subtraction of currents obtained at the different potentials did not provide accurate determinations of CF and IB, thus it was required to investigate correction factors to determine CF and IB without the interference from PC and CF using the respective amperometric signals obtained at E₂ and E₃. The proposed method was successfully applied for the determination of three drugs in pharmaceutical samples with low generation of residues and a high analytical frequency (150 h^?1) in comparison with HPLC‐DAD method.     

Simultaneous determination of caffeine,paracetamol, and ibuprofen in pharmaceutical formulations by high‐performance liquid chromatography with UV detection and by capillary electrophoresis with conductivity detection

Paracetamol, caffeine and ibuprofen are found in over‐the‐counter pharmaceutical formulations. In this work, we propose two new methods for simultaneous determination of paracetamol, caffeine and ibuprofen in pharmaceutical formulations. One method is based on high‐performance liquid chromatography with diode‐array detection and the other on capillary electrophoresis with capacitively coupled contactless conductivity detection. The separation by high‐performance liquid chromatography with diode‐array detection was achieved on a C₁₈ column (250×4.6 mm², 5 μm) with a gradient mobile phase comprising 20–100% acetonitrile in 40 mmol L^?1 phosphate buffer pH 7.0. The separation by capillary electrophoresis with capacitively coupled contactless conductivity detection was achieved on a fused‐silica capillary (40 cm length, 50 μm i.d.) using 10 mmol L^?1 3,4‐dimethoxycinnamate and 10 mmol L^?1 β‐alanine with pH adjustment to 10.4 with lithium hydroxide as background electrolyte. The determination of all three pharmaceuticals was carried out in 9.6 min by liquid chromatography and in 2.2 min by capillary electrophoresis. Detection limits for caffeine, paracetamol and ibuprofen were 4.4, 0.7, and 3.4 μmol L^?1 by liquid chromatography and 39, 32, and 49 μmol L^?1 by capillary electrophoresis, respectively. Recovery values for spiked samples were between 92–107% for both proposed methods.     

Ethylene‐vinyl alcohol copolymers partially modified with benzoate groups: Study of their polymorphic behavior

The crystalline structure exhibited by terpolymers obtained through chemical modification with benzoyl chloride from an ethylene‐vinyl alcohol copolymer with a molar fraction in vinyl alcohol of 68%, EVOH68, has been studied by either wide angle X‐ray diffraction or small angle X ray scattering experiments and differential scanning calorimetry. The type of crystal lattice developed has been found to be strongly dependent on modification degree and thermal history. A highly‐disordered crystalline lattice with very small crystallites has been found for the quenched specimen with the highest benzoate content while the rest of fast cooled samples crystallized into an orthorhombic lattice. On the other hand, a monoclinic crystal cell has been observed in the slowly cooled specimens with low benzoate incorporation. At the last given thermal treatment, this monoclinic lattice evolves and seems to be transformed into an orthorhombic‐like crystal for the terpolymer with the highest modification ratio. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 1026–1036, 2007     

Application of HPLC-PBMS to the identification of unknown components in a triterpenoid fraction of Arbutus unedo fruits

An extract fraction fruits of Arbutus unedo, L., was cleaned-up by column chromatography and shown by NMR to be a mixture of isomers that resists further attempts at separation by conventional chromatographic methods. High resolution gas chromatography-mass spectrometry (HRGC-MS) confirms the presence of triter-penoid isomers but does not allow separation of all the components. This can be improved by trimethylsilylation but the absence of molecular ions and the complex spectra are difficult to interpret. Complete separation can be achieved by high pressure liquid chro-matography (HPLC) coupled to a mass spectrometer by means of a particle beam interface (HPLC-PBMS). Four triterpene com-pounds are identified through analysis of the corresponding mass spectra: α-amyrin, β-amyrin, and Lupeol, have for the first time been identified in Arbutus unedo, L. Fruits. A new natural triterpene tentatively identified as olean-12-en-3β, 23-diol is described for the first time.