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The diffusion of seven arylpropionic acid non-steroidal anti-inflammatory drugs (NSAIDs) into the cerebrospinal fluid (CSF) has been investigated in male Wistar rats by means of quantitative structure-activity relationship (QSAR) study. After intraperitoneal administration of each drug (5 mg/kg), blood and CSF samples were collected at different times (0.5, 1, 3, and 6 h). The fraction bound to plasma proteins (fb) was determined using ultracentrifugation. The total (CT) and free (CF) plasma concentrations and the concentrations in CSF (CCSF) were measured by a reversed-phase high performance liquid chromatographic (RP-HPLC) method. The areas under the curve of the free plasma (AUCF) and CSF (AUCCSF) concentrations were calculated according to the trapezoidal rule. The overall drug transit into CSF was estimated by the ratio RAUC (AUCCSF: AUCF). The lipophilicity of the compounds was expressed as their polycratic capacity factors (log k'w) measured in a RP-HPLC system. The RAUC ranged from 0.24 to 6.58 and fb from 91.4 to 99.8%. The compounds with an intermediate lipophilicity value (3logk'w3.6) easily entered the CSF (RAUC1). A parabolic relationship was found between log k'w and log RAUC, emphasizing the role of molecular lipophilicity in the diffusion into CSF. Considering the fb value of each drug in regard to this non-linear relationship, it can be hypothesized that the diffusion rate of NSAIDs into the CSF depends primarily on the lipophilicity.

A new highly sensitive and compact 224 nm laser-induced native fluorescence (LINF) detector was developed using a new generation of deep-UV laser and an innovating elliptical flow cell. The use of deep-UV excitation at 224 nm allows to achieve fluorescence detection of an important range of molecules containing a single aromatic ring. The LINF detector was first evaluated in liquid chromatography. An improvement of a factor 500 over a conventional fluorimeter is reached with a limit of detection (LOD) of 1.5 pmole for ibuprofen. LODs were in the nanomole range for phenylalanine and in the picomole range for tyrosine and tryptophan. The LINF detector is able to detect the same levels of peptides concentrations as an ESI-ion trap spectrometer used in scan mode. In this application, LINF outperforms the UV detection at 214 or 254 nm and could be used with different additives with no noticeable effect on the detection.

The synthesis of six new huperzine analogues was reported. Each product presents an amidification of the free amine on huperzine A. The synthesis strategy of these new huperzine A derivatives is based on a condensation with an acyl anhydride. The binding on HSA of two molecule series (huperzine and benzodiazepine, respectively) was investigated with high performance liquid affinity chromatography (HPLAC) using an HSA column. A thermodynamic approach showed that binding huperzine A on HSA involved hydrophobic and Van der Waals interactions. A comparative thermodynamic study with benzodiazepine molecules was carried out to determine the potential binding site of huperzine derivatives on HSA.

The derivatization of racemic 5-[(2-methylphenoxy)methyl]-2-amino-2-oxazoline, developed as an imidazoline binding sites ligand, with (+)-(R)-alpha-methylbenzyl isocyanate was performed in chloroform. The reaction led to two pairs of diastereomers, which were separated by RP-HPLC. A kinetic study of the derivatization reaction was achieved in order to establish conditions suitable for experimental drug monitoring.

Alkylation of calix[4]arene by 2-tert-butoxyethyl bromide led to the tetraalkylatedcalix[4]arene in the 1,3-alternate, the conformation of which has been established byX-ray crystallography. This spatial structure included a cavity potentially useful forhost–guest complexes achieved with metal cations, especially with Ag+. The titlecompound crystallizes in the monoclinic space group Cc with cell constants a = 29.901(2),b = 8.139(1), c = 22.264(3) A, α = 90°, β = 117.08(1)°and γ = 90°. This conformer represents an example for Ag+-tunnelingacross an aromatic cavity. This behaviour could lead to important implications with regardto the metal cation-π interaction expected for metal transport through ion channels,metal inclusion in fullerenes, intercalation of metal cations into graphites, etc.

Published data conflict with respect to the enantioselective protein binding parameters of R(-) and S(+) ketoprofen. We studied whether differences in experimental conditions used and/or presence of interfering compounds could provide a possible explanation for these discrepancies. Equilibrium dialysis, supported by ultrafiltration (67 mM Sörensen phosphate buffer pH 7.4, 580 microM HSA, 37 degrees C) allowed the characteristics of the binding sites to be determined according to Scatchard's analysis. (R) and (S)-ketoprofen concentrations were measured by HPLC. The free (R)-ketoprofen/free (S)-ketoprofen (F(R)/F(S)) concentration ratio was calculated. The effect of octanoic acid (OA) found in currently marketed intravenous HSA solutions, and hippuric acid (HA), on F(R)/F(S) concentration ratio was considered. Two classes of binding sites were characterized for both enantiomers. The free (S)-ketoprofen concentrations remained equal to those of the (R)-antipode at low concentrations of racemate (2-35 microg ml(-1)) indicating non-stereoselective albumin binding over the therapeutic range. From 35 microg ml(-1), the free (S)-ketoprofen concentrations were slighty greater than those of its antipode. Both OA and HA induced an increase of the free fraction of the enantiomers by a two-fold to a 15-fold order of magnitude. OA, but not HA, showed a more pronounced effect for the (S)-form leading to a marked decrease in F(R)/F(S) concentration ratio (0.61). Differences in HSA preparations used and/or the presence of interfering compounds may explain the variability in the reported protein binding characteristics of ketoprofen enantiomers.

Two hydrophobic parameters (logkw-C18 and logkw-IAM, respectively) of a huperzine A series were extrapolated by high performance liquid chromatography (HPLC) using both C18 and immobilised artificial membrane (IAM) columns. A mathematical correlation between C18 and IAM hydrophobic parameters was completed, suggesting a similar behaviour on both columns. This behaviour was principally led by hydrophobic forces. The theoretical lipophilicity (logP) of each compound was computed using Pallas software and compared to experimental values, showing a similar lipophilic behaviour. Finally, the huperzine logkw-IAM and logkw-C18 values were correlated with the relative bound percentage of huperzine in human serum albumin, confirming that hydrophobic forces are predominant in the huperzine-HSA binding mechanism.

A rapid and stereospecific HPLC micromethod to quantify flurbiprofen enantiomers was developed. Both flurbiprofen enantiomers and indomethacin, used as internal standard, were extracted with methylene chloride from 100 µL of acidified plasma. The resolution of the R- and S-forms was performed on a bonded vancomycin chiral stationary phase (Chirobiotic V™) with 20% of tetrahydrofuran in ammonium nitrate (100 mm, pH 5) as mobile phase. Calibration curves were linear in the range 0.5–10 µg/mL for both enantiomers. A good accuracy (≤5%) was obtained for all quality controls, with intra-day and inter-day variation coefficients equal or less than 7.7%. Recovery of both enantiomers was found in the range 77.4–86.3%. The lower limit of quantitation was 0.25 µg/mL for both enantiomers, without interference of endogenous components. This validated micromethod has been successfully applied for quantifying R-flurbiprofen and S-flurbiprofen in rat plasma. Copyright © 2003 John Wiley & Sons, Ltd.

The retention and complexation mechanisms of a herbicide series were studied from a chromatographic approach using a novel column called "Nautilus((R))". The effects of water fraction and the hydroxy-propyl-beta-cyclodextrin (HP-beta-CD) concentration in the mobile phase were analysed in relation to the column temperature. Two retention models of phenoxy-propionic acid (PPA) derivatives were investigated. It was shown that the retention mechanism was led by free PPA herbicide for low HP-beta-CD concentrations and by the PPA/HP-beta-CD complex for the highest ones. In addition, an enthalpy-entropy compensation study revealed that both the solute retention and complexation mechanisms were independent of the number of chlorine atoms in the structure. Also the thermodynamic results showed that (1) the retention process depended on the water fraction (X) in the mobile phase and (2) the PPA/HP-beta-CD complexation mechanism was shown to be entropically controlled.

International audience; A solid-phase extraction procedure using a graphitized carbon black cartridge for extraction and cleaning of a series of five triazines (atrazine, deethylatrazine, deisopropylatrazine, ametryne and prometryne) from breast milk samples was developed. Using a chemometric methodology, the optimisation of both the analysis time and the triazinic herbicide separation by gas chromatography-mass spectrometry (GC-MS) was then carried out with only 18 experiments. Detection and quantification limits for 1ml breast milk sample were, respectively, 0.3 and 1 ppb for each studied compound. The variation coefficients were less than 5% over the concentration range from 1 to 100 ppb. The accuracy was between 98.63 and 104.62% for each triazinic herbicide. The recovery was between 58.64 and 63.22% for the concentration range from 1 to 100 ppb for each triazinic herbicide. The assay was successfully applied to the analysis of several breast milk samples.

International audience; This study demonstrates that the retention behavior of various circular double-stranded DNA molecules (3, 5, and 10 kb) increases over the entire flow-rate range (0.02-1.8 mL/min) at all the mobile phase viscosities (h). The transition between the two well-known nonequilibrium chromatography methods (slalom and hydrodynamic chromatography) is clearly visualized for proteins and does not appear for plasmids because of their strong compact structure. Also, the optimal conditions for F and h are determined to obtain the most efficient separation of these three plasmids in a minimum analysis time.

Poly( d,l )lactide nanocapsules (NCs) have been proposed as an alternative carrier for many drugs. We investigated the influence of this formulation on the pharmacokinetics of ketoprofen in the plasma and cerebrospinal fluid (CSF). Male Wistar rats were given intraperitoneal dose of ketoprofen (5 mg/kg) in a suspension of NCs or in a carboxymethylcellulose (CMC) solution (reference preparation). Blood and CSF samples were collected at different times up to 24 h after dosing. The unbound fraction of ketoprofen in plasma ( f u ) was determined using ultrafiltration. The total ( C T ) and free ( C F ) concentrations of ketoprofen in plasma and the simultaneous CSF concentrations ( C CSF ) were measured by a HPLC method and the areas under the curve (AUC T , AUC F , AUC CSF ) were calculated. AUC T of ketoprofen-loaded NCs in plasma was similar to that of the reference solution, while AUC F of the former (5.41 mg/l×h) was higher than that produced by the latter (4.03 mg/l×h). Accordingly, the unbound fraction ( f u ) was higher after administration of NCs than that of the solution (2.5 and 1.8%, respectively). Finally, AUC CSF were identical for both formulations. These findings suggest that the binding of ketoprofen to plasma proteins is not the major factor that governs its blood-to-CSF exchanges.