Automated docking of 82 N-benzylpiperidine derivatives to mouse acetylcholinesterase and comparative molecular field analysis with 'natural' alignment.

Automated docking and three-dimensional Quantitative Structure-Activity Relationship studies (3D QSAR) were performed for a series of 82 reversible, competitive and selective acetylcholinesterase (AChE) inhibitors. The suggested automated docking technique, making use of constraints taken from experimental crystallographic data, allowed to dock all the 82 substituted N-benzylpiperidines to the crystal structure of mouse AChE, because of short computational times. A 3D QSAR model was then established using the CoMFA method. In contrast to conventional CoMFA studies, the compounds were not fitted to a reference molecule but taken in their 'natural' alignment obtained by the docking study. The established and validated CoMFA model was then applied to another series of 29 N-benzylpiperidine derivatives whose AChE inhibitory activity data were measured under different experimental conditions. A good correlation between predicted and experimental activity data shows that the model can be extended to AChE inhibitory activity data measured on another acetylcholinesterase and/or at different incubation times and pH level.

Application of capillary gas chromatography to the study of hydrolysis of the nerve agent VX in rat plasma.

We present here a gas chromatography technique allowing the detection and quantification of VX [O-ethyl S-(2-diisopropylaminoethyl)methylphosphonothiolate] as well as its P-S bond hydrolysis product diisopropylaminoethanethiol directly from spiked rat plasma. This technique was applied to study VX hydrolysis in rat plasma. We observed that 53 +/- 4% of 374 microM VX disappeared from spiked plasma after 2 h. VX disappearance was mainly related to enzymatic cleavage of the P-S bond (Km = 2.5 mM and Vmax = 13.3 nmol min-1 ml-1 of rat plasma). The activity was totally inhibited by 1 mM Hg2+ and was also inhibited by metal chelators.

Distribution of [14C]sulfur mustard in rats after intravenous exposure.

The distribution of sulfur mustard, bis(2-chloroethyl)sulfide, was investigated in rats. After i.v. injection of [14C]sulfur mustard (10 mg/kg), distribution of 14C was rapid (within minutes) to all tissues that were sampled. Significant amounts of 14C were detected in the kidney, liver, lung, intestine, and stomach, organs all associated with elimination and transformation processes. No more than 3 +/- 2% of the 14C was recovered in fat tissues, indicating that fat was not a major storage site for sulfur mustard. In addition to wide distribution, a significant uptake of 14C was observed in an aponeurosis in the leg receiving the dose of [14C]sulfur mustard (10 mg/kg or 500 micrograms/kg) via the superficial femoral vein. After injection of [14C]sulfur mustard via the jugular vein, no preferential retention site for 14C was detected in the lung.

Biological fate of sulphur mustard in rat: toxicokinetics and disposition.

1. The toxicokinetics of sulphur mustard were studied after i.v. administration (10 mg/kg) to rat. 2. After i.v. administration, blood concentrations of sulphur mustard were best described by a two-compartment model with distribution and elimination half-lives of 5.6 min and 3.59 h, respectively. The apparent volume of distribution at steady state (Vdss) was 74.4 l/kg and total body clearance (Cl) was 21 l/h kg-1. 3. Unchanged sulphur mustard was still detectable in the systemic circulation 8 h after administration. Appreciable and long (96 h) accumulation of 14C was found in the systemic circulation, and significant high affinity of 14C-sulphur mustard for red blood cells. 4. The disposition of 14C was also investigated after i.v. injection of 14C-sulphur mustard to rat. Urine was the major route of excretion of sulphur mustard and/or its metabolites. Of the administered radioactivity 80% was excreted in urine over 96 h, the greater part in the first 24 h after administration. Residual 14C continued to be excreted until 4 days later. In urine, no sulpho- or glucuronyl-conjugates were detected. Of dose < 3% was recovered in faeces.

Specific and sensitive quantitation of 2,2'-dichlorodiethyl sulphide (sulphur mustard) in water, plasma and blood: application to toxicokinetic study in the rat after intravenous intoxication.

A sensitive and specific capillary gas chromatographic method has been developed to measure trace amounts of 2,2'-dichlorodiethyl sulphide (sulphur mustard) in environmental or biological samples. Sulphur mustard was isolated from water or plasma by a solid-phase extraction procedure and from blood by liquid-liquid extraction. The accuracy and precision of the methods were demonstrated using replicate analyses of spiked water, plasma or blood: within-run and between-run variabilities were less than 20%. These analytical methods were used to evaluate the rate of sulphur mustard degradation in water or plasma. Good linear calibration curves, with a detection limit of 45 ng/ml, were obtained for quantitation and determination of sulphur mustard in blood following its intravenous administration to rats. Initial toxicokinetic data were obtained.