[Analytical validation of a chromatographic method dedicated to search and identify natural and semi-synthetic opiates]. / Validation analytique d'une méthode chromatographique destinée à rechercher et à identifier les opiacés naturels ou (semi) synthétiques.

The identification of a product absorbed by an opiate consumer is sometimes problematic since there is no specific biomarker for all molecules. We developed an ultra-high pressure liquid chromatography coupled to tandem mass spectrometry technique which allows the identification and the quantification of 25 opiates in plasma. The sample preparation consists in a solid-phase extraction on Oasis MCX cartridges (Waters). The method has been validated according to FDA criteria completely for 21 substances and with some reservations for the remaining 4 analytes. This method has been applied to 80 patients treated at the University Hospital of Liege for whom the screening of opiates was positive. The identification of the product consumed was effective in 86% of cases.

6-Substituted 2-oxo-2H-1-benzopyran-3-carboxylic acid derivatives in a new approach of the treatment of cancer cell invasion and metastasis.

Novel 6-substituted 2-oxo-2H-1-benzopyran-3-carboxylic acid derivatives were synthesized and their potency in reducing the invasive behaviour of HT 1080 fibrosarcoma cells was evaluated. Structure-activity relationships were deduced from biological results and will be used in further design of new active compounds. In particular, the acetoxymethyl substituent found at the 6-position of previously described active compounds can be replaced by an acetamidomethyl substituent without loss of potency; while the presence of an aryl ester function at the 3-position was preferred to a thioester or an amide function to induce marked biological activity. This work confirms the interest of aryl esters of 6-substituted coumarin-3-carboxylic acids as potential new anti-cancer agents.

Three-dimensional quantitative structure-activity relationships of ATP-sensitive potassium (KATP) channel openers belonging to the 3-alkylamino-4H-1,2,4-benzo- and 3-alkylamino-4H-1,2,4-pyridothiadiazine 1,1-dioxide families.

Recent studies have demonstrated that selective activation of pancreatic ATP-sensitive potassium (KATP) channels could be of clinical value in the treatment of type I and type II diabetes, obesity, and hypersinsulinemia. Taking into account these promising therapeutic opportunities, we have explored the 3-alkylamino-4H-1,2,4-pyrido- and 3-alkylamino-4H-1,2,4-benzothiadiazine 1,1-dioxide families. Among these series, numerous drugs were identified as highly potent and selective openers of either the pancreatic or the aortic KATP channels. Thanks to comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA), quantitative structure-activity relationship approaches using more than 100 compounds, pharmacophoric models explaining the activity and selectivity of the drugs have been elaborated. These models highlighted the importance of several chemical regions for KATP channel activation and could be very helpful for future improvement of drug potency, selectivity, or both. Moreover, an original CoMSIA analysis, using a selectivity index (SI) as a dependent variable, was also performed with the aim of identifying the structural parameters influencing tissue selectivity.

In search of novel AMPA potentiators.

Glutamate is the major excitatory neurotransmitter in the brain. Amongst ionotropic receptors responding to glutamate, the AMPA subtype has been considered as essential for the fast excitatory neurotransmission in the central nervous system and the expression and maintenance of long-term potentiation. As glutamate is known to be involved in many neurological and psychiatric disorders, AMPA receptors seem to represent interesting targets to develop therapeutic drugs. Hence, the enhancement of AMPA signals is an approach currently investigated for the management of Alzheimer's disease, schizophrenia or mood disorders. In particular, many efforts are being conducted in the development of AMPA positive allosteric modulators ("potentiators"), which alter the rate of receptor desensitization. The major chemical families developed as AMPA potentiators are aniracetam derivatives, cyclothiazide derivatives and biarylpropylsulfonamides derivatives.

3-Alkylamino-4H-1,2,4-benzothiadiazine 1,1-dioxides as ATP-sensitive potassium channel openers: effect of 6,7-disubstitution on potency and tissue selectivity.

A series of 6,7-disubstituted 4H-1,2,4-benzothiadiazine 1,1-dioxides bearing a short alkylamino side chain in the 3-position were synthesized. These compounds were tested on rat pancreatic islets and on rat aorta rings. In vitro data indicated that in most cases substitution in the 6 and the 7 positions increased their activity as inhibitors of insulin secretion, while the myorelaxant potency of the drugs was maintained or enhanced according to the nature of the substituent in the 7-position. The presence of either chlorine or bromine atoms in the 6 and 7 positions did not improve the apparent selectivity of the drugs for the pancreatic tissue. By contrast, the introduction of one or two fluorine atoms, as well as the presence of a methoxy group in the 7-position, generated potent and selective inhibitors of insulin release. Radioisotopic and fluorimetric experiments performed with the most potent compound inhibiting insulin release (34, BPDZ 259, 6-chloro-7-fluoro-3-isopropylamino-4H-1,2,4-benzothiadiazine 1,1-dioxide) confirmed that the drug activated K(ATP) channels. 34 was found to be one of the most potent and selective pancreatic potassium channel openers yet described.

Effect on K(ATP) channel activation properties and tissue selectivity of the nature of the substituent in the 7- and the 3-position of 4H-1,2,4-benzothiadiazine 1,1-dioxides.

The present work explored 3-alkylamino-4H-1,2,4-benzothiadiazine 1,1-dioxides diversely substituted in the 7-position. Those compounds, structurally related to previously described potassium channel openers such as the benzothiadiazine dioxide BPDZ 73, were tested as putative K(ATP) channel activators on the pancreatic endocrine tissue and on the vascular smooth muscle tissue. The nature of the substituent introduced in the 7-position as well as the nature of the alkylamino side chain in the 3-position strongly affected both potency and tissue selectivity of 4H-1,2,4-benzothiadiazine 1,1-dioxides. Thus, compounds bearing in the 7-position a methyl or a methoxy group or devoid of a substituent in this position, and bearing an ethyl, an isopropyl, or a cyclobutylamino group in the 3-position were found to be potent and selective inhibitors of insulin release from rat pancreatic B-cells (i.e. 10a, 10b, 12b, 12d, 22c). In contrast, 3-alkylamino-7-trifluoromethyl- (20a-c) and 3-alkylamino-7-pentyl-4H-1,2,4-benzothiadiazine 1,1-dioxides (11a,b) expressed a marked myorelaxant activity on rat aorta ring. Among the latter compounds, the 3-alkylamino-7-pentyl derivative (11a) showed a clear selectivity for the vascular smooth muscle tissue. The present work gives new insights into the role of the substituent in both the 7- and the 3-position for the design of 4H-1,2,4-benzothiadiazine 1,1-dioxide potassium channel openers exhibiting different tissue selectivity profiles.