S. Khelili

Synthesis and activity on rat aorta rings and rat pancreatic beta-cells of ring-opened analogues of benzopyran-type potassium channel activators.

Ring-opened analogues of dihydrobenzopyran potassium channel openers (PCOs) were prepared and evaluated as putative PCOs on rat aorta rings (myorelaxant effect) and rat pancreatic beta-cells (inhibition of insulin secretion). These derivatives are characterized by the presence of a sulfonylurea, a urea or an amide function. Some compounds bearing an arylurea moiety provoked vasorelaxant effects and a marked inhibition of insulin release. Derivatives bearing a sulfonylurea or an amide function were, however, poorly active on both tissues. Structure-activity relationships and apparent tissue selectivity are discussed.

Preparation and pharmacological evaluation of the R- and S-enantiomers of 3-(2'-butylamino)-4H- and 3-(3'-methyl-2'-butylamino)-4H-pyrido[4,3-e]-1,2,4-thiadiazine 1,1-dioxide, two tissue selective ATP-sensitive potassium channel openers

The preparation and the pharmacological evaluation of the R- and S-isomers of 3-(2-butylamino)-4H-pyrido[4,3-e]-1,2,4-thiadiazine 1,1-dioxide (BPDZ 42) and 3-(3-methyl-2-butylamino)-4H-pyrido[4,3-e]-1,2,4-thiadiazine 1,1-dioxide (BPDZ 44), two potassium channel openers, is described. Their optical purity was estimated by means of capillary electrophoresis (R- and S-BPDZ 42) and chiral HPLC (R- and S-BPDZ 44). The absolute configuration of each isomer of BPDZ 44 was deduced from crystallographic data. Pharmacological assays performed with the R- and S-isomers of BPDZ 44 revealed only slight differences in their activity on pancreatic B-cells but significant differences in their activity on vascular smooth muscle cells: the R-isomer being sixfold more potent than its corresponding S-isomer. The R-isomer of BPDZ 42 was shown to be more potent than its corresponding S-isomer on the endocrine pancreas. S-BPDZ 44 as well as R- and S-BPDZ 42 were found to exhibit tissue selectivity for the pancreatic versus the vascular smooth muscle tissue.

Synthesis and pharmacological activity of N-(2,2-dimethyl-3,4-dihydro-2H-1-benzopyran-4-yl)-4H-1,2,4-benzothiadiazine-3-carboxamides 1,1-dioxides on rat uterus, rat aorta and rat pancreatic β-cells.

N-(2,2-Dimethyl-3,4-dihydro-2H-1-benzopyran-4-yl)-4H-1,2,4-benzothiadiazine-3-carboxamides 1,1-dioxides were prepared and evaluated on rat uterus, rat aortic rings and rat pancreatic β-cells. Pharmacological studies conducted on rat uterus indicated that several of these original hybrid compounds displayed a strong myorelaxant activity. The most active compounds hold a bromine atom at the 6-position of the dihydrobenzopyran ring. Moreover, the compounds failed to display a marked inhibitory effect on insulin secretion and vascular myogenic activity. These features suggest that the 6-bromo compounds could be relatively selective towards the uterine smooth muscle.

Design and synthesis of new potassium channel activators derived from the ring opening of diazoxide: Study of their vasodilatory effect, stimulation of elastin synthesis and inhibitory effect on insulin release

Benzenesulfonylureas and benzenesulfonylthioureas, as well as benzenecarbonylureas and benzenecarbonylthioureas, were prepared and evaluated as myorelaxants on 30mMKCl-precontracted rat aortic rings. The most active compounds were further examined as stimulators of elastin synthesis by vascular smooth muscle cells and as inhibitors of insulin release from pancreaticβ-cells. The drugs were also characterized for their effects on glycaemia in rats. Benzenesulfonylureas and benzenesulfonylthioureas did not display any myorelaxant activity on precontracted rat aortic rings. Such an effect could be attributed to their ionization at physiological pH. By contrast, almost all benzenecarbonylureas and benzenecarbonylthioureas displayed a myorelaxant activity, in particular the benzenecarbonylureas with an oxybenzyl group linked to the ortho position of the phenyl ring. The vasodilatory activity of the most active compounds was reduced when measured in the presence of 80mMKCl or in the presence of 30mM KCl and 10μM glibenclamide. Such results suggested the involvement, at least in part, of KATP channels. Preservation of a vasodilatory activity in rat aortic rings without endothelium indicated that the site of action of such molecules was located on the vascular smooth muscle cells and not on the endothelial cells. Some of the most active compounds also stimulated elastin synthesis by vascular smooth muscle cells. Lastly, most of the active vasorelaxant drugs, except 15k and 15t at high concentrations, did not exhibit marked inhibitory effects on the insulin releasing process and on glycaemia, suggesting a relative tissue selectivity of some of these compounds for the vascular smooth muscle.

Synthesis and pharmacological evaluation of KATP-channel openers related to cromakalim : Introduction of arylsulphonylurea moieties

A series of 4-(arylsulphonylaminocarbonylamino)-3,4-dihydro-2,2-dimethyl-2 H-1-benzo-pyran derivatives were prepared and evaluated as potential ATP-sensitive potassium-channel activators. Pharmacological studies showed that some compounds expressed vasodilator efficacy on vascular smooth muscle. The compounds had no inhibitory activity on insulin secretion from pancreatic β-cells.

Design, synthesis and biological evaluation of novel ring-opened cromakalim analogues with relaxant effects on vascular and respiratory smooth muscles and as stimulators of elastin synthesis

Two new series of ring-opened analogues of cromakalim bearing sulfonylurea moieties (series A: with N-unmethylated sulfonylureas, series B: with N-methylated sulfonylureas) were synthesized and tested as relaxants of vascular and respiratory smooth muscles (rat aorta and trachea, respectively). Ex vivo biological evaluations indicated that the most active compounds, belonging to series B, displayed a marked vasorelaxant activity on endothelium-intact aortic rings and the trachea. A majority of series B compounds exhibited a higher vasorelaxant activity (EC50 < 22 μM) than that of the reference compound diazoxide (EC50 = 24 μM). Interestingly, several tested compounds of series B also presented stronger relaxant effects on the trachea than the reference compound cromakalim (EC50 = 124 μM), in particular compounds B4, B7 and B16 (EC50 < 10 μM). By contrast, series A derivatives were poorly active on aortic rings (EC50 > 57 μM for all, and EC50 > 200 μM for a majority of them), but some of them showed an interesting relaxing effect on trachea (i.e. A15 and A33, EC50 = 30 μM). The most potent compounds of both series, i.e. A15, A33 and B16, tested on aortic rings in the presence of glibenclamide or 80 mM KCl, suggested that they acted as voltage-gated Ca2+ channel blockers, like verapamil, instead of being ATP-potassium channel activators, as is cromakalim, the parent molecule. Further investigations on cultured vascular smooth muscle cells showed a strong stimulating effect on elastin synthesis, especially compound B16, which was more active at 20 μM than diazoxide, a reference ATP-sensitive potassium channel activator. Taken together, our results show that the N-methylation of the sulfonylurea moieties of ring-opened cromakalim analogues led to new compounds blocking calcium-gated channels, which had a major impact on the arterial and tracheal activities as well as selectivity.

7-Chloro-(R)-3-[1-(cyclohexyl)ethylamino]-4H-1,2,4-benzothiadiazine 1,1-dioxide and 7-chloro-(S)-3-[1-(cyclohexyl)ethylamino]-4H-1,2,4-benzothiadiazine 1,1-dioxide

3-Alkylamino-4H-1,2,4-benzothiadiazine 1,1-dioxides structurally related to diazoxide are expected to present a pharmacological profile of potassium-channel openers. The influence on biological activity of the absolute configuration of the title compounds, both C 15 H 20 ClN 3 O 2 S, is being studied. The crystallographic results confirm the enantiomeric characterization of each compound.

3-Alkylamino-pyrido[4,3-e]-1,2,4-thiadiazine 1,1-dioxides as potent KATP-channel activators: structural study and influence of stereochemistry

Pyrido[4,3-e]-1,2,4-thiadiazine 1,1-dioxides bearing a short and branched alkylamino side chain in the 3 position, appear to be powerful and tissue selective pancreatic KATP-channel activators. In order to confirm the pharmacophoric model for the activation of pancreatic KATP channels, a structural study was undertaken on representative 3-alkyl-aminopyridothiadiazines. The influence on the biological activity of the stereochemistry associated to the first carbon atom of the 3-alkylamino chain was also examined.