Benoît Rigo

3-Carboxamido-5-aryl-isoxazoles as new CB2 agonists for the treatment of colitis.

Recent investigations showed that anandamide, the main endogenous ligand of CB1 and CB2 cannabinoid receptors, possesses analgesic, antidepressant and anti-inflammatory effects. In the perspective to treat inflammatory bowel disease (IBD), our approach was to develop new selective CB2 receptor agonists without psychotropic side effects associated to CB1 receptors. In this purpose, a new series of 3-carboxamido-5-aryl-isoxazoles, never described previously as CB2 receptor agonists, was designed, synthesized and evaluated for their biological activity. The pharmacological results have identified great selective CB2 agonists with in vivo anti-inflammatory activity in a DSS-induced acute colitis mouse model.

Synthesis and characterization of a quinolinonic compound activating ATP-sensitive K(+) channels in endocrine and smooth muscle tissues.

Original quinolinone derivatives structurally related to diazoxide were synthesized and their effects on insulin secretion from rat pancreatic islets and the contractile activity of rat aortic rings determined. A concentration‐dependent decrease of insulin release was induced by 6‐chloro‐2‐methylquinolin‐4(1H)‐one (HEI 713). The average IC50 values were 16.9±0.8 μM for HEI 713 and 18.4±2.2 μM for diazoxide. HEI 713 increased the rate of 86Rb outflow from perifused pancreatic islets. This effect persisted in the absence of external Ca2+ but was inhibited by glibenclamide, a KATP channel blocker. Inside‐out patch‐clamp experiments revealed that HEI 713 increased KATP channel openings. HEI 713 decreased 45Ca outflow, insulin output and cytosolic free Ca2+ concentration in pancreatic islets and islet cells incubated in the presence of 16.7 or 20 mM glucose and extracellular Ca2+. The drug did not affect the K+(50 mM)‐induced increase in 45Ca outflow. In aortic rings, the vasorelaxant effects of HEI 713, less potent than diazoxide, were sensitive to glibenclamide and to the extracellular K+ concentration. The drug elicited a glibenclamide‐sensitive increase in 86Rb outflow from perifused rat aortic rings. Our data describe an original compound which inhibits insulin release with a similar potency to diazoxide but which has fewer vasorelaxant effects. Our results suggest that, in both aortic rings and islet tissue, the biological effects of HEI 713 mainly result from activation of KATP channels ultimately leading to a decrease in Ca2+ inflow.

Synthesis and anticancer activity of analogues of phenstatin, with a phenothiazine A-ring, as a new class of microtubule-targeting agents.

A new family of microtubule-targeting agents with a phenothiazine A-ring was synthesized and evaluated for anti-proliferative activity and interaction with tubulin. These new derivatives showed significant activities against cellular proliferation and tubulin polymerization, rather similar to those of phenstatin. Phenothiazine derivative 21 proved to be the most potent compound synthesized with GI(50) values ranging from 29 to 93 nM on different cell lines. The same compound showed a better inhibition of COLO 205, A498, and MCF7 cell lines than the parent phenstatin.

Synthesis and biological evaluation of fluoro analogues of antimitotic phenstatin.

With the aim of investigating the influence of fluorine, in particular on the A-ring, a new series of fluoro analogues (7a-l) of phenstatin (3) was synthesized and tested for interactions with tubulin polymerization and evaluated for cytotoxicity on an NCI-60 human cancer cell lines panel. We have shown that the replacement of 3,4,5-trimethoxyphenyl A-ring of phenstatin with 2,4,5-trifluoro-3-methoxyphenyl unit, results in the conservation of both antitubulin and cytotoxic effect. Fluoro isocombretastatin 7k was the most effective anticancer agent in the present study and demonstrated the highest antiproliferative potential on leukemia cell lines SR (GI50=15 nM) and HL-60(TB) (GI50=23 nM) and on melanoma cell line MDA-MB-435 (GI50=19 nM).

On the cyclization of acyliminium salts derived from pyroglutamic acid

Abstract The Friedel Crafts reaction of pyroglutamic acid derivative 9 gives an acyliminium salt which cyclize to the condensed N-acylheterocycle 6 thus providing an easy access to the amine 1 .

Studies on Pyrrolidinones. An Improved One Pot Synthesis of 1,2,3,5,10,10a-Hexahydrobenz[f]indolizine-3,10-dione

Abstract Starting from the readily available N,O-bis trimethylsilyl pyroglutamate, an easy high yield one pot synthesis of ketone 1 was described.

Reaction of Hexamethyldisilazane with Diacylhydrazines : An Easy 1,3,4-Oxadiazole Synthesis

Abstract The reaction of diacylhydrazines with hexamethyldisilazane in the presence of tetrabutylammonium fluoride as catalyst results in cyclisation to give 1,3,4-oxadiazoles in good yield.

Enantioseparation of pyroglutamide derivatives on polysaccharide based chiral stationary phases by high-performance liquid chromatography and supercritical fluid chromatography: a comparative study.

Analytical enantioseparation of three pyroglutamide derivatives with pharmacological activity against the purinergic receptor P2X7, was run in both high-performance liquid chromatography and supercritical fluid chromatography. Four polysaccharide based chiral stationary phases, namely amylose and cellulose tris (3,5-dimethylphenylcarbamate), amylose tris ((S)-α-methylbenzylcarbamate) and cellulose tris (4-methylbenzoate) with various mobile phases consisted of either heptane/alcohol (ethanol and 2-propanol) or carbon dioxide/alcohol (methanol or ethanol) mixtures, were investigated. After analytical screenings, the best conditions were transposed, for compound 1, to semi-preparative scale. Each approach was fully validated to meet the International Conference on Harmonisation requirements and compared. Whereas the limits of detection and quantification were near six-fold better in HPLC than in SFC (respectively 0.20 and 0.66 μM versus 1.11 and 3.53 μM for one of the enantiomers), in terms of low solvent consumption (7.2 mL of EtOH versus 3.2 mL of EtOH plus 28.8 mL of toxic and inflammable heptane per injection in SFC and HPLC, respectively), time effective cost (9 min versus 40 min per injection in SFC and HPLC, respectively) and yields (98% versus 71% in SFC and HPLC, respectively), the latter method proved its ecological superiority.

Studies on Pyrrolidinones. A New Rearrangement of Pyrrolo[1,2-b]Isoquinolines Derivatives

Abstract New lactones are obtained as by-products during the Friedel-Crafts cyclization of N-arylmethyl pyroglutamoyl chlorides. A mechanism based on N-acyliminium salts is proposed to explain their formation.

Bis (trimethylsilyl) amide as nitrile precursor

Abstract Bis (trimethylsilyl) amides are converted into nitriles with high yields when they are treated wich a catalyst (tetrabutylammonium fluoride, Lewis acids or iron phthalocyanine).