Triphenylphosphonium salts of 1,2,4-benzothiadiazine 1,1-dioxides related to diazoxide targeting mitochondrial ATP-sensitive potassium channels.

The present work aims at identifying new ion channel modulators able to target mitochondrial ATP-sensitive potassium channels (mitoKATP channels). An innovative approach should consist in fixing a cationic and hydrophobic triphenylphosphonium fragment on the structure of known KATP channel openers. Such phosphonium salts are expected to cross the biological membranes and to accumulate into mitochondria. Previous works revealed that the presence of an (R)-1-hydroxy-2-propylamino chain at the 3-position of 4H-1,2,4-benzothiadiazine 1,1-dioxides KATP channel openers increased, in most cases, the selectivity towards the pancreatic-type (SUR1/Kir6.2) KATP channel. In order to target cardiac mitoKATP channels, we decided to introduce a triphenylphosphonium group through an ester link on the SUR1-selective (R)-7-chloro-3-(1-hydroxy-2-propyl)amino-4H-1,2,4-benzothiadiazine 1,1-dioxide. The new compounds were found to preserve an inhibitory activity on insulin secretion (SUR1-type KATP channel openers) while no clear demonstration of an impact on mitochondria from cardiomyocytes (measurement of oxygen consumption, respiratory parameters and ATP production on H9C2 cells) was observed. However, the most active (inhibition of insulin release) compound 17 was found to penetrate the cardiac cells and to reach mitochondria.

New fluorinated 1,2,4-benzothiadiazine 1,1-dioxides: discovery of an orally active cognitive enhancer acting through potentiation of the 2-amino-3-(3-hydroxy-5-methylisoxazol-4-yl)propionic acid receptors.

In the search of a potent cognitive enhancer, a series of 3,4-dihydro-2H-1,2,4-benzothiadiazine 1,1-dioxides have been synthesized and evaluated as positive allosteric modulators of the AMPA receptors. In the present work, we focused our efforts on the insertion of mono- or polyfluoro-substituted alkyl chains at the 4-position of the thiadiazine ring in an attempt to enhance the pharmacokinetic behavior of previously described compounds. Among all the described compounds, 7-chloro-4-(2-fluoroethyl)-3,4-dihydro-2H-1,2,4-benzothiadiazine 1,1-dioxide, 12b, was shown to exert a strong activity on AMPA receptors in vitro and a marked cognitive-enhancing effect in vivo after oral administration to Wistar rats. Considering its in vivo activity, the metabolic degradation of 12b was studied and compared to that of its nonfluorinated analogue 9b. Taken together, results of this study clearly validated the positive impact of the fluorine atom on the alkyl chain at the 4-position of benzothiadiazine dioxides on activity and metabolic stability.

Coupling of liquid chromatography/tandem mass spectrometry and liquid chromatography/solid-phase extraction/NMR techniques for the structural identification of metabolites following in vitro biotransformation of SUR1-selective ATP-sensitive potassium channel openers.

SUR1-selective ATP-sensitive potassium channel openers (PCOs) have been shown to be of clinical value for the treatment of several metabolic disorders, including type I and type II diabetes, obesity, and hyperinsulinemia. Taking into account these promising therapeutic benefits, different series of 3-alkylamino-4H-1,2,4-benzothiadiazine 1,1-dioxides structurally related to diazoxide were developed. In view of the lead optimization process of the series, knowledge of absorption, distribution, metabolism, excretion, and toxicity parameters, and more particularly the metabolic fate of these compounds, is a fundamental requirement. For such a purpose, two selected promising compounds [7-chloro-3-isopropylamino-4H-1,2,4-benzothiadiazine 1,1-dioxide (BPDZ 73) and 7-chloro-3-(3-pentylamino)-4H-1,2,4-benzothiadiazine 1,1-dioxide (BPDZ 157)] were incubated in the presence of phenobarbital-induced rat liver microsomes to produce expected mammal in vivo phase I metabolites. The resulting major metabolites were then analyzed by both mass spectrometry (MS) and NMR to completely elucidate their chemical structures. The two compounds were also further incubated in the presence of nontreated rats and human microsomes to compare the metabolic profiles. In the present study, the combined use of an exact mass liquid chromatography (LC)/tandem MS platform and an LC/solid-phase extraction/NMR system allowed the clarification of some unresolved structural assessments in the accurate chemical structure elucidation process of the selected PCO drugs. These results greatly help the optimization of the lead compounds.

LC/MS/NMR analysis of isomeric divanilloylquinic acids from the root bark of Fagara zanthoxyloides Lam.

Gradient HPLC coupled to DAD/UV, MS/MS and NMR has been applied to the rapid structure determination of three new isomeric divanilloylquinic acids from Fagara zanthoxyloides collected in Burkina Faso: 3,4-O-divanilloylquinic acid, 3,5-O-divanilloylquinic acid and 4,5-O-divanilloylquinic acid. Furthermore these new compounds named burkinabins A-C could play a useful role in sickle cell disease, as the active agents of Fagara zanthoxyloïdes are said to be unidentified aromatic compounds with carboxylic acid grouping (Adesanya, S.A., Sofowora, A., 1983. Biological standardisation of Zanthoxylum roots for antisickling activity. Planta Med. 48, 27-33).