Molecular modeling studies, synthesis, configurational stability and biological activity of 8-chloro-2,3,5,6-tetrahydro-3,6-dimethyl-pyrrolo[1,2,3-de]-1,2,4-benzothiadiazine 1,1-dioxide

The potential therapeutic benefit of compounds able to activate AMPA receptors (AMPArs) has led to a search for new AMPAr positive modulators. Among them, 8-chloro-2,3,5,6-tetrahydro-3,6-dimethyl-pyrrolo[1,2,3-de]-1,2,4-benzothiadiazine 1,1-dioxide (1) has attracted particular attention, because it is one of the most active benzothiadiazine\u2013derived positive modulators of the AMPA receptor. It possesses two stereogenic centers, C3 and C6, thus it can exist as four stereoisomers. In this work, preliminary in silico studies suggested that 1 interacts stereoselectively with AMPArs. Single stereoisomers of 1 were prepared in order to evaluate their biological activity. However, studies regarding the configurational stability of the investigated compounds suggested a rapid epimerization at C3 in aqueous solvents, and we can expect the same reaction in vivo. Thus, electrophysiological experiments were performed on the two epimeric mixtures, (3 17,6R)- and (3 17,6S)- 8-chloro-2,3,5,6-tetrahydro-3,6-dimethyl-pyrrolo[1,2,3-de]-1,2,4-benzothiadiazine 1,1-dioxide, in order to evaluate their activities as positive allosteric modulators of AMPArs. The obtained data suggest that the (3 17,6S) epimeric mixture is the most active in positively modulating AMPArs, confirming in silico results

Design, stereoselective synthesis, configurational stability and biological activity of 7-chloro-9-(furan-3-yl)-2,3,3a,4-tetrahydro-1H-benzo[e]pyrrolo[2,1-c][1,2,4]thiadiazine 5,5-dioxide

Chiral 5-arylbenzothiadiazine derivatives have recently attracted particular attention because they exhibit an interesting pharmacological activity as AMPA receptor (AMPAr) positive modulators. However, investigations on their configurational stability suggest a rapid enantiomerization in physiological conditions. In order to enhance configurational stability, preserving AMPAr activity, we have designed the novel compound (R,S)-7-chloro-9-(furan-3-yl)-2,3,3a,4-tetrahydro-1H-benzo[e]pyrrolo[2,1-c][1,2,4]thiadiazine 5,5-dioxide bearing a pyrrolo moiety coupled with the 5-(furan-3-yl) substituent on benzothiadiazine core. A stereoselective synthesis was projected to obtain single enantiomer of the latter compound. Absolute configuration was assigned by X-ray crystal structure. Patch clamp experiments evaluating the activity of single enantiomers as AMPAr positive allosteric modulator showed that R stereoisomer is the active component. Molecular modeling studies were performed to explain biological results. An on-column stopped-flow bidimensional recycling HPLC procedure was applied to obtain on a large scale the active enantiomer with enantiomeric enrichment starting from the racemic mixture of the compound

Enantiomerization and hydrolysis of (±)-7-chloro-3-methyl-3,4-dihydro-2H-1,2,4-benzothiadiazine 1,1-dioxide by stopped-flow multidimensional high-performance liquid chromatography

A novel stopped-flow multidimensional HPLC (sf-MD-HPLC) procedure has been developed to investigate simultaneously the effect of the pH on the enantiostability and hydrolysis of (±)-7-chloro-3-methyl-3,4-dihydro-2H-1,2,4-benzothiadiazine 1,1-dioxide [(±)IDRA21]. It was possible to determinate the rate constants and free energy barriers of enantiomerization and hydrolysis rate constants of (±)IDRA21, by using two chiral stationary phases (CSPs) and one achiral C18 column. A classical batchwise kinetic method was used to calculate rate constants of hydrolysis at the same temperature and in the same buffers used in sf-MD-HPLC. The good agreement of the results obtained validate the sf-MD-HPLC procedure. Furthermore, hydrolysis rate constants of (±)IDRA21 were calculated in a series of buffers over a pH range of 1.20-10.60 at 37 °C in order to evaluate the influence of the pH on hydrolysis

Enantiomerization of chiral 2,3,3a,4-tetrahydro-1H-pyrrolo[2,1-c][1,2,4] benzothiadiazine 5,5-dioxide by stopped-flow multidimensional HPLC

An on-column stopped-flow multidimensional HPLC (sfMDHPLC) procedure using two chiral stationaryphases (CSPs) and one achiral C18 column was developed for the determination of rateconstants and free energy barriers of enantiomerization of (\ub1)(R,S)-2,3,3a,4-tetrahydro-1H-pyrrolo[2,1-c][1,2,4]benzothiadiazine 5,5-dioxide. Moreover, a stopped-flow HPLC (sfHPLC) method previouslydeveloped was applied to the determination of kinetic parameters of enantiomerization of the abovecompound in the presence of a CSP. The individual enantiomers of the studied compound were isolatedin parallel by preparative HPLC and the rate constants and free energy barriers of enantiomerizationweredetermined in different solvents (off-column method). The data obtained by sfMDHPLC, sfHPLC and offcolumnmethods were compared. The (S) enantiomer of the studied compound (S18986) was preparedby asymmetric synthesis and subsequently purified by preparative HPLC, followed by the determinationof rate constants and free energy barriers of enantiomerization in different buffer solutions at pH 2\u20139.3

On-line racemization by high-performance liquid chromatography

An on-column stopped-flow bidimensional recycling HPLC procedure was developed to obtain an enantiomeric enrichment starting from a racemic mixture. The method developed was applied to two chiral compounds of pharmaceutical interest, (±)(R,S)-2,3,3a,4-tetrahydro-1H-pyrrolo[2,1-c][1,2,4]benzothiadiazine 5,5-dioxide (1) and (±)-7-chloro-3-methyl-3,4-dihydro-2H-1,2,4-benzothiadiazine 1,1-dioxide ((±)IDRA21, (2)), since the pharmacological activity of the two benzothiadiazine derivatives investigated has been ascribed to only one enantiomer. Starting from a racemic mixture it was possible to obtain about 95% of pure enantiomer. The procedure was applied both in reverse-phase mode and in normal-phase mode. The scaled up and automatization of the novel analytical HPLC procedure represents a powerful tool to obtain pure enantiomer starting from racemic compounds without cumbersome stereoselective synthesis or expensive enantiopurification processes

Simultaneous Determination of Enantiomerizationand Hydrolysis Kinetic Parameters of ChiralN-Alkylbenzothiadiazine Derivatives

On-column stopped flow multidimensional HPLC (sfMDHPLC) anddynamic high-performance liquid chromatography were applied to investigate the influenceof alkyl substituents at the sulfonamidic and amino moieties of benzothiadiazine1,1-dioxide derivatives on hydrolysis and enantiomerization rate constants. The dataobtained indicate the presence of pyrrolo substituent at the 3,4 positions on benzothiadiazinerings inhibits the hydrolysis, whereas the enantiomerization occurs in acidicmedium. Hydrolysis rates are quite similar for the two benzothiadiazines methyl substitutedto nitrogen at 2- and 4-positions. Conversely, enantiomerization rate of 4-N-methylsubstituted is significantly higher than 2-N-methyl substituted

Sintesi, separazione enantiomerica e studi di stabilit\ue0 di derivati diidropirrolo-benzotiadiazinici

Risoluzione cromatografica preparativa di benzotiadiazine enantiomeriche e studi di stabilit\ue

Epimerization and hydrolysis of 3,6-dimethyl-2,3,5,6-tetrahydro[1,2,4]thiadiazino[6,5,4-hi]indole 1,1-dioxide

In this study, configurational and chemical stability of (R,R),(S,S),(R,S),(S,R)-3,6-dimethyl-2,3,5,6-tetrahydro[1,2,4]thiadiazino[6,5,4-hi]indole 1,1-dioxide (1) were investigated by dynamic and stopped-flow HPLC methods. Single epimeric mixtures (R,R),(R,S)-1 and (S,S),(S,R)-1 were obtained combining synthetic and chromatographic strategies. Separation of (R,R)-1 and (R,S)-1 was achieved by chiral chromatography and absolute configuration of eluted epimers has been assigned basing on molecular modelling calculations. Epimerization and hydrolysis of (R,R),(R,S)-1 have been studied by classical off-column, dynamic HPLC and stopped-flow HPLC methods. The influence of different parameters, such as temperature, pH and dielectric constant was evaluated. The data obtained indicate that (R,R),(R,S)-1 undergoes to a rapid epimerization in aqueous solvent and hydrolysis in acidic conditions. Moreover, epimerization and hydrolysis were investigated in presence of an artificial membrane and in physiological buffers (pH 2.2 and 7.0 at 37.5 °C) to simulate in vivo conditions

Regioselective cyclization of chloroacylaminobenzenesulfonamide derivatives

Chloroacylaminobenzensulfonamides regioselectively thermally cyclize under solvent free conditions to 1,2,4-benzothiadiazines with five- and six-membered rings fused on face b

Influence of Parmigiano Reggiano diet on male sexual behavior in rats: behavioral and neurochemical study

Abstract: The influence of Parmigiano Reggiano (P.R.) cheese on copulatory behavior was studied in male rats. Sexually naїve, sluggish and potent rats were chronically fed with a diet of P.R. cheese for 10 d. Mount, intromission, ejaculation latencies and the percentage of mounting and ejaculating animals were recorded during the mating test. Microdialysis technique was used to detect the extracellular levels of dopamine (DA) and its metabolite dihydroxyphenylacetic acid (DOPAC) in rat brain following the P.R. diet. The P.R. diet was able to improve sexual behavior in naїve rats increasing the percentage of mounting and ejaculating animals. Moreover it was able to reduce latencies of mounts, intromissions and ejaculations and to increase the percentage of mounting and ejaculating animals in sluggish rats. Finally, in the microdialysis study an increase in DA and its metabolite DOPAC was found in P.R. fed naїve rats in comparison with control group