Studies on psychotropic drugs. 18. Synthesis and structure-activity relationships of 5-phenyl-1,3-dihydro-2H-thieno(2,3-e) (1,4) diazepin-2-ones

Synthesis and anti-Trypanosoma cruzi activity of diaryldiazepines

Chagas disease is a so-called “neglected disease” and endemic to Latin America. Nifurtimox and benznidazole are drugs that have considerable efficacy in the treatment of the acute phase of the disease but cause many significant side effects. Furthermore, in the Chronic Phase its efficiency is reduced and their therapeutic effectiveness is dependent on the type of T. cruzi strain. For this reason, the present work aims to drive basic research towards the discovery of new chemical entities to treat Chagas disease. Differently substituted 5,7-diaryl-2,3-dihydro-1,4-diazepines were synthesized by cyclocondensation of substituted flavones with ethylenediamine and tested as anti-Trypanosoma cruzi candidates. Epimastigotes of the Y strain from T. cruzi were used in this study and the number of parasites was determined in a Neubauer chamber. The most potent diaryldiazepine that reduced epimastigote proliferation exhibited an IC₅₀ value of 0.25 μM, which is significantly more active than benznidazole.

2-Amino-N-[3-(2-chlorobenzoyl)-5-ethylthiophen-2-yl]acetamide

In the title compound, C₁₅H₁₅ClN₂O₂S, the 2-amino­acetamide N—C(=O)—C—N unit is approximately planar, with an r.m.s. deviation of 0.020 (4) Å. The central thio­phene ring makes dihedral angles of 7.84 (11) and 88.11 (11)°, respectively, with the 2-amino­acetamide unit and the 2-chloro­phenyl ring. An intra­molecular N—H⋯O hydrogen bond generates an S(6) ring motif. In the crystal, mol­ecules are linked by an N—H⋯O hydrogen bond and weak C—H⋯O inter­actions into a chain along the c axis. A C—H⋯π inter­action is also present.

1,4-Thienodiazepine-2,5-diones via MCR (I): synthesis, virtual space and p53-Mdm2 activity

1,4-Thienodiazepine-2,5-diones have been synthesized via the Ugi-Deprotection-Cyclization (UDC) approach starting from Gewald 2-aminothiophenes in a convergent and versatile manner. The resulting scaffold is unprecedented, cyclic, and peptidomimetic with four points of diversity introduced from readily available starting materials. In addition to eighteen synthesized and characterized compounds, a virtual compound library was generated and evaluated for chemical space distribution and drug-like properties. A small focused compound library of 1,4-thienodiazepine-2,5-diones has been screened for the activity against p53-Mdm2 interaction. Biological evaluations demonstrated that some compounds exhibited promising antagonistic activity.

Mechanistic-based descriptors for QSAR study of psychotropic drug toxicity

A quantitative structure-activity relationship model has been developed for three important classes of psychotropic drugs including phenothiazines, antidepressants and anxiolitics. Toxicity was expressed as the oral LD(50) values for mice. Acute toxicity of drugs correlated with a proposed descriptor based on the oxidation mechanism of bioactivation. The new descriptor was named hydrogen charge (HC) descriptor, and it is the sum of the HCs of amine moiety, carbons in the alpha-position of the heteroatoms, carbonyl groups and unsaturated bonds. The results showed that the model with the descriptor of ratio of the HC over volume of the molecules, named the effective hydrogen charge (EHC) were superior to the model with the HC descriptor. Multiple linear regression was derived for the three categories of drugs separately predicting the LD(50) values. The linear models were found to describe the system with statistical parameters of RMSECV and RMSEP as follows: 41, 49 for phenothiazines, 111, 190 for antidepressants and 151, 276 for anxiolitics. The performance of the constructed models was examined using RMSECV (leave-one-out and leave-group-out), standard error, coefficient of determination (R(2)), R(2) cross-validated (q(2)), the average chance correlation and residual error plots. Finally, the LD(50) for a variety of compounds, with unknown experimental values, were predicted.

Reaction Pathways to 2-Aminothiophenes and Thiophene-3-carbonitriles

Over the past two decades 2-amino-3-benzoylthiophenes have been found to act as allosteric enhancers of the adenosine A1 receptor (A1AR). As such, compounds of this type have potential applications in the therapy of a variety of disorders by enhancing A1AR activation. Initial studies in this field identified various 2-amino-3-benzoylthiophenes as potential leads and of these PD 81723 1a has become the benchmark for comparative studies due to its favourable ratio of allosteric enhancement to antagonism. Surprisingly the synthesis and characterization of PD 81723 1a has not been previously reported. Herein we report the synthesis and characterization of this important A1AR allosteric enhancer. As part of this study we also found an unexpected reaction pathway to 2-phenylthiophene-3-carbonitriles.

Single and multiple dose pharmacokinetics of etizolam in healthy subjects

The pharmacokinetics of etizolam, a new thienodiazepine derivative, has been examined after single and multiple (0.5 mg tablet) (0.5 mg b.d for 1 week) oral therapeutic doses in healthy volunteers. The single-dose kinetic profile of etizolam suggested that absorption after oral dosage was reasonably rapid, the maximum plasma concentration (Cmax) being attained within 0.5-2 h in all subjects. The mean elimination half-life (t1/2) averaged 3.4 h. Consistent with this, steady-state concentration were rapidly achieved and accumulation was extremely limited. Predicted average plasma concentrations (Cp) did not differ significantly from those actually measured at steady-state, suggesting that the kinetics of etizolam was linear, at least at therapeutic doses. The mean wash-out t1/2 was comparable to the elimination t1/2 of the single dose, which means that the drug probably has no effect on hepatic microsomal enzymes and other kinetic variables after repeated dosing. At steady state plasma concentrations of the main metabolite, alpha-hydroxyetizolam, were higher and disappeared more slowly (mean t1/2 8.2 h) than those of the parent compound. Taken with the fact that in animals the metabolite shows almost the same potency of pharmacological action as etizolam, this suggests that it may contribute significantly to the clinical effects of the parent compound. Based on the kinetic characteristics of the parent drug and its metabolite, etizolam can be regarded as a short-acting benzodiazepine, with elimination kinetics between those of short-intermediate derivatives and ultra-rapidly eliminated benzodiazepines.