Benzodiazepine receptor ligands. 7. Synthesis and pharmacological evaluation of new 3-esters of the 8-chloropyrazolo[5,1-c][1,2,4]benzotriazine 5-oxide. 3-(2-Thienylmethoxycarbonyl) derivative: an anxioselective agent in rodents

Rational approaches for the design of various GABA modulators and their clinical progression

GABA (γ-amino butyric acid) is an important inhibitory neurotransmitter in the central nervous system. Attenuation of GABAergic neurotransmission plays an important role in the etiology of several neurological disorders including epilepsy, Alzheimer's disease, Huntington's chorea, migraine, Parkinson's disease, neuropathic pain, and depression. Increase in the GABAergic activity may be achieved through direct agonism at the GABAA receptors, inhibition of enzymatic breakdown of GABA, or by inhibition of the GABA transport proteins (GATs). These functionalities make GABA receptor modulators and GATs attractive drug targets in brain disorders associated with decreased GABA activity. There have been several reports of development of GABA modulators (GABA receptors, GABA transporters, and GABAergic enzyme inhibitors) in the past decade. Therefore, the focus of the present review is to provide an overview on various design strategies and synthetic approaches toward developing GABA modulators. Furthermore, mechanistic insights, structure-activity relationships, and molecular modeling inputs for the biologically active derivatives have also been discussed. Summary of the advances made over the past few years in the clinical translation and development of GABA receptor modulators is also provided. This compilation will be of great interest to the researchers working in the field of neuroscience. From the light of detailed literature, it can be concluded that numerous molecules have displayed significant results and their promising potential, clearly placing them ahead as potential future drug candidates.

Synthesis, in vivo evaluation, and molecular modeling studies of new pyrazolo[5,1-c][1,2,4]benzotriazine 5-oxide derivatives. Identification of a bifunctional hydrogen bond area related to the inverse agonism

A new series of pyrazolo[5,1-c][1,2,4]benzotriazine 5-oxide 8-alkyloxy-/aryloxy-/arylalkyloxy and 8-aryl-/arylalkylderivatives variously substituted at the 3-position were synthesized and binding studies at the benzodiazepine site on GABA(A) receptor were carried out. The pharmacological profile was identified for compounds 10, 11, 16(+), 16(-), and 17 by considering six potential benzodiazepine actions: motor coordination, anticonvulsant action, spontaneous motility and explorative activity, potential anxiolytic-like effects, mouse learning and memory modulation, and finally, ethanol-potentiating action. Compound 17 stands out as the compound that improves mouse memory processes selectively, safely, and in a statistically significant manner. From a ligand-based pharmacophoric model, we identified a hydrogen bond interaction area HBp-3 near the lipophilic area. This new pharmacophoric model allowed us to identify four structural compound typologies and thus to rationalize the affinity data of all compounds.

Animal models of anxiety and anxiolytic drug action

Animal models of anxiety attempt to represent some aspect of the etiology, symptomatology, or treatment of human anxiety disorders, in order to facilitate their scientific study. Within this context, animal models of anxiolytic drug action can be viewed as treatment models relevant to the pharmacological control of human anxiety. A major purpose of these models is to identify novel anxiolytic compounds and to study the mechanisms whereby these compounds produce their anxiolytic effects. After a critical analysis of "face," "construct," and "predictive" validity, the biological context in which animal models of anxiety are to be evaluated is specified. We then review the models in terms of their general pharmacological profiles, with particular attention to their sensitivity to 5-HTIA agonists and antidepressant compounds. Although there are important exceptions, most of these models are sensitive to one or perhaps two classes of anxiolytic compounds, limiting their pharmacological generality somewhat, but allowing in depth analysis of individual mechanisms of anxiolytic drug action (e.g., GABAA agonism). We end with a discussion of possible sources of variability between models in response to 5-HTIA agonists and antidepressant drugs.

Novel 3-iodo-8-ethoxypyrazolo[5,1-c][1,2,4]benzotriazine 5-oxide as promising lead for design of α5-inverse agonist useful tools for therapy of mnemonic damage

The synthesis and the binding study of new 3-iodiopyrazolo[5,1-c][1,2,4] benzotriazine 5-oxides 8-alkyloxy substituted are reported. The replacement at position 3 with an iodine atom, with respect to substituents capable to form a three centered hydrogen bond and/or to form pi-pi stacking interaction with receptor protein, gave high affinity ligands, independently of the 8-alkyloxy substituent. High-affinity ligands were studied in mice in vivo for their pharmacological effects, considering five potential benzodiazepine actions: anxiolytic-like effects, motor coordination, anticonvulsant action, mouse learning and memory impairment, and ethanol-potentiating action. Compounds 5c and 5'c have an inverse agonist profile and for the first time is evidenced a pro-mnemonic activity. These compounds were evaluated also for their binding at Benzodiazepine site on GABA(A) receptor complex (GABA(A)/BzR complex) subtype to evaluate their subtype selectivity.

Cytotoxic activity of 3-nitropyrazolo[5,1-c][1,2,4]benzotriazine derivatives: a new series of anti-proliferative agents

We report the synthesis and biological evaluation of a new series of 3-nitropyrazolo[5,1-c][1,2,4]benzotriazine derivatives (compounds 1-4) bearing appropriate substitutions in positions 7 and/or 8. The objective of this investigation was to study the effects of these substitutions on the cytotoxic activity of four new compounds against established human cancer cell lines (i.e. HT29 and HCT-8, colon carcinoma, MCF7, breast carcinoma, and A549, lung carcinoma cells). The inhibitory effects of compounds 1-4 on cell growth were assessed by the sulforhodamine B assay. Also, the effects of these compounds on cell cycle distribution of human colon carcinoma cells (HCT-8) were analyzed by flow cytometry. 3-Nitropyrazolo[5,1-c][1,2,4]benzotriazine derivatives displayed IC(50) values in the micromolar range on the growth of the four cell lines tested. Cell cycle perturbations induced on HCT-8 cells by study compounds at the IC(50) values consisted prevalently of a slight accumulation of cells in G(0)/G(1) phase and a slight decrease in G(2)/M phase. However, compound 3 induced a marked accumulation of cells into S phase with concomitant decrease in G(0)/G(1) and G(2)/M phases. Cytotoxicity data, compared to those obtained with 3-cyano-8-chloropyrazolo[5,1-c][1,2,4]benzotriazine 5-oxide (compound 5, NSC 683334) and other compounds previously synthesized in our laboratory, demonstrated a similar or even improved cytotoxic potency. Cell cycle perturbations caused by these compounds support the hypothesis that they may act by a direct or an indirect inhibition of DNA synthesis.

Benzodiazepine receptor ligands. 8: synthesis and pharmacological evaluation of new pyrazolo[5,1-c] [1,2,4]benzotriazine 5-oxide 3- and 8-disubstituted: high affinity ligands endowed with inverse-agonist pharmacological efficacy

The synthesis and the binding study of new 3-arylesters and 3-heteroarylpyrazolo[5,1-c][1,2,4]benzotriazine 5-oxide 8-substituted are reported. The nature of these substituents (in terms of lipophilic and electronic features) seems to influence the binding affinity. High-affinity ligands were studied in mice in vivo for their pharmacological effects, considering six potential benzodiazepine actions: anxiolytic-like effects, muscle relaxant effects, motor coordination, anticonvulsant action, spontaneous motor activity, and ethanol-potentiating action. Compounds 4d and 6d showed an inverse-agonist profile. These compounds were evaluated also for their binding at benzodiazepine site on GABAA receptor complex (GABAA/BzR complex) subtype to evaluate their subtype selectivity.