Structure-Guided Computational Methods Predict Multiple Distinct Binding Modes for Pyrazoloquinolinones in GABAA Receptors

Structure-function Studies of GABA (A) Receptors and Related computer-aided Studies

The γ-aminobutyric acid type A receptor (GABA (A) receptor) is a membrane protein activated by the neurotransmitter GABA. Structurally, this major inhibitory neurotransmitter receptor in the human central nervous system is a pentamer that can be built from a selection of 19 subunits consisting of α(1,2,3,4,5 or 6), β (1,2 or 3), γ (1,2 or 3), ρ (1,2 or 3), and δ, π, θ, and ε. This creates several possible pentameric arrangements, which also influence the pharmacological and physiological properties of the receptor. The complexity and heterogeneity of the receptors are further increased by the addition of short and long splice variants in several subunits and the existence of multiple allosteric binding sites and expansive ligands that can bind to the receptors. Therefore, a comprehensive understanding of the structure and function of the receptors is required to gain novel insights into the consequences of receptor dysfunction and subsequent drug development studies. Notably, advancements in computational-aided studies have facilitated the elucidation of residual interactions and exploring energy binding, which may otherwise be challenging to investigate. In this review, we aim to summarize the current understanding of the structure and function of GABA (A) receptors obtained from advancements in computational-aided applications.

Novel pyrazolothienopyridinones as potential GABAA receptor modulators

The synthesis of novel pyrazolothienopyridinone derivatives as potential GABAA receptor modulators was performed and is herein described. A crucial step of the synthesis involving handling unstable aminothiophenes was managed via two different synthetic strategies delivering a set of 8 target compounds.

Graphical abstract

Supplementary Information

The online version contains supplementary material available at 10.1007/s00706-023-03063-6.

GABAA Receptor Modulators with a Pyrazolo[1,5-a]quinazoline Core: Synthesis, Molecular Modelling Studies and Electrophysiological Assays

As a continuation of our study in the GABAA receptor modulators field, we report the design and synthesis of new 8-chloropyrazolo[1,5-a]quinazoline derivatives. Molecular docking studies and the evaluation of the 'Proximity Frequencies' (exploiting our reported model) were performed on all the final compounds (3, 4, 6a-c, 7a,b, 8, 9, 12a-c, 13a,b, 14-19) to predict their profile on the α1β2γ2-GABAAR subtype. Furthermore, to verify whether the information coming from this virtual model was valid and, at the same time, to complete the study on this series, we evaluated the effects of compounds (1-100 µM) on the modulation of GABAA receptor function through electrophysiological techniques on recombinant α1β2γ2L-GABAA receptors expressed in Xenopus laevis oocytes. The matching between the virtual prediction and the electrophysiological tests makes our model a useful tool for the study of GABAA receptor modulators.

Investigation of 1, 3, 4 Oxadiazole Derivative in PTZ-Induced Neurodegeneration: A Simulation and Molecular Approach

Objective

The study investigated the effect 5-[(naphthalen-2-yloxy) methyl]-1,3,4-oxadiaszole2-thiol (B3) in animal model of acute epileptic shock.

Methods

The pharmacokinetics profile of B3 was checked through SwissADME software. The binding affinities of B3, diazepam, and flumazenil (FLZ) were obtained through Auto Dock and PyRx. Post docking analysis and interpretation of hydrogen bonds were performed through Discovery Studio Visualizer 2016. Molecular dynamics simulations of three complexes were carried out through Desmond software package. B3 was then proceeded in PTZ-induced acute seizures models. Flumazenil was used in animal studies for elucidation of possible mechanism of B3. After behavioral studies, the animals were sacrificed, and the brain samples were isolated and stored in 4% formalin for molecular investigations including H and E staining, IHC staining and Elisa etc.

Results

The results demonstrate that B3 at 20 and 40 mg/kg prolonged the onset time of generalized seizures. B3 considerably increased the expression of protective glutathione S-transferase and glutathione reductase and reduced lipid peroxidation and inducible nitric oxide synthase (P < 0.001) in the cortex. B3 significantly suppressed (P < 0.01) the over expression of the inflammatory mediator tumor necrosis factor–α, whose up-regulation is reported in acute epileptic shocks.

Conclusion

Hence, it is concluded from the aforementioned results that B3 provides neuroprotective effects PTZ-induced acute epileptic model. FLZ pretreatment resulted in inhibition of the anticonvulsant effect of B3. B3 possesses anticonvulsant effect which may be mediated through GABA_A mediated antiepileptic pathway.