In-silico screening of NaV 1.1 inhibitors with potential antiepileptic activity: a structure-based approach.

LLANOS M; SBARAGLINI ML; MARTIN P; GAVERNET L

La Plata

Congreso; congreso biophisycs; 2018

Epilepsy is one of the most common neurological diseases globally, affecting near 50 million people worldwide. Although ion channels are of utmost importance among antiepileptic targets, with many examples of antiepileptic drugs acting on them, the lack of high quality structural data has hindered the rational design of novel antiepileptic compounds with improved therapeutic properties.To address this challenge, we have constructed an homology model of the human NaV 1.1 channel, based on the cryo-EM structure of a mammalian NaV channel. The model was carefully refined with Rosetta, to get a high resolution protein model suitable for docking simulations. A docking model of the channel?s small molecules site was developed and validated, using a test set of molecules evaluated on binding assays. Then, the resulting model was applied in a structure-based virtual screening campaign on DrugBank 5.0.10, a database of known drugs and nutraceutical compounds. All-atoms molecular dynamics simulations (MD) were conducted for some of the most interesting scaffolds identified in the screening, to get insight on the key molecular features responsibles for the activity.Novobiocin, an old antibiotic drug withdrawn from the market was identified as a NaV inhibitor by the model. The drug was evaluated on heterologously expressed NaV1.1 and NaV1.2 in HEK cells using the Patch-Clamp technique, showing a voltage-dependent inhibition on both isoforms (10 μM). When tested in-vivo on the Maximal Electroshock Seizure (MES) Test, Novobiocin has shown encouraging results, abolishing seizures on 75% of the animals (mice) at the lower dose tested (30 mg/Kg).In summary, we have developed and validated a docking model of the human NaV1.1 which is fast and accurate enough to be applied in virtual screening campaigns, to identify inhibitors acting on the channel?s small molecules site. Combining this model with more accurate simulations like MD and posterior MM-PBSA analysis will allow us to lead the rational design of novel NaV channel inhibitors, with potential antiepileptic activity. Finally, although a more exhaustive characterization is necessary on both in-vitro and in-vivo assays, Novobiocin seems to be a promising opportunity for drug repositioning against epilepsy.