Novel Vitamin K analogs suppress seizures in zebrafish and mouse models of epilepsy

Abstract

Epilepsy is a debilitating disease affecting 1-2% of the world’s population. Despite this high prevalence, 30% of patients suffering from epilepsy are not successfully managed by current medication suggesting a critical need for new anti-epileptic drugs (AEDs). In an effort to discover new therapeutics for the management of epilepsy, we began our study by screening drugs that, like some currently used AEDs, inhibit HDACs using a well-established larval zebrafish model. In this model, 7-day post fertilization (dpf) larvae are treated with the widely used seizure-inducing compound pentylenetetrazol (PTZ) which stimulates a rapid increase in swimming behavior previously determined to be a measurable manifestation of seizures. In our first screen, we tested a number of different HDAC inhibitors and found that one, NQN1, significantly decreased swim activity to levels equal to that of VPA. We continued to screen structurally related compounds including Vitamin K3 (VK3) and a number of novel Vitamin K (VK) analogues. We found that VK3 was a robust inhibitor of the PTZ-induced swim activity, as were several of our novel compounds. Three of these compounds were subsequently tested on mouse seizure models at the National Institute of Neurological Disorders and Stroke (NINDS) Anticonvulsant Screening Program. Compound 2h reduced seizures particularly well in the minimal clonic seizure (6 Hz) and corneal kindled mouse models of epilepsy, with no observable toxicity. As VK3 affects mitochondrial function, we tested the effects of our compounds on mitochondrial respiration and ATP production in a mouse hippocampal cell line. We demonstrate that these compounds affect ATP metabolism and increase total cellular ATP. Our data indicate the potential utility of these and other VK analogues for prevention of seizures and suggest the potential mechanism for this protection may lie in the ability of these compounds to affect energy production.

QUADrATiC: scalable gene expression connectivity mapping for repurposing FDA-approved therapeutics

“…Of particular interest is Menadione, or Vitamin K3. Interestingly, a review of the literature produces evidence that Vitamin K3 acts to inhibit HDAC6, [ 24 ], suggesting that this connection has been correctly identified by QUADrATiC.

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Advancements in zebrafish applications for 21st century toxicology

“…In an effort to identify novel therapeutics for treatment in humans, many high-throughput chemical screens using the zebrafish model have been aimed at modulating ototoxicity (Esterberg et al, 2013), seizures (Baraban et al, 2013; Rahn et al, 2014), and cancer (Lee et al, 2007; Nguyen et al, 2012). Work from Leonard Zon and colleagues at Harvard Medical School provides an excellent proof of concept on how to translate high-throughput zebrafish screens from the tank to the bedside.…”

Inherited mitochondrial genomic instability and chemical exposures

“…With these cells, it was found that the mitochondrial permeability transition pore inhibitor, cyclosporine A, as well as carnitine (fatty acid transport) and N-acetylcysteine (antioxidant), could prevent valproic acid-induced toxicity. We have also been testing new and old chemical compounds on Polg mutant zebrafish, which takes advantage of an in vivo vertebrate animal model that can be treated like cells in a dish due to its very small size (Garcia et al 2016; Rahn et al 2014; Rahn et al 2015). …”