From the North Sea to Drug Repurposing, the Antiseizure Activity of Halimide and Plinabulin

Abstract

PharmaSea performed large-scale in vivo screening of marine natural product (MNP) extracts, using zebrafish embryos and larvae, to identify compounds with the potential to treat epilepsy. In this study, we report the discovery of two new antiseizure compounds, the 2,5-diketopiperazine halimide and its semi-synthetic analogue, plinabulin. Interestingly, these are both known microtubule destabilizing agents, and plinabulin could have the potential for drug repurposing, as it is already in clinical trials for the prevention of chemotherapy-induced neutropenia and treatment of non-small cell lung cancer. Both halimide and plinabulin were found to have antiseizure activity in the larval zebrafish pentylenetetrazole (PTZ) seizure model via automated locomotor analysis and non-invasive local field potential recordings. The efficacy of plinabulin was further characterized in animal models of drug-resistant seizures, i.e., the larval zebrafish ethyl ketopentenoate (EKP) seizure model and the mouse 6 Hz psychomotor seizure model. Plinabulin was observed to be highly effective against EKP-induced seizures, on the behavioral and electrophysiological level, and showed activity in the mouse model. These data suggest that plinabulin could be of interest for the treatment of drug-resistant seizures. Finally, the investigation of two functional analogues, colchicine and indibulin, which were observed to be inactive against EKP-induced seizures, suggests that microtubule depolymerization does not underpin plinabulin’s antiseizure action.

Zebrafish as an Innovative Tool for Epilepsy Modeling: State of the Art and Potential Future Directions

“…Moreover, they displayed abnormal behavior with whole-body trembling, pectoral fin, jaw twitching, and some epileptiform discharges [90]. The duration and frequency of discharges were longer and higher, respectively than in the controls [77]. Of notice, these parameters were increased in light conditions.…”

“…These include N-methyl-D-aspartate (NMDA), a glutamatergic receptor agonist, administrated either by i.p. or by immersion, causing reproducible severe seizures in adults [75]; or ethyl ketopentenoate, a glutamate decarboxylase inhibitor, which induces pharmacoresistant seizures in ZF larvae [76,77]. Accordingly, another glutamate decarboxylase inhibitor, allyglycine, was shown to induce frequent seizures in ZF larvae which are prevented by a variety of ASDs [78].…”

“…Zebrafish larvae between 3 and 7 dpf are usually embedded in 1.2-2% low-melting-point agarose prepared in an embryo medium. One or two glass microelectrodes filled with NaCl (2 M) or with artificial cerebrospinal fluid (124 mM NaCl, 10 mM glucose, 2 mM KCl, 2 mM MgSO 4 , 2 mM CaCl 2 , 1.25 mM KH 2 PO 4 , and 26 mM NaHCO 3 NaCl) are inserted through the epidermis, into the intracranial space, into the midbrain or optic tectum or forebrain [31,63,77,78,82,87,88,91,92,[119][120][121][122][123][124]. Then, the larvae are usually treated with different doses of chemicals/drugs, and the activity is measured for 10-30 min and the obtained seizure events are compared to one of the control samples (untreated larvae).…”