Synergistic anticonvulsant P.677 effect of gidazepam and novel esters based on glycine and monoterpenes Mariia Nesterkina, Iryna Kravchenko

Odessa National Polytechnic University, Odessa, Ukraine E-mail: [email protected], [email protected]

Background: Most commonly prescribed anticonvulsant drugs Methods: The experiment was carried out with outbreed male are able to alter CNS excitability by effecting GABAergic or white mice distributed into 14 groups of five animals each, glycinergic neurotransmission. Although GABA and glycine do treated orally by: gidazepam (GDZ) 1 mg/kg (1); glycine ester not possess a significant antiseizure activity when administered of 200 mg/kg (2); glycine ester of 200 mg/kg themselves, they were found to potentiate the action of other (3); glycine ester of carvacrol 200 mg/kg (4); glycine ester of anticonvulsants. Glycine, for example, potentiates the clinical guaiacol 200 mg/kg (5); glycine ester of 200 mg/kg effect of such anticonvulsants as , and (6); glycine ester of eugenol 200 mg/kg (7); mixtures of GDZ in DBA/2 audiogenic, 3-MPA and PTZ-induced with each ester. The anticonvulsant activity of compounds 1−7 seizures. At the same time, recent studies reported that cyclic as well as mixtures of 1 with 2‒7 was evaluated in model of monoterpenes such as menthol, thymol and others also have acute generalized seizures induced by intravenous infusion of actions within the CNS and act as allosteric modulators of 1% pentylenetetrazole solution (PTZ) with the determination of GABA(A) receptors whereas some terpenes are also PTZ minimum effective doses (MED) inducing clonic-tonic antagonists of cortical glycine and GABA(A) receptors. convulsions (CTC) and tonic extension (TE) in test animals. Objective: To investigate co-administration effect of PTZ doses for inducing clonic-tonic convulsions (DCTC) and gidazepam (GDZ) and novel esters based on glycine and tonic extension (DTE) were calculated relative to control; monoterpenes – menthol, thymol, carvacrol, guaiacol, borneol pharmacological effect of compounds was estimated in 3 hours. and eugenol. All results are expressed as mean ± standard error mean (SEM). CH 3 CH3

O O NH 2 + NH2 O O

H C CH 3 3 H3C CH3 Gidazepam Menthol-glycine ester Synergistic effect

Results: All esters of glycine with monoterpenes reveal 400 antiseizure effect in 3 h after oral administration as evidenced 350 by increasing of DCTC and DTE values. GDZ was found to DCTC DTE protect against seizures with DCTC and DTE values of 181 and 300 191%, accordingly; whereas co-administration of GDZ and esters 2−7 was shown to increase anticonvulsant activity 250

compared with each compound alone. It is noteworthy that 200 glycine esters of alicyclic 2 and 6 (menthol and borneol esters) combined with GDZ demonstrated the highest 150 MED of PTZ, % of control control PTZ, of of MED% synergistic effect. 100 CH3 CH3 CH3 O 50 O O NH2

NH2 NH2 O O O 0 С 2 3 4 5 6 7 GDZ 2 3 4 5 6 7 H C CH H C CH H C CH 3 3 3 3 3 3 Co-administration with GDZ 2 3 4 Figure. Anticonvulsant activity of compounds. C – control; GDZ – gidazepam.

H C CH 3 3 O NH O 2 Conclusion: Our experimental data demonstrate that orally co- O NH2 administered gidazepam and glycine esters of monoterpenes H2C O O O produce synergistic effect in seizures prevention suggesting H C CH3 O 3 O H3C that these esters are not acting via the site of 5 6 NH 2 7 GABA(A) receptors; these results are in agreement with those DISCLOSURE: No potential conflict of interest obtained by electrophysiological investigation.