Introduction:
The aim of this study was to determine and compare the anticonvulsant activity of seven naturally occurring substances isolated from essential oils (i.e., anisic aldehyde, (-)carvone, linalool, menthol, (-)menthon, (+)menthofuran, and terpinen-4-ol) in the maximal electroshock-induced seizure (MES) test in mice, which is considered as an experimental model of tonic-clonic seizures and, to a certain extent, of partial onset seizures in humans.

Material and methods:
Each compound (0.5 ml) was suspended in a 1% aqueous solution of Tween (9.5 ml) and the anticonvulsant effects of the tested compounds were determined at 15, 30, 60 and 120 min after their systemic (i.p.) administration. Tonic hind limb extension (seizure activity) was evoked in adult albino Swiss mice by a current (25mA, 500V, 50Hz, 0.2s stimulus duration) delivered via auricular electrodes.

Results:
Time course of anticonvulsant action of the studied compounds isolated from essential oils revealed that (-)carvone, menthol and (-)menthon produced a clear-cut anticonvulsant activity, whereas anisic aldehyde, linalool, (+)menthofuran, and terpinen-4-ol exerted no anticonvulsant effect in the mouse MES test. The time to peak of maximanticonvulsant effect for menthol and (-)menthon was established at 15 min, while that for (-)carvone was documented at 60 min after their i.p. administration.

Conclusions:
In conclusion, (-)carvone, menthol and (-)menthon suppress seizure activity in the mouse MES test and these compounds may become a novel treatment option for epileptic patients following further investigation in other animal models of epilepsy and preclinical studies.