Introduction and objective:
The aim of this study was to perform the anticonvulsant screening test to determine whether two sesquiterpene lactones (alantolactone and isoalantolactone) isolated from herbs and medicinal plants offer a distinct protection against maximal electroshock (MES)-induced tonic seizures in mice.

Material and Methods:
The screening test was performed for alantolactone and isoalantolactone administered intraperitoneally in a constant dose of 300 mg/kg at 4 various pretreatment times (i.e., 15, 30, 60 and 120 min.) before the MES test. Tonic hind limb extension (seizure activity) was evoked in adult male albino Swiss mice by a current (sine-wave, 25 mA, 500 V, 50 Hz, 0.2 s stimulus duration) delivered via ear-clip electrodes. Subsequently, the median effective doses (ED50 values) for alantolactone and isoalantolactone were determined in the MES test in mice.

Results:
In the screening test, both compounds produced a 37.5% protection against MES-induced tonic seizures in mice, when administered i.p. at 15 min. prior to the MES test. In contrast, alantolactone and isoalantolactone administered i.p. at 30, 60 and 120 min. prior to the test produced no anticonvulsant activity in mice subjected to the MES test. The experimentally-derived ED50 values for alantolactone and isoalantolactone, administered intraperitoneally at 15 min. before the MES test, were 322 (281–369) mg/kg and 336 (285–396) mg/kg, respectively.

Conclusions:
Alantolactone and isoalantolactone (2 sesquiterpene lactones) are worth considering as potentially favourable compounds in epileptology, if the results from this study could be extrapolated into clinical settings.