The purpose of the present study was to test whether kava extract and its constituents
kawain,
dihydrokawain,
methysticin,
dihydromethysticin and
yangonin provide protection against ischemic brain damage. To this end, we used a model of focal
cerebral ischemia in mice and rats.
Ischemia was induced by microbipolar coagulation of the left middle cerebral artery (MCA). To quantify the size of the lesion in mice, the area of the
infarct on the brain surface was assessed planimetrically 48 h after MCA occlusion by transcardial perfusion of
carbon black. In the rat model
infarct volume was determined 48 h after MCA occlusion by planimetric analysis and subsequent integration of the
infarct areas on serial coronal slices. Compounds were administered i.p., except the kava extract, which was administered orally. The effects of the kava extract and its constituents were compared with those produced by the typical
anticonvulsant,
memantine. The kava extract,
methysticin and
dihydromethysticin produced effects similar to those of the reference substance
memantine. The kava extract (150 mg/kg, 1 h before
ischemia) diminished the
infarct area (P less than 0.05) in mouse brains and the
infarct volume (P less than 0.05) in rat brains.
Methysticin,
dihydromethysticin (both 10 and 30 mg/kg, 15 min before
ischemia) and
memantine (20 mg/kg, 30 min before
ischemia) significantly reduced the
infarct area in mouse brains. All other compounds failed to produce a beneficial effect on the
infarct area in mouse brains. In conclusion, the kava extract exhibited neuroprotective activity, which was probably mediated by its constituents
methysticin and
dihydromethysticin.