ATTENUATION OF RAT ISCHEMIC BRAIN-DAMAGE BY AGED GARLIC EXTRACTS - A POSSIBLE PROTECTING MECHANISM AS ANTIOXIDANTS

Effects of an aged garlic extract and its thioallyl components on rat brain ischemia were examined using a middle cerebral artery occlusion model and a transient global ischemia model. In focal ischemia, an age d garlic extract, S-allyl cysteine (SAC), Allyl sulfide (AS) or Allyl disulfide (ADS) was administered 30 min prior to ischemic insult. Thre e days after ischemic insult, water contents of both ischemic and cont ralateral hemispheres were measured to assess the degree of ischemic d amage. The water content of the ischemic control (no drug treatment) g roup was 81.50+/-0.07% (mean+/-SEM). It was significantly reduced with the administration of 300 mg/kg of SAC; the water content was 80.66+/ -0.11% (P < 0.001). The histological observation using 2,3,5-triphenyl tetrazolium chloride staining demonstrated that the administration of SAC reduced infarct volume. Neither AS nor ADS was effective. In globa l ischemia, the production of reactive oxygen species (ROS) was measur ed ex vivo using a spin-trapping agent, alpha-phenyl-N-tert-butylnitro ne, and electron paramagnetic resonance spectroscopy. The production o f ROS had two peaks; first at 5 min and second at 20 min after reperfu sion. Both SAC and 7-nitro indazole, a nitric oxide synthase inhibitor , did not attenuate the amount of ROS produced at the first peak, but did the amount of the second peak. A possible involvement of peroxinit rite, which may be formed from superoxide and nitric oxide and is know n to be highly toxic in ischemia/reperfusion injury of the brain, was suggested. Copyright (C) 1996 Elsevier Science Ltd.