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Abstract

Alzheimer's disease (AD) is a progressive and irreversible neurodegenerative disorder leading to dementia in the elderly inhabitants. Increasing evidence advises that oxidative stress that is normally associated with aging is an obvious and early feature of AD and plays a role in its pathogenesis. The present study was designed to evaluate the possible neuroprotective activity of Ginkgo biloba (Gb) and / or Peganum harmala (Ph) extract against AD in a rat model. AD was induced by chronic administration intraperitoneal injection of scopolamine (0.7 mg kg-1 , i.p.) to rats for a period of 7 days. The Gb (120 mg/kg b.wt.) and Ph (187.5 mg/kg b.wt.) were administrated to AD rat group orally daily for a period of 30 days. The results revealed that the levels of thiobarbituric acid reactive substances and Xanthine oxidase were significantly increased, even though the activities of superoxide dismutase and catalase, as well as the reduced glutathione, were significantly decreased in the brain homogenate of Alzheimer group. Additionally, brain acetylcholinesterase as well as alkaline phosphatase, acid phosphatase, alanine aminotransferase, aspartate aminotransferase and lactate dehydrogenase activities were significantly increased. On the other hand, the administration of Gb, Ph and coadministration of those test herbs acquired potential therapeutic effects on improving the neurodegenerative disorder in rats through suppressing lipid peroxidation, augmenting endogenous antioxidant enzymes, and reducing acetylcholinesterase activity in the brain. It might be concluded that a mixture extract, by its antioxidant constituents, could modulate scopolamine-induced oxidative stress and enzyme activities in the brain. INTRODUCTION: Alzheimer's disease is a pathological brain disease and the most frequent cause of dementia 1, 2. Patients with AD suffer a gradual deterioration of memory and other cognitive functions, which eventually causes a complete incapacity and fatal within 3 to 9 years after diagnosis 3 .