Effect of Natural Plant Products on Alzheimer’s Disease

Background: Plants and their extracts like ginger, garlic, Curcuma, Salvia, and Ginkgo are best known for their anti-oxidative and anti-inflammatory responses. These plants have shown their anti-Alzheimer’s properties in various in vivo and in vitro studies. Their diverse phytochemicals play a protective role against amyloid-beta-induced neurotoxicity and improve cognitive and learning impairments. These plants have a wide range of bioactive compounds, including alkaloids, flavonoids, phenols, glycosides, terpenoids, coumarins, and saponins. These chemicals scavenge the free radicals, lower the amyloid burden, improve memory dysfunction, and inhibit acetylcholinesterase activity. Some of the clinical trials and animal-based studies suggested the protective role of these plants and their extract mentioned in the literature. Methods: The articles for this review were majorly searched from popular search engines, viz, Google Scholar, PubMed, and Scopus. Results: Medicinal plants improve cognitive and memory impairments by inhibiting acetylcholinesterase activity and scavenging free oxygen species by activating superoxide dismutase, catalase, and GSH activity. The plant extracts reduce amyloid insult by inactivating the beta-site amyloid precursor protein cleaving enzyme (BACE). The inactivation of Caspase 3 and 9 reduces apoptosis. Furthermore, the stimulation of microglial cells and astrocyte reduce inflammation by lowering chemokines and interleukins. Discussion: The medicinal plants help to reduce AD pathogenesis by controlling different pathways and could be used as a therapeutic agent against the symptoms.