Abstract

Introduction: Alzheimer’s disease (AD) is a progressive, neurodegenerative disease that severely affects individuals' cognitive abilities, memory, and quality of life. It affects the elderly population, and there is no permanent prevention or cures available to date, treatments mainly aiming to alleviate the symptoms as and when they appear. Alternate therapeutic approaches are being researched constantly, and there is a growing focus on phytomedicine, herbal medicine, organic compounds, and ayurvedic compounds for the treatment of AD.

Methods: The current study aims to provide an extensive review of these plants against AD from the currently existing literature. Most relevant keywords like Alzheimer’s Disease, phytomedicines, ethnic medicines, the role of phytomedicine in neuroprotection, common phytomedicines against AD, etc., were used to select the plants and their metabolites effective in treating AD. The study focuses on six plants: Panax ginseng, Ginkgo biloba, Bacopa monnieri, Withania somnifera, Curcuma longa, and Lavandula angustifolia. Their active components have been studied along with neuroprotective properties, and evidence of in-vitro, pre-clinical, and clinical studies conducted to prove their therapeutic potential against the disease have been presented.

Results: All plants envisaged in the study show potential for fighting against AD to varying degrees. Their compounds have shown therapeutic effects by reversing the neurological changes such as clearing Aβ plaque and neurofibrillary tangle formation, and ameliorative effects against neurodegeneration through processes including improving concentration, memory, cognition and learning, higher working and cue memory, improved spatial memory, inhibition of NF-κB expression, inhibiting the release of pro-inflammatory cytokines, inhibition of AChE and lipid peroxidase enzymes, and reduction of interleukin levels and tumor necrosis factor-alpha.

Conclusion: The present review is a comprehensive and up-to-date analysis supported by the evidentiary proofs from pre-clinical studies, meta-analyses, and review papers related to natural phytochemicals' impact on neurodegenerative disorders like AD.

Keywords: Alzheimer’s disease, phytomedicines, neuroprotection by phytomedicines, neuroprotective phytoconstituents, Panax ginseng, Ginkgo biloba, Bacopa monnieri, Withania somnifera, Curcuma longa, Lavandula angustifolia.