Biophenols: Impacts and prospects in Anti-Alzheimer drug discovery

Alzheimer disease (AD) is a multifactorial neurodegenerative disorder and the most common form of dementia characterized by age-dependent memory loss, ultimately leading to a steady decline of cognitive function. Extracellular amyloid-β (A) deposition and intracellular deposits of the microtubule-associated protein tau as neurofibrillary tangles are the two main cellular events considered as the pathological hallmark of AD. Currently, there is no definite treatment and cure available for AD, while the approved medications, including cholinesterase and N-methyl d-aspartate antagonist, provide symptomatic relief to a limited extent. Increasing evidences supporting the dietary role in AD, including the intake of naturally occurring biophenols from the plants having pleiotropic bioactivity, which significantly decrease the Aβ burden and improve the cognitive impairment conditions through their potent antioxidant and peptide modification mechanisms. In this chapter, the in vitro and in vivo protective effects of different sources of biophenols and their antiamyloid, anti-tau, anticholinesterase, and cognitive enhancement activities are described, which have provided an evident background toward the future clinical research against AD.