Therapeutic Potential of Phyto-Constituents for the Treatment of Alzheimer’s Disease

Alzheimer’s disease (AD) is acknowledged as one of the most serious and progressive neurodegenerative disorder, and is the leading cause of dementia in late adult life having unknown etiological pathways. AD is characterized by the formation of intracellular neurofibrillary tangles leading to tau phosphorylation and extracellular amyloid deposits that develop into senile plaques. Amyloid beta (Aβ) plaques, the classic hallmarks of AD, in turn, cause the generation of free radical species of different metals (copper, iron) which modulate neuronal growth, differentiation, and progression of cell death through several signalling pathways. The conventional therapies recommended for the amelioration of AD are only restricted to treat the symptoms of AD and do not focus on the underlying causes of the disease. These allopathic medicines are non-economical and also have unwanted side-effects, which further decrease the quality of life (QOL) of the patients. Therefore, it is of utmost importance to explore alternatives to decrease the expression of neurodegeneration. Antioxidant and anti-inflammatory phytoconstituents play a crucial role in preventing the onset of neurodegenerative diseases and exert neuroprotection. Numerous antioxidant phytonutrients, herbal remedies, and food supplements have been reported for the prevention of cognitive decline and management of AD. The neuroprotective potential of phytotherapies has been demonstrated in numerous in vitro and in vivo studies. The purpose of this review is to describe phytoconstituents based on their therapeutic effects on etiological pathways (microglia, inflammasome, CB2, NLRP3 and NFKβ) of AD and their underlying molecular mechanisms of action involved in neuroprotection and prevention of AD.

Keywords: Alzheimer’s disease, Antioxidants, Cognition enhancement, Cognitive decline, Dementia, Dietary phytoconstituents, Microglial cell activation, Neuroinflammation, Neuronal cell injury, Reactive metal ion species.