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.