Cell Signaling Pathways and Iron Chelation in the Neurorestorative Activity of Green Tea Polyphenols: Special Reference to Epigallocatechin Gallate (EGCG)

Abstract

Although much progress has been made in understanding the pathogenesis of Alzheimer's disease (AD), the current therapeutic approaches are merely symptomatic, intended for the treatment of cognitive symptoms, such as disturbances in memory and perception. Novel promising strategies suggest the use of anti-inflammatory drugs, antioxidants including natural occurring plant flavonoids, iron-complexing molecules, neurotrophic factor delivery, inhibitors of the amyloid-beta protein precursor processing secretases, gamma and beta, that generate amyloid-beta peptides and the interference with lipid and cholesterol metabolism. Human epidemiological and new animal data suggest that tea drinking may decrease the incidence of dementia, AD and Parkinson's disease. In particular, its main catechin polyphenol constituent (-)-epigallocatechin-3-gallate (EGCG) has been shown to exert neuroprotective/neurorescue activities in a wide array of cellular and animal models of neurological disorders. This review provides a detailed overview on the multimodal activities of green tea polyphenols with emphasis on their iron chelating, neurorescue/neuroregenerative and mitochondrial stabilization action.