Neuroprotective Role of Natural Polyphenols.

Neurodegenerative diseases cause a progressive functional alteration of neuronal systems, resulting in a state of dementia which is considered one of the most common psychiatric disorders of the elderly. Dementia implies an irreversible impairment of intellect that increases with age causing alteration of memory, language and behavioral problems. The most common form, which occurs in more than half of all cases, is Alzheimer's disease, characterized by accumulation of amyloid plaques and neurofibrillary tangles. Neuroinflammation and oxidative stresses have been considered as a hallmark of Alzheimer disease, playing a crucial role in neurotoxicity. For this reason, an adequate antioxidant strategy may improve the treatment of neurodegenerative diseases and dementia. Several studies support the neuroprotective abilities of polyphenolic compounds resulting in neuronal protection against injury induced by neurotoxins, ability to suppress neuroinflammation and the potential to promote memory, learning and cognitive functions. We critically reviewed here the therapeutic potential of pure herbal compounds (e.g., green tea polyphenol (-)- epigallocatechin-3-gallate, resveratrol, curcumin, quercetin and others) and extracts enriched in polyphenols showing the most promising neuroprotective effects. We are also presenting data on the ability of an extract derived from elderberry, Sambucus nigra, possessing elevated polyphenolic content and antioxidant capacity to protect neuronal cells against oxidizing agents.