Neuroprotective role of natural polyphenols: a look to the potentiality of elderberry extracts

Abstract

Neurodegenerative diseases cause a progressive functional alteration of neuronal systems often resulting in a state of dementia considered one of the most common psychiatric disorders of the elderly. The most common form of dementia is the Alzheimer’s disease (AD), characterized by accumulation of amyloid plaques and neurofibrillary tangles that causes memory loss and impairment of multiple cognitive functions. The limited effectiveness of current therapies against AD highlights the need to intensify research aimed to develop new agents able to prevent or retard the disease progression. Polyphenols behave as potential neuroprotective agents since their ability to influence and modulate important cellular processes, such as signaling, proliferation, apoptosis, redox balance, and differentiation. A growing body of evidence suggest that the intake of polyphenols may contribute to counteract the neuronal injuries that trigger neurodegeneration, slowing the progression of the disease. Several studies support the neuroprotective abilities of pure herbal compounds (e.g., green tea polyphenol (-)-epigallocatechin-3-gallate, resveratrol, curcumin, quercetin) and extracts enriched in polyphenols. In this contest, we demonstrated that an extract derived from elderberry, Sambucus nigra, possessing elevated polyphenolic content and antioxidant capacity is able to protect neuronal cells against oxidizing agents. In order to reproduce in vitro the characteristics of AD, we differentiated a human neuroblastoma cell line, the IMR-32 and subsequently, cells were treated with Beta amyloid peptide (fragment 25-35) or hydrogen peroxide. The pretreatment of differentiated cells with the Sambucus nigra extract reduced significantly the cell death induced by Aβ and H2O2. These results represent an initial indication that Sambucus nigra extract may find a space in future clinical trials addressed to prove the preventive and/or therapeutic potential of this natural extract against neurodegenerative disease.