Neuroprotective Panel of Olive Polyphenols: Mechanisms of Action, Anti-Demyelination, and Anti-Stroke Properties

Abstract

Neurological diseases such as stroke and multiple sclerosis are associated with high morbidity and mortality, long-term disability, and social and economic burden. Therefore, they represent a major challenge for medical treatment. Numerous evidences support the beneficial effects of polyphenols from olive trees, which can alleviate or even prevent demyelination, neurodegeneration, cerebrovascular diseases, and stroke. Polyphenols from olive oils, especially extra virgin olive oil, olive leaves, olive leaf extract, and from other olive tree derivatives, alleviate inflammation and oxidative stress, two major factors in demyelination. In addition, they reduce the risk of stroke due to their multiple anti-stroke effects, such as anti-atherosclerotic, antihypertensive, antioxidant, anti-inflammatory, hypocholesterolemic, hypoglycemic, and anti-thrombotic effects. In addition, olive polyphenols have beneficial effects on the plasma lipid profiles and insulin sensitivity in obese individuals. This review provides an updated version of the beneficial properties and mechanisms of action of olive polyphenols against demyelination in the prevention/mitigation of multiple sclerosis, the most common non-traumatic neurological cause of impairment in younger adults, and against cerebral insult with increasing incidence, that has already reached epidemic proportions.

Potential Therapeutic Properties of Olea europaea Leaves from Selected Cultivars Based on Their Mineral and Organic Profiles

“…Regarding its chemical properties that allow an easy formulation free of toxicity, HT has been highly regarded as a prime food supplement by the nutraceutical and food industries and so it is of key importance to potentiate the extraction of this phenolic compound from the olive leaf [ 61 ]. Concerning the premium choice, the O. europaea Madural leaf extract presents as a worthy nutraceutical due to its HT levels, confirming the invaluable multidimensional properties of olive leaves as a low-cost source of high-added-value phenolic compounds, as determined by other authors [ 30 , 31 , 51 , 99 , 103 ].…”

“…Several studies report that polyphenols derived from the olive tree are implicated in the relief and prevention of bioprocesses, such as through neurodegenerative, anti-hypertensive, and cardioprotective effects, whilst exhibiting anti-thrombotic, anti-inflammatory, antioxidant, anticancer, antimicrobial, and immune-protective properties [ 50 , 51 ]. The TPCs of the studied extracts were found to exhibit the following waning order: O. europaea Verdeal (59.30 ± 4.30 mgGAE/g sample) > Madural (48.90 ± 2.40 mgGAE/g sample) > Cobrançosa (37.90 ± 4.20 mgGAE/g sample) ( Table 2 ), which are inferior to the values found for the same cultivars harvested from another geographical region in differential cultivation conditions, where O. europaea Cobrançosa (3.37 ± 0.25 mgGAE/g sample) > Verdeal (2.47 ± 0.2 mgGAE/g sample) > Madural (2.31 ± 0.22 mgGAE/g sample) [ 29 ].…”

Updated Organic Composition and Potential Therapeutic Properties of Different Varieties of Olive Leaves from Olea europaea

“…Olive tree polyphenols showed evidence of relieving or even preventing demyelination, neurodegeneration, antihypertensive and cardioprotective effects, while demonstrating anti-inflammation, antioxidant, antimicrobial and immune protective, hypocholesterolemic, hypoglycemic, anti-thrombotic, and anti-cancer properties [ 32 , 45 ]. In this study, the leaf sprouts of all the three cultivars were showed to be richer in total phenol content (TPC) compared to the respective elementary leaf sample ( Table 2 ).…”

EVOO Polyphenols Exert Anti-Inflammatory Effects on the Microglia Cell through TREM2 Signaling Pathway

“…The main polyphenols in EVOO, OleA and its main metabolite, HT, are well studied and can be easily administered through food or in other formulations and do not present adverse reactions in humans. In particular, OleA and HT exert their neuroprotective effects by their ability to cross the blood–brain barrier (BBB) [ 38 , 39 , 40 ]; indeed, the aglycone form can cross membranes by a passive diffusion [ 38 ]. This peculiarity makes EVOO polyphenols potential nutraceutical tools and promises the realistic use of these active principles in the treatment of neuroinflammation.…”