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Most chronic illnesses are caused by the biological reaction to an injury, rather than the initial injury or the injurious agent itselves as in neurodegeneration. With respect to this, notable attention is emerging on the therapeutic effects of dietary polyphenols for human health, able to counteract and neutralize oxidative stress and inflammatory processes involved in the etiopathogenesis of major neurodegenerative disorders, including Alzheimer's disease and Parkinson's disease. The acquired concept that cellular stress at low doses induces neuroprotective responses against degenerative processes is a frontier area of the neurobiological research focusing on the development of novel preventive and therapeutic interventions for neurodegenerative disorders. Notably, basal levels of prooxidant species are essential to promote adaptive redox cellular responses including vitagenes, tightly correlated to cell survival against age-related diseases. In this paper we discuss the concept of cellular stress response and hormesis and its applications to the field of neuroprotection and the potential therapeutic support provided by olive polyphenols, in particular hydroxytyrosol (HT)-rich aqueous olive pulp extract (Hidrox), as a pivotal activator of Nrf2 pathway and related vitagenes, and inhibitor of Keap1-Nrf2 interaction.Olive polyphenols are considered potential pharmacological modulators of neuroinflammation by upregulation of the Keap1/Nfr2/ARE pathway thus providing a strong rationale for treating neurodegenerative disorders., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Polyphenols are chemopreventive through the induction of nuclear factor erythroid 2 related factor 2 (Nrf2)-mediated proteins and anti-inflammatory pathways. These pathways, encoding cytoprotective vitagenes, include heat shock proteins, such as heat shock protein 70 (Hsp70) and heme oxygenase-1 (HO-1), as well as glutathione redox system to protect against cancer initiation and progression. Phytochemicals exhibit biphasic dose responses on cancer cells, activating at low dose, signaling pathways resulting in upregulation of vitagenes, as in the case of the Nrf2 pathway upregulated by hydroxytyrosol (HT) or curcumin and NAD/NADH-sirtuin-1 activated by resveratrol. Here, the importance of vitagenes in redox stress response and autophagy mechanisms, as well as the potential use of dietary antioxidants in the prevention and treatment of multiple types of cancer are discussed. We also discuss the possible relationship between SARS-CoV-2, inflammation and cancer, exploiting innovative therapeutic approaches with HT-rich aqueous olive pulp extract (Hidrox®), a natural polyphenolic formulation, as well as the rationale of Vitamin D supplementation. Finally, we describe innovative approaches with organoids technology to study human carcinogenesis in preclinical models from basic cancer research to clinical practice, suggesting patient-derived organoids as an innovative tool to test drug toxicity and drive personalized therapy., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Parkinson's disease (PD) is the second most prevalent late-age onset neurodegenerative disorder, affecting 1% of the population after the age of about 60 years old and 4% of those over 80 years old, causing motor impairments and cognitive dysfunction. Increasing evidence indicates that Mediterranean diet (MD) exerts beneficial effects in maintaining health, especially during ageing and by the prevention of neurodegenerative disorders. In this regard, olive oil and its biophenolic constituents like hydroxytyrosol (HT) have received growing attention in the past years. Thus, in the current study we test the health-promoting effects of two hydroxytyrosol preparations, pure HT and Hidrox ® (HD), which is hydroxytyrosol in its "natural" environment, in the established invertebrate model organism Caenorhabditis elegans . HD exposure led to much stronger beneficial locomotion effects in wild type worms compared to HT in the same concentration. Consistent to this finding, in OW13 worms, a PD-model characterized by α-synuclein expression in muscles, HD exhibited a significant higher effect on α-synuclein accumulation and swim performance than HT, an effect partly confirmed also in swim assays with the UA44 strain, which features α-synuclein expression in DA-neurons. Interestingly, beneficial effects of HD and HT treatment with similar strength were detected in the lifespan and autofluorescence of wild-type nematodes, in the neuronal health of UA44 worms as well as in the locomotion of rotenone-induced PD-model. Thus, the hypothesis that HD features higher healthspan-promoting abilities than HT was at least partly confirmed. Our study demonstrates that HD polyphenolic extract treatment has the potential to partly prevent or even treat ageing-related neurodegenerative diseases and ageing itself. Future investigations including mammalian models and human clinical trials are needed to uncover the full potential of these olive compounds.

Abstract: The olive fruit, its oil and the leaves of the olive tree have a rich history of nutritional, medicinal and ceremonial uses. Olive oil, table olives and olive products are an important part of the Mediterranean diet, the greatest value of which may be due to olive polyphenols that contribute to the modulation of the oxidative balance in vivo. The objective of this review is to examine the available safety/toxicity literature on olive polyphenols, particularly hydroxytyrosol, to determine the safety-in-use of a standardized aqueous olive pulp extract (HIDROX®). Among the polyphenols found in the extract, the major constituent of biological significance is hydroxytyrosol (50–70%). In oral bioavailability studies, urinary excretion of hydroxytyrosol and its glucuronide was found to be associated with the intake of hydroxytyrosol. Oral bioavailability of hydroxytyrosol in olive oil and in an aqueous solution was reported as 99% and 75%, respectively. In comparative studies, urinary excretion of hydroxytyrosol was greater in humans than in rats. The LD50 of the extract and hydroxytyrosol was reported to be greater than 2000mg/kg. In a subchronic study, the no observed adverse effect level (NOAEL) of the extract in rats was found to be 2000mg/kg/day. In developmental and reproductive toxicity studies, HIDROX® did not cause toxicity at levels up to 2000mg/kg/day. In an in vivo micronucleus assay, oral exposure of rats to HIDROX® at dose levels up to 5000mg/kg/day for 29 days did not induce increases in polychromatic erythrocytes in bone marrow. Based on the available studies of the extract and polyphenols, and a history of exposure and use of components of the extract through table olives, olive products and olive oil, the consumption of HIDROX® is considered safe at levels up to 20mg/kg/day. [Copyright &y& Elsevier]