Hydroxytyrosol, Tyrosol and Derivatives and Their Potential Effects on Human Health

Abstract

The Mediterranean diet and olive oil as its quintessential part are almost synonymous with a healthy way of eating and living nowadays. This kind of diet has been highly appreciated and is widely recognized for being associated with many favorable effects, such as reduced incidence of different chronic diseases and prolonged longevity. Although olive oil polyphenols present a minor fraction in the composition of olive oil, they seem to be of great importance when it comes to the health benefits, and interest in their biological and potential therapeutic effects is huge. There is a growing body of in vitro and in vivo studies, as well as intervention-based clinical trials, revealing new aspects of already known and many new, previously unknown activities and health effects of these compounds. This review summarizes recent findings regarding biological activities, metabolism and bioavailability of the major olive oil phenolic compounds—hydroxytyrosol, tyrosol, oleuropein, oleocanthal and oleacein—the most important being their antiatherogenic, cardioprotective, anticancer, neuroprotective and endocrine effects. The evidence presented in the review concludes that these phenolic compounds have great pharmacological potential, however, further studies are still required.

Potential Protective Role Exerted by Secoiridoids from Olea europaea L. in Cancer, Cardiovascular, Neurodegenerative, Aging-Related, and Immunoinflammatory Diseases

“…In this sense, Kendall et al reported that OL diffuses in the stomach and remained stable and intact at the gastric level during digestion being absorbed in the small intestine in healthy young adults [56]. Similarly, several studies have established that OL is stable at the gastric level during digestion, since the bioavailability of its main metabolite HTy is higher [57]. On the contrary, Corona et al determined that OL was absorbed in the colon and degraded by gut microbiota in rat intestinal segment that produces HTy, which expresses biological activity [58].…”

Impact of the Co-Administration of N-3 Fatty Acids and Olive Oil Components in Preclinical Nonalcoholic Fatty Liver Disease Models: A Mechanistic View

“…A comparable situation occurs with the combined administration of EPA and HT, in which attenuation in HFD-induced steatosis development is achieved, an effect characterized by the additivity of EPA and HT effects that mainly depend on HT [37][38][39][40]. Although HT exerts beneficial outcomes associated with its significant direct free radical scavenging action [73,74] (Figure 3), alternate mechanisms of action involve (i) antioxidant responses via Nrf2 activation [75]; (ii) antisteatotic effects underlying PPAR-α [76] and FGF21 [77] upregulation and ER stress downregulation; [78] (iii) improvement of mitochondrial oxidative function through AMPK/PGC-1α signaling to favor FAO [40,75,79]; and (iv) prevention or resolution of inflammatory processes due to NF-κB deactivation [76,80].…”

Metabolomic Study to Evaluate the Transformations of Extra-Virgin Olive Oil’s Antioxidant Phytochemicals during In Vitro Gastrointestinal Digestion

“…It is noteworthy that in the last years, great interest has been placed on hydroxytyrosol; in fact, this phenolic compound was entitled by the "health claim" from the European Food Safety Authority, reporting that "the consumption of olive oil rich in polyphenols (hydroxytyrosol, 5 mg/day) contributes to the protection of oxidative damage to lipids in blood" [14]. In addition, different studies focusing on hydroxytyrosol demonstrated several in vitro biological activities exerted by this compound, mainly related to the modulation of gene expression together with potential anticancer activities [15,16]. However, the amount and composition of these compounds in both olives and olive oils clearly result from the complex interactions between several factors, namely, genetic factors (cultivar) and pedoclimatic conditions [17].…”