Hydroxytyrosol Plays Antiatherosclerotic Effects through Regulating Lipid Metabolism via Inhibiting the p38 Signal Pathway

Synthesis and Health Effects of Phenolic Compounds: A Focus on Tyrosol, Hydroxytyrosol, and 3,4-Dihydroxyacetophenone

Tyrosol (Tyr), hydroxytyrosol (TH), and 3,4-Dihydroxyacetophenone (3,4-DHAP) are three phenolic compounds naturally present in plants that have attracted considerable research attention due to their potent antioxidant, anti-inflammatory, anticancer, and cardiovascular protective properties. In recent years, mounting evidence has indicated that these phenolic compounds hold broad potential in both disease prevention and treatment. This paper reviews the chemical structures and synthetic methods of Tyr, HT, and 3,4-DHAP, as well as their multifaceted effects on human health, particularly their roles and mechanisms in antioxidation, anti-inflammation, cardiovascular protection, neuroprotection, and anticancer activity. In addition, this paper explores the future prospects of these compounds and the current challenges associated with their application-such as low bioavailability and long-term safety concerns-and proposes directions for further investigation.

The Role of Olive Oil in Cardiometabolic Risk

Olive oil, the primary fat source in the Mediterranean diet (MedDiet), is rich in monounsaturated fatty acids (MUFA), especially oleic acid, which constitutes 70-80% of its composition. Extra-virgin olive oil (EVOO), produced by mechanically pressing olives, is the highest quality olive oil, with an intense flavor and acidity <1%. In contrast, refined olive oil (ROO), a blend of virgin and refined oils, contains fewer antioxidants and anti-inflammatory compounds. EVOO's health benefits stem largely from its MUFA content, which is linked to reduced risks of cardiovascular disease (CVD), neurodegenerative conditions, and certain cancers. Additionally, EVOO contains minor, but bioactive, components such as polyphenols, tocopherols, and phytosterols, contributing to its oxidative stability, sensory qualities, and health-promoting properties. These include polyphenols, like oleuropein, hydroxytyrosol, and tyrosol, which exhibit anti-inflammatory, cardioprotective, neuroprotective, and anticancer effects. Epidemiological studies suggest an inverse relationship between olive oil intake and CVD, with EVOO-enriched MedDiet interventions showing improved lipid profiles, reduced blood pressure, and lower cardiovascular event risk. The PREDIMED study highlights the significant role of EVOO in reducing cardiometabolic risk. This review explores the impact of EVOO's chemical components within the MedDiet framework on metabolic variables influencing cardiometabolic health.

Hydroxytyrosol isolation, comparison of synthetic routes and potential biological activities

Hydroxytyrosol (HT) is a polyphenol found in the olive plant (Olea europaea) that has garnered attention from the food, feed, supplement, and pharmaceutical industries. HT has evolved from basic separation and extraction to chemical and biocatalytic synthesis. The yield of HT can reach 1.93 g/L/h through chemical synthesis and 7.7 g/L/h through biocatalysis; however, both methods are subject to inherent limitations. Furthermore, the potential health benefits associated with HT have been highlighted, including its ability to act as an antioxidant, reduce inflammation, combat cancer and obesity, and exert antibacterial and antiviral effects. Its neuroprotective effects, skin protection, and wound healing capabilities are also discussed. Given these remarkable biological properties, HT stands out as one of the most extensively investigated natural phenols. This review highlights future methods and pathways for the synthesis of HT, providing insights based on its bioactivity characteristics, health benefits, and potential future applications.

Magnetic molecularly imprinted polymers using ternary deep eutectic solvent as novel functional monomer for hydroxytyrosol separation

In this work, magnetic molecularly imprinted polymers (MIPs) for specific recognition of Hydroxytyrosol (HT) were designed by vinyl-modified magnetic particles (Fe3O4@SiO2@VTEOs) as carrier, ternary deep eutectic solvent (DES) as functional monomer, while ethylene glycol dimethacrylate (EGDMA) as crosslinker. The optimum amount of DES was obtained by adsorption experiments (molar ratio, caffeic acid: choline chloride: formic acid = 1:6:3) which were 140 μL in total. Under the optimized amount of DES, the maximum adsorption capacity of the MIPs particles was 42.43 mg g-1, which was superior to non-imprinted polymer (4.64 mg g-1) and the imprinting factor (IF) is 9.10. Syringin and Oleuropicrin were used as two reference molecules to test the selectivity of the DES-MIPs particles. The adsorption capacity of HT was 40.11 mg g-1. Three repeated experiments show that the polymer has high stability and repeatability (RSD = 5.50).

High Tyrosol and Hydroxytyrosol Intake Reduces Arterial Inflammation and Atherosclerotic Lesion Microcalcification in Healthy Older Populations

Aging is an important risk factor for cardiovascular diseases and convincing data have shown that chronic low-grade inflammation, which develops with advanced age, contributes significantly to cardiovascular risk. The present study aimed to use 18F-FDG/18F-NaF-PET/CT imaging to, respectively, gauge arterial inflammation and microcalcification in a healthy elderly population and to assess the potential benefits of a tyrosol- and hydroxytyrosol-rich diet on these two markers of atherosclerotic plaque fragility. Eleven healthy participants (mean age 75 ± 5.67 years) were supplemented for 6 months with high polyphenol-rich extra virgin olive oil (HP-EVOO), extra virgin olive oil (EVOO), or refined olive oil (ROO). The participants underwent PET/CT imaging with 18F-FDG and 18F-NaF radiotracers at baseline and after 6 months. 18F-FDG and 18F-NaF uptakes were quantified using standardized uptake values (SUV) and were categorized based on artery calcification and olive oil type. A total of 324 slices of the aortas of the imaged participants were analyzed for arterial inflammation and 327 slices were analyzed for microcalcification. 18F-FDG uptake was significantly higher in the non-calcified segments than in the calcified segments (SUVmax = 2.70 ± 0.62 and SUVmax = 2.54 ± 0.44, respectively, p < 0.042). Conversely, the non-calcified segments displayed significantly lower 18F-NaF uptake than the calcified segments (SUVmax = 1.90 ± 0.37 and 2.09 ± 0.24, respectively, p < 0.0001). The 6-month supplementation with HP-EVOO induced a significant reduction in 18F-FDG uptake in both the non-calcified (2.93 ± 0.23 to 2.75 ± 0.38, p < 0.004) and calcified segments of the aortas (2.25 ± 0.29 to 2.15 ± 0.19, p < 0.02). 18F-NaF uptake was also significantly lower in patients supplemented with HP-EVOO (SUVmax = 1.98 ± 0.33 at baseline compared to 1.85 ± 0.28, after the 6-month supplementation, p < 0.004), whereas no significant effect was observed with EVOO. Conversely, participants supplemented with ROO displayed a significant increase in 18F-NaF uptake (SUVmax = 1.78 ± 0.34 to 1.95 ± 0.34, p < 0.0001). The present study confirmed that a phenolic-compound-rich diet reduces both arterial inflammation and atherosclerotic lesion microcalcification and demonstrated that 18F-FDG/18F-NaF-PET/CT imaging is a valuable approach for assessing age-related arterial damage.

Totum-070, a Polyphenol-Rich Plant Extract, Prevents Hypercholesterolemia in High-Fat Diet-Fed Hamsters by Inhibiting Intestinal Cholesterol Absorption

Atherosclerotic cardiovascular disease is the leading cause of mortality worldwide, and hypercholesterolemia is a central risk factor for atherosclerosis. This study evaluated the effects of Totum-070, a plant-based polyphenol-rich supplement, in hamsters with high-fat diet (HFD)-induced dyslipidemia. The molecular mechanisms of action were explored using human Caco2 enterocytes. Totum-070 supplementation reduced the total cholesterol (-41%), non-HDL cholesterol (-47%), and triglycerides (-46%) in a dose-dependent manner, compared with HFD. HFD-induced hepatic steatosis was also significantly decreased by Totum-070, an effect associated with the reduction in various lipid and inflammatory gene expression. Upon challenging with olive oil gavage, the post-prandial triglyceride levels were strongly reduced. The sterol excretion in the feces was increased in the HFD-Totum-070 groups compared with the HFD group and associated with reduction of intestinal cholesterol absorption. These effects were confirmed in the Caco2 cells, where incubation with Totum-070 inhibited cholesterol uptake and apolipoprotein B secretion. Furthermore, a microbiota composition analysis revealed a strong effect of Totum-070 on the alpha and beta diversity of bacterial species and a significant decrease in the Firmicutes to Bacteroidetes ratio. Altogether, our findings indicate that Totum-070 lowers hypercholesterolemia by reducing intestinal cholesterol absorption, suggesting that its use as dietary supplement may be explored as a new preventive strategy for cardiovascular diseases.

Oral Supplement Containing Hydroxytyrosol and Punicalagin Improves Dyslipidemia in an Adult Population without Co-Adjuvant Treatment: A Randomized, Double-Blind, Controlled and Crossover Trial

Hydroxytyrosol (HT) and punicalagin (PC) exert cardioprotective and antiatherosclerotic effects. This study evaluated the effect of an oral supplement containing HT and PC (SAx) on dyslipidemia in an adult population. A randomized, double-blind, controlled, crossover trial was conducted over a 20-week period. SAx significantly reduced the plasma levels of triglycerides (TG) in subjects with hypertriglyceridemia (≥150 mg/dL) (from 200.67 ± 51.38 to 155.33 ± 42.44 mg/dL; p < 0.05), while no such effects were observed in these subjects after the placebo. SAx also significantly decreased the plasma levels of low-density lipoprotein cholesterol (LDL-C) in subjects with high plasma levels of LDL-C (≥160 mg/dL) (from 179.13 ± 16.18 to 162.93 ± 27.05 mg/dL; p < 0.01), while no such positive effect was observed with the placebo. In addition, the placebo significantly reduced the plasma levels of high-density lipoprotein cholesterol (HDL-C) in the total population (from 64.49 ± 12.65 to 62.55 ± 11.57 mg/dL; p < 0.05), while SAx significantly increased the plasma levels of HDL-C in subjects with low plasma levels of HDL-C (<50 mg/dL) (from 44.25 ± 3.99 to 48.00 ± 7.27 mg/dL; p < 0.05). In conclusion, the supplement containing HT and PC exerted antiatherosclerotic and cardio-protective effects by considerably improving dyslipidemia in an adult population, without co-adjuvant treatment or adverse effects.

An Olive-Derived Extract 20% Rich in Hydroxytyrosol Prevents β-Amyloid Aggregation and Oxidative Stress, Two Features of Alzheimer Disease, via SKN-1/NRF2 and HSP-16.2 in Caenorhabditis elegans

Olive milling produces olive oil and different by-products, all of them very rich in different bioactive compounds like the phenolic alcohol hydroxytyrosol. The aim of the present study was to investigate the effects of an olive fruit extract 20% rich in hydroxytyrosol on the molecular mechanisms associated with Alzheimer disease features like Aβ- and tau- induced toxicity, as well as on oxidative stress in Caenorhabditis elegans. Moreover, characterization of the extracts, regarding the profile and content of phenolics, as well as total antioxidant ability, was investigated. The study of lethality, growth, pharyngeal pumping, and longevity in vivo demonstrated the lack of toxicity of the extract. One hundred μg/mL of extract treatment revealed prevention of oxidative stress and a delay in Aβ-induced paralysis related with a lower presence of Aβ aggregates. Indeed, the extract showed the ability to avoid a certain degree of proteotoxicity associated with aggregation of the tau protein. According to RNAi tests, SKN-1/NRF2 transcription factor and the overexpression of HSP-16.2 were mechanistically associated in the observed effects.

Strategies to gain novel Alzheimer's disease diagnostics and therapeutics using modulators of ABCA transporters

Adenosine-triphosphate-(ATP)-binding cassette (ABC) transport proteins are ubiquitously present membrane-bound efflux pumps that distribute endo- and xenobiotics across intra- and intercellular barriers. Discovered over 40 years ago, ABC transporters have been identified as key players in various human diseases, such as multidrug-resistant cancer and atherosclerosis, but also neurodegenerative diseases, such as Alzheimer's disease (AD). Most prominent and well-studied are ABCB1, ABCC1, and ABCG2, not only due to their contribution to the multidrug resistance (MDR) phenotype in cancer, but also due to their contribution to AD. However, our understanding of other ABC transporters is limited, and most of the 49 human ABC transporters have been largely neglected as potential targets for novel small-molecule drugs. This is especially true for the ABCA subfamily, which contains several members known to play a role in AD initiation and progression. This review provides up-to-date information on the proposed functional background and pathological role of ABCA transporters in AD. We also provide an overview of small-molecules shown to interact with ABCA transporters as well as potential in silico, in vitro, and in vivo methodologies to gain novel templates for the development of innovative ABC transporter-targeting diagnostics and therapeutics.