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Table olives and olive oils are the main dietary sources of hydroxytyrosol (HT), a natural antioxidant compound that has emerged as a potential aid in protection against cardiovascular risk. Bioavailability studies with olive oils showed that HT is bioavailable from its free form and from conjugated forms such as oleuropein and its aglycone. Still, its low dietary intake, poor bioavailability, and high inter-individual variability after absorption through the gastrointestinal tract hamper its full benefits. In a randomized, controlled, blinded, cross-over study, we investigated the impact of HT metabolism and bioavailability by comparing two olive-derived watery supplements containing different doses of HT (30.58 and 61.48 mg of HT/dosage). Additionally, HT-fortified olive oil was used in the control group. To this aim, plasma and urine samples were evaluated in 12 healthy volunteers following the intake of a single dose of the supplements or fortified olive oil. Blood and urine samples were collected at baseline and at 0.5, 1, 1.5, 2, 4, and 12 h after intake. HT and its metabolites were analyzed using UHPLC-DAD-MS/MS. Pharmacokinetic results showed that dietary HT administered through the food supplements is bioavailable and bioavailability increases with the administered dose. After intake, homovanillic acid, HT-3-O-sulphate, and 3,4-dihydroxyphenylacetic acid are the main metabolites found both in plasma and urine. The maximum concentrations in plasma peaked 30 min after intake. As bioavailability of a compound is a fundamental prerequisite for its effect, these results promise a good potential of both food supplements for protection against oxidative stress and the consequent cardiovascular risk.

Hydroxytyrosol (HT) is a potent polyphenolic antioxidant widely utilized in the biomedical and food industries. However, its high-level microbial biosynthesis is primarily hindered by the metabolic flux imbalances and severe cellular toxicity. In this study, an artificial synthetic pathway from 4-hydroxyphenylpyruvate was constructed in an engineered l-phenylalanine producing E. coli chassis. Building on this, the endogenous precursor supply was strengthened via targeted promoter engineering of aroK, aroC, and tyrA, and the heterologous HT biosynthetic pathway was enhanced by overexpressing ARO10. To mitigate intermediate l-DOPA accumulation, co-expression of l-DOPA decarboxylase (DODC) and tyramine oxidase (TYO) reduced l-DOPA by 63.7%, while expression of l-amino acid deaminase (LAAD) reduced l-DOPA by 76.1%. Additionally, precise cofactor engineering was implemented; overexpressing the riboflavin metabolic genes ribH, ribC, and ribF, alongside introducing pntAB, increased HT production by 30.9% and 12.7%, respectively. Furthermore, transcriptomic analysis under HT stress revealed significant upregulation of genes related to transport and stress responses. Among these targets, overexpressing marR substantially improved cellular tolerance and HT production. Finally, during a 5-L bioreactor fermentation supplemented with Fe2+ and ascorbic acid, the engineered strain achieved an HT titer of 9.25 g/L, a yield of 0.102 g/g glucose, and a productivity of 0.193 g/L/h. This study reports the highest HT titer to date in E. coli using glucose as the carbon source, providing a robust biomanufacturing platform.

Several studies investigate the use of bioactive compounds, especially those derived from the olive leaf, highlighted by its richness in these components. The extraction of these compounds generally uses conventional techniques, but there is a search for more economical and sustainable alternatives. The olive leaf is recognized for its high antioxidant capacity; however, factors such as temperature, pH, light and oxygen can compromise the bioactive extracts. Microencapsulation appears as a solution, offering conservation and controlled release of compounds. This technique, notable for its easy handling, economic viability and ability to delay degradation, is fundamental to preserving the effectiveness of the extracts. The article aimed to review research on the extraction of bioactive compounds from olive leaves using innovative technologies, in addition to elucidating important aspects on the use of spray-drying microencapsulation technology for the protection and controlled release of these compounds. RESUMO: Vários estudos investigam a utilização de compostos bioativos, especialmente os derivados da folha da oliveira, destacados pela sua riqueza nestes componentes. A extração desses compostos geralmente utiliza técnicas convencionais, mas há uma busca por alternativas mais econômicas e sustentáveis. A folha de oliveira é reconhecida pela sua alta capacidade antioxidante, porém fatores como temperatura, pH, luz e oxigênio podem comprometer os extratos bioativos. A microencapsulação surge como solução, oferecendo conservação e liberação controlada de compostos. Esta técnica, que se destaca pela facilidade de manuseio, viabilidade econômica e capacidade de retardar a degradação, é fundamental para preservar a eficácia dos extratos. O artigo tem como objetivo revisar pesquisas sobre extração de compostos bioativos de folhas de oliveira utilizando tecnologias inovadoras, além de elucidar aspectos importantes sobre a utilização da tecnologia de microencapsulação por spray-drying para proteção e liberação controlada desses compostos.

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.

The Mediterranean diet, renowned for its health benefits, especially in reducing cardiovascular risks and protecting against diseases like diabetes and cancer, emphasizes virgin olive oil as a key contributor to these advantages. Despite being a minor fraction, the phenolic compounds in olive oil significantly contribute to its bioactive effects. This review examines the bioactive properties of hydroxytyrosol and related molecules, including naturally occurring compounds (-)-oleocanthal and (-)–oleacein, as well as semisynthetic derivatives like hydroxytyrosyl esters and alkyl ethers. (-)-Oleocanthal and (-)–oleacein show promising anti-tumor and anti-inflammatory properties, which are particularly underexplored in the case of (-)–oleacein. Additionally, hydroxytyrosyl esters exhibit similar effectiveness to hydroxytyrosol, while certain alkyl ethers surpass their precursor’s properties. Remarkably, the emerging research field of the effects of phenolic molecules related to virgin olive oil on cell autophagy presents significant opportunities for underscoring the anti-cancer and neuroprotective properties of these molecules. Furthermore, promising clinical data from studies on hydroxytyrosol, (-)–oleacein, and (-)–oleocanthal urge further investigation and support the initiation of clinical trials with semisynthetic hydroxytyrosol derivatives. This review provides valuable insights into the potential applications of olive oil-derived phenolics in preventing and managing diseases associated with cancer, angiogenesis, and atherosclerosis.

The increasing extension in life expectancy of human beings in developed countries is accompanied by a progressively greater rate of degenerative diseases associated with lifestyle and aging, most of which are still waiting for effective, not merely symptomatic, therapies. Accordingly, at present, the recommendations aimed at reducing the prevalence of these conditions in the population are limited to a safer lifestyle including physical/mental exercise, a reduced caloric intake, and a proper diet in a convivial environment. The claimed health benefits of the Mediterranean and Asian diets have been confirmed in many clinical trials and epidemiological surveys. These diets are characterized by several features, including low meat consumption, the intake of oils instead of fats as lipid sources, moderate amounts of red wine, and significant amounts of fresh fruit and vegetables. In particular, the latter have attracted popular and scientific attention for their content, though in reduced amounts, of a number of molecules increasingly investigated for their healthy properties. Among the latter, plant polyphenols have raised remarkable interest in the scientific community; in fact, several clinical trials have confirmed that many health benefits of the Mediterranean/Asian diets can be traced back to the presence of significant amounts of these molecules, even though, in some cases, contradictory results have been reported, which highlights the need for further investigation. In light of the results of these trials, recent research has sought to provide information on the biochemical, molecular, epigenetic, and cell biology modifications by plant polyphenols in cell, organismal, animal, and human models of cancer, metabolic, and neurodegenerative pathologies, notably Alzheimer’s and Parkinson disease. The findings reported in the last decade are starting to help to decipher the complex relations between plant polyphenols and cell homeostatic systems including metabolic and redox equilibrium, proteostasis, and the inflammatory response, establishing an increasingly solid molecular basis for the healthy effects of these molecules. Taken together, the data currently available, though still incomplete, are providing a rationale for the possible use of natural polyphenols, or their molecular scaffolds, as nutraceuticals to contrast aging and to combat many associated pathologies.

Oxidative stability of food is one of the most important parameters affecting integrity and consequently nutritional properties of dietary constituents. Antioxidants are widely used to avoid deterioration during transformation, packaging, and storage of food. In this paper, novel poly (vinyl alcohol) (PVA)-based films were prepared by solvent casting method adding an hydroxytyrosol-enriched extract (HTyrE) or an oleuropein-enriched extract (OleE) in different percentages (5, 10 and 20% w/w) and a combination of both at 5% w/w. Both extracts were obtained from olive oil wastes and by-products using a sustainable process based on membrane technologies. Qualitative and quantitative analysis of each sample carried out by high performance liquid chromatography (HPLC) and nuclear resonance magnetic spectroscopy (NMR) proved that the main components were hydroxytyrosol (HTyr) and oleuropein (Ole), respectively, two well-known antioxidant bioactive compounds found in Olea europaea L. All novel formulations were characterized investigating their morphological, optical and antioxidant properties. The promising performances suggest a potential use in active food packaging to preserve oxidative-sensitive food products. Moreover, this research represents a valuable example of reuse and valorization of agro-industrial wastes and by-products according to the circular economy model.

The antitumor activity of polyphenols derived from extra virgin olive oil and, in particular the biological activity of HTyr, has been studied extensively. However, the use of HTyr as a therapeutic agent for clinical applications is limited by its low bioavailability and rapid excretion in humans. To overcome these limitations, several synthetic strategies have been optimized to prepare lipophenols and new compounds derived from HTyr to increase lipophilicity and bioavailability. One very promising ester is hydroxytyrosyl oleate (HTyr-OL) because the chemical structure of HTyr, which is responsible for several biological activities, is linked to the monounsaturated chain of oleic acid (OA), giving the compound high lipophilicity and thus bioavailability in the cellular environment. In this study, the in vitro cytotoxic, anti-proliferative, and apoptotic induction activities of HTyr-OL were evaluated against SH-SY5Y human neuroblastoma cells, and the effects were compared with those of HTyr and OA. The results showed that the biological activity of HTyr was maintained in HTyr-OL treatments at lower dosages. In addition, the shotgun proteomic approach was used to study HTyr-OL-treated and untreated neuroblastoma cells, revealing that the antioxidant, anti-proliferative and anti-inflammatory activities of HTyr-OL were observed in the unique proteins of the two groups of samples.

The main phenolics compounds in Olea europaea L . leaves are oleuropein, hydroxytyrosol, hydroxytyrosol hexoside, verbascoside and apingenin-7-glucoside, being oleuropein the most abundant. In the literature, there are different methods to determine some of these compounds, which imply an analytical preparation for their determination. In this line, the use of techniques based on infrared spectroscopy is presented as a promising alternative. Therefore, a near-infrared spectroscopy (NIR) calibration, validation and prediction to determine the main metabolites in olive leaves has been developed. To achieve this, olive leaves samples were analysed by HPLC–DAD to quantify the concentrations of the main phenolic metabolites. Subsequently, a predictive model was developed through NIR calibration, achieving a good R 2 value in all cases, being higher than 0.9 and close to 1 in all calibrations, as the same for R 2 cv in all validations, with an excellent value for oleuropein (R 2 cv  = 93%). The RPD values were close to 4 for oleuropein and verbascoside and higher than 4 for hydroxytyrosol hexoside and apingenin-7-glucoside, indicating that the model has good reliability. So, good predictive models have been developed to determine the content of the main phenolic compounds in Olea europaea L . leaves, not only for the most abundant, but also for others with important bioactive properties.

Beneficial effects of natural plant polyphenols on the human body have been evaluated in a number of scientific research projects. Bioactive polyphenols are natural compounds of various chemical structures. Their sources are mostly fruits, vegetables, nuts and seeds, roots, bark, leaves of different plants, herbs, whole grain products, processed foods (dark chocolate), as well as tea, coffee, and red wine. Polyphenols are believed to reduce morbidity and/or slow down the development of cardiovascular and neurodegenerative diseases as well as cancer. Biological activity of polyphenols is strongly related to their antioxidant properties. They tend to reduce the pool of reactive oxygen species as well as to neutralize potentially carcinogenic metabolites. A broad spectrum of health-promoting properties of plant polyphenols comprises antioxidant, anti-inflammatory, anti-allergic, anti-atherogenic, anti-thrombotic, and anti-mutagenic effects. Scientific studies present the ability of polyphenols to modulate the human immune system by affecting the proliferation of white blood cells, and also the production of cytokines or other factors that participate in the immunological defense. The aim of the review is to focus on polyphenols of olive oil in context of their biological activities.