Hydroxytyrosol attenuates ethanol-induced liver injury by ameliorating steatosis, oxidative stress and hepatic inflammation by interfering STAT3/iNOS pathway

Objective: Hydroxytyrosol (HT) is a polyphenol with a wide range of biological activities. Excessive drinking can lead to oxidative stress and inflammation in the liver, which usually develop into alcohol liver disease (ALD). At present, there is no specific drug to treat ALD. In this paper, the protection effect of HT on ALD and the underline mechanism were studied.Methods: HepG2 cells were exposed to ethanol in vitro and C57BL/6J mice were fed with a Lieber-DeCarli ethanol liquid diet in vivo.Results: triglyceride (TG) level in serum and the expression of fatty acid synthase (FASN) were reduced significantly by the treatment with HT The acetaldehyde dehydrogenase (ALDH) activity was increased, the serum level of malondialdehyde (MDA) was decreased, catalase (CAT) and glutathione (GSH) were increased, suggesting that HT may reduce its oxidative damage to the body by promoting alcohol metabolism. Furthermore, according to the mRNA levels of tnf-α, il-6 and il-1β, HT inhibited ethanol-induced inflammation significantly. The anti-inflammatory mechanism of HT may be related to suppress the STAT3/iNOS pathway.Dissussion: Our study showed that HT could ameliorate ethanol-induced hepatic steatosis, oxidative stress and inflammation and provide a new candidate for the prevention and treatment of ALD.

Olive juice dry extract containing hydroxytyrosol, as a nontoxic and safe substance: Results from pre-clinical studies and review of toxicological studies

Products derived from olives, such as the raw fruit and oils, are widely consumed due to their taste, and purported nutritional/health benefits. Phenolic compounds, especially hydroxytyrosol (HT), have been proposed as one of the key substances involved in these effects. An olive juice extract, standardized to contain 20% HT ("OE20HT"), was produced to investigate its health benefits. The aim of this study was to demonstrate the genotoxic safety of this ingredient based on in vitro Ames assay and in vitro micronucleus assay. Results indicated that OE20HT was not mutagenic at concentrations of up to 5000 µg/plate, with or without metabolic activation, and was neither aneugenic nor clastogenic after 3-hour exposure at concentrations of up to 60 µg/mL with or without metabolic activation, or after 24-hour exposure at concentrations of up to 40 µg/mL. To further substantiate the safety of OE20HT following ingestion without conducting additional animal studies, a comprehensive literature review was conducted. No safety concerns were identified based on acute or sub-chronic studies in animals, including reproductive and developmental studies. These results were supported by clinical studies demonstrating the absence of adverse effects after oral supplementation with olive extracts or HT. Based on in vitro data and the literature review, the OE20HT extract is therefore considered as safe for human consumption at doses up to 2.5 mg/kg body weight/day.

Table olives and health: a review

Table olives, a product of olive tree (Olea europaea L.), is an important fermented product of the Mediterranean Diet. Agronomical factors, particularly the cultivar, the ripening stage and the processing method employed are the main factors influencing the nutritional and non-nutritional composition of table olives and their organoleptic properties. The important nutritional value of this product is due to its richness in monounsaturated fat (MUFA), mainly oleic acid, fibre and vitamin E together with the presence of several phytochemicals. Among these, hydroxytyrosol (HT) is the major phenolic compound present in all types of table olives. There is a scarcity of in vitro, in vivo and human studies of table olives. This review focused comprehensively on the nutrients and bioactive compound content as well as the health benefits assigned to table olives. The possible health benefits associated with their consumption are thought to be primarily related to effects of MUFA on cardiovascular health, the antioxidant (AO) capacity of vitamin E and its role in protecting the body from oxidative damage and the anti-inflammatory and AO activities of HT. The influence of multiple factors on composition of the end product and the potential innovation in the production of table olives through the reduction of its final salt content was also discussed.

Olive oil with high polyphenolic content induces both beneficial and harmful alterations on rat redox status depending on the tissue

Olive oil (OO) possesses a predominant role in the diet of Mediterranean countries. According to a health claim approved by the European Food Safety Authority, OO protects against oxidative stress‑induced lipid peroxidation in human blood, when it contains at least 5 mg of hydroxytyrosol and its derivatives per 20 g. However, studies regarding the effects of a total OO biophenols on redox status in vivo are scarce and either observational and do not provide a holistic picture of their action in tissues. Following a series of in vitro screening tests an OO containing biophenols at 800 mg/kg of OO was administered for 14 days to male Wistar rats at a dose corresponding to 20 g OO/per day to humans. Our results showed that OO reinforced the antioxidant profile of blood, brain, muscle and small intestine, it induced oxidative stress in spleen, pancreas, liver and heart, whereas no distinct effects were observed in lung, colon and kidney. The seemingly negative effects of OO follow the recently formulated idea in toxicology, namely the real life exposure scenario. This study reports that OO, although considered a nutritional source rich in antioxidants, it exerts a tissues specific action when administered in vivo.