Effects of Olive and Pomegranate By-Products on Human Microbiota: A Study Using the SHIME® in Vitro Simulator

Virgin Olive Oil By-Products: Biological Activity of Phenolic Extract of Pâté on AGS Gastric Cells

Pâté is a by-product of olive oil production which represents an abundant source of phenolic compounds and can be used for food formulation, reducing its environmental impact and promoting a circular economy. In this context, the effects of a hydroalcoholic extract of pâté were evaluated for the first time in an AGS human cell line commonly used as model of gastric mucosa. Pâté was obtained from Tuscan olives; the total phenolic content was 16.6 mg/g dried extract, with verbascoside and secoiridoid derivatives as the most abundant phenols. The phenolic pâté extract did not alter viability, distribution of cell cycle phases or proliferation and migration of AGS cells at the tested concentrations. Seven enzymes were chosen to investigate the metabolic effect of the pâté extract in the context of oxidative stress. Pâté produced a statistically significant increase in the activity of key enzymes of some metabolic pathways: Lactate dehydrogenase, Enolase, Pyruvate kinase, Glucose 6-phosphate dehydrogenase, Citrate synthase, 3-Hydroxyacyl-CoA dehydrogenase and Hexokinase. Pre-treatments with the extract of pâté at 100 µg/mL or 200 µg/mL, as observed through PCA analysis, appeared able to counteract the enzymatic activity alterations due to oxidative stress induced by H₂O₂ 1 mM and 2 mM. The results indicate that dried pâté, due to its phenolic components, can be proposed as a new functional food ingredient.

In vivo evidences of the health-promoting properties of bioactive compounds obtained from olive by-products and their use as food ingredient

Olea europaea L. is the source of virgin olive oil (VOO). During its extraction, a high amount of by-products (pomace, mill wastewaters, leaves, stones, and seeds) is originated, which possess an environmental problem. If the generation of waste cannot be prevented, its economic value must be recovered and its effects on the environment and climate change must be avoided or minimized. The bioactive compounds (e.g., phenols, pectins, peptides) of these by-product fractions are being investigated as nutraceutical due to the beneficial properties it might have. In this review, the aim is to summarize the in vivo studies carried out in animals and humans with bioactive compounds exclusively obtained from olive by-products, aiming to demonstrate the potential health benefits these products can exert, as well as to describe its use in the food industry as bioactive ingredient. Several food matrices have been fortified with olive by-products fractions, leading to an improvement of properties. Animal and human studies suggest the benefits of ingesting olive-derived products to promote health. However, the investigation until now is scarce and consequently, well-designed human studies are required in order to fully address and confirm the safety and health-promoting properties of olive oil by-products.

Evaluation of Different Advanced Approaches to Simulation of Dynamic In Vitro Digestion of Polyphenols from Different Food Matrices-A Systematic Review

Phenolic compounds have become interesting bioactive antioxidant compounds with implications for obesity, cancer and inflammatory gastrointestinal pathologies. As the influence of digestion and gut microbiota on antioxidant behavior is yet to be completely elucidated, and due to limitations associated to in vivo studies, dynamic in vitro gastrointestinal models have been promoted. A systematic review was conducted of different databases (PubMed, Web of Science and Scopus) following PRISMA guidelines to assess different dynamic digestion models and assay protocols used for phenolic compound research regarding bioaccesibility and interaction with colonic microbiota. Of 284 records identified, those including dynamic multicompartmental digestion models for the study of phenolic compound bioaccesibility, bioactivity and the effects of microbiota were included, with 57 studies meeting the inclusion criteria. Different conditions and experimental configurations as well as administered doses, sample treatments and microbiological assays of dynamic digestion studies on polyphenols were recorded and compared to establish their relevance for the dynamic in vitro digestion of phenolic compounds. While similarities were observed in certain experimental areas, a high variability was found in others, such as administered doses. A description of considerations on the study of the digestion of phenolic compounds is proposed to enhance comparability in research.

Biochemistry of Antioxidants: Mechanisms and Pharmaceutical Applications

Natural antioxidants from fruits and vegetables, meats, eggs and fish protect cells from the damage caused by free radicals. They are widely used to reduce food loss and waste, minimizing lipid oxidation, as well as for their effects on health through pharmaceutical preparations. In fact, the use of natural antioxidants is among the main efforts made to relieve the pressure on natural resources and to move towards more sustainable food and pharmaceutical systems. Alternative food waste management approaches include the valorization of by-products as a source of phenolic compounds for functional food formulations. In this review, we will deal with the chemistry of antioxidants, including their molecular structures and reaction mechanisms. The biochemical aspects will also be reviewed, including the effects of acidity and temperature on their partitioning in binary and multiphasic systems. The poor bioavailability of antioxidants remains a huge constraint for clinical applications, and we will briefly describe some delivery systems that provide for enhanced pharmacological action of antioxidants via drug targeting and increased bioavailability. The pharmacological activity of antioxidants can be improved by designing nanotechnology-based formulations, and recent nanoformulations include nanoparticles, polymeric micelles, liposomes/proliposomes, phytosomes and solid lipid nanoparticles, all showing promising outcomes in improving the efficiency and bioavailability of antioxidants. Finally, an overview of the pharmacological effects, therapeutic properties and future choice of antioxidants will be incorporated.

A biochemical perspective on the fate of virgin olive oil phenolic compounds in vivo

The chemistry of the phenolic compounds found in virgin olive oil (VOO) is very complex due, not only to the different classes of polyphenols that can be found in it, but, above all, due to the existence of a very specific phenol class found only in oleaceae plants: the secoiridoids. Searching in the Scopus data base the keywords flavonoid, phenolic acid, lignin and secoiridoid, we can find a number of 148174, 79435, 11326 and 1392 research articles respectively, showing how little is devote to the latter class of compounds. Moreover, in contrast with other classes, that include only phenolic compounds, secoiridoids may include phenolic and non-phenolic compounds, being the articles concerning phenolic secoiridoids much less than the half of the abovementioned articles. Therefore, it is important to clarify the structures of these compounds and their chemistry, as this knowledge will help understand their bioactivity and metabolism studies, usually performed by researchers with a more health science's related background. In this review, all the structures found in many research articles concerning VOO phenolic compounds chemistry and metabolism was gathered, with a special attention devoted to the secoiridoids, the main phenolic compound class found in olives, VOO and olive leaf.

Potential of Establishing the Corresponding Human Microbial Community in Pseudo Germ-Free Mice through Fecal Microbe Transfer from Three Urolithin Metabotypes

Three urolithin metabotypes (UMs) have been defined in the population according to final urolithins converted by gut microbiota. Currently, it is difficult to establish the cause-and-effect relationship between urolithins and microbiota in human studies. Studies on the health effects of ellagic acid (EA) in animal models rarely consider the differences in the urolithin production. Therefore, the objective of this study is to establish human microbiota-associated (HMA) mice, imitating the microbiota composition of the three UMs. Antibiotic-induced pseudo germ-free mice were gavaged with fecal bacteria of the three UM donors for four weeks. The results showed that the ability to produce corresponding urolithins was successfully transferred from the donor of the three UMs to HMA mice. The three UM HMA mice adopted a humanized microbiota profile similar to their corresponding donor. The family Eggerthellaceae and genera Eggerthella and Gordonibacter were successfully transferred and colonized from UM-A/B donors to HMA mice. Overall, the three UM HMA mouse models were successfully established, which provide a basis for exploring the health effects of EA.

Health Effect of N-Nitroso Diethylamine in Treated Water on Gut Microbiota Using a Simulated Human Intestinal Microbiota System

Chlorination disinfection byproducts (CDBPs) can exert adverse human health effects. Many toxicology-based studies confirmed the health hazards of CDBPs, but little research has been done on gut microbiome. We explored the effect of CDBPs on intestinal microbiota in the Simulator of the Human Intestinal Microbial Ecosystem (SHIME). The results showed that CDBPs slightly inhibited the production of short-chain fatty acids, and the abundance of Actinobacteria decreased in the transverse colon and descending colon. The abundance of Proteobacteria increased in the ascending colon and descending colon, while it decreased in the transverse colon. The abundance of Firmicutes decreased in both the ascending colon and descending colon. In particular, the abundance of Lachnospiraceae members, Bilophila, Oscillospira, Parabacteroides, Desulfovibrio, and Roseburia increased in the ascending colon, while the abundance of Sutterella, Bacteroides, Escherichia, Phascolarctobacterium, Clostridium, Citrobacter, and Klebsiella increased in the descending colon. The Shannon index differed significantly in both the ascending colon and descending colon before and after exposure. Overall, we demonstrate the feasibility of applying the SHIME model to studying the effects of intestinal toxicity on health of chlorinated by-products. The findings of this study improve our understanding of the health impact of CDBPs on the intestinal microbiota and better control of CDBPs in treated water is recommended.

Gastrointestinal Distribution of Tyrosol Acyl Esters in Orally Infected Mice and Their Hydrolysis by Lactobacillus Species Isolated from the Feces of Mice

Phenolipids, which have been widely used as food antioxidants, are also a potential functional ingredient. However, their characteristics of gastrointestinal distribution and microbial hydrolysis remain unexplored. In this study, an in vivo mouse model and an in vitro anaerobic fermentation model were used to evaluate the above characteristics of tyrosol acyl esters (TYr-Es) with fatty acids (FAs) of C12:0, C18:0, and C18:2. HPLC-UV measurements indicated that oral TYr-Es were remarkably stable in the stomach environment of mice. However, TYr-Es were hydrolyzed to free TYr by lipase in the small intestine, which showed a sustained-release behavior. Specially, TYr was rapidly and almost completely absorbed in the small intestine. By contrast, detectable amounts of TYr-Es were found in the cecum and colon and could be further hydrolyzed to free TYr and FAs by Lactobacillus. These TYr and FAs can participate in regulating the composition of the intestinal microorganisms, which may lead to some health benefits.

Distribution of tyrosol fatty acid esters in the gastrointestinal tract of mice and their hydrolysis characteristic by the gut microbiota

Phenolic lipids have been approved as safe and effective antioxidants, are also a potential ingredient for functional foods. However, the characteristics of gastrointestinal distribution and microbial hydrolysis in the gastrointestinal...

Absorption, Distribution, Metabolism, and Excretion of the Main Olive Tree Phenols and Polyphenols: A Literature Review

The effects of olive tree (poly)phenols (OPs) are largely dependent upon their bioavailability and metabolization by humans. Absorption, distribution, metabolism, and excretion (ADME) are fundamental for the nutritional efficacy and toxicological impact of foods containing OPs. This review includes studies on the administration of hydroxytyrosol (HT), oleuropein (Ole), or other OPs and foods, products, or mixtures that contain them. Briefly, data from in vivo studies indicate that OPs are absorbable by intestinal cells. Both absorption and bioavailability depend upon each compound and/or the matrix in which it is contained. OPs metabolism begins in enterocytes and can also continue in the liver. Metabolic phase I mainly consists of the hydrolysis of Ole, which results in an increase in the HT content. Phase II metabolic reactions involve the conjugation of (poly)phenols mainly with glucuronide and sulfate groups. This review offers a complete perspective of the ADME processes of OPs, which could support the future nutritional and/or toxicological studies in this area.

Intestinal fermentation in vitro models to study food-induced gut microbiota shift: an updated review

In vitro gut fermentation models were firstly introduced in nutrition and applied microbiology research back in the 1990s. These models have improved greatly during time, mainly over the resemblance to the complexity of digestion stages, the replication of experimental conditions, the multitude of ecological parameters to assay. The state of the science is that the most competitive models shall include a complex gut microbiota, small working volumes, distinct interconnected compartments and rigorous bio-chemical and ecological settings, controlled by a computer, as well as a free-hands accessibility, not to contaminate the mock microbiota. These models are a useful tool to study the impact of a given diet compound, e.g. prebiotics, on the human gut microbiota. The principal application is to focus on the shift of the core microbial groups and selected species together with their metabolites, assaying their diversity, richness and abundance in the community over time. Besides, it is possible to study how a compound is digested, which metabolic pathways are triggered, and the type and quantity of microbial metabolites produced. Further prospective should focus on challenges with pathogens as well as on ecology of gut syndromes. In this minireview an updated presentation of the most used intestinal models is presented, basing on their concept, technical features, as well as on research applications.

Olive Fruit Extracts Supplement Improve Antioxidant Capacity via Altering Colonic Microbiota Composition in Mice

Oxidative stress, one of the most common biological dysfunctions, is usually associated with pathological conditions and multiple diseases in humans and animals. Chinese olive fruit (Canarium album L.) extracts (OE) are natural plant extracts rich in polyphenols (such as hydroxytyrosol, HT) and with antioxidant, anti-hyperlipidemia, and anti-inflammatory potentials. This study was conducted to investigate the antioxidant capacity of OE supplementation and its related molecular mechanism in mice. Mice (25.46 ± 1.65 g) were treated with 100 mg/kg body weight (BW) OE or saline solution for 4 weeks, and then the antioxidant and anti-inflammatory capacities of mice were examined. The results showed that OE supplement significantly increased the serum antioxidative enzyme activities of total antioxidant activity (T-AOC), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and catalase and decreased the serum malondialdehyde (MDA) level, indicating that OE treatment enhanced the antioxidant capacity in mice. qPCR results showed that the transcriptional expression of antioxidant SOD1, CAT, Gpx1, and Gpx2 were significantly down-regulated in the small intestine (jejunum and ileum) after OE administration. Meanwhile, OE treatment significantly decreased the T-AOC and increased the MDA level in the small intestine. Furthermore, OE administration dramatically reduced the mRNA expression of pro-inflammatory cytokines (TNF-α and IL-1β), which confirmed its antioxidant and anti-inflammatory capacities with OE administration. Using amplicon sequencing technology, 16S rRNA sequencing results showed that OE supplement significantly increased the colonic Firmicutes/Bacteroidetes ratio, which also had a negative correlation with the serum MDA level and positively correlated with serum GSH-Px activity through Pearson correlation analysis. Besides that, Alloprevotella was negatively correlated with serum T-AOC. Colidextribacter was positively correlated with serum MDA and negatively correlated with serum T-AOC, SOD, and GSH-Px levels. In summary, this study showed that treatment with 100 mg/kg BW polyphenol-rich OE could alter colonic microbiota community, which was strongly associated with improved antioxidant capacity in mice.

Extra virgin olive oil and related by-products (Olea europaea L.) as natural sources of phenolic compounds for abdominal pain relief in gastrointestinal disorders in rats

Management of abdominal pain, a common symptom of IBDs and IBS, is still a clinical problem. Extra virgin olive oil (EVOO), a main component of the Mediterranean diet, shows positive effects on chronic inflammation in IBDs. In this study, the effect of the oral administration of EVOO (3 mL) and two olive milling by-products, DPA (300 mg kg^-1) and DRF (300 mg kg^-1), on preventing the development of abdominal pain in a DNBS-induced colitis model in rats was evaluated. The doses were chosen with the aim of simulating a plausible daily intake in humans. DPA and EVOO treatments significantly reduced the abdominal viscero-motor response to colon-rectal distension at 2 and 3 mL of balloon distension volume, both 7 and 14 days after the DNBS-injection. DRF showed efficacy in the reduction of visceral hypersensitivity only with 3 mL balloon inflation. In awake animals, DPA and DRF reduced pain perception (evaluated as abdominal withdrawal reflex) with all balloon distension volumes, while EVOO was effective only with higher distension volumes. Fourteen days after the DNBS-injection, all samples reduced the macroscopic intestinal damage (quantified as the macroscopic damage score) also showing, at the microscopic level, a reduction of the inflammatory infiltrate (quantified by hematoxylin and eosin analysis), fibrosis (highlighted by picrosirius red staining), the increase in mast cells and their degranulation (analyzed by triptase immunohistochemistry). This is the first report on the promotion of abdominal pain relief in a rat model obtained administering EVOO and two derived by-products. Our results suggest a protective role of phenol-rich EVOO and milling by-products, which may be proposed as food ingredients for novel functional foods.

The Role of Fruit by-Products as Bioactive Compounds for Intestinal Health

The fruit processing industry generates large amounts of wastes (pomace, seeds, peels) that causes negative environmental impact with considerable treatment expenses. Nevertheless, various studies demonstrated that these by-products are still rich in bioactive compounds, especially dietary fibres and phenolic compounds, thus leading to significant chemical, physical and biological properties. These characteristics make fruits by-products a good source for new supplements in food products having important effect on intestinal function. Thus, the aim of this review is to evaluate the different bioactive compounds isolated from fruit by-products and to analyse their application in various formulations for the food and nutraceutical industries. In consideration of the biological properties of these compounds, their role in the functioning and action on intestine and gut flora was discussed.