Oleacein Intestinal Permeation and Metabolism in Rats Using an In Situ Perfusion Technique

From the gut to the brain: the long journey of phenolic compounds with neurocognitive effects

The human gut microbiota is a complex community of micro-organisms that play a crucial role in maintaining overall health. Recent research has shown that gut microbes also have a profound impact on brain function and cognition, leading to the concept of the gut-brain axis. One way in which the gut microbiota can influence the brain is through the bioconversion of polyphenols to other bioactive molecules. Phenolic compounds are a group of natural plant metabolites widely available in the human diet, which have anti-inflammatory and other positive effects on health. Recent studies have also suggested that some gut microbiota-derived phenolic metabolites may have neurocognitive effects, such as improving memory and cognitive function. The specific mechanisms involved are still being studied, but it is believed that phenolic metabolites may modulate neurotransmitter signaling, reduce inflammation, and enhance neural plasticity. Therefore, to exert a protective effect on neurocognition, dietary polyphenols or their metabolites must reach the brain, or act indirectly by producing an increase in bioactive molecules such as neurotransmitters. Once ingested, phenolic compounds are subjected to various processes (eg, metabolization by gut microbiota, absorption, distribution) before they cross the blood-brain barrier, perhaps the most challenging stage of their trajectory. Understanding the role of phenolic compounds in the gut-brain axis has important implications for the development of new therapeutic strategies for neurological and psychiatric disorders. By targeting the gut microbiota and its production of phenolic metabolites, it may be possible to improve brain function and prevent cognitive decline. In this article, the current state of knowledge on the endogenous generation of phenolic metabolites by the gut microbiota and how these compounds can reach the brain and exert neurocognitive effects was reviewed.

Studies on pharmacokinetic properties and intestinal absorption mechanism of sanguinarine chloride: in vivo and in situ

Sanguinarine (SAN) is an alkaloid with multiple biological activities, mainly extracted from Sanguinaria canadensis or Macleaya cordata. The low bioavailability of SAN limits its utilization. At present, the nature and mechanism of SAN intestinal absorption are still unclear. The pharmacokinetics, single-pass intestinal perfusion test (SPIP), and equilibrium solubility test of SAN in rats were studied. The absorption of SAN at 20, 40, and 80 mg/L in different intestinal segments was investigated, and verapamil hydrochloride (P-gp inhibitor), celecoxib (MPR2 inhibitor), and ko143 (BCRP inhibitor) were further used to determine the effect of efflux transporter proteins on SAN absorption. The equilibrium solubility of SAN in three buffer solutions (pH 1.2, 4.5 and 6.8) was investigated. The oral pharmacokinetic results in rats showed that SAN was rapidly absorbed (Tmax=0.5 h), widely distributed (Vz/F = 134 L/kg), rapidly metabolized (CL = 30 L/h/kg), and had bimodal phenomena. SPIP experiments showed that P-gp protein could significantly affect the effective permeability coefficient (Peff) and apparent absorption rate constant (Ka) of SAN. Equilibrium solubility test results show that SAN has the best solubility at pH 4.5. In conclusion, SAN is a substrate of P-gp, and its transport modes include efflux protein transport, passive transport and active transport.

Comparative Analysis on Polyphenolic Composition of Different Olive Mill Wastewater and Related Extra Virgin Olive Oil Extracts and Evaluation of Nutraceutical Properties by Cell-Based Studies

This study reports a comparative analysis of the polyphenolic composition and nutraceutical properties of different olive mill wastewater (OMWW) and corresponding extra virgin olive oil (EVOO) extracts. Specifically, four OMWWs and corresponding EVOOs from cultivars Frantoio (A) and Leccino (B) obtained from different crushing seasons (early-stage (A1 and B1) and later-stage (A2 and B2)) were analyzed. Employing HPLC-DAD and LC-MS methods, the primary polyphenol content was identified and quantified. Overall, OMWW extracts showed a greater polyphenolic content compared to corresponding EVOO extracts, with OMWW B1 displaying the highest levels of polyphenols. The antiradical properties of extracts towards radical species (DPPH, ABTS, O2-, and HOCl-) were demonstrated in vitro, revealing a correlation with polyphenolic content. In fact, OMWW B1 and B2 demonstrated the strongest antiradical activity. Exploring nutraceutical properties of OMWWs, the intestinal permeation of the main polyphenols in a co-culture model (Caco-2 and HT29-MTX cell lines) was assessed, with tyrosol achieving a permeation of almost 60%. Furthermore, the involvement in the inflammation process has been evaluated in cell studies on THP1-derived macrophages by immunocytochemistry, demonstrating that OMWW B1 may exert an anti-inflammatory effect by modulating specific phenotype expression on macrophages. In conclusion, this study provides evidence supporting the reuse of OMWWs as a source of polyphenols with nutraceutical properties.

Pharmacokinetics and Metabolism Investigation of Oleocanthal

Oleocanthal is a secoiridoid found in olive oil, which lately gained great scientific interest due to its important pharmacological spectrum and biological properties. However, limited data exist on the metabolic fate of oleocanthal in vivo, a commonly underestimated aspect in natural products research. Especially, its pharmacokinetic (PK) characteristics have never been described so far. Thus, in the current study, a mouse-based protocol was designed, and oleocanthal was administered intraperitoneally in a standard dose of 5 mg/kg. In order to determine the PK parameters of oleocanthal or its metabolites, plasma samples were collected at 10 time points. Extraction and analysis protocols were developed and applied for the recovery and detection of oleocanthal in plasma, as well as the identification of its metabolites, using LC-HRMS/MS. Oleocanthal was not detected, proving the short lifetime of the compound in vivo, and 13 metabolites were identified. Among them, oleocanthalic acid and tyrosol sulfate were proposed as oleocanthal's biomarkers, in vivo. This is the first report associating oleocanthalic acid with oleocanthal administration in vivo, while its PK parameters, Tmax (T0) and Cmax (926 μg/mL), were also determined. The current study enlightens bioavailability and metabolism aspects of oleocanthal and suggests the association of specific metabolites with the biological effects attributed to oleocanthal administration. More studies are needed to give better insights into the metabolism and the mechanism of action of secoiridoids as well as to respond to identification challenges related to secoiridoid in vivo setups.

Oleacein: A comprehensive review of its extraction, purification, absorption, metabolism, and health effects

Extra virgin olive oil (EVOO) consumption reduces the risk of cardiovascular disease in high-risk groups and the polyphenols in EVOO play an important health effect on it. As one of the most abundant polyphenols in EVOO, oleacein (OLEA) has many health benefits. However, there is no review article that focus comprehensively on OLEA, and most articles have limited data and information on OLEA. The purpose of this review is to summarize the results of all available studies, to present and compare the main traditional and novel techniques for the extraction and isolation and purification of OLEA, to elucidate the absorption and metabolic pathways of OLEA, and finally, to illustrate the health-promoting properties. Hopefully, this review can promote the use of OLEA in functional foods and therapeutic fields.

Insights into the Antioxidant/Antiradical Effects and In Vitro Intestinal Permeation of Oleocanthal and Its Metabolites Tyrosol and Oleocanthalic Acid

(1) Background: In recent years, numerous studies have highlighted the beneficial effects of extra virgin olive oil (EVOO) as an active ingredient against chronic diseases. The properties of EVOO are due to its peculiar composition, mainly to its rich content of polyphenols. In fact, polyphenols may contribute to counteract oxidative stress, which often accompanies chronic diseases. In this work, the antioxidant effects of high-value polyphenol oleocanthal (OC) and its main metabolites, tyrosol (Tyr) and oleocanthalic acid (OA), respectively, have been investigated along with their impact on cell viability. (2) Methods: OC, Tyr, and OA have been evaluated regarding antiradical properties in term of scavenging capacity towards biologically relevant reactive species, including O2●-, HOCl, and ROO●, as well as their antioxidant/antiradical capacity (FRAP, DPPH●, ABTS●+). Moreover, the ability to permeate the intestinal membrane was assessed by an intestinal co-culture model composed by Caco-2 and HT29-MTX cell lines. (3) Results: The capacity of OC and Tyr as radical oxygen species (ROS) scavengers, particularly regarding HOCl and O2●-, was clearly demonstrated. Furthermore, the ability to permeate the intestinal co-culture model was plainly proved by the good permeations (>50%) achieved by all compounds. (4) Conclusions: OC, OA, and Tyr revealed promising properties against oxidative diseases.

Treatment with the Olive Secoiridoid Oleacein Protects against the Intestinal Alterations Associated with EAE

Multiple sclerosis (MS) is a CNS inflammatory demyelinating disease. Recent investigations highlight the gut-brain axis as a communication network with crucial implications in neurological diseases. Thus, disrupted intestinal integrity allows the translocation of luminal molecules into systemic circulation, promoting systemic/brain immune-inflammatory responses. In both, MS and its preclinical model, the experimental autoimmune encephalomyelitis (EAE) gastrointestinal symptoms including "leaky gut" have been reported. Oleacein (OLE), a phenolic compound from extra virgin olive oil or olive leaves, harbors a wide range of therapeutic properties. Previously, we showed OLE effectiveness preventing motor defects and inflammatory damage of CNS tissues on EAE mice. The current studies examine its potential protective effects on intestinal barrier dysfunction using MOG_35-55-induced EAE in C57BL/6 mice. OLE decreased EAE-induced inflammation and oxidative stress in the intestine, preventing tissue injury and permeability alterations. OLE protected from EAE-induced superoxide anion and accumulation of protein and lipid oxidation products in colon, also enhancing its antioxidant capacity. These effects were accompanied by reduced colonic IL-1β and TNFα levels in OLE-treated EAE mice, whereas the immunoregulatory cytokines IL-25 and IL-33 remained unchanged. Moreover, OLE protected the mucin-containing goblet cells in colon and the serum levels of iFABP and sCD14, markers that reflect loss of intestinal epithelial barrier integrity and low-grade systemic inflammation, were significantly reduced. These effects on intestinal permeability did not draw significant differences on the abundance and diversity of gut microbiota. However, OLE induced an EAE-independent raise in the abundance of Akkermansiaceae family. Consistently, using Caco-2 cells as an in vitro model, we confirmed that OLE protected against intestinal barrier dysfunction induced by harmful mediators present in both EAE and MS. This study proves that the protective effect of OLE in EAE also involves normalizing the gut alterations associated to the disease.

Nano-encapsulation of halofuginone hydrobromide enhances anticoccidial activity against Eimeria tenella in chickens

Coccidiosis is a worldwide epidemic intestinal disease with high incidence, which causes huge economic losses. Halofuginone hydrobromide (HF) is widely applied as an effective anticoccidial drug in the poultry industry. However, its therapeutic efficacy is severely restrained due to toxic effects, poor aqueous solubility and low permeability. Nanotechnology can improve the biological effect of drugs, and thus, reduce administered doses and toxic effects. The objective of this study was to investigate the therapeutic and preventive potential of novel HF-loaded D-α-tocopherol polyethylene glycol 1000 succinate (TPGS) polymer micelles (HTPM) for preventing coccidiosis in chickens. The HTPM were approximately spherical with a hydrodynamic diameter of 12.65 ± 0.089 nm, a zeta potential of 8.03 ± 0.242 mV, a drug loading of 14.04 ± 0.12%, and an encapsulation efficiency of 71.1 ± 4.15%. HF was encapsulated in the polymer micelles through interactions with TPGS, as characterized by X-ray diffraction (XRD) and Fourier transform infrared (FT-IR) spectroscopy. Cellular take up assays showed that TPGS polymer micelles could enhance drug internalization to alleviate intestinal apoptosis induced by coccidiosis and promote the necrosis of second-generation merozoites of E. tenella. Notably, clinical trials proved that 1.5 mg L^-1 HTPM had a stronger anticoccidial effect on E. tenella than that of 3 mg kg^-1 HF premix. Amplicon sequencing identified that HTPM could alleviate coccidiosis by restoring the structure of the gut microbiome. These findings indicated that the anticoccidial efficacy of HF was significantly enhanced after being encapsulated in polymer micelles, and further demonstrated the potential protective application of nano-encapsulating anticoccidial drugs as a promising approach to control coccidiosis in poultry. In summary, HTPM hold huge potential as an effective therapeutic agent for coccidiosis.

Anti-Inflammatory Activity of Olive Oil Polyphenols-The Role of Oleacein and Its Metabolites

The anti-inflammatory potential of oleacein, the main polyphenolic compound found in olive oil, and its main metabolites were characterized by their effects on RAW 264.7 macrophages challenged with lipopolysaccharide (LPS), and by their ability to inhibit enzymes of the arachidonic acid metabolism with a key role in the synthesis of pro-inflammatory lipid mediators. Oleacein at 12.5 µM significantly decreased the amount of L-citrulline and ^●NO generated by LPS-stimulated macrophages. Hydroxytyrosol, hydroxytyrosol acetate and hydroxytyrosol acetate sulfate were also able to reduce the cellular amount of ^●NO, although to a lesser extent. In contrast, hydroxytyrosol glucuronide and sulfate did not show detectable effects. Oleacein was also able to inhibit the coupled PLA₂ + 5-LOX enzyme system (IC₅₀ = 16.11 µM), as well as the 5-LOX enzyme (IC₅₀ = 45.02 µM). Although with lower activity, both hydroxytyrosol and hydroxytyrosol acetate were also capable of inhibiting these enzymes at a concentration of 100 µM. None of the other tested metabolites showed a capacity to inhibit these enzymes. In contrast, all compounds, including glucuronides and sulfate metabolites, showed a remarkable capacity to inhibit both cyclooxygenase isoforms, COX-1 and COX-2, with IC₅₀ values lower than 3 µM. Therefore, oleacein and its metabolites have the ability to modulate ^●NO- and arachidonic acid-dependent inflammatory cascades, contributing to the anti-inflammatory activity associated with olive oil polyphenols.

Synergistic effects of trans-p-coumaric acid isolated from the ethanol extract of Gynura procumbens in promoting intestinal absorption of chlorogenic acid and reversing alcoholic fatty liver disease

ETHNOPHARMACOLOGICAL RELEVANCE

Our previous studies found that the ethanol extract of Gynura procumbens (EEGS) reduced hepatic steatosis in alcoholic fatty liver disease (AFLD).

AIM OF THE STUDY

To explore the active ingredients from EEGS and their relevant mechanism of action in alleviating alcoholic liver injuries.

AIM OF THE STUDY

To explore the active ingredients from EEGS and their intestinal absorption characteristics as an approach for understanding mechanism of action in alleviating alcoholic liver injuries.

MATERIALS AND METHODS

Monitored by high-performance liquid chromatography (HPLC) and thin-layer chromatography (TLC), chemical constituents from the prepared EEGS were isolated by means of solvent extraction, repeated column chromatography, preparative HPLC and other methods, and their structures were identified based on spectroscopic methods. The in vivo intestinal absorption rate of chlorogenic acid (CA), the active component of the EEGS, both in a single form and in the EEGS were monitored by the single-pass intestinal perfusion (SPIP) method in rats. The protective effect of EEGS and its active components on alcoholic liver injuries was evaluated in the alcoholic liver injury model of C57BL/6J male mice induced by Lieber-DeCarli alcohol liquid feed.

RESULTS

Three noncaffeoyl quinic acid components were isolated and identified from the EEGS, namely, 3-trans-p-coumaroyl quinic acid (0.9%), 3-cis-p-coumaroyl quinic acid (2.7%), and trans-p-coumaric acid (0.6%). In vivo intestinal absorption of CA decreased with the increase of pH value of perfusion solution in the range of 5.5-7.8. The maximum absorption percentage of CA alone was 6.7 ± 2.4%, while the maximum absorption percentage of CA in the EEGS was 16.0 ± 2.2%, which was 2.4 times higher than that of CA alone. The results of animal experiments showed that the degree of fatty liver of mice treated with EEGS was significantly lower than that of the CA, trans-p-coumaric acid, and the combination group of CA and trans-p-coumaric acid alone.

CONCLUSION

The above results indicated that trans-p-coumaric acid isolated from the dried stems of Gynura procumbens assisted CA being absorbed into the body and worked together with CA to improve the function of liver lipid metabolism, reduce hepatic lipid accumulation in a mouse model of AFLD and effectively counteract alcohol-induced fatty liver disease.

Metabolism and Bioavailability of Olive Bioactive Constituents Based on In Vitro, In Vivo and Human Studies

Consumption of olive products has been established as a health-promoting dietary pattern due to their high content in compounds with eminent pharmacological properties and well-described bioactivities. However, their metabolism has not yet been fully described. The present critical review aimed to gather all scientific data of the past two decades regarding the absorption and metabolism of the foremost olive compounds, specifically of the phenylalcohols hydroxytyrosol (HTyr) and tyrosol (Tyr) and the secoiridoids oleacein (Olea), oleocanthal (Oleo) and oleuropein (Oleu). A meticulous record of the in vitro assays and in vivo (animals and humans) studies of the characteristic olive compounds was cited, and a critical discussion on their bioavailability and metabolism was performed taking into account data from their gut microbial metabolism. The existing critical review summarizes the existing knowledge regarding the bioavailability and metabolism of olive-characteristic phenylalchohols and secoiridoids and spotlights the lack of data for specific chemical groups and compounds. Critical observations and conclusions were derived from correlating structure with bioavailability data, while results from in vitro, animal and human studies were compared and discussed, giving significant insight to the future design of research approaches for the total bioavailability and metabolism exploration thereof.

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.

Recent Analytical Approaches for the Study of Bioavailability and Metabolism of Bioactive Phenolic Compounds

The study of the bioavailability of bioactive compounds is a fundamental step for the development of applications based on them, such as nutraceuticals, functional foods or cosmeceuticals. It is well-known that these compounds can undergo metabolic reactions before reaching therapeutic targets, which may also affect their bioactivity and possible applications. All recent studies that have focused on bioavailability and metabolism of phenolic and terpenoid compounds have been developed because of the advances in analytical chemistry and metabolomics approaches. The purpose of this review is to show the role of analytical chemistry and metabolomics in this field of knowledge. In this context, the different steps of the analytical chemistry workflow (design study, sample treatment, analytical techniques and data processing) applied in bioavailability and metabolism in vivo studies are detailed, as well as the most relevant results obtained from them.

LC-ESI-LTQ-Orbitrap-MS for Profiling the Distribution of Oleacein and Its Metabolites in Rat Tissues

The purpose of this work was to study the distribution of oleacein (OLEA) and its metabolites in rat plasma and different tissues, namely brain, heart, kidney, liver, lung, small intestine, spleen, stomach, skin, and thyroid, following the acute intake of a refined olive oil containing 0.3 mg/mL of OLEA. For this purpose, a distribution kinetics study was carried out. The plasma and tissues were collected at 1, 2, and 4.5 h after the intervention, and analyzed by LC-ESI-LTQ-Orbitrap-MS. Unmetabolized OLEA was detected in the stomach, small intestine, liver, plasma and, most notably, the heart. This finding may be useful for the development of new applications of OLEA for cardiovascular disease prevention. Noteworthy are also the high levels of hydroxytyrosol (OH-TY) and OLEA + CH₃ found in the small intestine, liver, and plasma, and the detection of nine OLEA metabolites, five of them arising from conjugation reactions. Liver, heart, spleen, and lungs were the target tissues where the metabolites were most distributed. However, it is important to note that OH-TY, in our experimental conditions, was not detected in any target tissue (heart, spleen, thyroids, lungs, brain, and skin). These results shed further light on the metabolism and tissue distribution of OLEA and contribute to understanding the mechanisms underlying its effect in human health.

Metabolomics Technologies for the Identification and Quantification of Dietary Phenolic Compound Metabolites: An Overview

In the search for natural products with properties that may protect against or slow down chronic and degenerative diseases (e.g., cancer, and cardiovascular and neurodegenerative conditions), phenolic compounds (PC) with benefits for human health have been identified. The biological effects of PC in vivo depend on their bioavailability, intestinal absorption, metabolism, and interaction with target tissues. The identification of phenolic compounds metabolites (PCM), in biological samples, after food ingestion rich in PC is a first step to understand the overall effect on human health. However, their wide range of physicochemical properties, levels of abundance, and lack of reference standards, renders its identification and quantification a challenging task for existing analytical platforms. The most frequent approaches to metabolomics analysis combine mass spectrometry and NMR, parallel technologies that provide an overview of the metabolome and high-power compound elucidation. In this scenario, the aim of this review is to summarize the pre-analytical separation processes for plasma and urine samples and the technologies applied in quantitative and qualitative analysis of PCM. Additionally, a comparison of targeted and non-targeted approaches is presented, not available in previous reviews, which may be useful for future metabolomics studies of PCM.