In Vitro Glucuronidation and Sulfation of ε-Viniferin, a Resveratrol Dimer, in Humans and Rats

Stilbenes, a Versatile Class of Natural Metabolites for Inflammation-An Overview

Stilbenes are polyphenolic allelochemicals synthesized by plants, especially grapes, peanuts, rhubarb, berries, etc., to defend themselves under stressful conditions. They are now exploited in medicine for their antioxidant, anti-proliferative and anti-inflammatory properties. Inflammation is the immune system's response to invading bacteria, toxic chemicals or even nutrient-deprived conditions. It is characterized by the release of cytokines which can wreak havoc on healthy tissues, worsening the disease condition. Stilbenes modulate NF-κB, MAPK and JAK/STAT pathways, and reduce the transcription of inflammatory factors which result in maintenance of homeostatic conditions. Resveratrol, the most studied stilbene, lowers the Michaelis constant of SIRT1, and occupies the substrate binding pocket. Gigantol interferes with the complement system. Besides these, oxyresveratrol, pterostilbene, polydatin, viniferins, etc., are front runners as drug candidates due to their diverse effects from different functional groups that affect bioavailability and molecular interactions. However, they each have different thresholds for toxicity to various cells of the human body, and thus a careful review of their properties must be conducted. In animal models of autoinflammatory diseases, the mode of application of stilbenes is important to their absorption and curative effects, as seen with topical and microemulsion gel methods. This review covers the diversity seen among stilbenes in the plant kingdom and their mechanism of action on the different inflammatory pathways. In detail, macrophages' contribution to inflamed conditions in the liver, the cardiac, connective and neural tissues, in the nephrons, intestine, lungs and in myriad other body cells is explored, along with detailed explanation on how stilbenes alleviate the symptoms specific to body site. A section on the bioavailability of stilbenes is included for understanding the limitations of the natural compounds as directly used drugs due to their rapid metabolism. Current delivery mechanisms include sulphonamides, or using specially designed synthetic drugs. It is hoped that further research may be fueled by this comprehensive work that makes a compelling argument for the exploitation of these compounds in medicine.

Beneficial Effects of ε-Viniferin on Obesity and Related Health Alterations

Viniferin is a phenolic compound belonging to the group of stilbenoids. In particular, ε-viniferin is a dimer of resveratrol, found in many plant genders, among which grapes (Vitis vinifera) are a primary source. Due to the fact that ε-viniferin is mainly present in the woody parts of plants, their use as a source of this bioactive compound is a very interesting issue in a circular economy. Both, in vitro studies carried out in pre-adipocytes and mature adipocytes and in vivo studies addressed in mice show that ε-viniferin is able to reduce fat accumulation. Moreover, it prevents the development of some obesity co-morbidities, such as type 2 diabetes, dyslipidemias, hypertension and fatty liver. ε-viniferin can be absorbed orally, but it shows a very low bioavailability. In this scenario, further research on animal models is needed to confirm the effects reported in a great number of studies; to determine which metabolites are involved, including the main one responsible for the biological effects observed and the mechanisms that justify these effects. In a further phase, human studies should be addressed in order to use ε-viniferin as a new tool for obesity management, as a nutraceutical or to be included in functional foods.

Oxyresveratrol and Gnetol Glucuronide Metabolites: Chemical Production, Structural Identification, Metabolism by Human and Rat Liver Fractions, and In Vitro Anti-inflammatory Properties

Stilbene metabolites are attracting great interest because many of them exhibit similar or even stronger biological effects than their parent compounds. Furthermore, the metabolized forms are predominant in biological fluids; therefore, their study is highly relevant. After hemisynthesis production, isolation, and structural elucidation, three glucuronide metabolites for oxyresveratrol (ORV) were formed: trans-ORV-4'-O-glucuronide, trans-ORV-3-O-glucuronide, and trans-ORV-2'-O-glucuronide. In addition, two glucuronide metabolites were obtained for gnetol (GN): trans-GN-2'-O-glucuronide and trans-GN-3-O-glucuronide. When the metabolism of ORV and GN is studied in vitro by human and rat hepatic enzymes, four of the five hemisynthesized compounds were identified and quantified. Human enzymes glucuronidated preferably at the C-2' position, whereas rat enzymes do so at the C-3 position. In view of these kinetic findings, rat enzymes have a stronger metabolic capacity than human enzymes. Finally, ORV, GN, and their glucuronide metabolites (mainly at the C-3 position) decreased nitric oxide, reactive oxygen species, interleukin 1β, and tumor necrosis factor α production in lipopolysaccharide-stimulated macrophages.

Chemistry, Biosynthesis and Pharmacology of Viniferin: Potential Resveratrol-Derived Molecules for New Drug Discovery, Development and Therapy

Viniferin is a resveratrol derivative. Resveratrol is the most prominent stilbenoid synthesized by plants as a defense mechanism in response to microbial attack, toxins, infections or UV radiation. Different forms of viniferin exist, including alpha-viniferin (α-viniferin), beta-viniferin (β-viniferin), delta-viniferin (δ-viniferin), epsilon-viniferin (ε-viniferin), gamma-viniferin (γ-viniferin), R-viniferin (vitisin A), and R2-viniferin (vitisin B). All of these forms exhibit a range of important biological activities and, therefore, have several possible applications in clinical research and future drug development. In this review, we present a comprehensive literature search on the chemistry and biosynthesis of and the diverse studies conducted on viniferin, especially with regards to its anti-inflammatory, antipsoriasis, antidiabetic, antiplasmodic, anticancer, anti-angiogenic, antioxidant, anti-melanogenic, neurodegenerative effects, antiviral, antimicrobial, antifungal, antidiarrhea, anti-obesity and anthelminthic activities. In addition to highlighting its important chemical and biological activities, coherent and environmentally acceptable methods for establishing vinferin on a large scale are highlighted to allow the development of further research that can help to exploit its properties and develop new phyto-pharmaceuticals. Overall, viniferin and its derivatives have the potential to be the most effective nutritional supplement and supplementary medication, especially as a therapeutic approach. More researchers will be aware of viniferin as a pharmaceutical drug as a consequence of this review, and they will be encouraged to investigate viniferin and its derivatives as pharmaceutical drugs to prevent future health catastrophes caused by a variety of serious illnesses.

Trans-ε-Viniferin Encapsulation in Multi-Lamellar Liposomes: Consequences on Pharmacokinetic Parameters, Biodistribution and Glucuronide Formation in Rats

Trans-ε-viniferin (εVin) is a resveratrol dimer exhibiting promising biological activities for human health. Its bioavailability being low, the development of encapsulation methods would be used to overcome this issue. The aim of this study was to measure the consequences of the encapsulation of εVin in multilamellar liposomes on its pharmacokinetic parameters, metabolism and tissue distribution in rats. After oral administration of εVin (20 mg/kg body weight), either as free or encapsulated forms, plasmas were sequentially collected (from 0 to 4 h) as well as liver, kidneys and adipose tissues (4 h after administration) and analyzed by LC-HRMS. The glucuronide metabolites (εVG) were also produced by hemisynthesis for their quantification in plasma and tissues. The encapsulation process did not significantly modify the pharmacokinetic parameters of εVin itself. However, a significant increase of the T1/2 was noticed for εVG after administration of the encapsulated form as compared to the free form. An accumulation of εVin and εVG in adipose tissues was noticed, and interestingly a significant increase of the latter in the mesenteric one after administration of the encapsulated form was highlighted. Since adipose tissues could represent storage depots, and encapsulation allows for prolonging the exposure time of glucuronide metabolites in the organism, this could be of interest to promote their potential biological activities.

ε-Viniferin, a promising natural oligostilbene, ameliorates hyperglycemia and hyperlipidemia by activating AMPK in vivo

ε-Viniferin (VNF), a naturally occurring oligostilbene (a resveratrol dimer), is mainly found in grapes and red wines. However, unlike resveratrol, the biological activity of VNF has not been widely studied. This study was conducted to investigate the beneficial effects of VNF on hyperglycemia and hyperlipidemia and further to reveal the underlying mechanism. The ameliorative effects of VNF in high-fat-diet and streptozotocin-induced type 2 diabetic rats were assessed physiologically, biochemically and histologically after oral administration of VNF (30 mg kg-1 and 60 mg kg-1) for 8 weeks. Western blotting and immunohistochemistry experiments were performed to determine the effects of VNF on the AMPK phosphorylation levels in the livers of diabetic rats. Molecular docking and molecular dynamics simulation were further performed to study the molecular-level interaction between VNF and AMPK. Meanwhile, the protective effects of VNF on the liver and kidney were also evaluated. The results showed that the VNF treatment caused a significant decrease in the concentrations of fasting blood glucose (FBG), total cholesterol (TC), triglyceride (TG), and low density lipoprotein-cholesterol (LDL-C), and improved the glucose tolerance of diabetic rats. In addition, the liver and kidney damage indices such as alanine aminotransferase (ALT), aspartate aminotransaminase (AST), creatinine (CR), and blood urea nitrogen (BUN) were also lowered and improved. Moreover, VNF could increase the AMPK activation and attenuate histopathological changes in the liver of diabetic rats. The molecular docking and molecular dynamics simulation results revealed for the first time that VNF bound to the hinge region between the α- and β-units of AMPK and interacted with the active site of AMPK. In conclusion, VNF can effectively improve hyperglycemia and hyperlipidemia and exhibit protective effects on the liver and kidney functions. The underlying mechanism of VNF in hyperglycemia and hyperlipidemia may be related to the activation of AMPK in vivo. Our findings indicate that VNF is a potentially useful natural agent for the treatment of metabolic diseases, especially type 2 diabetes and hyperlipidemia.

Intestinal pharmacokinetics of resveratrol and regulatory effects of resveratrol metabolites on gut barrier and gut microbiota

Resveratrol, a dietary polyphenol, has a variety of intestinal bioactivities. However, its material basis remains unknown. This study examined the intestinal pharmacokinetics of resveratrol using HPLC-MS/MS. After oral ingestion in mice, resveratrol and its sulfation metabolites were identified in copious amount in the entire intestinal tract and feces. The glucuronidation metabolites were found in major quantity only in the small intestine. The amount of resveratrol and its metabolites in the total intestine peaked at 4 h, with a concentration of 200 ± 74.8 μM, which corresponded to 14.0% of the administrated dose. During in vitro fermentation, resveratrol-3-O-sulfate, but not resveratrol, significantly promoted the growth of Lactobacillus reuteri (10-fold higher). During the incubation with Caco-2 cells, resveratrol-3-O-sulfate significantly up-regulated the mRNA expressions of tight junction and mucin-related proteins. In conclusion, the intestinal concentration of resveratrol could partially support its intestinal bioactivities, which may be mediated through the actions of its metabolites.

In Vivo Genotoxicity Evaluation of a Stilbene Extract Prior to Its Use as a Natural Additive: A Combination of the Micronucleus Test and the Comet Assay

Genotoxic data of substances that could be used as food additives are required by the European Food Safety Authority. In this sense, the use of an extract from grapevine shoots containing a stilbene richness of 99% (ST-99), due to its antioxidant and antibacterial activities, has been proposed as an alternative to sulfur dioxide in wine. The aim of this work was to study, for the first time, the in vivo genotoxic effects produced in rats orally exposed to 90, 180, or 360 mg ST-99/kg body weight at 0, 24, and 45 h. The combination of micronucleus assay in bone marrow (OECD 474) and standard (OECD 489) and enzyme-modified comet assay was used to determine the genotoxicity on cells isolated from stomach, liver, and blood of exposed animals. The ST-99 revealed no in vivo genotoxicity. These results were corroborated by analytical studies that confirm the presence of stilbenes and their metabolites in plasma and tissues. Moreover, to complete these findings, a histopathological study was performed under light microscopy in liver and stomach showing only slight modifications in both organs at the highest concentration used. The present work confirms that this extract is not genotoxic presenting a good profile for its potential application as a preservative in the wine industry.

Whole-cell biocatalytic, enzymatic and green chemistry methods for the production of resveratrol and its derivatives

Resveratrol and the biosynthetically related stilbenes are plant secondary metabolites with diverse pharmacological effects. The versatile functions of these compounds in plant defense mechanisms as phytoalexins on one hand, and in human health as potential pharmaceutical agents on the other, have attracted lots of interest in recent years to understand their biosynthetic pathways and their biological properties. Because of difficulties in obtaining resveratrol and its glucosylated derivatives as well as oligomeric forms in sufficient amounts for evaluation of their activity by plant sourcing or total synthesis, biotechnology may provide a competitive approach for the large-scale and low cost production of biologically active stilbenes. Additionally, one major limitation in the use of resveratrol and related aglycone derivatives as therapeutic agents is associated with their inherent poor aqueous solubility and low bioavailability. This article examines approaches for the synthesis of potential pharmacologically resveratrol derivatives in vivo by exploiting whole microorganisms, enzymatic and biocatalytic approaches allowing their full utilization for medicine, food and cosmetic applications. These methods also have the advantage of enabling the one-step production of stilbene compounds, compared to the time-consuming and environmentally unfriendly procedures used for their total synthesis or their extraction from plants. Increasing the desired products yield and biological activity through glucosylation (β-D-glucosides versus α-D-glucosides) and oligomerization methodologies of resveratrol including green chemistry methods in organic solvent-free media are discussed as well.

Plant-Derived Purification, Chemical Synthesis, and In Vitro/In Vivo Evaluation of a Resveratrol Dimer, Viniferin, as an HCV Replication Inhibitor

Oligostilbenoid compounds, a group of resveratrol multimers, display several anti-microbial activities through the neutralization of cytotoxic oxidants, and by inhibiting essential host and viral enzymes. In our previous study, we identified a series of oligostilbenoid compounds as potent hepatitis C virus (HCV) replication inhibitors. In particular, vitisin B, a resveratrol tetramer, exhibited the most dramatic anti-HCV activity (EC₅₀ = 6 nM and CC₅₀ > 10 μM) via the disruption of the viral helicase NS3 (IC₅₀ = 3 nM). However, its further development as an HCV drug candidate was halted due to its intrinsic drawbacks, such as poor stability, low water solubility, and restricted in vivo absorption. In order to overcome these limitations, we focused on (+)-ε-viniferin, a resveratrol dimer, as an alternative. We prepared three different versions of (+)-ε-viniferin, including one which was extracted from the grapevine root (EVF) and two which were chemically synthesized with either penta-acetylation (SVF-5Ac) or no acetylation (SVF) using a newly established synthesis method. We confirmed their anti-HCV replication activities and minimal cytotoxicity by using genotype 1b and 2a HCV replicon cells. Their anti-HCV replication action also translated into a significant reduction of viral protein expression. Anti-HCV NS3 helicase activity by EVF was also verified in vitro. Finally, we demonstrated that SVF has improved pharmacokinetic properties over vitisin B. Overall, the favorable antiviral and pharmacokinetic properties of these three versions of viniferin warrant their further study as members of a promising new class of anti-HCV therapeutics.

Tissular Distribution and Metabolism of trans-ε-Viniferin after Intraperitoneal Injection in Rat

Background: Recent studies showed that trans-ε-viniferin (ε-viniferin), a trans-resveratrol dehydrodimer, has anti-inflammatory and anti-obesity effects in rodents. The main purpose of this work was to assess the tissue distribution study of ε-viniferin and its metabolites after intraperitoneal (IP) administration in rat. Methods: After IP injection of 50 mg/kg, ε-viniferin and its metabolites were identified and quantified in plasma, liver, kidneys, adipose tissues, urine, and faeces by Liquid Chromatography-High Resolution Mass Spectrometry (LC-HRMS). Results: ε-Viniferin underwent a rapid hepatic metabolism mostly to glucuronides but also to a lesser extent to sulphate derivatives. The highest glucuronide concentrations were found in liver followed by plasma and kidneys whereas only traces amounts were found in adipose tissues. In contrast the highest ε-viniferin areas under concentration (AUC) and mean residence times (MRT) values were found in white adipose tissues. Finally, much lower levels of ε-viniferin or its metabolites were found in urine than in faeces, suggesting that biliary excretion is the main elimination pathway. Conclusion: A rapid and large metabolism of ε-viniferin and a high bioaccumulation in white adipose tissues were observed. Thus, these tissues could be a reservoir of the native form of ε-viniferin that could allow its slow release and a sustained presence within the organism.

Neuroprotective Mechanisms of Resveratrol in Alzheimer's Disease: Role of SIRT1

Alzheimer's disease (AD) is a progressive and neurodegenerative disorder of the cortex and hippocampus, which eventually leads to cognitive impairment. Although the etiology of AD remains unclear, the presence of β-amyloid (Aβ) peptides in these learning and memory regions is a hallmark of AD. Therefore, the inhibition of Aβ peptide aggregation has been considered the primary therapeutic strategy for AD treatment. Many studies have shown that resveratrol has antioxidant, anti-inflammatory, and neuroprotective properties and can decrease the toxicity and aggregation of Aβ peptides in the hippocampus of AD patients, promote neurogenesis, and prevent hippocampal damage. In addition, the antioxidant activity of resveratrol plays an important role in neuronal differentiation through the activation of silent information regulator-1 (SIRT1). SIRT1 plays a vital role in the growth and differentiation of neurons and prevents the apoptotic death of these neurons by deacetylating and repressing p53 activity; however, the exact mechanisms remain unclear. Resveratrol also has anti-inflammatory effects as it suppresses M1 microglia activation, which is involved in the initiation of neurodegeneration, and promotes Th2 responses by increasing anti-inflammatory cytokines and SIRT1 expression. This review will focus on the antioxidant and anti-inflammatory neuroprotective effects of resveratrol, specifically on its role in SIRT1 and the association with AD pathophysiology.