Fact-checked by Grok 2 weeks ago

Ellagitannin

Ellagitannins are a diverse subclass of hydrolyzable tannins, comprising polyphenolic compounds characterized by the presence of at least one hexahydroxydiphenoyl (HHDP) unit esterified to a polyol core, most commonly β-D-glucopyranose, and capable of hydrolyzing to ellagic acid.^[1] They constitute the largest group among over 500 known hydrolyzable tannins, with more than 1,000 natural variants identified, and are classified into subtypes such as simple ellagitannins, C-glycosidic ellagitannins, complex tannins (which incorporate flavan-3-ol units), and oligomers ranging from dimers to pentamers.^[1]^[2] These compounds are biosynthesized exclusively in dicotyledonous angiosperms through the oxidative coupling of adjacent galloyl groups on galloylglucoses, forming the biaryl HHDP moiety via C-C bond formation, often exhibiting chirality (S or R configuration) detectable by circular dichroism.^[1] Ellagitannins are widely distributed across plant families, particularly those in the order Myrtales—including Myrtaceae (e.g., Eucalyptus species), Lythraceae, Onagraceae, Melastomataceae, and Combretaceae (e.g., Terminalia species)—as well as Punicaceae (e.g., pomegranate, Punica granatum), where they serve chemotaxonomic markers and defensive roles against herbivores and pathogens.^[1] In human diets, they occur prominently in select foods such as berries (e.g., raspberries at 326 mg/100 g fresh weight, strawberries, blackberries, and cloudberries), nuts (e.g., walnuts at 864 mg/100 g), and tropical fruits (e.g., pomegranate at 58–177 mg/100 g and jabuticaba at 900 mg/100 g), contributing to typical daily intakes of 5–12 mg depending on regional consumption patterns.^[2]^[3] Upon ingestion, ellagitannins exhibit low direct bioavailability and are primarily metabolized by gut microbiota into ellagic acid and, subsequently, urolithins (e.g., urolithin A and B), which are absorbed into the bloodstream and detectable in plasma and urine for up to seven days, with interindividual variability influenced by microbiome composition (e.g., metabotypes A, B, or 0).^[2] Biologically, ellagitannins and their derivatives demonstrate potent antioxidant activity due to multiple phenolic hydroxyl groups, alongside antitumor effects (e.g., oenothein B extending life span by 196% in tumor-bearing mice at 10 mg/kg), antibacterial properties (e.g., casuarinin inhibiting HSV-2 with IC₅₀ of 1.5–3.6 μM), and enzyme-inhibitory actions, positioning them as promising candidates for applications in food preservation, nutraceuticals, and therapeutics targeting inflammation, cancer, and cardiovascular health.^[1]^[2]

Chemical Structure and Classification

Basic Structure

Ellagitannins are a subclass of hydrolyzable tannins defined as esters formed between hexahydroxydiphenoic acid (HHDP) and a monosaccharide, most commonly glucose.^[4]^[5] The HHDP unit arises from the oxidative coupling of two galloyl groups through a biaryl C-C bond, which imparts axial chirality due to atropisomerism from restricted rotation around this bond.^[6]^[7] This core motif distinguishes ellagitannins structurally, as the HHDP is esterified to the hydroxyl groups of the central sugar, often resulting in multiple attachments that form a polyol ester framework.^[2] The hydrolyzable nature of ellagitannins stems from their ester linkages, which can be cleaved under acidic or enzymatic conditions to yield ellagic acid from the HHDP unit and the free monosaccharide.^[8]^[9] In contrast to gallotannins, which feature galloyl units connected via meta-depside ester bonds between phenolic hydroxyls, ellagitannins rely on the stable yet hydrolyzable C-C linkage within the HHDP for their characteristic reactivity and stability.^[10]^[11] The general architecture thus centers on a glucose core with HHDP groups bridging adjacent or non-adjacent positions, providing a scaffold for further structural diversity in subclasses, with the HHDP exhibiting (S) or (R) configurations due to atropisomerism.^[2]

Types and Subclasses

Ellagitannins are classified primarily according to their structural complexity, encompassing monomeric forms with a single central glucose unit esterified by hexahydroxydiphenoyl (HHDP) and galloyl groups, as well as dimeric, oligomeric, and polymeric variants where multiple glucose cores are interconnected through C-C or O-C bonds. This classification reflects the oxidative coupling mechanisms that form biaryl linkages like HHDP from galloyl precursors, leading to diverse architectures that influence solubility, reactivity, and biological roles. Simple ellagitannins (Type I) represent the foundational subclass with O-linked HHDP on a closed glucopyranose ring, while C-glycosidic ellagitannins (Type II) feature an open-chain glucose. Complex tannins, or flavono-ellagitannins, combine ellagitannin units with flavan-3-ols like catechin through C-C bonds, and higher oligomers often feature additional depside or depsidone bridges, enhancing molecular weight and astringency.^[12]^[1] Within the simple subclass, ellagitannins often have HHDP groups linking adjacent hydroxyl positions on glucose, such as the 4,6- or 2,3- arrangements, which can stabilize the glucose in a skewed boat conformation due to steric constraints from the bulky biaryl unit; these exhibit stereospecific (S)- or (R)-configurations at the chiral axis. A classic example is tellimagrandin II, featuring a 4,6-(S)-HHDP alongside galloyl esters at positions 1,2, and 3 of β-D-glucopyranose, exemplifying the foundational O-aryl ester linkages. Dimeric structures, like punicalagin, extend this by incorporating a valoneoyl group—a depsidic linkage between a galloyl and an HHDP unit—bridging two glucose cores via an ether bond, resulting in a macrocyclic framework with enhanced hydrolytic stability. The valoneoyl moiety, characterized by its 5,5'-biaryl ether connection, distinguishes many dimers from simple monomers by facilitating intermolecular coupling.^[12]^[13]^[1] C-glycosidic ellagitannins form a specialized subclass distinguished by direct C-C bonds between the glucose anomeric carbon (C-1) and an HHDP or related unit, bypassing traditional ester linkages and conferring resistance to hydrolysis. Vescalagin exemplifies this, with a C-1-linked flavogalloyl group and an HHDP bridging positions 4 and 6, along with additional O-galloyl groups, often occurring as atropisomeric pairs due to the biaryl axis; it is classified under the castalagin-type, where a flavogalloyl substituent participates in the C-glycosidic bond. These differ from O-glycosidic monomers in biogenetic origin and metabolic persistence, with oligomers like castamollinin extending the subclass through C-O or C-C interdimer links. Chemotaxonomically, such structural patterns hold significance: monomeric HHDP types predominate in families like Rosaceae, while C-glycosidic oligomers mark Myrtaceae and Lythraceae, and punicalagin-like dimers characterize Punicaceae and Combretaceae, aiding phylogenetic delineations within orders such as Myrtales.^[12]^[1]^[13]

Biosynthesis

Biosynthetic Pathway

The biosynthesis of ellagitannins in plants originates from the shikimate pathway, a central metabolic route that produces aromatic compounds from precursors such as phosphoenolpyruvate and erythrose-4-phosphate, leading to chorismate. Gallic acid is biosynthesized from the shikimate pathway via intermediates such as 3-dehydroshikimate, protocatechuate, and gallate, serving as the fundamental building block for these polyphenols.^[14]^[15] A key intermediate in the pathway is 1,2,3,4,6-penta-O-galloyl-β-D-glucose, formed by sequential galloylation starting from β-glucogallin (1-O-galloyl-β-D-glucose), with subsequent steps using β-glucogallin as the acyl donor to build up polygalloylglucoses. This pentagalloyl glucose acts as a common precursor for both gallotannins and ellagitannins. The formation of the characteristic hexahydroxydiphenoyl (HHDP) unit in ellagitannins occurs through oxidative coupling of adjacent galloyl groups on the pentagalloyl glucose, creating biaryl (C-C) linkages via laccase-like phenol oxidases, resulting in monomeric ellagitannins such as tellimagrandin II.^[16]^[8]^[14] This biosynthetic process primarily takes place in the cytoplasm, with ellagitannins accumulating in vacuoles or cell walls of dicotyledonous plants, where they reach high concentrations. Ellagitannins are widespread, occurring in approximately 40% of dicotyledonous species, and play a crucial role in plant defense by deterring herbivores and pathogens through their astringent and antimicrobial properties, contributing to evolutionary adaptations in these taxa.^[8]^[17]^[18]

Enzymatic Steps

The initial step in ellagitannin biosynthesis involves the formation of β-glucogallin (1-O-galloyl-β-D-glucopyranose) from gallic acid and UDP-glucose, catalyzed by the enzyme UDP-glucose:galloyl-1-β-D-glucosyltransferase (UGGT), also known as gallate 1-β-glucosyltransferase. Upstream, shikimate dehydrogenase (SDH) catalyzes the conversion of 3-dehydroshikimate to protocatechuate in the gallic acid pathway, with isoforms identified in species like grapevine (VvSDH3, VvSDH4) and pomegranate.^[19] This transferase activity has been identified in species such as oak (Quercus spp.) and strawberry (Fragaria vesca), where UGGT genes (e.g., UGT84A13) facilitate the esterification, marking the entry point for hydrolyzable tannin assembly. Additional UGTS, such as PgUGT84A23 and PgUGT84A24 in pomegranate, have been characterized.^[20]^[21] Subsequent galloylation proceeds through depside formation, primarily via β-glucogallin O-galloyltransferases, which utilize β-glucogallin as both acyl donor and acceptor to produce di- and polygalloylglucoses.^[19] For instance, β-glucogallin:β-glucogallin 6-O-galloyltransferase from oak leaves synthesizes 1,6-digalloylglucose, enabling stepwise addition up to pentagalloylglucose, the key precursor for ellagitannin diversification.^[22] These acyltransferases exhibit regioselectivity, with five distinct enzymes characterized from sumac (Rhus typhina) leaves that further galloylate pentagalloylglucose to higher analogs.^[19] The critical oxidative coupling to form the hexahydroxydiphenoyl (HHDP) moiety, characteristic of ellagitannins, is mediated by laccase-like phenol oxidases, though these enzymes remain incompletely characterized.^[19] In Tellima grandiflora, a specific laccase oxidizes adjacent galloyl groups on pentagalloylglucose to yield tellimagrandin II, the simplest monomeric ellagitannin, via stereospecific C-C bond formation. A related oxidase produces the dimeric ellagitannin cornusiin E from tellimagrandin II.^[19] As of 2025, while UGGT and β-glucogallin O-galloyltransferases remain key characterized enzymes, additional progress includes shikimate dehydrogenases (SDH) and new UGTs in species like pomegranate; however, significant gaps persist in the oxidative coupling and polymerization steps for complex ellagitannins.^[19]^[20]^[18] Enzyme regulation in ellagitannin biosynthesis is influenced by environmental stresses, including UV radiation and herbivory, which upregulate transferase and oxidase activities to enhance tannin production as a defense response.^[23]^[24]

Metabolism

Hydrolysis

Ellagitannins, as hydrolyzable tannins, undergo chemical breakdown primarily through the cleavage of ester bonds linking hexahydroxydiphenoyl (HHDP) units to a central glucose core. In acid or base-catalyzed hydrolysis, these ester bonds are disrupted, yielding ellagic acid—formed via spontaneous lactonization of the liberated HHDP moiety—along with glucose and, in cases involving depside linkages, gallic acid derivatives.^[25]^[26] The generalized reaction can be represented as:

\text{Ellagitannin} + \text{H}_2\text{O} \rightarrow \text{Ellagic acid} + \text{Glucose} + \text{Gallic acid derivatives}

This process is pH-dependent, with ellagitannins exhibiting greater stability under acidic conditions (pH < 4) where hydrolysis proceeds slowly, but rapid degradation occurs in neutral to mildly basic environments (pH 7–8), facilitating the release of phenolic products.^[26] Additionally, the atropisomerism arising from restricted rotation around the biaryl axis in HHDP units contributes to the structural rigidity and overall stability of ellagitannins, influencing the rate of ester bond cleavage during hydrolysis.^[27] Enzymatic hydrolysis of ellagitannins is mediated by tannase (tannin acyl hydrolase, EC 3.1.1.20), an esterase that specifically targets the acyl linkages between galloyl or HHDP groups and the polyol core, producing similar breakdown products including ellagic acid, glucose, and gallic acid.^[28] Tannase activity is present in various organisms, including plants where it supports localized metabolism, as well as in microbes capable of degrading complex tannins for nutrient acquisition.^[29] In the gastrointestinal context, microbial tannases further contribute to this breakdown, though the primary enzymatic mechanism remains consistent across sources.^[8] In plants, ellagitannin hydrolysis plays a key role in defense mechanisms, particularly during tissue damage from herbivory or pathogen attack, where controlled enzymatic release of ellagic acid provides antimicrobial protection and deters further invasion.^[30] This rapid hydrolysis upon injury ensures the deployment of bioactive phenolics at wound sites, enhancing resistance without compromising the intact tannin's role in storage.^[31]

Gut Microbiota Transformation

Ellagitannins ingested from dietary sources are metabolized by the gut microbiota primarily in the colon, where they are first converted to ellagic acid through hydrolysis, followed by further microbial transformation into urolithins, including urolithin A, urolithin B, urolithin C, and urolithin D.^[32] This multi-step process involves lactone ring cleavage, decarboxylation, and dehydroxylation reactions carried out by specific bacterial genera such as Gordonibacter and Ellagibacter.^[33] For example, Gordonibacter urolithinfaciens has been identified as a key player in producing urolithin A from ellagic acid. The efficiency of urolithin production exhibits significant inter-individual variability, largely dependent on the composition of the gut microbiota. Individuals are classified into metabotypes based on their microbial capacity: metabotype A producers generate urolithin A as the primary metabolite, while others may produce urolithin B or no urolithins (metabotype 0). Approximately 40% of people are capable of producing urolithin A from ellagitannin precursors. This variability is influenced by factors such as age, diet, and health status, with lower production observed in certain populations.^[33] Ellagitannins and ellagic acid demonstrate low bioavailability, with minimal absorption in the upper gastrointestinal tract, but their microbial metabolites, the urolithins, are efficiently absorbed in the colon and enter the systemic circulation to exert effects throughout the body.^[32] Urolithins such as urolithin A reach detectable plasma concentrations, enabling their distribution to tissues.^[33] Ellagitannins also display prebiotic effects by serving as substrates that promote the growth and diversity of beneficial gut bacteria, thereby modulating overall microbiome composition.^[33] Recent studies through 2025 have highlighted urolithins' role in anti-inflammatory benefits, such as inhibiting NF-κB and MAPK pathways to reduce pro-inflammatory cytokine production like IL-6.^[34] For instance, urolithin A has been shown to enhance gut barrier integrity and immune modulation in preclinical models.

Natural Occurrence

In Plants

Ellagitannins are found exclusively in dicotyledonous angiosperms, particularly in families within the order Myrtales and others such as Rosaceae (e.g., raspberries and strawberries), Fagaceae (e.g., oaks), and Lythraceae (e.g., pomegranates), as well as Onagraceae, Myrtaceae, and Geraniaceae.^[1]^[35] This distribution highlights their role in the chemical diversity of eudicotyledons, with oligomeric forms common in woody species like those in Fagaceae and Rosaceae.^[1] Concentrations of ellagitannins vary by plant tissue but are typically highest in bark, leaves, and fruits, where they can constitute a significant portion of the dry weight. In oak (Quercus spp.) heartwood and bark, for instance, ellagitannins may reach up to 10% of the dry weight, contributing to the material's durability and extractability.^[36] Such elevated levels in protective tissues like bark underscore their accumulation in response to environmental pressures.^[37] Ellagitannins also function as chemotaxonomic markers, with specific structural types indicating phylogenetic lineages within plant families. For example, C-glycosidic ellagitannins are characteristic of Myrtaceae and related orders like Myrtales, distinguishing them from O-glycosidic forms more common in other dicot groups.^[1] These structural variations aid in classifying plant evolution and relationships, as seen in the diverse ellagitannin profiles across Lythraceae and Combretaceae.^[38] As secondary metabolites, ellagitannins play an evolutionary role in plant adaptation, enabling defense against herbivores, pathogens, and abiotic challenges through their astringent and antimicrobial properties.^[39] Their biosynthesis likely evolved to enhance survival in diverse habitats, correlating with primitive dicot characteristics and contributing to ecological fitness.^[40] Environmental stresses further induce ellagitannin production, with levels increasing under conditions like drought, pathogen attack, or wounding to bolster plant resilience. For instance, pathogen infection in strawberry plants triggers ellagitannin accumulation in leaves, eliciting defensive responses.^[41] This inducible response highlights their dynamic role in abiotic and biotic stress adaptation.^[42]

In Foods and Beverages

Ellagitannins are prominent in several edible plants and derived products, serving as key contributors to dietary polyphenol intake. Pomegranates (Punica granatum) represent a major source, with punicalagin, the predominant ellagitannin, reaching concentrations up to 2 g/100 g in fruit peels and approximately 1-2 g/L in commercial juices.^[43] Berries such as strawberries (Fragaria × ananassa), raspberries (Rubus idaeus), and blackberries (Rubus fruticosus) also contain significant levels, typically 71-83 mg/100 g fresh weight in strawberries and 150-330 mg/100 g in raspberries and blackberries, primarily as agrimoniin and sanguiin H-6.^[2] Walnuts (Juglans regia) provide another rich source, with total ellagitannin content equivalent to about 800 mg ellagic acid per 100 g fresh weight, concentrated in the pellicle.^[44] In beverages, oak-aged wines and whiskeys acquire ellagitannins from barrel wood, including vescalagin and castalagin, which enhance flavor and structure during maturation.^[45] Dietary intake of ellagitannins in Western populations is estimated at 5-15 mg per day, primarily from berries and nuts, though consumption can be higher in Mediterranean diets due to greater reliance on fruits, nuts, and pomegranate-based products.^[2]^[36] Food processing significantly influences ellagitannin levels and bioavailability. In juice production from pomegranates and berries, extraction methods like pressing can retain high concentrations, though clarification steps may lead to losses of up to 50% in blackberry juices.^[46] Cooking and thermal processing, such as boiling or pasteurization, often cause degradation through hydrolysis, reducing content by 20-40% in berry purees, while freezing and canning preserve most ellagitannins effectively.^[47] Barrel aging in wines and whiskeys enriches products with ellagitannins leached from oak, where toasting intensity and aging duration (e.g., 6-24 months) can increase concentrations by 2-5 fold compared to unaged spirits.^[48] Quantification of ellagitannins in foods typically employs high-performance liquid chromatography (HPLC) coupled with UV or mass spectrometry detection, allowing separation and measurement of individual compounds like punicalagin after extraction and hydrolysis.^[49] Cloudberries (Rubus chamaemorus) are a source of ellagitannins exceeding 100 mg/100 g fresh weight, suitable for functional foods and processed products due to stability.^[50]

Biological Properties

Antioxidant and Health Effects

Ellagitannins and their hydrolysis product, ellagic acid, exhibit potent antioxidant activity primarily through scavenging reactive oxygen species (ROS) and chelating metal ions, facilitated by the multiple phenolic hydroxyl groups in their structure.^[51] These compounds donate hydrogen atoms to neutralize free radicals, as demonstrated in in vitro assays where ellagic acid effectively inhibits lipid peroxidation and protects cellular components from oxidative damage.^[52] Additionally, ellagic acid's ability to chelate pro-oxidant metals like iron and copper prevents Fenton reactions that generate hydroxyl radicals, thereby mitigating oxidative stress in biological systems.^[36] The anti-inflammatory effects of ellagitannins are largely mediated by their gut microbiota-derived metabolites, such as urolithins, which inhibit the NF-κB signaling pathway.^[53] Urolithin A, for instance, suppresses NF-κB activation by blocking its translocation to the nucleus, reducing the expression of pro-inflammatory cytokines like TNF-α and IL-6 in activated macrophages and colonic cells.^[54] This mechanism has been observed in both in vitro and animal models, where urolithins attenuate inflammation in response to lipopolysaccharide stimulation.^[55] In anti-cancer research, ellagitannins and ellagic acid promote apoptosis and inhibit angiogenesis in various cancer cell lines, particularly those from prostate and colon tissues.^[56] For example, ellagic acid induces caspase-3 activation and cell cycle arrest at the G1 phase in prostate cancer cells, leading to reduced proliferation, while in colon cancer models, it downregulates vascular endothelial growth factor (VEGF) to impair tumor angiogenesis.^[57] Urolithin A further enhances these effects by triggering autophagy and sensitizing colon cancer cells to chemotherapy.^[58] Ellagitannins contribute to cardiovascular health by improving endothelial function and reducing low-density lipoprotein (LDL) oxidation.^[59] In endothelial cells, ellagic acid enhances nitric oxide production via eNOS activation, promoting vasodilation and countering atherosclerosis progression.^[60] Furthermore, pomegranate-derived ellagitannins inhibit LDL oxidation more effectively than anthocyanins, with an IC50 value half that of the latter in ex vivo assays, thereby lowering the risk of plaque formation.^[59] Clinical evidence from meta-analyses indicates that ellagitannin-rich interventions, such as pomegranate extracts, yield benefits in metabolic syndrome parameters, including reduced total cholesterol and inflammation markers, though outcomes vary due to inter-individual differences in gut microbiota composition.^[61] A 2023 review of randomized trials confirmed ellagic acid's role in lowering LDL and triglycerides while increasing HDL, with effects more pronounced in doses exceeding 100 mg/day over 8 weeks.^[62] However, a 2025 meta-analysis of 34 trials on pomegranate products highlighted inconsistent glycemic improvements, such as no significant effect on HbA1c.^[63]

Ecological Roles

Ellagitannins serve as key defensive compounds in plants, primarily functioning to deter herbivory through mechanisms such as protein precipitation and the induction of astringency, which reduce palatability and digestibility for feeding animals. By binding to salivary and gut proteins, these hydrolyzable tannins form insoluble complexes that inhibit nutrient absorption and disrupt digestive processes in herbivores, including mammals and insects. For instance, in species like oaks (Quercus spp.), ellagitannins exhibit pro-oxidant activity in the alkaline guts of caterpillars, generating reactive oxygen species that cause oxidative damage and lower herbivore performance.^[64]^[65] In addition to anti-herbivore effects, ellagitannins contribute to plant antimicrobial defense by inhibiting the growth of fungal and bacterial pathogens through membrane disruption, metal ion chelation, and the inactivation of extracellular enzymes. These compounds, often concentrated in plant tissues under pathogen attack, prevent microbial adhesion and nutrient uptake, with effective concentrations ranging from 0.012 g/L for fungi to 0.5–20.0 g/L for bacteria. In plants like pomegranate (Punica granatum), ellagitannins specifically target fungal pathogens, enhancing overall resistance to infections.^[66]^[30] Ellagitannins also act as allelochemicals, exerting inhibitory effects on competing plants and soil microbes to suppress germination and growth in the rhizosphere. For example, the ellagitannin isocorilagin from certain species strongly inhibits seed germination in weeds like Mimosa pudica, altering soil microbial communities and reducing competitive pressure on the producing plant. This allelopathic activity helps establish dominance in resource-limited environments.^[65] In specific plant-pest interactions, such as those in oak systems, ellagitannins modulate insect detoxification enzymes, thereby enhancing plant resistance by overwhelming or inhibiting the pests' metabolic responses. These tannins interfere with cytochrome P450 enzymes and other detoxifiers in herbivores like the gypsy moth (Lymantria dispar), reducing the insects' ability to process and tolerate the compounds. Recent research highlights ellagitannins' role in climate resilience, particularly in providing UV protection; under UV-A exposure, their accumulation in species like Eucalyptus camaldulensis bolsters antioxidant defenses against radiation-induced oxidative stress, aiding adaptation to changing environmental conditions. Biosynthesis of ellagitannins often increases under such abiotic stresses, as detailed in related pathways.^[67]^[68]^[30]

References

[1]
Structural Features and Biological Properties of Ellagitannins ... - NIH
Jan 6, 2010 · This review outlines and describes the chemotaxonomic significance of structural features in various types of ellagitannins found in plants ...Missing: definition | Show results with:definition
[2]
Food Ellagitannins: Structure, Metabolomic Fate, and Biological ...
Ellagitannin is a hydrolyzable polymer contrary to the rest of the family of tannins and can be hydrolyzed to more simple monomers that can be eventually ...
[3]
Contents of Anthocyanins and Ellagitannins in Selected Foods ...
Ellagitannins were screened in 33 food items, but were detected only in 5 species of berries, that is, in cloudberry, raspberry, rose hip, strawberry, and sea ...
[4]
Ellagitannin - an overview | ScienceDirect Topics
Ellagitannins are esters of hexahydroxydiphenoic acid and monosaccharide and are classified under hydrolyzable tannins.
[5]
[PDF] Structure, occurrence and biological activity of ellagitannins
Ellagitannins belong to the class of hydrolysable tannins, they are esters of hexahydroxydiphenoic acid and monosac- charide (most commonly glucose).
[6]
Recent Advances in the Production and Applications of Ellagic Acid ...
ETs are formed via oxidative C-C coupling of at least two galloyl units of ... HHDP or galloyl groups (e.g., Corilagin, Figure 2). Trimer and tetramer ...
[7]
Fundamental Methods in Ellagitannin Synthesis - Sage Journals
Synthesis of the HHDP group is the formation of the C–C bond between two galloyl groups. In the early developments, couplings of fully O-methylated gallates ...Missing: atropisomeric | Show results with:atropisomeric
[8]
Ellagitannins and Their Derivatives: A Review on the Metabolization ...
Ellagitannins are bioactive phenolic compounds classified as hydrolyzable tannins [7]. They are currently considered phenolic acids belonging to the ...
[9]
Fig. 1. Chemical structure of the ellagitannin derivate. HHDP,...
Together with gallotannins, they are called hydrolyzable tannins, and upon hydrolysis release ellagic acid, although other metabolites can be produced and are ...
[10]
Gallotannin - an overview | ScienceDirect Topics
Gallotannins are formed by galloyltransfer from 1-O-galloylglucose to the galloyl residues of the central glucose leading to meta-depside bonds (Glc = glucose).
[11]
[PDF] Chapter 10. Tannins - Sci-Hub
The HT encompass the polyesters of gallic and hexahydroxydiphenic acid (gallotannins and ellagitannins, respectively), ... In meta-depsides, galloyl residues are ...<|control11|><|separator|>
[12]
Ellagitannin Chemistry | Chemical Reviews - ACS Publications
... ellagitannin chemistry. This hypothesis offers (1) a logical and highly ... Stéphane Quideau - Department of Chemistry, The Pennsylvania State ...
[13]
New Type of Tannins Identified from the Seeds of Cornus officinalis ...
Regarding the polyphenol structure of tannin, the moieties attached to the polyol are galloyl group in gallotannin (type I), HHDP group in ellagitannin (type II) ...
[14]
https://doi.org/10.3389/fgene.2022.870976
[15]
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8885183/
[16]
https://doi.org/10.1016/j.phytochem.2005.01.009
[17]
Toward Understanding Monomeric Ellagitannin Biosynthesis
Ellagitannins are found in approximately 40 percent of all dicotyledenous plants ranging from raspberries to the oaks.1–3 By definition, this class of ...
[18]
Regulation of Plant Tannin Synthesis in Crop Species - Frontiers
This enzyme exists in two types: type I and type II, but with no sequential ... Regarding ellagitannin biosynthesis, formation of HHDP through the C4 ...
[19]
Enzymology of gallotannin and ellagitannin biosynthesis - PubMed
Gallotannins and ellagitannins, the two subclasses of hydrolyzable tannins, are derivatives of 1,2,3,4,6-penta-O-galloyl-beta-D-glucopyranose.
[20]
Formation of β-glucogallin, the precursor of ellagic acid in strawberry ...
Feb 16, 2016 · The biosynthesis starts with the formation of β-glucogallin (1-O-galloyl-β-d-glucopyranose), which is generated by esterification of gallic acid ...Missing: UGGT coupling laccase
[21]
Enzymatic Synthesis of 1,6-Digalloylglucose from β-Glucogallin by β ...
Feb 1, 1987 · Enzymatic Synthesis of 1,6-Digalloylglucose from β-Glucogallin by β-Glucogallin: β-Glucogallin 6-O-Galloyltransferase from Oak Leaves.Missing: steps UGGT coupling laccase
[22]
A Comprehensive Analysis of Diversity, Structure, Biosynthesis and ...
Environmental factors, such as light, temperature, water availability, and nutrient status, also influence tannin biosynthesis by modulating the expression of ...
[23]
https://pmc.ncbi.nlm.nih.gov/articles/PMC11173854/
[24]
Transformation of Oligomeric Ellagitannins, Typical for Rubus and ...
Jul 10, 2020 · In mildly acidic conditions (pH 6) ellagitannins hydrolyze to intermediate products, i.e., sanguiin H-10 isomers, sanguiin H-2, and galloyl-HHDP ...
[25]
Stability and transformations of raspberry (Rubus idaeus L ...
Dec 18, 2018 · It is generally acknowledged that ellagitannins are hydrolyzed by acids and bases, as a result of which HHDP residues split from the molecules ...
[26]
Ellagic Acid and Schisandrins: Natural Biaryl Polyphenols with ... - NIH
Feb 21, 2021 · ... atropisomerism' [60,61]. EA is generated via a hydrolysis reaction ... Feldman K.S. Recent progress in ellagitannin chemistry.
[27]
Novel Strategies for Upstream and Downstream Processing of ...
Sep 19, 2011 · Tannin acyl hydrolase also known as tannase is an enzyme (EC 3.1.1.20) that catalyzes the hydrolysis of ester bonds present in gallotannins, ...
[28]
Biodegradation of Punicalagin into Ellagic Acid by Selected ...
Punicalagin is a natural component in pomegranate and belongs to the family of ellagitannins. The biological interest of punicalagins arises from being the ...Analysis Of Phenolic... · Proteomic Analysis · Figure 1<|control11|><|separator|>
[29]
Plant Protection by Tannins Depends on Defence-Related ...
Mar 26, 2024 · The presence of tannins in these organs serves to protect plants against herbivorous and pathogenic attack through their antidigestive and ...
[30]
The Chemistry and Chemical Ecology of Ellagitannins in Plant ...
Aug 11, 2014 · This chapter reviews our current knowledge of the chemistry and chemical ecology of ellagitannins (ETs), placing particular emphasis on the ...
[31]
https://onlinelibrary.wiley.com/doi/abs/10.1002/9781118329634.ch4
[32]
https://doi.org/10.1080/10408398.2022.2106179
[33]
https://doi.org/10.3390/foods12020270
[34]
Distribution and content of ellagitannins in Finnish plant species
Plant families that were rich in ellagitannins (>90 mg g−1 of the crude extract) were Onagraceae, Lyhtraceae, Geraniaceae, Elaeagnaceae, Fagaceae and some ...Missing: Lythraceae | Show results with:Lythraceae
[35]
The Impact of Ellagitannins and Their Metabolites through Gut ...
... ellagitannin content expressed as total ellagic acid); HHDP—hexahydroxydiphenic acid. ... Type I Interferons and Microbial Metabolites of Tryptophan ...
[36]
Influence of the botanical origin and toasting level on the ...
The toasting level also exerts a major influence on the ellagitannins content of oak (Doussot et al., 2002, Chira and Teissedre, 2013a). High temperatures ...
[37]
(PDF) Structural Features and Biological Properties of Ellagitannins ...
Jan 2, 2010 · This review outlines and describes the chemotaxonomic significance of structural features in various types of ellagitannins found in plants ...
[38]
Plant Secondary Metabolites: The Weapons for Biotic Stress ...
These mechanisms use a variety of secondary metabolites as weapons to avoid obstacles, adapt to their changing environment, and survive in less-than-ideal ...
[39]
A NOTE ON ELLAGITANNINS AS INDICATORS OF ...
Statistical analysis confirms that, among dicotyledons, not only are leuco-anthocyanins cor- related with primitive characters but so, also, are ellagitannins.Missing: percentage | Show results with:percentage
[40]
Pathogen-induced accumulation of an ellagitannin elicits plant ...
Results obtained suggested that HeT could be a common plant defense response molecule capable of inducing pathogen resistance in different plant species. MeSH ...Missing: evolution | Show results with:evolution
[41]
Ellagic acid alleviates aluminum and/or drought stress through ...
Ellagic acid alleviates aluminum and/or drought stress through morpho-physiochemical adjustments and stress-related gene expression in Zea mays L. · 4 Citations.
[42]
unravelling the efficient applications of plant phenolics and tannins ...
The aim of this review is to discuss the role of phenolic compounds in the interactions of plants with various stress factors, both biotic and abiotic
[43]
Pomegranate Juice Ellagitannin Metabolites Are Present in Human ...
The potent antioxidant properties of PJ have been attributed to its high content of punicalagin isomers that can reach levels >2 g/L juice (3, 4, 5).
[44]
Ellagitannin - an overview | ScienceDirect Topics
Hydrolysable and condensed tannins are widely distributed in the plant kingdom and are thought to be biosynthesized and accumulated as defensive compounds ...
[45]
Quantitative conversion of free, acid-hydrolyzable, and bound ...
Jan 30, 2023 · The total ellagic acid content (823 mg/100 g FW) of walnuts accounted for about 32.9% of the total phenol content (2,499 ± 94 mg/100 g FW) (Abe ...
[46]
Ellagitannins and lignins in aging of spirits in oak barrels
Evolution of the Phenolic Fraction and Aromatic Profile of Red Wines Aged in Oak Barrels. ... Phenolic Composition and Related Properties of Aged Wine Spirits: ...
[47]
Processing and Storage Effects on the Ellagitannin Composition of ...
Ellagitannins are well retained in canned, pureed, and frozen blackberries, but methods are needed to prevent losses during juice processing.
[48]
Food ellagitannins-occurrence, effects of processing and storage
This paper reviews research about occurrence in foods, change during process, and antioxidant activity of ellagitannins and ellagic acid. Publication types.Missing: juices aging
[49]
Impact of Barrel Toasting on Ellagitannin Composition of Aged ... - NIH
Apr 14, 2022 · Longer aging seems to have accentuated the differences in C-glucosidic ellagitannin concentrations according to toasting level, because although ...
[50]
Ellagitannin Composition of Blackberry As Determined by HPLC-ESI ...
The MALDI analysis verified the presence of the ellagitannins identified by HPLC-ESI-MS including lambertianin A/sanguiin H-6, lambertianin C, and lambertianin ...
[51]
Antioxidant Activity of Isolated Ellagitannins from Red Raspberries ...
While the radical scavenging activity of the berry phenolics containing 60% ellagitannins of the total phenolic content (red raspberries) or 80% (cloudberries) ...Missing: walnuts | Show results with:walnuts
[52]
Oxidative Stress, Antioxidant Capabilities, and Bioavailability
This review focuses on the pathophysiology of OS; on EA and UROs chemical features and on the mechanisms of their antioxidant activity.
[53]
Ellagic Acid: A Review on Its Natural Sources, Chemical Stability ...
A characteristic feature of the chemical structure of all ellagitannins is the presence of at least one HHDP unit, which is esterified to a polyol, typically β ...
[54]
Biological Significance of Urolithins, the Gut Microbial Ellagic Acid ...
The anti-inflammatory effects of urolithins may be mediated through regulation of the transcription factor NF-κB since both urolithins are able to inhibit the ...
[55]
NF-kappaB-dependent anti-inflammatory activity of urolithins, gut ...
Mar 26, 2010 · The present results suggest that Uro, mainly Uro-A, are the main compounds that are responsible for the pomegranate anti-inflammatory properties.
[56]
The gut microbiota metabolite urolithin A inhibits NF-κB activation in ...
Mar 29, 2021 · We suggest that urolithin A is a promising therapeutic agent for treating inflammatory diseases through suppression of NF-κB and preserving DNA.
[57]
Ellagitannins in Cancer Chemoprevention and Therapy - PMC
May 13, 2016 · At low concentrations, the extract promoted initiation of apoptotic cell death, while at higher doses necrosis was the predominant type of cell ...
[58]
Experimental Evidence of the Antitumor, Antimetastatic and ...
The antitumor activity of EA has been mostly attributed to direct antiproliferative and apoptotic effects. Moreover, EA can inhibit tumour cell migration, ...
[59]
Metabolite of ellagitannins, urolithin A induces autophagy and ... - NIH
This study found that submicromolar concentrations of urolithin A, a major polyphenol metabolite, induced autophagy in SW620 colorectal cancer (CRC) cells.
[60]
Pomegranate Protection against Cardiovascular Diseases - PMC
The tannin fraction was more potent than the anthocyanin fraction in inhibiting LDL oxidation, and the IC50 of the tannins was half that of the anthocyanins.
[61]
Protective Effects of Polyphenols Present in Mediterranean Diet on ...
Aug 6, 2020 · Urolithins are the major metabolites of dietary ellagic acid, found in the form of ellagitannin in foods such as walnuts, strawberries, and ...1.2. Polyphenols · 2. Quercetin · 5. Urolithin
[62]
Meta-Analysis of the Effects of Foods and Derived Products ...
Both anthocyanin- and ellagitannin-containing products reduced total-cholesterol with nuts and berries yielding more significant effects than pomegranate and ...2. Results · 2.1. Description Of The... · 3. Discussion
[63]
The effect of ellagic acid on the metabolic syndrome: A review article
Oct 31, 2023 · EA is beneficial for lowering TC, TG, LDL, and inflammation, and increasing HDL and bile acid secretion. Furthermore, EA demonstrates beneficial ...
[64]
The effect of pomegranate products on glycemic profile in adults: a ...
Aug 22, 2025 · To address these inconsistencies, we conducted a meta-analysis of 34 randomized clinical trials (RCTs) evaluating the effects of pomegranate on ...
[65]
Ellagitannins have Greater Oxidative Activities than Condensed ...
Aug 10, 2025 · The results suggest that ellagitannin-rich plants have active oxidative defenses against herbivores, such as caterpillars, whereas the opposite ...
[66]
Diverse Ecological Roles of Plant Tannins: Plant Defense and Beyond
Feb 2, 2018 · This chapter provides an overview of their diverse functions in defense against leaf-eating herbivores and pathogens, in modulating dispersal in fruits and ...
[67]
https://doi.org/10.3390/plants14030493
[68]
[PDF] 1 Effects of Three Natural Dietary Compounds on Insect Pests 1
May 29, 2025 · the digestive system of insect larvae. The increase in the ... impact on some detoxification enzymes. J. Entomol. Acarol. Res., 54 ...
[69]
Light regulates the synthesis and accumulation of plant secondary ...
UV-A significantly enhances the content of gallotannins and ellagitannins in Eucalyptus camaldulensis by altering the expression of phenolic compounds (Khanal ...