tannins and ellagitannin

Tannins are plant defense substances that exhibit a strong astringent taste and precipitate proteins, leading to the inhibition of protein functions; however, owing to their relatively low toxicity, tannins must be accumulated in high concentrations in cell vacuoles. Therefore, the solubility of tannins is crucial for their functions. In this review, the structure and reactions of tannins related to solubility; insolubilization of persimmon proanthocyanidins on fruit ripening; pigment formation from cinnamon procyanidins by reaction with cinnamaldehyde in case of wounding; and insolubilization of ellagitannins in chestnut wood is discussed. In addition, the development of functional polyphenols including oil-soluble tea catechins is introduced.

Topics: Acrolein; Aesculus; Antioxidants; Catechin; Cinnamomum zeylanicum; Diospyros; Hydrolyzable Tannins; Oils, Volatile; Oxidation-Reduction; Polyphenols; Proanthocyanidins; Solubility; Tannins; Tea; Water

Topics: Animals; Antineoplastic Agents; Antioxidants; Hydrolyzable Tannins; Molecular Structure; Oxidation-Reduction; Plants; Tannins

Isolation and structure determination, accompanied by measurement of various biological activities of each isolated tannin, particularly of ellagitannins, have brought about a marked change in the concept of tannins as active constituents of medicinal plants. Their biological activities should now be discussed on the basis of the structural differences among each tannin, in a way similar to that of the other types of natural organic compounds. The anti-tumor activity exclusively exhibited by several oligomeric ellagitannins, and their anti-HIV activities are examples of such biological activities. The inhibitory activity against lipid peroxidation, which is different in the strength among tannins of various structures, is exhibited in general more strongly by ellagitannins than by the other types of tannins of similar structures. The radical-scavenging activities of tannins as the mechanism of their inhibition, which is regarded to participate in several biological activities of tannins, have been supported by the ESR spectral measurements. Other biological activities, i.e., inhibition of mutagenicity of carcinogens, inhibition of tumor promotion, etc., have been found for tannins including ellagitannins.

Topics: Hydrolyzable Tannins; Plants, Medicinal; Structure-Activity Relationship; Tannins

Ellagitannins are the main extractible phenolic compounds in oak wood. They can be extracted by eaux-de-vie aging in barrels but rapidly undergo chemical transformations, such as hydrolysis, reduction, oxidation, or even substitution reactions. Given gaps in knowledge about their composition in spirits, the goal of this work was to explore ellagitannin behavior during Cognac eaux-de-vie aging and search for new C-glucosidic ellagitannin-derived compounds. A purification protocol was followed to isolate the new formed compounds. UPLC-UV-Q-ToF and NMR spectroscopy were used to characterize a new C-glucosidic ellagitannin, named brandy tannin B. Two new forms of whiskey tannins were also isolated. The new compound, Brandy tannin B along with β-1-O-ethylvescalagin and β-1-O-ethylvescalin, and whiskey tannins were identified and quantified for the first time in Cognac eaux-de-vie. In addition, the organoleptic impact of brandy tannin B was evaluated. This work brings new insights into ellagitannin composition and their contribution to spirit quality.

Topics: Glucosides; Hydrolyzable Tannins; Quercus; Tannins; Wine; Wood

Neuraminidaseis a key enzyme in the life cycle of influenza viruses and is present in some bacterial pathogens. We here assess the inhibitory potency of plant tannins versus clinically used inhibitors on both a viral and a bacterial model neuraminidase by applying the 2'-(4-methylumbelliferyl)-α-d-

Topics: Anti-Bacterial Agents; Antiviral Agents; Drug Synergism; Enzyme Assays; Hydrolyzable Tannins; Inhibitory Concentration 50; Neuraminidase; Oseltamivir; Tannins; Vibrio cholerae; Viral Proteins; Zanamivir

Hepatocellular carcinoma (HCC) is the fifth most common cancer worldwide and is the third most common cause of cancer-related deaths. Currently available treatment options for HCC patients are scarce resulting in an urgent need to develop a novel effective cure. Polygonum capitatum is a medicinal herb which has been used to treat inflammatory diseases in Miao nationality of China. We recently isolated a pure compound davidiin from P. capitatum extract. Four HCC cell lines were treated with davidiin. Cell viability was recorded by MTT assay. siRNAs targeting enhancer of zeste homolog 2 (EZH2) were applied to modulate the expression of EZH2. Established xenograft mice models of HCC were applied to evaluate the in vivo anticancer activity of davidiin. We investigated the anticancer activity and the underlying mechanism of davidiin. The compound inhibited HCC cell growth and also suppressed tumor growth in xenografted HCC mouse. Such inhibition was facilitated by specifically downregulation on EZH2. The compound possesses anticancer activity both in vitro and in vivo which warrants further clinical investigation as a potential anti-HCC agent.

Topics: Animals; Apoptosis; Carcinoma, Hepatocellular; Cell Line, Tumor; Cell Proliferation; Disease Models, Animal; Drug Resistance, Neoplasm; Enhancer of Zeste Homolog 2 Protein; Gene Expression Regulation, Neoplastic; Gene Knockdown Techniques; Humans; Hydrolyzable Tannins; Liver Neoplasms; Male; Mice; Polycomb Repressive Complex 2; Proteasome Endopeptidase Complex; Tannins; Tumor Burden; Xenograft Model Antitumor Assays

Four hydrolyzable tannins, nobotanins Q, R, S, and T, were isolated from the aqueous acetone extract of the dried leaves of Monochaetum multiflorum (Melastomataceae), a plant indigenous to Colombia. Their dimeric and tetrameric structures were elucidated by spectral and chemical methods. Eight known hydrolyzable tannin monomers and eight ellagitannin oligomers characteristic of melastomataceous plants were also characterized as tannin constituents of the plant.

Topics: Dimerization; Glucose; Hydrolysis; Hydrolyzable Tannins; Melastomataceae; Molecular Structure; Nuclear Magnetic Resonance, Biomolecular; Plant Extracts; Plant Leaves; Tannins

A new ellagitannin, jolkinin (2), was isolated from the fresh whole plant of Euphorbia jolkinii, and its structure, including absolute configuration, was determined on the basis of spectroscopic and chemical evidence. A highly oxygenated acyl group with unique hexacyclic structure is attached to the 2,4-positions of 1-O-galloyl-3,6-(R)-hexahydroxydiphenoyl-beta-d-glucopyranose. The structural similarity to elaeocarpusin (4) suggests that jolkinin is produced by a condensation reaction between ascorbic acid and geraniin (1), the dominant ellagitannin in this plant, which contains a dehydrohexahydroxydiphenoyl group. A plausible mechanism for jolkinin formation is also proposed.

Topics: Euphorbia; Glucosides; Hydrolyzable Tannins; Japan; Molecular Structure; Nuclear Magnetic Resonance, Biomolecular; Stereoisomerism; Tannins

A new enzyme has been isolated from leaves of the weed Tellima grandiflora (fringe cups, Saxifragaceae) that catalyzed the O(2)-dependent oxidation of 1,2,3,4,6-penta-O-galloyl-beta-D-glucopyranose to tellimagrandin II, the first intermediate in the (4)C(1)-glucose derived series of ellagitannins. CD-spectra revealed that the 4,6-O-HHDP-residue of the in vitro product had the (S)-stereoconfiguration characteristic of tellimagrandin II from natural sources. The enzyme, for which a M(r) of ca. 60,000 was determined, was purified to apparent homogeneity. It had a pH-optimum at pH 5.0, an isoelectric point at pH 6.3 and was most stable at pH 4.2. Inhibition studies suggested that this new enzyme, for which the systematic name 'pentagalloylglucose: O(2) oxidoreductase' is proposed, belongs to the vast group of laccase-type phenol oxidases (EC 1.10.3.2).

Topics: Chromatography, High Pressure Liquid; Electrophoresis, Polyacrylamide Gel; Enzyme Inhibitors; Gallic Acid; Glucosides; Hydrogen-Ion Concentration; Hydrolyzable Tannins; Molecular Weight; Monophenol Monooxygenase; Oxidation-Reduction; Plant Leaves; Saxifragaceae; Stereoisomerism; Tannins

Fourteen extracts from Brazilian traditional medicinal plants used to treat infectious diseases were used to look for potential antimicrobial activity against multiresistant bacteria of medical importance. Staphylococcus aureus strains were susceptible to extracts of Punica granatum and Tabebuia avellanedae. The minimum inhibitory concentrations (MICs) of the total extracts and of additional fractions of these plants were determined by employing strains of methicillin-resistant (MRSA) and -sensitive (MSSA) S. aureus, including isolates of the PFGE clone A, which is prevalent in Brazil and two ATCC reference strains. A mixture of ellagitannins isolated from P. granatum and two naphthoquinones isolated from T. avellanedae demonstrated antibacterial activity against all S. aureus strains tested. Semi-synthetic furanonaphthoquinones (FNQs) showed lower MICs than those exhibited by natural occurring naphthoquinones. The results indicate that these natural products can be effective potential candidates for the development of new strategies to treat MRSA infections.

Topics: Brazil; Humans; Hydrolyzable Tannins; In Vitro Techniques; Lythraceae; Methicillin Resistance; Microbial Sensitivity Tests; Naphthoquinones; Phytotherapy; Plant Extracts; Plants, Medicinal; Staphylococcal Infections; Staphylococcus aureus; Tabebuia; Tannins

Tannins and lignins are natural compounds contained in plants such as tea leaves. Previously, we demonstrated that tannic acid represses 12-o-tetra-decanoyl phorbol-13-acetate (TPA)-induced human immunodeficiency virus (HIV) promoter activity. Furthermore, we demonstrated that a 30-bp element located just downstream of the NF-kappaB element in the HIV promoter responds negatively to tannic acid. However, the kinds of molecules responsible for this suppressive effect have remained unknown, because tannic acid is a mixture of various galloylglucoses. Here, we examined structure-defined natural compounds for HIV promoter-suppressive effects. We found that ellagitannins suppress TPA-induced HIV promoter activity to the same extent as tannic acid. 3-phenylcoumarins, isoflavone and chalcones have more suppressive effects than ellagitannins. On the other hand, other flavonoids and acetogenins have no suppressive effect. 3-phenylcoumarins and chalcones showed no suppressive effect on the cytomegalovirus (CMV) promoter, suggesting that they act specifically on the HIV promoter. These results suggest that 3-phenylcoumarin or chalcone compounds could be used to develop novel anti-HIV drugs with an action targeted at HIV promoter activity.

Topics: Anti-HIV Agents; Chalcone; Coumarins; Flavonoids; Gene Expression Regulation, Viral; HIV; HIV Infections; Humans; Hydrolyzable Tannins; Jurkat Cells; Promoter Regions, Genetic; Tannins; Tetradecanoylphorbol Acetate; Transfection

Four new dimeric ellagitannins, paeonianins A-D (2-5), were isolated from the fruits of Paeonia lactiflora, together with a new ellagitannin monomer, paeonianin E (1). Their structures were determined by spectroscopic methods. Paeonianins A-D (2-5) are positional isomers formed by condensation of pentagalloyl-beta-D-glucose (8) with 5-desgalloylstachyurin (6) or casuariin (7). Paeonianin E is a C-glycosidic ellagitannin having a gallic acid methyl ester moiety at the glucose C-1 position. This is the first report of the isolation of dimeric ellagitannins from a plant in the family Paeoniaceae.

Topics: Fruit; Glucosides; Hydrolyzable Tannins; Japan; Molecular Structure; Nuclear Magnetic Resonance, Biomolecular; Paeonia; Plants, Medicinal; Stereoisomerism; Tannins

The new natural caffeoyl esters, 3,6-di-O-caffeoyl-(alpha/beta)-glucose and 1-O-caffeoyl-beta-xylose, together with the hitherto unknown natural tannin, 2,3-O-hexahydroxydiphenoyl-4,6-O-sanguisorboyl-(alpha/beta)-glucose, have been isolated from the aqueous alcohol aerial part extract of Rubus sanctus. Establishment of all structures was based on the chemical and spectral evidence, including ESI-MS and 2D NMR.

Topics: Caffeic Acids; Carbohydrate Conformation; Esters; Glucose; Hydrolyzable Tannins; Molecular Structure; Nuclear Magnetic Resonance, Biomolecular; Plants, Medicinal; Rosaceae; Spectrophotometry, Ultraviolet; Tannins; Xylose

First evidence for the in vitro synthesis of a dimeric ellagitannin has been obtained with cell-free extracts from the weed Tellima grandiflora (fringe cups, Saxifragaceae). Partially purified enzyme preparations from leaves of this plant catalyzed the oxidation of 1,2,3,4,6-pentagalloyl-beta-D-glucose to the monomeric ellagitannin, tellimagrandin II, followed by oxidative coupling of two units of this intermediate to yield a dimeric derivative. Chemical degradation, MALDI-TOF mass spectrometry, 1H and 13C nuclear magnetic resonance, and CD spectroscopy were employed to identify this enzyme reaction product as cornusiin E which is characterized by a (S)-valoneoyl bridge between glucose-positions 2, 4' and 6'. This result was supported by comparison with data obtained for cornusiin E that had been isolated from leaves of intact T. grandiflora plants. No indication for the earlier proposed existence of rugosin D (an isomer with a 1,4',6'-bound valoneoyl unit) in T. grandiflora has been obtained in this investigation.

Topics: Dimerization; Gallic Acid; Glucosides; Hydrolyzable Tannins; Magnetic Resonance Spectroscopy; Monophenol Monooxygenase; Oxidation-Reduction; Plant Leaves; Saxifragaceae; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; Tannins

The synthesis of a 2,4-HHDP containing glucopyranose ellagitannin model system has been achieved. Attempts to prepare a related target bearing a 1,6 bridge led instead to the discovery of a likely strain-driven tautomerization to cyclohexadienone intermediates.

Topics: Biphenyl Compounds; Glucose; Hydrolyzable Tannins; Models, Molecular; Plants; Tannins

An enzyme has been purified from leaves of the weed Tellima grandiflora (fringe cups, Saxifragaceae) that catalyzed the O2-dependent oxidation of the monomeric ellagitannin, tellimagrandin II, to a dimeric derivative, cornusiin E. The apparently homogeneous enzyme preparation had a Mr of ca. 160,000 (with four subunits of Mr 40,000), a pH-optimum and an isoelectric point at pH 5.2, and was most stable at pH 4.3. Inhibition studies revealed that this new enzyme, for which the systematic name 'tellimagrandin II: O2 oxidoreductase' is proposed, is a member of the laccase (EC 1.10.3.2) family of phenol oxidases. The properties of this enzyme differed from that of a related laccase that catalyzed the transition of 1,2,3,4,6-pentagalloylglucopyranose to tellimagrandin II, the preceding step in the biosynthetic route to cornusin E.

Topics: Catalysis; Dimerization; Enzyme Inhibitors; Gallic Acid; Glucosides; Hydrolyzable Tannins; Laccase; Oxidation-Reduction; Plant Leaves; Saxifragaceae; Tannins

Topics: Benzopyrans; Enzyme Inhibitors; Flavonoids; Hydrolyzable Tannins; Tannins; Topoisomerase I Inhibitors; Wine

Analysis of extracts of Glen Ample raspberries (Rubus idaeus L.) by gradient, reverse phase HPLC with diode array and tandem mass spectrometry identified eleven anthocyanins, including cyanidin-3-sophoroside, cyanidin-3-(2(G)-glucosylrutinoside), cyanidin-3-glucoside, cyanidin-3-rutinoside, pelargonidin-3-sophoroside, pelargonidin-3-(2(G)-glucosylrutinoside), and pelargonidin-3-glucoside. Significant quantities of an ellagitannin, sanguiin H-6, with an M(r) of 1870 were detected along with lower levels of a second ellagitannin, lambertianin C, which has an M(r) of 2804. Other phenolic compounds that were detected included trace levels of ellagic acid and its sugar conjugates along with one kaempferol- and four quercetin-based flavonol conjugates. Fractionation by preparative HPLC revealed that sanguiin H-6 was a major contributor to the antioxidant capacity of raspberries together with vitamin C and the anthocyanins. Vasodilation activity was restricted to fractions containing lambertianin C and sanguiin H-6.

Topics: Animals; Anthocyanins; Antioxidants; Chemical Fractionation; Chromatography, High Pressure Liquid; Electron Spin Resonance Spectroscopy; Flavonoids; Fruit; Hydrolyzable Tannins; Male; Mass Spectrometry; Phenols; Plant Extracts; Rabbits; Rosaceae; Tannins; Vasodilator Agents

Scottish-grown red raspberries are a rich source of vitamin C and phenolics, most notably, the anthocyanins cyanidin-3-sophoroside, cyanidin-3-(2(G)-glucosylrutinoside), and cyanidin-3-glucoside, and two ellagitannins, sanguiin H-6 and lambertianin C, which are present together with trace levels of flavonols, ellagic acid, and hydroxycinnamates. The antioxidant capacity of the fresh fruit and the levels of vitamin C and phenolics were not affected by freezing. When fruit were stored at 4 degrees C for 3 days and then at 18 degrees C for 24 h, mimicking the route fresh fruit takes after harvest to the supermarket and onto the consumer's table, anthocyanin levels were unaffected while vitamin C levels declined and those of elligitannins increased, and overall, there was no effect on the antioxidant capacity of the fruit. It is concluded, therefore, that freshly picked, fresh commercial, and frozen raspberries all contain similar levels of phytochemicals and antioxidants per serving.

Topics: Antioxidants; Ascorbic Acid; Coumaric Acids; Electron Spin Resonance Spectroscopy; Ellagic Acid; Flavonoids; Food Preservation; Freezing; Fruit; Hydrolyzable Tannins; Phenols; Rosaceae; Tannins

The chemical composition of cooperage oak wood is highly variable, depending upon the tree species (Quercus robur L. versus Quercus petraea Liebl.), its geographic location, and the single-tree effect. In the process of cask-making, natural seasoning and toasting contribute strongly to the modification of the oak wood chemical composition and therefore influence wine cooperaging. HPLC and GC quantification of ellagitannins and volatile compounds such as whiskey-lactones, eugenol, and vanillin over a sample set of 61 pedunculate oaks and 72 sessile oaks originating from six different forests showed that natural drying leads to a decrease of the ellagitannins and total extractives content level and a quasi constant level of the volatile compounds. Toasting (medium type) drastically enhanced the loss of ellagitannins and the gain in volatile compounds. Statistical treatment showed that the species effect remained significant throughout the process of drying and toasting, but not the provenance. The poor correlation with ring width of extractives levels measured on fresh timber remained unchanged as did the single-tree effect, with high variability found for all chemical parameters. These results provide further evidence that cooperage oak selection should not be based solely on the wood grain or the provenance but rather on a species-provenance combination.

Topics: Benzaldehydes; Chromatography, Gas; Chromatography, High Pressure Liquid; Desiccation; Eugenol; Hydrolyzable Tannins; Lactones; Quercus; Species Specificity; Tannins; Volatilization; Wine; Wood

The inhibitory effect of galloyl pedunculagin (GP) isolated from Platycarya strobilacea on the activity and autophosphorylation of Ca(2+)- and phospholipid-dependent protein kinase (C-kinase) was examined in vitro. It was found that (i). GP inhibited the activity (phosphorylation of complement C3 from guinea pig) of C-kinase alpha (rat brain) in a dose-dependent manner with an ID(50) of approx. 0.12 micro M (ii). GP at lower doses (ID(50)=approx. 6 nM) inhibited autophosphorylation of C-kinase alpha; and (iii). the GP-induced inhibition of autophosphorylation of C-kinase alpha and its enzyme activity was a manner non-competitive to ATP. Similar inhibitory effect of GP on autophosphorylation of recombinant human C-kinase eta (rhC-kinase eta) and its phosphorylating activity was observed. These results suggest that GP is an effective autophosphorylation inhibitor of these two C-kinase isoforms (alpha and eta) in vitro. In addition, the CD analysis suggests that the proline-containing six amino acid residues (PVLTPP) including a threonine residue (autophosphorylation site) at the C-terminal region (positions 635-640) of C-kinase alpha may be one of the GP-binding sites.

Topics: Animals; Carrier Proteins; Guinea Pigs; Humans; Hydrolyzable Tannins; Intracellular Signaling Peptides and Proteins; Isoenzymes; Phosphorylation; Plant Extracts; Protein Kinase C; Rats; Tannins

Oenotherin T(1) was isolated from leaves of Oenothera tetraptera as a major ellagitannin. Its structure, that of a macrocyclic trimer with a new acyl group, an isodehydrovaloneoyl group, was established. This compound was also produced by callus tissues induced from O. laciniata leaves.

Topics: Cells, Cultured; Hydrolyzable Tannins; Onagraceae; Plant Leaves; Plants, Medicinal; Tannins

Glucose transport enhancers were searched for in Lagerstroemia speciosa, a Philippine local herbal medicine used for diabetes mellitus. Bioassay-guided fractionation of the aqueous acetone extract of the leaves afforded three active ellagitannins, lagerstroemin, flosin B and reginin A, identified by NMR and optical rotation. These compounds increased glucose uptake of rat adipocytes, and could be responsible for lowering the blood glucose level.

Topics: Adipocytes; Animals; Biological Transport; Deoxyglucose; Hydrolyzable Tannins; Lythraceae; Monosaccharide Transport Proteins; Philippines; Plant Extracts; Plant Leaves; Rats; Tannins

A widely used method for analyzing hydrolyzable tannins afer reaction with KIO(3) has been modified to include a methanolysis step followed by oxidation with KIO(3). In the new method, hydrolyzable tannins (gallotannins and ellagitannins) are reacted at 85 degrees C for 20 h in methanol/sulfuric acid to quantitatively release methyl gallate. Dried plant samples can be methanolyzed under the same conditions to convert hydrolyzable tannins to methyl gallate. Oxidation of the methyl gallate by KIO(3) at pH 5.5, 30 degrees C, forms a chromophore with lambda(max) 525 nm, which is determined spectrophotometrically. The detection limit of the method is 1.5 microg of methyl gallate, and with plant samples, relative standard deviations of less than 3% were obtained.

Topics: Chromatography, High Pressure Liquid; Gallic Acid; Hydrolysis; Hydrolyzable Tannins; Iodates; Methanol; Oxidation-Reduction; Plants, Edible; Potassium Compounds; Spectrophotometry; Sulfuric Acids; Tannins

A mechanism for the formation of water-insoluble sediments in wines and juices made from red and white muscadine grapes (Vitis rotundifolia) was investigated as a function of processing methodology and storage. Sediments are considered quality defects in muscadine grape products, and their presence may influence consumer acceptability and expansion of retail markets. Processing regimes included both hot (70 degrees C) and cold (25 degrees C) press techniques for wine or juice production, and fermentations in contact with grape skins for 3, 5, and 7 days. Relationships between free ellagic acid (FE), total ellagitannins (ET), and total ellagic acid (TE) concentrations were evaluated initially in each product and in sediments that formed during storage for 50 and 120 days at 20 degrees C. Processing techniques influenced initial concentrations of these compounds and the extent of sediment formation. Following storage, juices generally had higher concentrations of FE in sediments compared to wines, but sedimentation was independent of initial FE or TE concentrations. Decreases in ET were observed for hot-pressed juice and skin-fermented wines after storage indicating their hydrolysis during storage and possible contribution to FE in sediments. However, quantitative analysis of the collected sediments revealed that no more than 12% FE by weight was actually present in the sediments, with the remainder consisting of either unidentified compounds or conjugated forms of ellagic acid. This work elucidated a potential mechanism for the presence of FE in muscadine wine and juice sediments through ellagitannin hydrolysis and suggests that sedimentation from mechanisms other than ellagic acid precipitation may also contribute to wine and juice quality.

Topics: Beverages; Chromatography, High Pressure Liquid; Ellagic Acid; Food Technology; Hydrolyzable Tannins; Spectrophotometry, Ultraviolet; Tannins; Vitis; Wine

A new ellagitannin, methyl (S)-flavogallonate (14) along with fourteen known compounds, gallic acid, methyl gallate, ethyl gallate, 2,3-di-O-[( S)-4,5,6,4',5',6'-hexahydroxybiphenyl-2,2'-diyldicarbonyl]-(alpha/beta)-D-glucopyranose (4), vitexin, isovitexin, orientin, iso-orientin, kaempferol 3-O-beta-D-rutinoside, rutin, neosaponarin, ellagic acid, flavogallonic acid (13), and (alpha/beta)-punicalagin (15) have been isolated from the leaves of Terminalia myriocarpa Heurck. Protective effect of the major and structurally related compounds 4, 13, 15 and the new compound 14 against CCl 4 -induced hepatotoxicity has been evaluated and compared, using adult male rats weighing 200-250 g. Serum levels of glutamic oxaloacetic transaminase (GOT), glutamic pyruvic transaminase (GPT), lipid peroxide and nitric oxide production were significantly increased by administration of CCl 4 to rats and then reduced significantly only by treatment with compounds 4, 14 and 15 in a dose-dependent manner. Comparison of the protective properties of these compounds showed that compound 14 is more potent than compound 15 than 4 and that compound 13 has a non-significant effect at the used two dose levels.

Topics: Alanine Transaminase; Animals; Antioxidants; Aspartate Aminotransferases; Carbon Tetrachloride; Hydrolyzable Tannins; Lipid Peroxidation; Lipid Peroxides; Magnetic Resonance Spectroscopy; Male; Nitric Oxide; Plant Extracts; Plant Leaves; Rats; Rats, Sprague-Dawley; Silymarin; Tannins; Terminalia

The inhibitory effects of galloyl pedunculagin (GP) and eugeniin on the phosphorylation of histone H2B by cAMP-dependent protein kinase (A-kinase) and autophosphorylation of its beta-regulatory subunit (A-kinase beta) were examined in vitro. It was found that (i) GP (ID(50) = approx. 50 nM) effectively inhibits the activity of A-kinase (heterodimer), but high doses are required to inhibit the activities of the alpha-catalytic subunit (ID(50) = approx. 0.25 microM) and casein kinase II (CK-II, ID(50) = approx. 0.6 microM); (ii) GP inhibits the autophosphorylation of A-kinase beta in a dose-dependent manner with an ID(50) of approx. 6.6 nM, which is about 30-fold lower than that observed with CK-II beta; and (iii) GP reduces the suppressive effect of the beta-subunit on the activity of the alpha-subunit. In addition, purified bovine heart A-kinase precipitates when incubated with excess GP at pH 5.0. A similar precipitation of A-kinase was observed with eugeniin. These results show that the direct binding of GP to the beta-subunit prevents the physiological interaction between the beta- and alpha-subunits of A-kinase in vitro. This conclusion is presumably consistent with the binding affinity of proline-rich proteins with tannins, since A-kinase beta contains a proline-rich domain that interacts with GP or eugeniin. Therefore, GP will serve as a powerful inhibitor for in vitro and in vivo cellular studies of A-kinase beta-mediated signal transduction.

Topics: Animals; Antioxidants; Binding Sites; Casein Kinase II; Catalytic Domain; Cattle; Chemical Precipitation; Cyclic AMP-Dependent Protein Kinases; Dimerization; Dose-Response Relationship, Drug; Enzyme Inhibitors; Flavonoids; Gallic Acid; Glucosides; Histones; Hydrolyzable Tannins; Kinetics; Molecular Structure; Phenols; Phosphorylation; Polymers; Protein Binding; Protein Serine-Threonine Kinases; Protein Structure, Tertiary; Protein Subunits; Quercetin; Substrate Specificity; Swine; Tannins

The clove ellagitannins and their related polygalloyl-glucoses inhibited maltase activity of rat intestinal alpha-glucosidases. The structure-activity relationship study of those galloylglucoses, varying the extent of galloylation on the glucose core, with the ellagitannins, indicated that an increasing number of galloyl units in the molecule lead to an increase in the inhibitory activity. Penta-O-galloyl-beta-D-glucose, with five galloyl groups showed the highest inhibitory activity. On the other hand, hexahydroxydiphenoyl units contained in the ellagitannins had little effect on the activity. After separation of maltase-glucoamylase and sucrase-isomaltase complexes from the crude mixture of the rat alpha-glucosidases, the inhibitory activities of the galloylglucose derivatives against each complex were examined. The inhibitory influence on the maltase-glucoamylase complex was more potent than on the sucrase-isomaltase complex.

Topics: Animals; Biphenyl Compounds; Gallic Acid; Glucose; Glucosides; Glycoside Hydrolase Inhibitors; Hydrolyzable Tannins; Molecular Structure; Rats; Tannins

The evolution of tannins in Spanish oak heartwood of Quercus robur L., Quercus petraea Liebl.,Quercus pyrenaica Wild., and Quercus faginea Lam. was studied in relation to the processing of wood in barrel cooperage. Their evolution was compared with that of French oak of Q. robur (Limousin, France) and Q. petraea (Allier, France) and American oak of Quercus alba L. (Missouri), which are habitually used in cooperage. Two stages of process were researched: the seasoning of woods during 3 years in natural conditions and toasting. Total phenol and total ellagitannin contents and optical density at 420 nm of wood extracts were determined. The ellagitannins roburins A-E, grandinin, vescalagin, and castalagin were identified and quantified by HPLC, and the molecular weight distribution of ellagitannins was calculated by GPC. During the seasoning process the different ellagitannin concentrations decreased according to the duration of this process and in the same way as those in French and American woods. The toasting process also had an important influence on the ellagitannin composition of wood. Roburins A-E, grandinin, vescalagin, and castalagin decreased during this process in the Spanish wood species, in the same proportion as in the French and American ones. Also, the seasoning and toasting processes lead to qualitative variations in the structure of ellagitannins, especially in the molecular weight distribution, as was evidenced by GPC analysis of their acetylated derivatives.

Topics: Chromatography, High Pressure Liquid; Food Handling; Hydrolyzable Tannins; Molecular Weight; Phenols; Tannins; Wood

Ellagitannins isolated from various plant sources as well as newly synthesized n-alkyl (C(1)-C(18)) esters of hexahydroxydiphenyl (HHDP) dicarboxylic acid were evaluated as enzyme inhibitors of recombinant rat squalene epoxidase, a rate-limiting enzyme of cholesterol biosynthesis. Among the ellagitannins tested, pedunculagin (IC(50) = 2.0 microM) and eugeniin (IC(50) = 1.6 microM), both containing (S)-HHDP ester group(s), showed remarkable inhibition, which was more potent than those of previously reported substrate analogue inhibitors. Furthermore, ellagic acid (IC(50) = 2.0 microM), a bislactone formed by hydrolytic release of a HHDP group from ellagitannins, was also a good inhibitor of the enzyme. On the other hand, the synthetic HHDP esters with C(6) (IC(50) = 0.93 microM) and C(8) alkyl side chains (IC(50) = 0.83 microM) showed potent enzyme inhibition at the submicromolar concentration range, while esters with shorter chain lengths (C(1)-C(4)) and a C(18) ester exhibited moderate inhibition (IC(50) = 8-47 microM).

Topics: Animals; Biphenyl Compounds; Chromatography, Thin Layer; Enzyme Inhibitors; Esters; Farnesyl-Diphosphate Farnesyltransferase; Hydrolyzable Tannins; Molecular Structure; Rats; Recombinant Proteins; Squalene; Structure-Activity Relationship; Substrate Specificity; Tannins

The synthesis of "naked" ellagitannin analogues 1 and 2, having a preferred sense of twist of the diphenyl moiety, with a rhamnose and a glucose template, is reported. A clear induction in the chirality of the diphenyl moiety, mediated through a 10-membered ring via ester linkages, was observed. The chiral scaffold of glucose (diequatorial 2,3-hydroxyl groups) exerts a remarkable stronger atropdiastereoselective effect onto the diphenoyl group than the rhamnose ring (axial-equatorial 2,3-hydroxyl groups), according to the Schmidt-Haslam hypothesis.

Topics: Biphenyl Compounds; Carbohydrates; Circular Dichroism; Hydrolyzable Tannins; Indicators and Reagents; Spectrophotometry, Ultraviolet; Stereoisomerism; Tannins

Six new ellagitannins, phyllanemblinins A-F (1-6), were isolated from Phyllanthus emblica, along with 30 known tannins and related compounds. Their structures were determined by spectral and chemical methods. Phyllanemblinins A (1) and B (2) were confirmed to be ellagitannins having a tetrahydroxybenzofuran dicarboxyl group and a hexahydroxydiphenoyl group, respectively, by chemical synthesis from furosin (8). Phyllanemblinin C (3) has a new acyl group at the glucose 2,4-positions and is structurally related to chebulagic acid. Phyllanemblinins D (4), E (5), and F (6) were found to be positional isomers of neochebuloyl 1(beta)-O-galloylglucose.

Topics: Antineoplastic Agents, Phytogenic; Chemical Phenomena; Chemistry, Physical; Chromatography, Thin Layer; Circular Dichroism; Crystallography, X-Ray; Drug Screening Assays, Antitumor; Drugs, Chinese Herbal; Euphorbiaceae; Fruit; HeLa Cells; HL-60 Cells; Humans; Hydrolyzable Tannins; Molecular Conformation; Molecular Structure; Nuclear Magnetic Resonance, Biomolecular; Plant Bark; Plant Leaves; Plant Stems; Plants, Medicinal; Spectrophotometry, Infrared; Spectrophotometry, Ultraviolet; Stereoisomerism; Tannins; Tumor Cells, Cultured

We investigated a number of natural polyphenols representing flavan-3-ols, gallotannins, and ellagitannins with regard to their antioxidant potential. For this purpose we used pulse radiolysis to determine scavenging rate constants with hydroxyl radicals and decay rates of the respective aroxyl radicals and EPR spectroscopy to identify the radicals after in situ oxidation. Using NMR spectroscopy, we could confirm phenolic coupling reactions of epigallocatechin gallate and pentagalloyl glucose after radical-induced oxidation.

Topics: Anthocyanins; Antioxidants; Catechin; Dimerization; Electron Spin Resonance Spectroscopy; Hydrogen Peroxide; Hydrolysis; Hydrolyzable Tannins; Hydroxyl Radical; Magnetic Resonance Spectroscopy; Models, Chemical; Oxygen; Phenol; Proanthocyanidins; Tannins; Time Factors

Polyphenols are major components of many traditional herbal remedies, which exhibit several beneficial effects including anti-inflammation. The exact mechanism of the anti-inflammatory action of polyphenols, however, has not been determined. In the present study, we examined the effects of eight different polyphenols isolated from Chinese herbs, including two flavonoids (myricitrin and oroxylin A), four ellagitannins (penta-O-galloyl-beta-glucopyranose, woodfordin C, oenothein B, and cuphiin D1), and two anthraquinones (emodin and physcion), on lipopolysaccharide (LPS)-induced nitric oxide (NO) production, and inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) gene expression in RAW264.7 macrophages. The results indicated that only oroxylin A and emodin concentration-dependently inhibited LPS-induced NO production. The remaining compounds slightly inhibited LPS-induced NO production only at the highest concentration examined. Furthermore, oroxylin A inhibited the expression of LPS-induced iNOS and COX-2 proteins and mRNAs without an appreciable cytotoxic effect on RAW264.7 cells. Emodin also inhibited LPS-induced iNOS protein as potently as oroxylin A, but it inhibited LPS-induced iNOS mRNA expression only slightly and did not affect COX-2 mRNA and proteins. This was consistent with the findings that oroxylin A but not emodin or physcion inhibited prostaglandin E(2) synthesis induced by LPS. The inhibitory effects of oroxylin A on LPS-induced iNOS and COX-2 gene expression were also demonstrated in Bcl-2-overexpressing RAW264.7 macrophages, suggesting that oroxylin A inhibition of iNOS and COX-2 expression was not due to its antioxidant effect. Furthermore, oroxylin A but not emodin blocked nuclear factor-kappaB (NF-kappaB) binding and transcriptional activation associated with decreased p65 proteins in the nucleus induced by LPS. These results indicated that oroxylin A, an active component in Huang Qin, inhibited LPS-induced iNOS and COX-2 gene expression by blocking NF-kappaB activation, whereas emodin inhibition of LPS-induced iNOS expression may be mediated by a different transcription factor.

Topics: Animals; Anthraquinones; Cells, Cultured; Cyclooxygenase 2; Emodin; Flavonoids; Gene Expression Regulation, Enzymologic; Hydrolyzable Tannins; Isoenzymes; Lipopolysaccharides; Macrophages; Mice; NF-kappa B; Nitric Oxide; Nitric Oxide Synthase; Nitric Oxide Synthase Type II; Phenols; Polymers; Prostaglandin-Endoperoxide Synthases; Tannins

The range of natural ellagitannins is extended by identification of five new metabolites with 1C4 glucose core, designated as pelargoniins A-D and isocorilagin, and the new phyllanthusiin E methyl ester. They are accompanied in the aerial parts of Pelargonium reniforme by two known structurally related metabolites, corilagin and phyllanthusiin C, two phenolcarboxylic acids, brevifolincarboxylic acid and phyllanthusiin E, the gallotannin 1-O-galloyl-beta-D-glucopyranose, and the ellagitannins strictinin and isostrictinin having a 4C1-glucose core. The structures of these compounds were established from spectroscopic studies. This is the first example of the co-occurrence of ellagitannins with 4C1 and 1C4 glucopyranose core demonstrated for a member of the Geraniaceae.

Topics: Chromatography, Ion Exchange; Hydrolyzable Tannins; Molecular Structure; Rosales; Spectrum Analysis; Tannins

The total synthesis of the dimeric ellagitannin coriariin A is reported. The key reaction to access the dimeric framework was realized early in the synthesis pathway via a bis acylation reaction of a dehydrodigalloyl diacid with 2 equiv of a glucopyranose trichloroacetimidate. The glucose rings were subsequently functionalized, culminating in a double oxidative cyclization to form stereoselectively both (S)-HHDP ester units. This bis acylation strategy was also employed to prepare a gallotannin analogue of coriariin A whose earlier synthesis by orthoquinone dimerization was plagued by yield-limiting side reactions.

Topics: Hydrolyzable Tannins; Tannins

Terminalia macroptera roots are used in Guinea-Bissau and other West African countries to treat infectious diseases like gonorrhoea. Previous work showed an ethanol extract of T. macroptera roots (T) to have an in vitro antimicrobial profile against Neisseria gonorrhoae (including resistant strains) and enteropathogenic agents. The most active fractions of this extract were identified as the diethyl ether (T2) and water (T5) fractions. The aim of the present study was the identification of major compounds present in T and simultaneously in T2 or T5.. The T extract and T2 and T5 fractions were analysed by high performance liquid chromatography coupled with ultraviolet photodiode array (LC-UV) spectroscopy and electrospray ionization mass spectrometry (ES-MS). These analyses indicated the presence of ellagitannin derivatives. In order to confirm the identities of the detected compounds, they were isolated from T2 and T5 by preparative chromatographic techniques and identified by spectroscopic methods including tandem mass spectrometry.. By using LC-UV-ES-MS, four major compounds (ellagic acid, gallic acid, punicalagin, terchebulin) could be identified in the T extract. Three other compounds (3,3'di-O-methylellagic acid, 3,4,3',4'-tetra-O-methylellagic acid, terflavin A) were also isolated and identified.. LC-UV-ES-MS is a useful technique for the analysis of mixtures containing ellagitannins.

Topics: Chromatography, High Pressure Liquid; Hydrolyzable Tannins; Nuclear Magnetic Resonance, Biomolecular; Plant Extracts; Plant Roots; Plants, Medicinal; Spectrometry, Fluorescence; Spectrometry, Mass, Electrospray Ionization; Tannins

Seven ellagitannins isolated from Phyllanthus myrtifolius and P. urinaria (Euphorbiaceae) have been shown, for the first time, to be active against Epstein-Barr virus DNA polymerase (EBV-DP) at the microM level. All these compounds have the same moiety of a corilagin, and differ from each other by different substitutions at C-2 and C-4 of the glucose core. SAR analysis and molecular modeling reveal that the essential pharmacophore of these tannins resides in the corilagin moiety. The outer complex carboxylic acid moieties appear to act only as auxopharmacore.

Topics: Antiviral Agents; Cell Line; DNA Polymerase I; Euphorbiaceae; Herpesvirus 4, Human; Humans; Hydrolyzable Tannins; Molecular Structure; Spectrum Analysis; Structure-Activity Relationship; Tannins

Brandies, cognac, armagnac, whiskeys, and rums are aged in oak barrels to improve their organoleptic properties. During this period, numerous compounds such as ellagitannins are extracted from the wood and can subsequently be transformed into new derivatives by chemical reactions. Model solutions of castalagin and vescalagin have been studied to determine the behavior of polyphenols in ethanol-water. Upon prolonged exposure to 40 and 70% (v/v) ethanol at room temperature, hemiketal derivatives containing ethoxy groups have been characterized by LC/MS and NMR. These compounds further evolve to afford the corresponding ketals. They have also been detected in the extracts of oak wood stored under similar conditions.

Topics: Alcoholic Beverages; Antihypertensive Agents; Biphenyl Compounds; Catechols; Chromatography, High Pressure Liquid; Ethanol; Food Handling; Hydrolyzable Tannins; Molecular Conformation; Molecular Structure; Solutions; Tannins; Wood

Topics: Animals; Antineoplastic Agents, Phytogenic; Cell Survival; China; HeLa Cells; Humans; Hydrolyzable Tannins; Japan; KB Cells; Molecular Structure; Plants, Medicinal; Structure-Activity Relationship; Tannins; Tumor Cells, Cultured

Callus cultures of Oenothera laciniata grown on LS agar medium supplemented with IAA and kinetin produced large amounts of the macrocyclic ellagitannin dimer, oenothein B, and a trimer, oenothein A, accompanied with related monomeric hydrolysable tannins. The content of the main compound oenothein B (65 mg/g dry wt) in calli cultured on modified LS medium containing 10 mM NH4+ and 5 mM NO3- was nearly two times higher than that in intact leaves.

Topics: Biopolymers; Carbohydrate Sequence; Culture Techniques; Hydrolyzable Tannins; Molecular Sequence Data; Plants; Tannins

Among the nine ellagitannins, rugosin E was the most potent platelet aggregating agent with an EC50 of 1.5 +/- 0.1 microM in rabbit platelets and 3.2 +/- 0.1 microM in human platelets. The aggregations caused by rugosin E and ADP were inhibited by EGTA, PGE1, mepacrine, sodium nitroprusside and neomycin, but not by indomethacin, verapamil, TMB-8, BN52021 and GR32191B. Rugosin E-induced thromboxane formation was suppressed by indomethacin, EGTA, PGE1, verapamil, mepacrine, TMB-8 and neomycin. ADP-scavenging agents, such as CP/CPK and apyrase inhibited concentration-dependently ADP (20 microM)-, but not rugosin E (5 microM)-induced platelet aggregation. In thrombin (0.1 U/ml)-treated and degranulated platelets, rugosin E and ADP still caused 63.5 +/- 3.0% and 61.2 +/- 3.5% of platelet aggregation, respectively. Selective ADP receptor antagonists, ATP and FSBA inhibited rugosin E- and ADP-induced platelet aggregations in a concentration-dependent manner. Both rugosin E and ADP did not induce platelet aggregation in ADP (1 mM)-desensitized platelets. In contrast to ADP, rugosin E did not decrease cAMP formation in washed rabbit platelets. Both rugosin E and ADP did not cause phosphoinositide breakdown in [3H]myo-inositol-labeled rabbit platelets. In fura-2/AM-load platelets, both rugosin E and ADP induced increase in intracellular calcium concentration and these responses were inhibited by ATP and PGE1. All these data suggest that rugosin E may be an ADP receptor agonist in rabbit platelets.

Topics: Adenosine; Adenosine Diphosphate; Adenosine Triphosphate; Affinity Labels; Animals; Apyrase; Blood Platelets; Calcium; Creatine Kinase; Humans; Hydrolyzable Tannins; Inositol Phosphates; Phosphocreatine; Plant Extracts; Plants, Medicinal; Platelet Aggregation; Platelet Aggregation Inhibitors; Rabbits; Tannins; Thromboxane B2

The ellagitannins 2,3-(S)-hexahydroxydiphenoyl-glucose, pedunculagin, vescalagin, and castalagin; the flavanoellagitannins acutissimin A, acutissimin B, eugenigrandin A, guajavin B, and stenophyllanin C; and the procyanidinoellagitannin mongolicanin have been isolated from the bark of Quercus petraea. The ellagitannin fraction had a weak antisecretory effect.

Topics: Anthelmintics; Biphenyl Compounds; Catechols; Hydrolyzable Tannins; Magnetic Resonance Spectroscopy; Tannins; Trees

Seven highly active inhibitors against carbonic anhydrase (CA, EC 4.2.1.1), punicalin (2), punicalagin (3), granatin B (5), gallagyldilactone (7), casuarinin (8), pedunculagin (9) and tellimagrandin I (10), and four weakly active inhibitors, gallic acid (1), granatin A (4), corilagin (6) and ellagic acid (11), were isolated from the pericarps of Punica granatum L. (Punicaceae). They are ellagitannins. The type of inhibition by 3 and 7 using p-nitrophenyl acetate as a substrate, is noncompetitive. The structure-activity relationship of inhibitory effects on CA is discussed.

Topics: Animals; Carbonic Anhydrase Inhibitors; Carbonic Anhydrases; Cattle; Hydrolyzable Tannins; Kinetics; Nitrophenols; Plant Extracts; Plants; Structure-Activity Relationship; Tannins

The inhibitory effects on poly(ADP-ribose) glycohydrolase purified from human placenta of three classes of chemically defined tannins; gallotannins, ellagitannins and condensed tannins, were examined in vitro. Oligomeric ellagitannins were found to be most potent inhibitors of poly(ADP-ribose) glycohydrolase, their potencies increasing with increasing number of monomeric residues (dimer < trimer < tetramer). Monomeric ellagitannins and gallotannins were less inhibitory. Condensed tannins, which consist of an epicatechin gallate oligomer without a glucose core, were not appreciably inhibitory. A structure-activity study showed that higher-order conformations of the conjugates with glucose of hexahydroxydiphenoyl and valoneoyl groups, which are unique components of ellagitannins, cooperatively potentiated the inhibitory activity.

Topics: Enzyme Inhibitors; Glycoside Hydrolases; Humans; Hydrolyzable Tannins; Placenta; Structure-Activity Relationship; Tannins

Forty-five ellagitannins and related compounds were intraperitoneally injected into mice once, 4 d before intraperitoneal inoculation of S-180 cells, and their antitumor activities were evaluated. When an antitumor-active tannin was defined as one producing a 70% increase or more in the mean life span of mice or one regressor out of six mice, twenty-one ellagitannins were active. Among monomeric ellagitannins, tellimagrandin II was most active. Most of the oligomeric ellagitannins, consisting of tellimagrandins I and II as the monomer unit, had a significant antitumor activity. Macrocyclic ellagitannins were all active. Oenothein B, among them, had the most potent antitumor activity. In contrast, ellagitannins containing a casuarictin or potentillin moiety in their molecules, except for extensively oligomerized ones, showed very low or negligible activity. These results suggest that tannins need the ellagitannin monomer units, having galloyl groups at the O-2 and O-3 positions on the glucose core(s), such as tellimagrandins, in order to exhibit a strong antitumor activity.

Topics: Animals; Antineoplastic Agents, Phytogenic; Female; Hydrolyzable Tannins; Mice; Mice, Inbred Strains; Neoplasm Transplantation; Sarcoma 180; Structure-Activity Relationship; Tannins

Chemical examination of the leaves of Rubus lambertianus Seringe (Rosaceae) has led to the isolation of four new ellagitannins, which were characterized on the basis of chemical and spectroscopic evidence to be dimers [lambertianins A (6) and B (7)], a trimer [lambertianin C (8)] and a tetramer [lambertianin D (10)], all having sanguisorbic acid ester group(s) as linking unit(s) between glucopyranose moieties. Furthermore, HPLC analyses of fifteen Rubus species collected in Japan and Taiwan revealed that the trimer (8) and the tetramer (10), together with sanguiin H-6 (1), occur widely in these species.

Topics: Chromatography, High Pressure Liquid; Hydrolyzable Tannins; Japan; Plants, Medicinal; Taiwan; Tannins

Many tannins were previously identified as candidate topoisomerase poisons. Here we report further studies on sanguiin H-6, a dimeric ellagitannin isolated from Sanguisorba officinalis as an inhibitor of DNA topoisomerases. Catalytic strand-passing activities of topoisomerases I and II were inhibited in vitro with IC50 values of 1 microM and 0.01 microM, respectively. This inhibition was not associated with stabilization of covalent enzyme-DNA complexes but rather by a mechanism preventing formation of such covalent intermediates, as measured by interference with drug-induced cleavage in vitro. The IC50 values for topoisomerase I-DNA complexes induced by camptothecin and with topoisomerase II-DNA complexes induced by VP-16 were 0.02 microM and 0.16 microM, respectively. Pre-incubation studies followed by drug-dilution revealed that the in vitro inhibitory effects of sanguiin H-6 were irreversible, and for topoisomerase I, the test compound prevented enzyme-DNA interaction as seen by shifts in mobility on agarose gels. By measuring interference with drug-induced protein-linked DNA breaks in isolated HeLa nuclei, inhibition of topoisomerases I and II on a natural chromatin template was demonstrated with IC50 values of 5 microM and > 10 microM, respectively. Sanguiin H-6 inhibited HeLa cell growth with an ED50 of 12 microM and also interfered in a dose-dependent fashion with intracellular topoisomerase activities but with lower potencies than those observed using subcellular assay systems. Based on these studies, sanguiin H-6 could be broadly classified as a type of poison which does not stimulate the formation of cleavable-complexes, with intracellular activity but without any marked selectivity.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Catalysis; Cell Division; Cell Nucleus; DNA; DNA Topoisomerases, Type I; HeLa Cells; Humans; Hydrolyzable Tannins; Molecular Structure; Plants; Tannins; Topoisomerase I Inhibitors; Tumor Cells, Cultured

Topics: Chemical Phenomena; Chemistry; Hydrolyzable Tannins; Plants, Medicinal; Tannins