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At least 19 recordsLinked to original sources
PubMed1989

Tannins of cornaceous plants. I. Cornusiins A, B and C, dimeric monomeric and trimeric hydrolyzable tannins from Cornus officinalis, and orientation of valoneoyl group in related tannins.

Cornusiin A (1), cornusiin B (2) and cornusiin C (3), new dimeric, monomeric and trimeric hydrolyzable tannins, were isolated from the fruits of Cornus officinalis (Cornaceae). Their structures, including the orientation of the valoneoyl group in 1 and 3, were established on the basis of chemical and spectroscopic data. 2,3-Di-O-galloyl-D-glucose (7), 1,2,3-tri-O-galloyl-beta-D-glucose, 1,2,6-tri-O-galloyl-beta-D-glucose, 1,2,3,6-tetra-O-galloyl-beta-D-glucose, gemin D (5), isoterchebin, tellimagrandin I (6) and tellimagrandin II were also isolated from the fruits. The orientation of the valoneoyl group in camptothin A (14) and that in camptothin B (15), which had been isolated from Camptotheca acuminata (Nyssaceae), were also determined based on that in 1.

Antineoplastic Agents, Phytogenic↗
PubMed1989

Deactivation of tannin in high tannin milo by treatment with urea.

Experiments were conducted to determine the effectiveness of urea in deactivating tannin in high tannin milo. High tannin milo (Pioneer B 815, 3.4 +/- .3% tannin) was reconstituted with aqueous urea solutions to give combinations of 26, 30, and 34% moisture with 2, 3, and 4% urea (percentage of urea per dry weight of milo). All treatments were maintained at 25 degrees C and were effective in deactivating tannin with no differences among moisture or urea content. The average rate of tannin deactivation was 68 +/- 2% d-1. Temperature affected rate of tannin deactivation in milo reconstituted to 30% moisture and 3% urea when stored at 25 or 60 degrees C. Rate of tannin deactivation was 44 +/- 5 and 89 +/- 18% d-1 at 25 and 60 degrees C, respectively. Tannin in high tannin milo can be deactivated rapidly and completely by reconstitution with aqueous urea. These studies demonstrate that tannin is deactivated completely under conditions where urea is an effective preservative of high moisture milo.

Analysis of Variance↗
PubMed1990

Effects of interaction of tannins with co-existing substances. VII. Inhibitory effects of tannins and related polyphenols on xanthine oxidase.

The inhibitory effects of hydrolyzable tannins, condensed tannins and related polyphenols on the activity of xanthine oxidase (XOD), catalyzing uric acid formation from xanthine, were investigated. Marked differences in the strength of the inhibition were observed. Some of the differences among the monomeric hydrolyzable tannins were due to their molecular weights, reflecting the number of phenolic hydroxyl groups in the molecule. However, the inhibitory activity of several oligomeric hydrolyzable tannins seemed particularly low in spite of their large molecular size. It was also observed that differences in location of acyl groups on the carbohydrate cores caused differences in the inhibitory activity among monomeric and oligomeric hydrolyzable tannins. A caffeic acid derivative (caffeetannin), 3,5-di-O-caffeoylquinic acid (24), also inhibited this enzyme. Galloylation and the degree of polymerization in proanthocyanidins were also shown to affect remarkably the strength of the inhibition. Among the compounds tested in the present study, valoneic acid dilactone (29), isolated from Mallotus japonicus, inhibited the enzyme most effectively. A kinetic study showed that this dilactone inhibited XOD non-competitively. Comparison of the inhibitory effect on XOD, with the binding activity to hemoglobin, for each tannin, suggests that their inhibition of XOD is not based on non-specific binding to the protein. Similar comparison of the inhibitory effect on XOD with the inhibitory effect on the generation of superoxide anion radical (O2-.) from the hypoxanthine-XOD system revealed that the inhibition of O2-. generation by tannins is due to their radical-scavenging activity, and not due to their inhibitory activity upon the enzyme.

Flavonoids↗
PubMed1987

Protein precipitation assay for quantitation of tannins: determination of protein in tannin-protein complex.

A protein precipitation method for the determination of tannins has been developed. The protein in the tannin-protein complexes was measured using the ninhydrin assay of amino acids released by alkaline hydrolysis of the complex. Standard protein and the complex were hydrolyzed with 13.5 N NaOH at 120 degrees C for 20 min and the amino acids released were measured with ninhydrin. Tannins did not interfere in the determination of protein by ninhydrin assay. The bovine serum albumin (BSA) precipitated (y; mg) increased linearly with increase in tannic acid (x) from 0.2 to 0.9 mg (y = 2.598x - 0.258). The protein precipitation capacities (mg BSA precipitated/g dry wt) measured by the method for young and mature leaves of oaks were Quercus incana (young, 42.21; mature, 79.51), Q. ilex (young, 1.86; mature, 1.86), and Q. semecarpifolia (young, 733.54; mature, 304.32). The method can provide valuable information on the mechanisms of protein-tannin interactions and nutritional and physiological significances of tannins.

Animals↗
PubMed1995

[Effect of the interaction of tannins with coexisting substances. VIII. Inhibitory effect of tannins on discoloration of natural pigments].

The discoloration of shikonin (1) and beta-carotene (2), occurring during storage of their ethanol solutions in the presence of oxygen in an illuminated room, was remarkably suppressed by hydrolyzable tannins, such as geraniin (4) and tannic acid JP (3) in the solution. The inhibitory effect of tannins was enhanced by the coexistence of metallic ion. The irradiation with ultraviolet lamp (254 and 365 nm) gave, at the first stage of the discoloration, two products, one of which was found to be 5,8-dihydroxy-2-(1-hydroxy-3-oxo-4-methyl-4-pentenyl)-1,4-naphthoquinone (7). The presence of hydrolyzable tannins induced higher accumulation of these two products in the solution, showing that the secondary structural transformations of these two products were strongly inhibited by these coexisting tannins. These results suggest that tannins could be efficient inhibitors of discoloration of natural pigments.

Carotenoids↗
PubMed1986

Endothelial cell cytotoxicity of cotton bracts tannin and aqueous cotton bracts extract: tannin is the predominant cytotoxin present in aqueous cotton bracts extract.

Using an in vitro cytotoxicity assay based on the release of 51Cr from cultured porcine thoracic aortic and pulmonary arterial endothelial cells, we have demonstrated that cotton bracts tannin is a potent endothelial cell cytotoxin. It produces dose-dependent lethal injury to both types of endothelial cells with the aortic cells being somewhat more sensitive to tannin-mediated injury than the pulmonary arterial cells. Cytotoxic injury to the cells was biphasic. During the first 3 hr of exposure to tannin, no lethal injury was detected. However, during this period, profound changes in morphology were observed suggesting sublethal injury to the cells preceded the ultimate toxic damage. Comparison of the cytotoxicity dose curves for aqueous bracts extracts with those for tannin demonstrated that tannin was the major cytotoxin present in bracts.

Animals↗
PubMed2003

Antioxidants in the midgut fluids of a tannin-tolerant and a tannin-sensitive caterpillar: effects of seasonal changes in tree leaves.

The seasonal decline in foliar nutritional quality in deciduous trees also effects the availability of essential micronutrients, such as ascorbate and alpha-tocopherol, to herbivorous insects. This study first examined whether there are consistent patterns of seasonal change in antioxidant concentrations in deciduous tree leaves. Alpha-tocopherol concentrations increased substantially through time in late summer in sugar maple (Acer saccharum), red oak (Quercus rubra), and trembling aspen (Populus tremuloides). However, seasonal change in the concentrations of other antioxidants differed between each species: P. tremuloides had higher levels of ascorbate and glutathione in the spring, Q. rubra had higher levels of glutathione but lower levels of ascorbate in the spring, and A. saccharum had lower levels of both ascorbate and glutathione in the spring. To test the hypothesis that tannin-tolerant caterpillars maintain higher concentrations of antioxidants in their midgut fluids than do tannin-sensitive species, we measured antioxidants in Orgyia leucostigma (a spring- and summer-feeding, tannin-tolerant species) and Malacosoma disstria (a spring-feeding, tannin-sensitive species) that were fed tree leaves in the spring and summer. The midgut fluids of O. leucostigma larvae generally had higher concentrations of antioxidants in the summer than did those of M. disstria, and were significantly higher overall. The results of this study are consistent with the hypothesis that higher concentrations of antioxidants form an important component of the defenses of herbivores that feed on mature, phenol-rich tree leaves. Some limitations of the interpretation of total antioxidant capacity are also discussed.

Acer↗
PubMed2002

A modified dot-blot method of protein determination applied in the tannin-protein precipitation assay to facilitate the evaluation of tannin activity in animal feeds.

Tannins have received considerable attention from animal nutritionists as potential agents for modifying ruminal fermentation patterns, or for exploring new feed resources. This group of secondary plant compounds is defined by their ability to form complexes with proteins. A widely accepted method for assaying the biological activity of extracted tannins is the precipitation of bovine serum albumin. The protein carries a radioactive label (125I) to allow direct quantification from the precipitate. Tannin-protein complexes dissolve in sodium dodecylsulfate solution. A dot-blot assay for protein determination, which is based on the reversible binding of a fluorochrome, benzoxanthene yellow, to the protein spots and is not disturbed by the presence of detergents, can replace the radioactive method by a fluorimetric measurement. A novel alternative to the last part of the dot-blot assay is to scan the stained protein spots in situ using a video camera and computer image analysis. Several filter sets were tested and, within a concentration range of 0.1-2.0 mg protein/ml, each of them yielded results identical to the original method while the time required was only 30 % of the working time consumed by the original procedure. The modified dot-blot assay should be applicable to the evaluation of tannin activity in all shrub and tree foliages considered as animal feed.

Animal Feed↗
PubMed1980

Carcinogenicity of tannin and tannin-free extracts of bracken fern (Pteridium aquilinum) in rats.

F344 inbred and Sprague-Dawley noninbred rats were fed a basic diet (groups 1 and 7) or a basic diet supplemented with 0.1% (later, 0.2 and 0.4%) tannin (group 2) isolated from bracken fern (Pteridium aquilinum) (BF), 33% BF (groups 3 and 6), 2% chloroform fraction of BF (group 4), or 4% tannin-free fraction of BF (group 5). The following incidences of intestinal or bladder tumors were observed: group 1, intestinal and bladder, 0/16; group 2, 0/21; group 7, 0/16; groups 4 and 5, intestinal, 7/15, bladder, 0/15; group 3, intestinal, 19/20, bladder, 12/20; and group 6, intestinal, 22/30, bladder, 15/30. The chloroform-methanol fraction prepared from urine of rats fed BF, chloroform fraction of BF, or tannin-free fraction of BF demonstrated mutagenicity for Salmonella typhimurium TA 100 but not for TA 98. No mutagenicity was detected in other prepared fractions. F344 rats in group 8 received weekly sc injections of tannin solution (0.1 g/kg body wt) for 38 weeks, and 16/20 developed palpable tumors that were malignant fibrous histiocytomas at the injection site. No tumor was present in any rat of control group 9.

Animals↗
PubMed1965

The origins of tannins and flavonoids in black-wattle barks and heartwoods, and their associated "non-tannin" components.

1. The distributions of flavonoid, carbohydrate, amino acid and imino acid components in the leaves, twig bark, stem bark, root bark and heartwoods of the black-wattle tree were compared by paper chromatography after their isolation from specific portions of the tree. 2. Wattle leaves contain mainly myricitrin, (+)-gallocatechin, an unknown myricetin glycoside and leuco-delphinidin tannins, together with smaller amounts of (+)-catechin, quercitrin and other flavonol glycosides. These are prominent in the twig bark, but decline progressively with age in the stem bark and are absent from root bark. 3. The non-phenolic components of the mature stem bark were shown to be (+)-pinitol, sucrose, glucose, fructose, l(-)-pipecolic acid, trans-4-hydroxy-l(-)-pipecolic acid, alpha-alanine, arginine, aspartic acid, glutamic acid, l(-)-proline, serine, a ;steroid' alcohol and a long-chain beta-diketone. 4. Wattle bark and heartwood ;tannins' consist of the analogues of closely related prototypes with common origins in the vascular tissues of the bark. Leaf ;tannins' are superimposed on the bark components mainly during the initial stages of bark growth. 5. Origins of the pipecolic acids and the transformations of carbohydrates in the sap- and heart-woods are discussed.

Amino Acids↗
PubMed1989

Tannins and related compounds. LXXXIV. Isolation and characterization of five new hydrolyzable tannins from the bark of Mallotus japonicus.

A chemical examination of the bark of Mallotus japonicus (Thunb.) Mueller-Arg. (Euphorbiaceae) has led to the isolation of five new hydrolyzable tannins (16-20), together with fourteen known tannins (1-14). On the basis of chemical and spectroscopic evidence, the structures of compounds 16 and 17 were established as 1,2-di-O-galloyl-3,6-(R)-hexahydroxydiphenoyl-beta-D-glucose and 1-O-digalloyl-3,6-(R)-hexahydroxydiphenoyl-beta-D-glucose, respectively, while compounds 18 (mallojaponin) and 19 (mallonin) were shown to be 1-O-galloyl-2,4-elaeocarpusinoyl-3,6-(R)-valoneayl-bet a-D-glucose and 1-O-galloyl-2,4-elaeocarpusinoyl-beta-D-glucose. Compound 20 (mallotusinin) was characterized as a novel ellagitannin which possesses a unique 1,1'-(3,3',4,4'-tetrahydroxy)dibenzofurandicarboxyl group. On the other hand, examination of the leaves revealed the presence of hydrolyzable tannins (8-10, 12-15) all containing a beta-D-glucopyranose core with 1C4-conformation. Furthermore, the orientation of the valoneayl group in mallotinic acid (13) and mallotusinic acid (14), which had remained unclarified, was determined on the basis of 1H-13C shift correlation spectral analysis and chemical correlations.

Anti-Ulcer Agents↗
PubMed1975

[Interaction of yeasts with tannins. II. Study of various yeasts hydrolysing tannic acid in tannin culture media].

Growth and hydrolytic action on tannins of 6 strains of yeasts (isolated from tanning liquors and xylophagous insects) are studied in culture media containing various concentrations of tannic acid. The influence of medium acidity is also considered. According to the strains, growth is more or less restrained and hydrolytic activity is variable. Except for gallotannins, hydrolysable tannins are not hydrolysed.

Candida↗
PubMed1994

Tannins of theaceous plants. V. Camelliatannins F, G and H, three new tannins from Camellia japonica L.

Two new complex tannins, camelliatannins F (3) and G (4), were isolated from the leaves of Camellia japonica L. (Theaceae), and their structures, each consisting of an epicatechin unit and a C-glucosidic ellagitannin moiety, were elucidated. A new dimeric hydrolyzable tannin, named camelliatannin H (5), was isolated from the fruits of this plant. Camelliins A (6) and B (7), and camelliatannin A (1) and 3 were also isolated from the fruits.

Carbohydrate Sequence↗
PubMed1994

Tannins and related polyphenols of euphorbiaceous plants. XI. Three new hydrolyzable tannins and a polyphenol glucoside from Euphorbia humifusa.

Three new hydrolyzable tannins, euphormisins M1, M2, and M3, were isolated from Euphorbia humifusa WILLD., and respectively characterized as 1,3,6-tri-O-galloyl-4-O- brevifolincarboxyl-beta-D-glucose (19), an oxidative metabolite (23) of geraniin, and 1,3,6-tri-O-galloyl-alpha-D-glucose (18), by spectroscopic and chemical methods. A new ellagic acid glucoside (16) and fifteen known tannins, including geraniin (8) and four dimers [euphorbins A (13), B (14), excoecarianin (15) and eumaculin A (12)], were also isolated.

Flavonoids↗
PubMed1999

Tannins and related polyphenols of melastomataceous plants. VIII. Nobotanins L, M and N, trimeric hydrolyzable tannins from Tibouchina semidecandra.

Three hydrolyzable tannins, nobotannins L, M and N, were isolated from the water-soluble portion of the leaf extract of Tibouchina semidecandra, and their trimeric structures were elucidated from spectral and chemical evidence. Nobotanins L and N exist as equilibrium mixtures of four anomers due to the presence of two unacylated anomeric centers.

Carbohydrate Sequence↗
PubMed1986

The role of condensed tannins in the nutritional value of Lotus pedunculatus for sheep. 4. Sites of carbohydrate and protein digestion as influenced by dietary reactive tannin concentration.

1. Vegetative secondary growth Lotus pedunculatus was cut daily, and fed fresh at hourly intervals (600 g dry matter (DM)/d) to three groups each of three sheep fitted with permanent cannulas into the rumen and duodenum. Lotus fed to two of the groups was sprayed with low and high rates of polyethylene glycol (PEG; molecular weight 3350), which specifically binds the condensed tannins (CT). Nutrient intake and faecal excretion were measured directly, duodenal flows estimated from continuous intraruminal infusion of inert ruthenium phenanthroline (Ru-P) and CrEDTA markers, and rumen pool sizes measured at slaughter. 2. Dietary concentrations of total reactive CT (i.e. that not bound to PEG) were 95, 45 and 14 g/kg DM, whilst the corresponding values for free CT were 15, 5 and 2 g/kg DM. 3. Increasing dietary reactive CT concentration linearly increased duodenal flows of non-ammonia nitrogen, but linearly decreased the apparent digestibility of energy and organic matter, and rumen digestion of hemicellulose but not of cellulose. Rumen digestion as a proportion of total digestion was increased by the higher PEG rate for organic matter, energy, pectin and lignin. 4. High dietary CT concentration was associated with increased N retention. Rumen ammonia concentration and pool size showed only a slight decline on this diet, indicating that there must have been increased recycling of N into the rumen. 5. Increasing dietary reactive CT concentration had no effect on the rate at which carbohydrate constituents were degraded in the rumen per unit time (FDR), but increased the rate at which their undegraded residues (FOR) left the rumen per unit time. The latter appeared to be the principal mechanism by which rumen digestion as a proportion of total digestion was reduced at high dietary CT concentrations. From a comparison of FDR and FOR of carbohydrate components in lotus and Brassica oleracea diets, it was concluded that hemicellulose digestion was rate-limiting for rumen cell-wall digestion, probably due to bonding with lignin. However, the considerable post-rumen digestion of hemicellulose was not associated with post-rumen lignin digestion. 6. It was concluded that a desired concentration of CT in Lotus sp. should represent a balance between the positive effect of CT in improving the efficiency of N digestion and their negative effect in depressing rumen carbohydrate digestion. A recommended concentration is 30-40 g/kg DM.

Animals↗
PubMed1997

Relationship between hydrophobicity and structure of hydrolyzable tannins, and association of tannins with crude drug constituents in aqueous solution.

The hydrophobicity values of hydrolyzable tannins were evaluated by measuring the distribution of the compounds between n-octanol and water. Of 8 gallotannins and 13 ellagitannins examined, pentagalloylglucose (7), the major polyphenol of Paeoniae Radix, showed the largest partition coefficient value. In aqueous solution, pentagalloylglucose associated with various crude drug constituents, such as paeoniflorin, glycyrrhizin potassium salt, aconitine trifluoroacetate, liquiritin apioside and amygdalin. The 1H-NMR spectroscopic examination suggested that the association occurred preferentially at the most hydrophobic sites of the molecules. The association with these compounds inhibited the distribution of pentagalloylglucose into the n-octanol phase and adsorption on hide powder. In addition, the water solubility of the biologically active polymeric proanthocyanidins of rhubarb was increased by association with rhein 8-O-glucoside potassium salt, the major anthraquinone glycoside of rhubarb.

1-Octanol↗