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PubMed2003

Removal of lead from aqueous solutions by condensed tannin gel adsorbent.

Lead has caused serious environmental pollution due to its toxicity, accumulation in food chains and persistence in nature. In this paper, lead removal from aqueous solutions was investigated using condensed tannin gel adsorbent synthesized from a natural tannin compound. It is found that the adsorption is strongly affected by pH values of aqueous solutions. Within pH range of 3.5-6, when initial lead concentration is 100 mg/L, removal efficiency is more than 90%. Adsorption equilibrium is reached within 150 minutes. The adsorption isotherm fits well with the Langmuir equation, by which the saturated adsorption uptake of 190 mg Pri2+ /g dry tannin gel adsorbent is obtained. By means of thermodynanamics analysis, it is revealed that the process is exothermic and the adsorption heat is up to 38.4 kJ/mol. With respect to high efficiency, moderate pH requirement and minimized second pollution, the tannin gel adsorbent exhibits a promising potential in the removal of lead from wastewater.

Adsorption↗
PubMed2004

Tannin inhibits HIV-1 entry by targeting gp41.

AIM: To investigate the mechanism by which tannin inhibits HIV-1 entry into target cells. METHODS: The inhibitory activity of tannin on HIV-1 replication and entry was detected by p24 production and HIV-1-mediated cell fusion, respectively. The inhibitory activity on the gp41 six-helix bundle formation was determined by an improved sandwich ELISA. RESULTS: Tannins from different sources showed potent inhibitory activity on HIV-1 replication, HIV-1-mediated cell fusion, and the gp41 six-helix bundle formation. CONCLUSION: Tannin inhibits HIV-1 entry into target cells by interfering with the gp41 six-helix bundle formation, thus blocking HIV-1 fusion with the target cell.

Anti-HIV Agents↗
PubMedDate not supplied

Stimulation of monocyte iodination and IL-1 production by tannins and related compounds.

Various tannins and related compounds were compared for their ability to stimulate the iodination (incorporation of radioactive iodine into an acid-insoluble fraction) of human peripheral blood monocytes. The stimulating activity of most of the monomeric and dimeric hydrolyzable tannins was generally higher than that of the trimeric and tetrameric compounds. Compounds that had dehydrohexahydroxydiphenoyl or chebuloyl groups had considerably less activity than those that had other functional groups (hexahydroxydiphenoyl, valoneoyl, dehydrodigalloyl, isodehydrodigalloyl, lactonized valoneoyl, hellinoyl, euphorbinoyl, dehydroeuphorbinoyl or woodfordinoyl group). The methylated derivative, nonacosa-O-methylcoriariin A, was essentially inactive, suggesting the requirement of a phenolic hydroxyl group. Three condensed tannins ((-)-epicatechin 3-O-gallate (ECG)-dimer, ECG-trimer and ECG-tetramer) significantly stimulated both monocyte iodination and their interleukin-1-like factor production. The results suggest the dependence of stimulation of monocyte iodination by tannins and related polyphenols on molecular weight.

Animals↗
PubMedDate not supplied

Stimulation of granulocytic cell iodination by tannins and related compounds.

Tannic acid stimulated the iodination (incorporation of radioactive iodine into an acid-insoluble fraction) of human peripheral blood polymorphonuclear cells (PMN) and human promyelocytic leukemic HL-60 cells, without affecting the iodination of 9 other cultured cell lines. The stimulation of both PMN and HL-60 cells depended on incubation time and temperature, and was significantly suppressed by myeloperoxidase inhibitors. Among chemically defined natural polyphenols, condensed tannins (epicatechin gallate oligomers) and monomeric and oligomeric hydrolyzable tannins potently stimulated PMN iodination, whereas polyphenols of lower molecular weight (gallic acid, alkyl gallates, epicatechin, epicatechin gallate, epigallocatechin, caffeic acid derivatives and licorice flavonoids) had much less activity. Various synthetic polyphenolic compounds structurally unrelated to tannins also stimulated PMN iodination depending upon their molecular weight, but to a slightly lesser extent. The results suggest that the stimulation activity of tannins and related polyphenols might depend more on their molecular weights than the number of hydroxyl groups on each benzene ring in the molecule, or the presence of sugars or hexahydroxydiphenoyl groups.

Animals↗
PubMed1989

Inhibitory effect of tannin on poly(ADP-ribose) glycohydrolase from human placenta.

Tannin, a naturally occurring polyphenolic compound, was found to inhibit the activity of purified poly(ADP-ribose) glycohydrolase from human placenta. The inhibition was dose-dependent and half maximal with 2.8 micrograms/ml of tannin. The inhibitory effect of tannin was two and three orders of magnitude more than those of ADP-ribose and cAMP, respectively. Kinetic analysis revealed that the inhibition by tannin was competitive with respect to the substrate poly(ADP-ribose).

Binding Sites↗
PubMed1987

Induction of proline-rich proteins in hamster salivary glands by isoproterenol treatment and an unusual growth inhibition by tannins.

Treatment of hamsters with the beta-agonist isoproterenol caused a dramatic increase in a series of unusual proteins in the parotid and submandibular glands. These proteins are acid soluble and they contain high amounts (mol%) of glutamate plus glutamine (30-35), proline (23-30), and glycine (12-25). Three proteins (HP45, HP43a, and HP43b) were isolated from trichloroacetic acid extracts of parotid glands of isoproterenol-treated hamsters. The basic protein (HP45) was not retained by DEAE-cellulose and did not contain phosphate or carbohydrate. Two acidic proteins (HP43a and HP43b) had the same apparent molecular weight on sodium dodecyl sulfate-polyacrylamide gel electrophoresis, but these were separated by DEAE-cellulose chromatography. HP43a and HP43b contained 4.3 and 5.7 phosphate residues/mol of protein, respectively. Levels of mRNAs encoding this series of proteins showed striking increases following isoproterenol treatment as determined by cell-free translations and Northern analysis. Feeding tannins to rats and mice mimicks the effects of isoproterenol treatment on the parotid gland (Mehansho, H., Hagerman, A., Clements, S., Butler, L., Rogler, J., and Carlson, D.M. (1983) Proc. Natl. Acad. Sci. U.S.A. 80, 3948-3952; Mehansho, H., Clements, S., Sheares, B. T., Smith, S., and Carlson, D. M. (1985) J. Biol. Chem. 260, 4418-4423]. However, hamsters on a high tannin diet (2%) did not respond like rats and mice and instead displayed an unusual growth inhibition. Weanling hamsters maintained on a 2% tannin diet initially lost weight for 3 days and then failed to gain weight for up to 6 months when kept on this diet. Essentially a normal growth rate was observed when the tannin-fed hamsters were switched to a normal diet.

Adenylyl Cyclases↗
PubMedDate not supplied

Antitumor activity and interleukin-1 induction by tannins.

The relationships between structures, antitumor activities and interleukin-1 (IL-1) induction by fifteen tannins were studies. When tannins (10 mg/kg) were intraperitoneally injected into mice once, 4 days before intraperitoneal inoculation of S-180 cells, tellimagrandin II, rugosin A, hirtellin B, oenothein B and oenothein A, which have only tellimagrandins I or II units in their molecules, had significant antitumor activity. Although casuarictin and its related tannins were ineffective, agrimonin, which is a dimer, had a strong effect, as previously reported. On the other hand, monomeric ellagitannins such as tellimagrandins I and II, rugosin A and casuarictin also increased IL-1 beta production from human peripheral macrophages in vitro by 2-fold over the non-stimulated basal production and oligomeric ellagitannins with strong antitumor activity more potently stimulated the IL-1 beta induction. Other tannins having no antitumor activity induced less IL-beta. This study indicates that oligomeric ellagitannins, which consist of tellimagrandin I or II, casuarictin or their related structure units, have antitumor activity and induce IL-1 beta.

Animals↗
PubMedDate not supplied

Induction of DNA fragmentation by tannin- and lignin-related substances.

A variety of tannin and lignin-related compounds were compared for their ability to induce nucleosome-sized DNA fragmentation (a biochemical hallmark of apoptosis), using agarose gel electrophoresis and a fluorescence activated cell sorter. Monomeric, dimeric, trimeric and tetrameric hydrolysable tannins induced nucleosome-sized DNA fragmentation in HL-60 cells, more potently than condensed tannins. The highest activity was detected in gallic acid, a component unit of tannins. Natural lignified materials, except for caffeic acid and its dehydrogenation polymer, showed much weaker activity. Protein-bound polysaccharide (PSK) was inactive. Gallic acid induced DNA fragmentation in four human myelogenous leukaemic cell lines, but not in human T-cell leukaemia and erythroleukaemia cell lines. Ca2+ depletion from the culture medium slightly, but significantly, reduced the apoptosis-inducing activity of gallic acid, but did not significantly affect that of tannic acid or caffeic acid. After treatment with gallic acid, intracellular Ca2+ concentration was significantly elevated. The apoptosis-inducing activity of polyphenols may further emphasize their medicinal efficacy.

Apoptosis↗
PubMed1994

[Factors which modify the nutritional state of iron: tannin content of herbal teas].

Tannins are natural compounds that abound in herbs, wood and fruits. Their numerous hydroxyl radicals confer them a strong avidity for metals such as Fe, Zn and Cu. This property makes them strong inhibitors for the gastrointestinal absorption of these metals. Our purpose was to determine the tannin content of herbal infusions commonly consumed in Chile and other Latino American countries. The determination was performed from dessicated herbs with the Folin-Denis technique. Yerba mate, tea and oregano had the highest tannin content (117, 100 and 84 mg of tannic acid/g dry herb respectively). An intermediate level (between 20 and 40 of tannic acid/g) was for coca, matico, boldo, palto, laurel, orange and binojo. The lowest level of tannin for paico, cedrón, apio and manzanilla (< 10 mg/g). We conclude that the consumption of herbal teas at or around meals may inhibit the absorption of metals such as Fe, Zn, or Cu by decreasing their bioavailability.

Beverages↗
PubMed2006

Do high-tannin leaves require more roots?

The well-known deceleration of nitrogen (N) cycling in the soil resulting from addition of large amounts of foliar condensed tannins may require increased fine-root growth in order to meet plant demands for N. We examined correlations between fine-root production, plant genetics, and leaf secondary compounds in Populus angustifolia, P. fremontii, and their hybrids. We measured fine-root (<2 mm) production and leaf chemistry along an experimental genetic gradient where leaf litter tannin concentrations are genetically based and exert strong control on net N mineralization in the soil. Fine-root production was highly correlated with leaf tannins and individual tree genetic composition based upon genetic marker estimates, suggesting potential genetic control of compensatory root growth in response to accumulation of foliar secondary compounds in soils. We suggest, based on previous studies in our system and the current study, that genes for tannin production could link foliar chemistry and root growth, which may provide a powerful setting for external feedbacks between above- and belowground processes.

Hybridization, Genetic↗
PubMedDate not supplied

Condensed tannins induce micronuclei in cultured V79 Chinese hamster cells.

The tannins, delphinidin and procyanidin were isolated from flowers of white clover (Trifolium repens) and the leaves of Arnot Bristly Locust (Robina fertilis) respectively, and tested for mutagenic properties in a range of systems. There was no evidence for either compound causing significant levels of frameshift or base-pair mutagenesis in bacterial mutagenicity assays, although both were weakly positive in a bacterial DNA-repair test. Both compounds very slightly increased the frequency of petite mutagenesis in Saccharomyces cerevisiae strain D5. In V79 Chinese hamster cells, both were efficient inducers of micronuclei. In each of these test systems, increasing the potential of the compound for metabolic activation by addition of 'S9' mix had little effect on toxicity or mutagenicity of either tannin. It would seem that potential chromosome-breaking activity of condensed tannins could represent a carcinogenic hazard for animals grazing on pastures of white clover in flower. It may also have wider implications for human carcinogenesis by some, if not all, condensed tannins.

Animal Feed↗
PubMed2000

Determination of condensed tannin monomers in environmental samples by capillary gas chromatography of acid depolymerization extracts

A method for molecular-level quantification of condensed tannin is described that uses acid depolymerization and carbocation capture by phloroglucinol. Resulting monomers and phloroglucinol adducts are trimethylsilyl derivatized, separated by capillary gas chromatography, detected by flame ionization, and quantified relative to standards. Optimal depolymerization conditions were determined for acid strength, phloroglucinol concentration, time, and temperature. The method gives reproducible results in leaf litter that are linear over 2 orders of magnitude with detection limits down to approximately 100 ng condensed tannin. In addition to tannin, triterpenoids were also identified and can be quantified with this method. Analyses of soils and sediments indicate that mineral interactions with condensed tannin are important both analytically and environmentally.

Journal Article↗
PubMed2005

The effect of a condensed tannin-containing forage on methane emission by goats.

The objective of this study was to compare methane emission by goats consuming the condensed tannin-containing forage sericea lespedeza (Les-pedeza cuneata) or a mixture of crabgrass (Digitaria ischaemum) and Kentucky 31 tall fescue (Festuca arundinacea). Two groups of 12 Angora does (initial average BW = 41.5 +/- 2.7 kg) that previously grazed a pasture of sericea lespedeza or crabgrass/tall fescue for approximately 4 mo were used. After 1 wk of adaptation to metabolism cages, gas exchange was measured for 24 h in an open-circuit respiration calorimetry system with four head boxes. Forage harvested daily from the previously grazed pastures was consumed ad libitum. Crude protein concentration was 10.3 and 13.0%, IVDMD was 64.5 and 75.3%, and the level of condensed tannins was 17.7 and 0.5% for sericea lespedeza and crabgrass/tall fescue, respectively. Dry matter intake (1.11 vs. 0.67 kg/d) and digestible DMI (estimated from IVDMD; 0.71 vs. 0.51 kg/d) were greater (P < 0.01) for sericea lespedeza than for crabgrass/tall fescue. Ruminal ammonia N (3.7 and 9.9 mg/dL; P < 0.001) and plasma urea-N concentrations (16.7 and 20.9 mg/dL; P = 0.07) were lower for sericea lespedeza than for crabgrass/tall fescue. Concentrations of individual and total VFA and the acetate-to-propionate ratio in ruminal fluid did not differ between treatments (P > 0.19). Despite higher DMI by goats fed sericea lespedeza, daily energy expenditure (409 vs. 431 kJ/kg BW(0.75)), heart rate (70 vs. 73 beats/min), and the ratio of energy expenditure to heart rate (5.82 vs. 5.94) did not differ between sericea lespedeza and crabgrass/tall fescue, respectively (P > 0.13). Methane emission expressed as both quantity per day or relative to DMI was lower (P <0.001) for sericea lespedeza than for crabgrass/tall fescue (7.4 vs. 10.6 g/d and 6.9 vs. 16.2 g/kg DMI). Substantial differences between the forages in condensed tannins concentration and methane emission by Angora goats suggest that condensed tannins decreased methane emission.

Ammonia↗
PubMed1992

Inhibition of human immunodeficiency viral replication by tannins and related compounds.

Among 87 chemically defined tannins and related compounds, several hydrolyzable tannins, but not condensed tannins or other lower molecular weight polyphenols, significantly inhibited both the cytopathic effect of human immunodeficiency virus (HIV) and the expression of HIV antigen in human lymphotropic virus type I (HTLV-1)-positive MT-4 cells. The 50% effective concentrations (2.0-4.8 micrograms/ml) of the active compounds were 13- to 15-fold lower than their 50% cytotoxic concentrations. Their anti-HIV activity was demonstrated to be mediated, at least in part, by inhibition of HIV adsorption to the cells.

Adsorption↗
PubMed2004

Oligomeric hydrolyzable tannins from Monochaetum multiflorum.

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.

Dimerization↗
PubMed1997

Clinical observations of noncoping overdenture abutments protected by tannin-fluoride preparation.

STATEMENT OF PROBLEM: The exposed dentin of overdenture abutments can lead to caries. Therefore chemical protection is needed to prevent caries. Considering that dentin contains both organic and inorganic components, reinforcement of both components should give reasonable results. Tannin-fluoride preparation strengthens both the organic and inorganic components of teeth. PURPOSE: This study examined whether the tannin-fluoride preparation protects noncoping abutments. MATERIAL AND METHODS: Thirty-one subjects aged 36 to 86 years participated in the clinical trial. A trial autopolymerizing resin containing the preparation or a conventional autopolymerizing resin was applied to the inner surface of the denture base, which was in contact with the abutments. When there were autopolymerizing resin group abutments, there was also at least one preparation group abutment under the overdenture. RESULTS: The incidence of caries in the preparation and autopolymerizing resin groups were 0% and 0%, respectively, for the first 2 years, 4.5% and 0%, respectively, during the 3- to 4-year period, 13.8% and 75%, respectively, during the 5- to 8-year period, and 10% and 15%, respectively, in total. Gingival crevicular fluid demonstrated a tendency to decrease in both groups over time. CONCLUSION: The trial autopolymerizing resin containing the preparation has a long-term caries prevention effect, and helps to maintain gingival health. Without adding clinical steps, abutments can be protected by the tannin-fluoride preparation.

Adult↗
PubMed2002

Determination of hydrolyzable tannins (gallotannins and ellagitannins) after reaction with potassium iodate.

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.

Chromatography, High Pressure Liquid↗
PubMed2025

WRKY14-DPB Module Enhances Drought Tolerance by Activating the Expression of UGT84B1 Involved in Hydrolyzable Tannin Biosynthesis.

Drought stress severely limits the growth and development of trees. Tannins, which serve as vital secondary metabolites in plant roots, help mitigate drought stress. The Lauraceae family, which holds major economic and ecological value, faces substantial developmental challenges due to its sensitivity to drought conditions. Despite this, research on the regulatory mechanisms governing tannin-specific accumulation under drought stress remains limited. In this study, we aim to explore how WRKY14 interacts with DPB to regulate the metabolism of hydrolyzable tannin (HT) via the key enzyme UGT84B1, thereby enhancing drought tolerance in Litsea cubeba, a main species within the Lauraceae family. The WRKY-DPB-UGT84B1 module was specifically expressed in roots in response to drought stress. LcUGT84B1 was found to generate 1-O-Galloyl-&#x3b2;-d-glucose in vitro and in overexpressing L. cubeba. Moreover, molecular biology and transformation experiments demonstrated that LcWRKY14 and LcDPB formed a complex that directly bound to the LcUGT84B1 promoter, activating its expression and thereby facilitating HT synthesis. Co-overexpression of LcWRKY14 and LcDPB significantly enhanced drought tolerance by increasing HT accumulation. These findings provide new insights into the regulatory mechanisms of the WRKY-DPB-UGT84B1 module in promoting drought tolerance and offer a potential breeding strategy for developing drought-resistant varieties.

Drought Resistance↗