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PubMed2005

Relative contribution of phytates, fibers, and tannins to low iron and zinc in vitro solubility in pearl millet (Pennisetum glaucum) flour and grain fractions.

In vitro digestions were performed on pearl millet flours with decreased phytate contents and on two dephytinized or nondephytinized pearl millet grain fractions, a decorticated fraction, and a bran fraction with low and high fiber and tannin contents, respectively. Insoluble residues of these digestions were then incubated with buffer or enzymatic solutions (xylanases and/or phytases), and the quantities of indigestible iron and zinc released by these different treatments were determined. In decorticated pearl millet grain, iron was chelated by phytates and by insoluble fibers, whereas zinc was almost exclusively chelated by phytates. In the bran of pearl millet grain, a high proportion of iron was chelated by iron-binding phenolic compounds, while the rest of iron as well as the majority of zinc were chelated in complexes between phytates and fibers. The low effect of phytase action on iron and zinc solubility of bran of pearl millet grain shows that, in the case of high fiber and tannin contents, the chelating effect of these compounds was higher than that of phytates.

6-Phytase↗
PubMed2005

Phenolic antioxidants (hydrolyzable tannins, flavonols, and anthocyanins) identified by LC-ESI-MS and MALDI-QIT-TOF MS from Rosa chinensis flowers.

Rosa chinensis (Yuejihua) is a well-known ornamental plant, and its flowers are commonly used in traditional Chinese medicine. Methanolic crude extracts of dried R. chinensis flowers were used for simultaneous determination of phenolic constituents by liquid chromatography-mass spectrometry (LC-MS) and matrix-assisted laser desorption/ionization quadrupole ion trap time-of-flight mass spectrometry (MALDI-QIT-TOF MS). A total of 36 known and unknown phenolics were identified as hydrolyzable tannins, flavonols, and anthocyanins, mainly including gallotannins (mono-, di-, or trigalloylglucopyranosides), ellagitannins, quercetin, quercetin/kaempferol mono- and diglycosides, and cyanidin/pelargonidin diglycosides. MALDI-QIT-TOF MS was applied not only to verify most phenolics isolated and identified by LC-MS but also to tentatively identify two ellagitannins (rugosins B and C) not isolated and unidentified by LC-MS. This study is the first to demonstrate the rapid and successful use of MALDI-QIT-TOF MS and LC-MS to directly and simultaneously identify phenolics in the crude extracts of R. chinensis flowers without any purification. The antioxidant activity of the crude extracts from R. chinensis flowers was also measured with three assay methods. The results showed that the phenolic antioxidants from R. chinensis flowers exhibited very strong radical scavenging effect and antioxidant power. High levels of flavonols and hydrolyzable tannins might be important bioactive principles in the dried R. chinensis flowers.

Anthocyanins↗
PubMed2000

Extraction of natural complex phenols and tannins from grape seeds by using supercritical mixtures of carbon dioxide and alcohol.

Proanthocyanidins are supposed to have some therapeutical properties as antioxidants and antineoplasics. Most of the proanthocyanidins, however, are not commercialized since their separation from natural sources is either very expensive or not well-known. In this work, the feasibility of application of mixtures of carbon dioxide and alcohol under supercritical conditions for selective extraction of some phenolic compounds from grape seeds has been studied, among them some low polymerized proanthocyanidins, their main monomer units, (+)-catechin and (-)-epicatechin, and some low molecular weight phenolic compounds, like gallic acid. An analytical-scale supercritical fluid extractor, whose operation was previously optimized, was used to carry out the experiments. A commercial concentrate of complex phenols and tannins from grape seeds was subjected to supercritical extraction in order to find the best operation conditions before directly extracting defatted milled grape seeds. The solvent capacity was found to increase with pressure and with the amount of alcohol used as cosolvent as expected. Such variation in solvent capacity could be used for design of a selective separation process where individual phenolic compounds or groups of them could be obtained. HPLC coupled with two types of detectors, diode array and mass spectrometry, was used for tentative identification and quantification of complex phenols and tannins in the extracts and in the raw materials used for extraction.

Alcohols↗
PubMed1997

Expression of an Antirrhinum dihydroflavonol reductase gene results in changes in condensed tannin structure and accumulation in root cultures of Lotus corniculatus (bird's foot trefoil).

Condensed tannins (proanthocyanidins) are an important factor in the nutritive and dietary quality of many forage crops. We report here experiments aimed at altering the levels and monomer composition of condensed tannins (CTs) in 'hairy root' cultures of Lotus corniculatus (bird's foot trefoil) using genetic manipulation. An Antirrhinum majus dihydroflavonol reductase (DFR) cDNA was expressed in sense in L. corniculatus and CT levels in transgenic root cultures were analysed. Two co-transformed lines were noted with decreased CT content relative to controls and these levels were comparable with antisense-DFR phenotypes. In ADFR10, a co-transformed line with the highest CT levels, CT structure was altered in a manner consistent with the substrate specificity of the introduced gene; that is an increase in pro-pelargonidin monomers noted after hydrolysis of CTs. RT-PCR confirmed the expression of endogenous DFR gene(s) in both putatively co-suppressed lines and also in ADFR10. Analysis of selected root culture lines indicated that the monomer composition of CTs did not change during growth and development but that levels of CTs varied in a regulated manner.

Alcohol Oxidoreductases↗
PubMed2003

Effects of high-tannin sorghum and bentonite on the performance of laying hens.

The effects of feeding high-tannin sorghum (HTS) (5% catechin equivalents (CE)) on the performance of laying hens were examined in two experiments. In experiment 1, the effects of including varying levels of HTS in layer diets were investigated. Sixty-three Isabrown hens were randomly assigned to each of the seven diets over a period of 56 days. In experiment 2, the effects of bentonite on the utilization of HTS (3.74% CE) by laying hens were investigated. Forty-five Isabrown hens were randomly assigned to each of five diets over a period of 42 days. In both experiments, weekly measurements were made for feed intake (FI), percent hen-house production (% HHP), egg weight and egg specific gravity (ESG). The results of experiment 1 showed that the different sorghum inclusion levels had no effect (p > 0.05) on HHP, egg weight and ESG, while those of experiment 2 showed that maize and LTS diets gave similar weight gain. FI and FE (p > 0.05). However, HHP was higher (p < 0.05) for the LTS diet than for the other diets. The addition of bentonite of 0.25% or 0.5% to the HTS diet did not improve (p > 0.05) layer performance. When all the results were considered together, it was concluded that HTS can be used in layer diets without adverse effects on performance. The use of bentonite to deactivate sorghum tannins is not considered necessary.

Animal Feed↗
PubMed2003

Effects of sample drying and storage, and choice of extraction solvent and analysis method on the yield of birch leaf hydrolyzable tannins.

In this study, I investigated the effects of different methods of sample drying and storage, and the choice of extraction solvent and analysis method on the concentrations of 14 individual hydrolyzable tannins (HTs), and insoluble ellagitannins in birch (Betula pubescens) leaves. Freeze- and vacuum-drying of birch leaves were found to provide more reliable results than air- or oven-drying. Storage of leaves at -20 degrees C for 3 months before freeze-drying did not cause major changes in tannin content, although levels of 1,2,3,4,6-penta-O-galloylglucose and isostrictinin were altered. Storage of dried leaf material at -20 degrees C is preferred because 1 year storage of freeze-dried leaves at 4 degrees C and at room temperature decreased the concentration of the pedunculagin derivative, one of the main ellagitannins of birch. Furthermore, storage at room temperature increased the levels of isostrictinin and 2,3-(S)-HHDP-glucose, indicating possible HT catabolism. Of the extraction solvents tested, aqueous acetone was superior to pure acetone, or aqueous or pure methanol. The addition of 0.1% ascorbic acid into 70% acetone significantly increased the yield of ellagitannins. presumably by preventing their oxidation. By comparing the conventional rhodanine assay and the HPLC-ESI-MS assay for quantification of leaf galloylglucoses, the former tends to underestimate total concentrations of galloylglucoses in birch leaf extract. On the basis of the outcomes of all the method and solvent comparisons, their suitability for qualitative and quantitative analysis of plant HTs is discussed, emphasizing that each plant species, with its presumably unique HT composition, is likely to have a unique combination of ideal conditions for tissue preservation and extraction.

Betula↗
PubMed1999

Flavonoids and tannins: plant-based antioxidants with vitamin character.

Persistent activation of the neuroendocrine stress axis is the major cause of a continuous catabolic alteration of the metabolism. This often causes an oxidative stress situation with increased release of O2 and NO radicals and pro-inflammatory cytokines. For the correction of these metabolic states, an adequate supply of plant-based antioxidants, especially flavonoids and tannins, is indicated. These are plant-based polyphenols which, like vitamins cannot be synthesized by the animal organism. Vitamin E in combination with vitamin C and beta-carotene are currently considered worldwide as the standard antioxidative therapy. However, it has recently been shown that, depending on the iron status of the recipient, pharmacological doses of these vitamins sometimes have beneficial, but often also no effect or harmful effects, so that, for a more reliable antoxidative action, adequate dietary supply of a mixture of flavonoids and tannins seems preferable.

Antioxidants↗
PubMed2001

Antileishmanial activity of hydrolyzable tannins and their modulatory effects on nitric oxide and tumour necrosis factor-alpha release in macrophages in vitro.

A series of 27 hydrolyzable tannins and related compounds was tested for antiparasitic effects against both extracellular promastigote and intracellular amastigote Leishmania donovani organisms. In parallel, the compounds were evaluated for their immunomodulatory effects on macrophage functions, including release of nitric oxide (NO), tumour necrosis factor-alpha (TNF-alpha) and interferon (IFN)-like properties using several functional assays. Of the series of polyphenols tested, only gallic acid (54 microM NO) and its methyl ester (32 microM NO) induced murine macrophage-like RAW 264.7 cells to release NO in appreciable amounts (IFN-gamma/LPS 119 microM NO). The in vitro TNF-inducing potential of the polyphenols examined increased in the order of oligomeric ellagitannins (EC(50) > 25 microg/ml) < monomeric ellagitannins, gallotannins (EC(50) 8.5 to > 25 microg/ml) < C-glucosidic ellagitannins, dehydroellagitannins (EC(50) 0.6 - 2.8 microg/ml) at the host cell subtoxic concentration of 50 microg/ml. Furthermore, promastigotes of Leishmania donovani were assayed in the presence of these polyphenols and the results showed that none of the compounds was significantly toxic (EC(50) > 25 microg/ml) to the extracellular forms. In contrast, all polyphenols showed pronounced antileishmanial activities (EC(50) < 0.4 - 12.5 versus 7.9 microg/ml for Pentostam) against intracellular amastigotes of L. donovani residing within RAW cells. Noteworthy, most compounds exhibited low cytotoxicity against the murine host cells (EC(50) >25 microg/ml). Furthermore, some ellagitannins and the majority of dehydroellagitannins induced potent interferon-like activities as reflected by inhibition of the cytopathic effect of encephalomyocarditis virus on fibroblast L929 cells. This is the first report on hydrolyzable tannins as a new class of natural products with leishmanicidal activity including their potential for inducing the release of NO, TNF and IFN-like activity in macrophage-like RAW cells.

Animals↗
PubMed1995

Antimicrobial activity of tannins from Terminalia citrina.

Isolation of the fruit CH3OH extract of Terminalia citrina yielded five known tannins identified as corilagin (1) (3), punicalagin (2) (4), 1,3,6-tri-O-galloyl-beta-D-glucopyranose (3) (5), chebulagic acid (4) (6), and 1,2,3,4,6-penta-O-galloyl-beta-D-glucopyranose (5) (7) by comparison of their physical and spectral data with those of authentic samples. These tannins were tested for antimicrobial action.

Anti-Infective Agents↗
PubMed1999

Evaluation of the antimicrobial potency of tannins and related compounds using the microdilution broth method.

The antimicrobial activity of a total of 27 tannins and related compounds was evaluated against 8 microorganisms, including 2 Gram-positive (Bacillus subtilis, Staphylococcus aureus), 4 Gram-negative bacteria (Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Proteus mirabilis), and 2 yeasts (Candida albicans, Cryptococcus neoformans). The compounds tested were generally found to possess only weak to moderate antibacterial, but fairly high anticryptococcal activities. Attention is given to structure-activity relationships with emphasis on simple galloyl esters, hydrolyzable tannins and proanthcyanidins among this class of secondary products.

Anti-Bacterial Agents↗
PubMed2001

The effects of condensed tannins supplementation of foods with different protein content on parasitism, food intake and performance of sheep infected with Trichostrongylus colubriformis.

The aims of the present study were to investigate (1), the potential anthelmintic properties and (2), the nutritional consequences of commercially available condensed tannins on parasitised sheep fed, ad libitum, either a high- or a low-protein food. For this purpose, forty-eight previously parasite-naïve sheep (n 12) were infected with 2000 Trichostrongylus colubriformis larvae/d for a 67-d experimental period. Two experimental foods were made: a low (L), formulated to be inadequate in meeting the requirements of growing sheep for metabolisable protein (MP), and based on wheat, citrus pulp, and oatfeed; a high (H), expected to be above the requirements of growing sheep for MP, based on similar ingredients but supplemented with protected soyabean meal. Two additional foods were made by adding 60 g Quebracho (a condensed tannins (CT) extract)/kg fresh matter to foods L and H (foods LQ and HQ respectively). This level of Quebracho supplementation has been previously shown to reduce the level of parasitism in restrictedly fed, parasitised sheep. The experiment was divided into two periods: period 1 (P1, day 1-38) and period 2 (P2, day 39-67), each one associated with different phases of an intestinal parasitic infection. Six sheep from each group were slaughtered at the end of P1, and the remaining sheep were slaughtered at the end of P2 (day 67). Although faecal egg counts (FEC; number of parasite eggs/g faeces) and total egg output were reduced in sheep offered the supplemented foods during P1 (P<0.05), worm burdens on day 38 were unaltered. Neither Quebracho supplementation nor food protein content during P2 affected FEC and worm burdens. Food intake and performance were higher in sheep offered food HQ compared with sheep offered food H (P<0.05); no differences were observed in sheep offered foods LQ and L throughout the experiment. The previously shown anthelmintic properties of CT were not observed following ad libitum intake of either low- or high-protein foods supplemented with Quebracho extract. Higher levels of CT supplementation may be required to reduce parasitism and consequently improve the performance of parasitised sheep, when fed ad libitum. Supplementation with CT conferred advantages on the performance of parasitised sheep on a high- but not on a low-protein food.

Animal Feed↗
PubMed1994

Effects of faba bean tannins on the growth and histological structure of the intestinal tract and liver of chicks and rats.

1. Diets containing a freeze-dried tannin extract from faba beans (Vicia faba L.) at concentrations of 0, 8 and 16 g/kg were fed to growing chicks and rats. 2. Chicks fed on the tannin-containing diets exhibited a high mortality and significant decreases in body-weight as well as lower food intakes and higher food intake:weight gain ratios (P < 0.01). In rats there was no mortality but the growth and food intake were adversely affected (P < 0.05). 3. Histological changes occurred in the ileal mucosa of chicks. Atrophy and shortening of villi with distortion of their architecture were observed. Similar histological disorders but less pronounced were also found in rats. 4. Histopathology of the liver of both chicks and rats showed an hydropic degeneration of hepatocytes, clearly more severe in the former than in the latter.

Analysis of Variance↗
PubMed2007

Biomass allocation is an important determinant of the tannin concentration in growing plants.

BACKGROUND AND AIMS: Condensed tannins (CTs) in the diet affect consumers in a concentration-dependent manner. Because of their importance in plant defence against herbivores and pathogens as well as their potential application against gastrointestinal parasites of ruminants in agronomy, an understanding of the seasonal dynamics of CT concentrations during plant growth is essential. METHODS: Over a vegetation period, CT concentrations in leaves, stems and roots and the biomass proportions between these organs were investigated in Onobrychis viciifolia, Lotus corniculatus and Cichorium intybus. Based on the experimental data, a model has been suggested to predict CT concentrations in harvestable biomass of these species. KEY RESULTS: During the experiment, leaf mass fractions of plants decreased from 85, 64, 85 to 30, 18, 39 % d. wt in Onobrychis, Lotus and Cichorium, respectively, and proportions of stems and roots increased accordingly. While CT concentrations almost doubled in leaves in Onobrychis (from 52 to 86 mg g(-1) d. wt, P<0.001) and Lotus (from 25 to 54 mg g(-1) d. wt, P<0.001), they were stable at low levels in expanding leaves of Cichorium (5 mg g(-1) d. wt) and in stems and roots of all investigated species. Due to an inverse effect of the increasing CT concentrations in leaves and simultaneous dilution from increasing proportions of 'CT-poor' stems, CT concentrations in harvestable biomass were stable over time in all investigated species: 62, 26 and 5 mg g(-1) d. wt for Onobrychis, Lotus and Cichorium, respectively. CONCLUSIONS: As a consequence of the unequal distribution of tannins in different plant parts and due to the changing biomass proportions between them, various herbivores (e.g. a leaf-eating insect and a grazing ruminant) may find not only different concentrations of CT in their diets but also different CT dynamics during the season. For the prediction of seasonal variations of CT concentrations, biomass allocation and accumulation of none-CT plant material are likely to be as important predictors as the knowledge of CT synthesis and its regulation.

Biomass↗
PubMed1996

Correlation between colorimetric and protein-precipitation assays of tannins dissolved in treehole water.

There was a significant correlation between colorimetric and protein-precipitation assays of tannins dissolved in treehole water. The protein-precipitation potential of early-season treehole water was extremely low relative to total phenolics measured by colorimetry. The protein-precipitation method is recommended because it directly measures protein binding, the property of dissolved tannins relevant to mosquito development. Furthermore, the procedure is not affected by treehole water color and does not produce dangerous wastes.

Colorimetry↗
PubMed1976

Carcinogenicity of Camellia sinensis (tea) and some tannin-containing folk medicinal herbs administered subcutaneously in rats.

In an attempt to correlate the high incidence of esophageal carcinoma in natives of certain places with their habit of using herbaceous folk medicines, we performed bioassays of several plant extracts and the fractions prepared from them. Fourteen extracts and fractions from 6 plants were injected sc into NIH Black rats. The tannin fractions from Quercus falcata pagodaefolia, Diospyros virginiana, and Camellia sinensis were very active and produced tumors at the injection site in 66% or more of the treated animals. Tannin fractions from 3 other plants and total aqueous extracts from 5 to 6 tested plants were also tumorigenic rats. The induced tumors were malignant fibrous histiocytomas similar, if not identical, to those encountered in humans. The experiment indicated a possibility of induction of tumor in man by the tested plant materials.

Animals↗
PubMed1989

Tannin-rich carob pod for the treatment of acute-onset diarrhea.

Infants aged 3-21 months with acute diarrhea of bacterial and viral origin were treated as inpatients with oral rehydration fluid and randomly received for up to 6 days either a tannin-rich carob pod powder (40% tannins or 21.2% polyphenols and 26.4% dietary fiber), 1.5 g/kg/day (n = 21) to a maximum of 15 g, or an equivalent placebo (n = 20). The duration of the diarrhea from admission was 2.0 +/- 0.27 days in the test group and 3.75 +/- 0.30 days in the placebo group (p less than 0.001). Normalized defecation, body temperature, and weight and cessation of vomiting were reached more quickly by the patients who received the test substance. The test substance was well accepted and tolerated.

Acute Disease↗
PubMed1990

The influence of selected tannin-containing plant species on the tenacity of pathogenic bacteria in an in-vitro rumen system. 1. Communication: the influence of selected plant species on the tenacity of Cl. perfringens.

The effect of plant species containing tannins on the tenacity of Cl. perfringens was elucidated. Trials were purchased in physiological saline solution and in a rumen-fluid-medium under anaerobic conditions. The results obtained show, that within minutes the tenacity of Cl. perfringens can be reduced by some of the tested plant material not only in physiological saline solution but also in a rumen-fluid-medium. The results indicate that the reaction of some vegetable tannins and Clostridium perfringens germs is a specific one and could be used in controlling diseases caused by Clostridium perfringens.

Acacia↗
PubMed1976

Microbial degradation of condensed tannins.

A strain of Penicillium adametzi Zaleski was isolated from enrichment cultures with condensed tannins as the carbon source. Low-molecular-weight condensed tannins, extracted and purified from Pinus radiata bark, were used as substrates for quantitative growth measurements on this fungus in defined culture conditions.

Penicillium↗