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PubMed1990

Iron retention by rats from casein-legume test meals: effect of tannin level and previous diet.

The effect of tannin content on iron (Fe) bioavailability from several legumes was evaluated. Absorption of Fe from a casein (C), isolated soy protein (ISP), chickpea (CP) or red kidney bean (RKB) test meal was tested in marginally Fe-deficient rats [9.9 +/- 0.2 g Hb/100 mL (mean +/- SD)] using the extrinsic tag technique. Also, the effects of a casein habitual diet or of one of three casein-legume habitual diets fed before and after the test meal were investigated. Weanling male rats were fed the habitual diets containing 23 +/- 4 mg Fe/kg of diet (range 17-28) for 13 d. On d 14, after an overnight fast, rats were fed the test meal (1.5 g + 0.1 microCi 59Fe), and whole-body radioactivity was determined. The same habitual diet was refed for seven additional days, and whole-body radioactivity was determined again. Rats retained more iron from C (86%) than from ISP, CP or RKB test meals (73%, 75% and 67%, respectively) when the respective casein-legume habitual diets were fed before and after the test meals. With the casein habitual diet, there was no difference in retained iron from C, ISP, CP or RKB test meals (86%, 87%, 83% and 82%, respectively). Retention of iron from an RKB test meal was increased from 69.6 to 73% when about 90% of the extractable tannins were removed, but the difference was not statistically significant. Thus, feeding a casein-legume diet but not a casein diet prior to a test meal apparently predisposes the rat to lower iron absorption. However, in these studies, tannins per se did not significantly depress iron bioavailability.

Absorption↗
PubMed2005

Light and an exogenous transcription factor qualitatively and quantitatively affect the biosynthetic pathway of condensed tannins in Lotus corniculatus leaves.

The effects of increasing light and of a heterologous bHLH transcription factor on the accumulation of condensed tannins (CT) were investigated in leaves of Lotus corniculatus, a model legume species which accumulates these secondary metabolites in leaves as well as reproductive tissues. Light and expression of the transgene increased the level of CT in a synergistic way. To monitor how the changes in accumulation of condensed tannins were achieved, the level of expression of four key genes in the flavonoid pathway was estimated by real-time RT-PCR analysis. Early genes of the pathway (PAL and CHS) were affected less in their expression and so appeared to be less involved in influencing the final level of CT than later genes in the pathway (DFR and ANS). Steady-state levels of DFR and ANS transcripts showed a strong positive correlation with CT and these genes might be considered the first rate-limiting steps in CT biosynthesis in Lotus leaves. However, additional factors mediated by light are limiting CT accumulation once these genes are up-regulated by the transgene. Therefore, the increment of the steady-state mRNA level for DFR and ANS might not be sufficient to up-regulate condensed tannins in leaves. The real-time RT-PCR approach adopted showed that members within the CHS and DFR gene families are differentially regulated by the exogenous bHLH gene and light. This finding is discussed in relation to the approaches for controlling CT biosynthesis and for studying the expression profile of multi-gene families.

Amino Acid Sequence↗
PubMed1992

Tannin-protein complex-degrading enterobacteria isolated from the alimentary tracts of koalas and a selective medium for their enumeration.

Tannin-protein complex (T-PC)-degrading enterobacteria (T-PCDE) were isolated from the feces and from a layer of bacteria attached to the cecal wall of koalas. The T-PCDE were facultatively anaerobic, gram-negative, pleomorphic, nonmotile bacilli. The bacteria were also oxidase and catalase negative and resistant to vancomycin, reduced nitrates to nitrites, and grew on MacConkey agar. Growth on tannin-treated agar media showed a distinctive clear zone around the colony. From these observations, a selective agar plate medium (vancomycin- and tannin-treated Wilkins-Chalgren anaerobe agar) was developed to enumerate T-PCDE isolated from the feces of koalas. This medium was highly selective in the enumeration of the fecal T-PCDE and inhibited the growth of concomitant T-PC-degrading Streptococcus bovis. The T-PCDE were isolated from 10 of the 12 captive koalas studied; in 8 of these 10 koalas, the facultatively anaerobic bacterial flora was dominated (more than 60%) by T-PCDE. Viable numbers of T-PCDE were, in most of the animals, much larger (more than 100 times) than the numbers of T-PC-degrading S. bovis, suggesting that T-PCDE played a more active role in digesting T-PC in the alimentary tracts of koalas.

Animals↗
PubMed1995

Isolation and characterization of an anaerobic ruminal bacterium capable of degrading hydrolyzable tannins.

An anaerobic diplococcoid bacterium able to degrade hydrolyzable tannins was isolated from the ruminal fluid of a goat fed desmodium (Desmodium ovalifolium), a tropical legume which contains levels as high as 17% condensed tannins. This strain grew under anaerobic conditions in the presence of up to 30 g of tannic acid per liter and tolerated a range of phenolic monomers, including gallic, ferulic, and p-coumaric acids. The predominant fermentation product from tannic acid breakdown was pyrogallol, as detected by high-performance liquid chromatography and mass spectrometry. Tannic acid degradation was dependent on the presence of a sugar such as glucose, fructose, arabinose, sucrose, galactose, cellobiose, or soluble starch as an added carbon and energy source. The strain also demonstrated resistance to condensed tannins up to a level of 4 g/liter.

Animals↗
PubMed2000

Effects of short-term exposure to condensed tannins on adult Trichostrongylus colubriformis.

Twelve parasite-naive sheep were used to study the possible direct anthelmintic effect of a condensed tannin extract (quebracho) on the population and fecundity of the intestinal nematode Trichostrongylus colubriformis. The sheep were infected with a single dose of 20,000 L3 of T colubriformis. Twenty-eight days later, six of them were drenched daily for a week with quebracho extract at 8 per cent by weight of their food intake. All lambs were then slaughtered, and their small intestines removed to estimate the worm burdens and the numbers of eggs in utero. Two days after the first drench with tannin extract the faecal egg counts of the treated sheep were approximately 50 per cent of those of the control sheep (P<0.01), but there was no further reduction with continued drenching. In the treated sheep the worm burdens and number of eggs per gram faeces per worm were reduced by 30 per cent compared with the controls (P<0.05), but the sex ratios, the number of eggs in utero and length of the worms were not affected by drenching with tannin.

Administration, Topical↗
PubMed1993

Inhibitory effect of tannin in green tea on the proliferation of mesangial cells.

The effect of green tea tannin on the proliferation of mesangial cells was determined in terms of [3H]thymidine uptake. When green tea tannin was added to the medium of mesangial cell cultures, it suppressed the proliferation of mesangial cells markedly. In particular, (-)-epigallocatechin 3-O-gallate, the predominant component of the green tea tannin mixture, exerted an inhibitory effect at a relatively low concentration, suggesting a direct corroboration of the renal effects.

Animals↗
PubMed2000

Tannins protect against skin tumor promotion induced by ultraviolet-B radiation in hairless mice.

We recently showed that Tarapod tannic acid (TA), a hydrolyzable tannin extracted from the pods of the Tara tree (Caesalpinia spinosa), was more effective than other tannins tested at inhibiting ultraviolet-B (UV-B)-stimulated hydrogen peroxide activity (an indirect measure of free radicals) in the skin of hairless mice. We also found that Tarapod TA inhibited UV-B-induced ornithine decarboxylase activity and UV-B-stimulated DNA synthesis, two biochemical markers linked to the skin tumor-promoting ability of this physical carcinogen. For this reason, we examined the effect of topical application, force feeding (gavage), and intraperitoneal injections of Tarapod TA on mouse skin chronically treated with UV-B light. Mice were initiated by a single topical application of 7,12-dimethylbenz[a]anthracene (50 nmol) and promoted by two weekly treatments with UV-B light (250 mJ/cm2) for 25 weeks. Topical application of Tarapod TA, 20 minutes before irradiation, resulted in a dose-dependent inhibition of tumor incidence (number of mice with tumors) and tumor yield (number of tumors/mouse), with 8 mg of TA inhibiting tumor yield by 70% at Week 25. Intraperitoneal injections of low doses (10 mg/kg mouse body wt), but not of high doses (25 mg/kg body wt), of TA afforded protection against UV-B-induced papillomas. However, the protection by intraperitoneal injection was lower than that observed by topical application: 10 mg/kg body wt of TA reduced tumor yield by 55%. The force feeding of 10 mg of Tarapod TA before irradiation failed to significantly inhibit the yield of tumors at the end of the experiment but delayed tumor appearance by six weeks. These results suggest that plant tannins administered topically or injected intraperitoneally reduce the tumor-promoting effects of UV-B radiation and thus could be useful photoprotectants.

Administration, Oral↗
PubMed2001

Antimicrobial activity of tannin components from Vaccinium vitis-idaea L.

Reactive oxygen species have been implicated as important pathological mediators in many clinical disorders, including periodontal disease. As a possible alternative for the treatment of periodontal disease, the antimicrobial activity of six tannins isolated from Vaccinium vitis-idaea L., with confirmed antioxidant activity, were assayed by the agar dilution method against selected periodontal pathogens, Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis and Prevotella intermedia. The results showed that epicatechin-(4beta-->8)-epicatechin-(4beta-->8, 2beta-->O-->7)-catechin had strong antimicrobial activity against P. gingivalis and P. intermedia, but not A. actinomycetemcomitans. The other tannins tested did not show antimicrobial activity. We conclude that tannins isolated from V. vitis-idaea L. with antimicrobial activity could potentially be used for the treatment of periodontal disease.

Aggregatibacter actinomycetemcomitans↗
PubMed2002

Association of tannins and related polyphenols with the cyclic peptide gramicidin S.

The association of 10 different tannins and related polyphenols with gramicidin S, a cyclic peptide having a rigid beta-turn structure, has been examined using 1H-NMR spectroscopy. In the presence of pentagalloylglucose and epigallocatechin-3-O-gallate, the proton signals due to proline and the adjacent phenylalanine moieties selectively shifted to up field, suggesting a regioselective association with the beta-turn structure. The association was also supported by the observation of intermolecular nuclear Overhauser effects between epigallocatechin-3-O-gallate and the peptide. In contrast, ellagitannins, biogenetically derived from pentagalloylglucose, showed small and non-selective chemical shift changes, suggesting that interaction with these tannins is relatively weak. The hydrophobicity of the tannin molecules and the steric hindrance of the interaction site are thought to be important in the association.

Flavonoids↗
PubMedDate not supplied

Tannins and related compounds: killing of amastigotes of Leishmania donovani and release of nitric oxide and tumour necrosis factor alpha in macrophages in vitro.

The antileishmanial and immunomodulatory potencies of a series of 28 polyphenols were evaluated in terms of extra- and intracellular leishmanicidal activity and macrophage activation for release of nitric oxide (NO), tumour necrosis factor (TNF) and interferon (IFN)-like properties. For this, several functional bioassays were employed including an in vitro model for leishmaniasis in which murine bone marrow-derived macrophages (BMMphi) were infected with the obligate intracellular parasite Leishmania donovani, an extracellular Leishmania proliferation assay, a fibroblast-lysis assay (TNF-activity), and a biochemical assay for NO. Except for gallic acid, its methyl ester, shikimic acid and catechin (EC50 25.8-67.9 nM) all polyphenols tested significantly inhibited the intracellular survival of L. donovani amastigotes (EC50 0.4-13.9 nM) when compared with the clinically used agent, sodium stibogluconate (EC50 10.6 nM). In contrast, none of the samples proved to be directly toxic for the extracellular promastigote form of the parasite. Noteworthy, the phenolic samples showed only moderate or no cytotoxicity against the murine host cells (EC50 10 to >144 nM). Although NO is an important effector molecule in macrophage microbicidal activity, the inducing potential of the test compounds for its release was found to be very moderate ranging from 7-54 microM (IFN-gamma/LPS 119 microM). On the other hand, inhibition of NO production had no apparent effect on intracellular leishmanicidal activity of polyphenols. Their in vitro TNF-inducing potential producing 50% lysis in murine L929 cells increased in the order of simple phenols and flavanols (34-48 U/ml) < A-type proanthocyanidins (53-80 U/ml) < B-type proanthocyanidins (64-200 U/ml) < hydrolyzable tannins (287-350 U/ml) at the host cell subtoxic concentration of 50 microg/ml. Furthermore, gallic acid and some hydrolyzable tannins showed appreciable IFN-like activities (14-23 U/ml) as reflected by inhibition of the cytopathic effect of encephalomyocarditis virus on fibroblast L 929 cells. The results provide a rational basis for the recorded anti-infectious efficacy of traditionally used herbal medicines containing tannins in vivo, in the light of both only moderate direct antimicrobial activities of distinct polyphenols in vitro and the limited knowledge on their uptake in humans.

Animals↗
PubMed2005

Selective determination of aluminum bound with tannin in tea infusion.

In this study, an analytical method for indirect measurement of Al bound with tannin in tea infusion was studied. This method utilizes the ability of the tannins to precipitate with protein. Separation conditions were investigated using model solutions. This method is uncomplicated, inexpensive and suitable for real samples. About 34% of the total Al in brew extracted from commercially available teas was bound to condensed and hydrolyzable tannins.

Aluminum↗
PubMed1995

Effects of hulls of faba beans (Vicia faba L.) with a low or high content of condensed tannins on the apparent ileal and fecal digestibility of nutrients and the excretion of endogenous protein in ileal digesta and feces of pigs.

In three experiments (Exp. 1, 2, and 3) with young pigs (BW 10 to 26 kg), the effects of dietary inclusion of hulls of faba beans (Vicia faba L.) (200 g/kg) with a low (< .1% catechin equivalents; LT) or high tannin content (3.3% catechin equivalents; HT) on the apparent ileal (Exp. 1 and 2) and fecal (Exp. 3) digestibility of nutrients were determined. In addition, the true digestibility of protein of the diets and the excretion of endogenous protein (N x 6.25) in ileal digesta and feces of pigs were measured, using the 15N isotope dilution technique (Exp. 3). Diets contained either casein and faba bean cotyledons as highly soluble (HS) protein sources (Exp. 1 to 3) or potato protein, soy concentrate, sunflower meal, meat meal, and fish meal as protein sources with a low solubility (LS) (Exp. 1). Control diets contained cellulose as a fiber source (64 to 73 g/kg). Inclusion of either type of hulls decreased the apparent ileal digestibility for DM, organic matter (OM), and nonprotein organic matter (NPOM) (P < .05). Inclusion of LT hulls instead of cellulose only reduced the apparent ileal digestibility of crude protein (N x 6.25; CP) in Exp. 3 (P < .05). Inclusion of HT instead of LT hulls reduced the apparent ileal digestibility of CP (by 7 to 10 units) and amino acids (by 4 to 29 units) (P < .05). The LT hulls decreased apparent and true ileal digestibility of CP from 88 to 83 and from 97 to 94, respectively (P < .05). Inclusion of HT instead of LT hulls decreased apparent and true ileal CP digestibility from 83 to 74 and 94 to 90 (P < .05) and increased the excretion of endogenous CP from 22 to 32 and from 13 to 23 g/kg of DM intake at the ileal and fecal level, respectively (P < .05). It is concluded that condensed tannins in faba beans interact with both dietary and endogenous proteins in the digestive tract of pigs. This reduces the true digestibility of dietary protein and increases the excretion of endogenously secreted proteins. Tannins from faba beans show some preference to interact with proteins with a high content of proline and histidine.

Amino Acids↗
PubMed1975

Vanillin-hydrochloric acid as a histochemical test for tannin.

Condensed tannin (leucoanthocyanins and catechins) can be demonstrated in fresh plant sections with saturated alcoholic vanillin followed by addition of concentrated HCl. Bright red vanillin-tannin condensates are formed immediately. Preparations may then be made permanent by mounting in a 1:1 mixture of Hoyer's medium and concentrated HCl. Some fading and loss of tannin occurs. The phloroglucinol-HCl test for lignin can also be made permanent with this acidic mountant.

Flavoring Agents↗
PubMed1976

Differential staining of tannin in sections of epoxy-embedded plant cells.

A staining procedure is described for the light microscopic localization of ergastic tannins in epoxy sections of plant cells embedded for study by transmission electron microscopy. Callus and cell suspensions of Pseudotsuga menziesii and Pinus taeda fixed in glutaraldehyde:acrolein and then OsO4, followed by epoxy embedding, were sectioned 0.5 mum thick, stained on a glass slide with ethanolic Sudan black B at 60 C as described by Bronner, and then mounted in Karo syrup. Tannin deposits stained brownish-orange and were easily distinguished from lipid bodies of similar size, which stained dark blue to black, and from starch grains, which were unstained. The significance of this differential polychromasia was confirmed by transmission electron microscopy. This staining procedure should prove valuable in the cytoplasmic evaluation of the plant cell ergastics (especially tannins) via light microscopy whether or not electroc microscopic examination is intended.

Plant Cells↗
PubMed2003

Effect of soaking prior to cooking on the levels of phytate and tannin of the common bean (Phaseolus vulgaris, L.) and the protein value.

The effect of soaking in domestic processing, on the nutritive value of the common bean (Phaseolus vulgaris, L.) cv IAC-Carioca, was studied. Five treatments were carried out with experimental diets, and offered to male, recently weaned Wistar rats. The protein sources were, respectively, control diet (casein) (CC), casein plus the soluble solids found in the soaking water (CSS), freeze dried bean cooked without soaking (BNS), freeze dried bean cooked with the non-absorbed soaking water (BSW), freeze dried bean cooked without the non-absorbed soaking water (BSNW). and an aproteic diet (AP) for corrective purposes. The anti-nutritional factors (phytates and tannins), were determined in the differently processed beans and in the soaking water. The following values for the reduction of phytates were obtained: BNS (20.9%), BSNW (60.8%) and BSW (53.0%), and the tannins were reduced by: BNS (86.6%), BSNW (88.7%) and BSW (89.0%). No significant differences were observed between the various treatments using the common bean as protein source, with respect to the net protein ratio (NPR). With respect to the digestibility corrected by non-protein diet, values varying between 94.1% and 94.6% for casein, and between 57.5% and 61.4% for the common bean, were observed, the treatment BNS being more digestible. It was concluded that soaking did not interfere with the NPR of the experimental diets containing the common bean as protein source, nor did it reduce the tannin content. However soaking was capable of reducing the phytate levels in the common bean. On the other hand, soaking was unable to increase the protein digestibility of the common bean, since the treatment BNS showed the highest value for digestibility.

Amino Acids↗
PubMed1980

Additive toxicity of aflatoxin and dietary tannins in broiler chicks.

In two experiments graded levels of either aflatoxin and tannic acid (experiment 1) or aflatoxin and a high-tannin variety of grain sorghum (BR-64) (experiment 2) were incorporated into broiler chick starting diets in a factorial design. When present singly, aflatoxin and both tannic acid and high tannin sorghum significantly depressed chick growth. When present in combination, and deleterious effects of aflatoxin and either tannic acid or high tannin sorghum on chick growth and feed conversion ratios were found to be additive.

Aflatoxins↗
PubMed1987

Response of growth-selected Japanese quail lines to tannin levels in grain sorghum diets with suboptimal protein.

Growth of selected lines of Japanese quail fed grain sorghum diets was evaluated. Suboptimal protein levels (23 and 25%) were used in conjunction with two varieties of sorghum differing in tannin content (.02 vs. 6.06%). Chicks of three related lines of quail differing in growth rates and mature body sizes were fed the diets from 0 to 28 days of age. Growth was significantly reduced (14 and 6%) by substitution of high tannin sorghum for low tannin sorghum in the 23 and 25% protein diets, respectively. No line X diet interaction was observed.

Animal Feed↗
PubMedDate not supplied

Plant tannins as inhibitors of hydroperoxide production and tumor promotion induced by ultraviolet B radiation in mouse skin in vivo.

The anti-oxidant and anti-tumor promotion activities of several tannins extracted from plants were examined in mouse skin treated with ultraviolet B (UVB) radiation in vivo. Hydroperoxide production was found to be maximally stimulated at a UVB dose of 200 mj/cm2, beyond which no further stimulation occurred. Treatment of mouse skin with two UVB doses of 225 mj/cm2 each, applied at a 48 h interval gradually increases the hydroperoxide (HPx)-producing activity of the epidermis, which is maximally stimulated at 4 days and returns to control levels at 15 days. The magnitude of the HPx response is found to increase with repeated UVB treatments applied at a 48 h interval and reaches a maximum level following four treatments. Of the three tannins tested (Commercial TA, Tarapod TA, and Oak TA), Tarapod TA is found to be the most effective inhibitor of UVB-stimulated HPx activity. Pretreatment with Tarapod TA inhibits, in a dose-dependent manner, this HPx response to UVB radiation. Inhibition by Tarapod TA occurs when it is applied at distant times before (-12 h) or after (+24 h) UVB radiation. When applied 20 min before UVB radiation, twice a week for 25 weeks, 8 mg of Tarapod TA inhibits the incidence and yield of papillomas promoted by UVB light in initiated skin by 34 and 70% respectively. Furthermore, when 10 mg/kg of mouse body weight of Tarapod TA was injected intraperitoneally, for a period of 25 weeks, 20 min prior to UVB treatment, it inhibited the yield of papillomas by 44%, suggesting that plant tannins when administered by various means are useful photoprotectants.

Animals↗