Effect of Soaking and Germination on Polyphenol Content and Polyphenol Oxidase Activity of Mung Bean (Phaseolus Aureus L.) Cultivars Differing in Seed Color

Five mung bean cultivars varying in seed coat color were analyzed for polyphenol content. The effect of soaking and germination on the polyphenol content and polyphenol oxidase activity was investigated. The level of total polyphenols was found to be in the range of 310–340 mg/100 g in whole seeds. Soaking reduced the total polyphenols, whereas germination for 48 h increased total polyphenol content by 41–76%. The hydrolysable tannins, condensed tannins, and hydrolysable tannins/condensed tannins index increased with an increase in period of germination. The total and percent condensed tannins content slightly decreased while hydrolysable tannins increased during germination. Maximum polyphenol oxidase activity of 102–108 units was observed in 24 h germinated seeds. There was no significant correlation found between the polyphenolic content and polyphenol oxidase activity in germinating mung bean seeds. These findings demonstrated that the mung beans are fair sources of polyphenols, thus having great potential as a source of natural antioxidants.     

Inhibition of digestive enzymes by condensed tannins from green and ripe carobs

The degree of inhibition of trypsin, β-amylase and lipase by condensed carob tannins was determined, and compared with that caused by a glucoside of m-digallic acid. the carob tannins were strongly inhibitory to all the enzymes assayed; β-amylase was the most sensitive and lipase the least sensitive. Only in the case of lipase was the hydrolysable tannin a more active inhibitor than the condensed carob tannins. Polyvinyl pyrrolidone reactivated trypsin and lipsse, but not β-amylase. The inhibitors were found to change the maximum reaction velocities of crystalline trypsin and β-amylase, indicating non-competitive reaction kinetics.     

Comparison of the Precipitation of Alfalfa Leaf Protein and Bovine Serum Albumin by Tannins in the Radial Diffusion Method

The precipitation of protein by condensed and hydrolysable tannins was evaluated with the radial diffusion method of Hagerman (1987) using bovine serum albumin (BSA) and isolated leaf protein from fresh alfalfa (Medicago sativa). Alfalfa leaf protein (AALP) was included at two concentrations, 25 and 156 mg N litre^-1, at pH 6·8 and 39°C to simulate rumen conditions. The condensed tannins were purified from lyophilised samples of Arachis pintoi, Desmodium ovalifolium, Gliricidia sepium, Manihot esculenta and quebracho (Schinopsis balansae). Hydrolysable tannins from tannic acid (TA) were used as well. There was a significant interaction (P<0·001) between tannin and protein source, and protein level on protein precipitation. Most purified condensed tannins (CTs) precipitated more AALP than BSA when protein was included at the same level. Purified CT from quebracho and hydrolysable tannin from TA failed to precipitate AALP at both protein levels. In a second experiment, tannins from crude plant extracts were studied in the radial diffusion method using BSA and two levels of AALP. The crude plant extracts were obtained from lyophilised plant samples of A pintoi, Centrosema macrocarpum, Clitoria ternatea, D ovalifolium, Erythrina berteroana, E poepigiana, G sepium, M esculenta, Pueraria montana and P phaseoloides. The protein precipitated by soluble tannins in the plant samples was correlated to the total phenolic content and to the soluble CT estimated by the acid butanol assay or by the radial diffusion method. Tannins from different plant species precipitated different amounts of BSA and AALP. Therefore, the measures of the biological activity of tannins based on BSA precipitation may not reflect the ability of tannins to precipitate proteins of plant origin such as those commonly found in the diets of herbivores. The present study offers the possibility of using the radial diffusion method with plant proteins at precipitation conditions similar to those in the rumen. © 1997 SCI.     

Tannin–protein interaction is more closely associated with astringency than tannin–protein precipitation: experience with two oenological tannins and a gelatin

Relative abilities of two commercial oenological tannins to interact with a single oenological gelatin were compared with their relative abilities to elicit astringency. A trained sensory panel assessed astringency, whereas the interaction between tannins and gelatin was estimated by observing the ability of tannins both to interfere with gelatin diffusion on a cellulose membrane and to form tannin–gelatin precipitates. HPLC‐DAD chromatography and spectroscopic analysis showed that one of the commercial tannins was a hydrolysable tannin, while the other one was a condensed. The majority of the sensory panelists recognised the hydrolysable tannin as far more astringent than the condensed. The more astringent oenological tannin was found to interfere markedly with gelatin diffusion on a cellulose membrane, but it failed to produce tannin–gelatin precipitation. The condensed oenological tannin both interfered with gelatin diffusion and was a powerful gelatin‐precipitant. This study supports the hypothesis that astringency correlates better with tannin–gelatin interaction than tannin–gelatin precipitation.     

Factors affecting in vitro formation of tannin-protein complexes

In interaction of condensed tannins from Desmodium intortum and Lotus pedunculatus and tannic acid (hydrolysable tannin) with salivary mucoproteins (from sheep and goats), plant leaf proteins and bovine serum albumin were evaluated. These studies were carried out over a pH range of 2-0-9-0 and different inorganic ion conditions to simulate conditions in which dietary proteins would interact with tannins in a ruminant digestive tract. Insoluble tannin-protein interactions were found at pH 4–5–5–5 for bovine serum albumin and 3–5–5–5 for plant leaf protein. The present study showed that pH alone was not the sole determinant for tannin-protein complex formation, since tannin-protein complexation was found in the pH range 6-0–6-5 when different inorganic ions were added to the solutions. Insoluble complexes were not formed with salivary proteins, although precipitation by tannic acid was achieved at 5°C. This suggests that tannins may form soluble rather than insoluble complexes with salivary proteins. It was concluded that purified F1 leaf protein (the major protei occurring in leaf tissue) ought to be used as the test protein for evaluating tannin-protein interactions for in vitro assay procedures. Using this method it was calculated that 27–43% and 19–40% of available plant protein may interact with condensed tannins from Desmodium intortum and Lotus pedunculatus, respectively.     

Phenolic composition of Flacourtia indica, Opuntia megacantha and Sclerocarya birrea

The phenolic acid composition of the peel and pulp of the fruits of Flacourtia indica (Burm. f.) Merr., Opuntia megacantha (L.) Mill and Sclerocarya birrea (A. Rich.) Hochst., from Zimbabwe, were analysed using traditional colorimetric as well as HPLC methods. The total phenolics, flavanoids and condensed tannin levels varied with species. Sclerocarya birrea pulp had the highest total phenolics, flavanoids and condensed tannins, i.e., 2262 μg GAE/g, 202 μg catechin/g and 6.0% condensed tannins, respectively. Flacourtia indica pulp contained the least total phenolics, flavanoids and condensed tannins 334 μg GAE/g, 41 μg catechin/g and 1.4%, respectively. There were no significant differences in the total phenolics between the peels and the pulps of the individual fruits. However, significant differences were noted in the flavanoids and the condensed tannins between the peels and pulps of the fruits assayed. Ferulic acid, caffeic acid and vanillic acid were the dominant phenolic acids in the three fruits. There were differences between the phenolic acids in the peels and the pulps of the fruits.     

橄榄果实单宁的抗氧化能力研究

对橄榄果实中的总酚含量与可溶缩合单宁含量进行了测定,并利用二苯基苦基苯肼自由基(DPPH)和铁离子还原/抗氧化能力测定(FRAP)法,研究了橄榄果实中单宁的自由基清除能力及抗氧化活性。结果表明:橄榄果实中总酚含量较高[(572.35±39.72)mg/g(干重)],用正丁醇-HCl法测得缩合单宁的含量为(1.47±0.02)mg/g(干重),用DPPH法和FRAP法研究其自由基清除能力及抗氧化活性表明,橄榄果实单宁具有较高的自由基清除能力(IC_(50)为48.45μg/mL),及较强的抗氧化能力(2.955 mmol AAE/g)。     

Estimation of the degree of polymerization of condensed tannins of some wild fruits of Zimbabwe (Uapaca kirkiana and Ziziphus mauritiana) using the modified vanillin‐HCl method

Methanol and glacial acetic acid were compared for their effect in the vanillin assay for tannins. The time taken for the development of colour was followed using a spectrophotometer. By reacting vanillin and condensed tannins in the presence of acetic acid, the time for the development of the chromogenic substance was reduced approximately threefold compared with the time taken in the presence of methanol. The degree of polymerization was followed by reacting a catechin standard, the tannin of the Uapaca kirkiana and Ziziphus mauritiana, with vanillin in acetic acid medium at 30 °C and measuring absorbance at intervals. The values obtained suggested between 4 and 10 monomer units of catechin per polymer of tannins for the different portions of the two fruits. Copyright © 2005 Society of Chemical Industry     

Effects of tannic acid and quebracho tannins on in vitro ruminal fermentation of wheat and corn grain

Current understanding of the effect of moderate amounts of tannins on the utilization of protein contained in forages indicates beneficial effects when fed to ruminants. Nevertheless, there is little knowledge about the effects of tannins on the ruminal hydrolysis of starch‐rich concentrates. Modulation of the hydrolysis of starch may reduce the occurrence of metabolic disorders, such as acidosis, in ruminants consuming high‐grain diets. The effects of commercial tannic acid (hydrolysable tannins) and quebracho tannins (condensed tannins) (50 g kg^?1 DM) on the in vitro fermentation of ground wheat and corn grains by mixed ruminal bacteria was examined. The architecture and chemical composition of wheat and corn endosperms might explain differences in fermentation rates, as well as in response to similar concentrations of tannins. Regardless of the source of tannin, microbial fermentation was inhibited in both grains, as demonstrated by a decline in gas production, DM disappearance, volatile fatty acids and ammonia production. However, these effects were more pronounced for wheat than corn grain, mostly during the initial stages of the incubation. Scanning electron microscopy revealed that both sources of tannins inhibited the microbial hydrolysis of the endosperm protein matrix. Tannins did not prevent bacterial attachment to starch granules, but starch hydrolysis was slowed indirectly as a result of a tannin‐mediated reduction in the degradation of the surrounding protein matrix. Tannins are likely to be more effective at modulating the rate of starch digestion in grains that possess a readily degradable protein matrix. Copyright © 2006 Society of Chemical Industry     

Oral administration of apple condensed tannins delays rheumatoid arthritis development in mice via downregulation of T helper 17 (Th17) cell responses

Apples are known to contain high concentrations of phenolic compounds such as condensed tannins. Consumption of condensed tannins has been reported to reduce the risk of many types of chronic diseases including allergies. However, their therapeutic effectiveness and potential in treating autoimmune disease remain controversial. Here, the effect of oral administration of apple condensed tannins (ACT) prepared from apples (Malus pumila cv. Fuji) on bovine type II collagen (CII)‐induced arthritis in DBA1/J mice, a well‐established murine model of human rheumatoid arthritis (RA), was evaluated. As compared to the control (without ACT administration) group, RA development was delayed and a significant reduction in the RA clinical score was observed in the ACT‐administered group. Using cultured splenocytes isolated from CII‐immunized mice, ACT‐administration was shown to decrease the CII‐induced increases in IL‐17 expression and production in vitro. We propose that downregulation of T helper (Th) 17 cells is responsible for the ACT‐induced RA suppression.     

酸枣叶缩合单宁的分离鉴定及其对黑色素生成的抑制机制

目的:研究酸枣叶缩合单宁的结构特征及其对酪氨酸酶的效应和黑色素生成的抑制机制。方法:利用Sephadex LH-20凝胶柱色谱技术分离制备酸枣叶缩合单宁纯化物,采用硫醇降解结合高效液相色谱-电喷雾电离质谱（Thiolysis-HPLC-ESI-MS）解析酸枣叶缩合单宁的结构单元组成,运用酶动力学、紫外光谱、荧光猝灭等方法系统研究酸枣叶缩合单宁对酪氨酸酶的抑制作用机理,应用CCK-8法、多巴氧化法、NaOH裂解法和实时荧光定量PCR检测酸枣叶缩合单宁对小鼠黑色素瘤细胞（B16F10）的增殖、酪氨酸酶活性、黑色素合成及其相关基因表达水平的影响。结果:构成酸枣叶缩合单宁的主要结构单元是（表）儿茶素和（表）棓儿茶素;酸枣叶缩合单宁具有较强的酪氨酸酶单酚酶和二酚酶抑制活性,是二酚酶可逆的混合型抑制剂;酸枣叶缩合单宁可有效抑制B16F10细胞的增殖、酪氨酸酶活性、黑色素生成量以及酪氨酸酶（TYR）、酪氨酸酶相关蛋白-1（TRP-1）、小眼畸形相关转录因子（MITF）等基因的表达。结论:通过在酶水平和细胞水平的综合分析,阐明酸枣叶缩合单宁对B16F10细胞黑色素合成的分子抑制机制,为后期酸枣叶缩合单宁开发为新的美白化妆品添加剂和果蔬保鲜剂提供理论依据。     

Leucoanthocyanins and related phenolic compounds of carob pods (Ceratonia siliqua)

The phenolic compounds present in green carob pods were separated into five components. These were characterised on the bases of solubility, mobility on paper, nature of products of hydrolysis by Penicillium tannase, nature of products yielded on heating with dilute and concentrated hydrochloric acid solution, and nature of products yielded on alkali fusion. The major leucoanthocyanins in green carob pods were highly polymerised leucodelphinidins. A large amount of, and many kinds of, hydrolysable tannins were found. Two crystalline galloyl glucose compounds were isolated. The phenolic compounds present in ripe carob pods were fractionated into four preparations. Hydrolysable tannins present in green pods, were either not found or present only in low concentrations. On the other hand, gallic acid was found in large amounts in ripe pods. The main leucoanthocyanin in ripe pods also was leucodelphinidin. The gallic acid found in ripe pods could be derived from the hydrolysable tannins in green pods by enzymic hydrolysis.     

Effect of the Prefermentative Addition of Five Enological Tannins on Anthocyanins and Color in Red Wines

Abstract: The effects of prefermentation addition of 5 exogenous tannins with different‐origin anthocyanins and color characteristics were investigated in “Cabernet Sauvignon wines” at the end of alcoholic fermentation and the end of malolactic fermentation, and after 6 mo and 9 mo of bottle aging, respectively. The results showed that the application of GSKT2 could significantly retard the degradation of most anthocyanins in the process of alcoholic fermentation and the decrease of some pyranoanthocyanins during the subsequent 3 stages, thus causing more yellowness of wine in comparison with the control. Three other condensed tannins, GSKT1, QUET, and GSET, had a positive impact only on several anthocyanin components. Four condensed tannins all contributed to more redness, suggesting that the action mechanism might be to protect wine against oxidation or contribute to form copigmented anthocyanidins, or polymeric pigments. The application of FOLT (hydrolysable tannin) did not produce any influence on wine redness even after 9 mo of bottle aging. This work provides some reasons for the reasonable application of tannin additives. Practical Application: The prefermentative application of condensed tannins overall could protect some pigment components from degradation and enhance wine redness. Tannin additives with different origins have different effectiveness. The tannin additive obtained from grape skins, like GSKT2, could produce significant promotion on both redness and yellowness in wine. The prefermentation addition of hydroxylase tannin like FOLT seems not to have a significant effect on wine color.     

Exploitation of dietary tannins to improve rumen metabolism and ruminant nutrition

Tannins (hydrolysable and condensed tannin) are polyphenolic polymers of relatively high molecular weight with the capacity to form complexes mainly with proteins due to the presence of a large number of phenolic hydroxyl groups. They are widely distributed in nutritionally important forage trees, shrubs and legumes, cereals and grains, which are considered as anti‐nutritional compounds due to their adverse effects on intake and animal performance. However, tannins have been recognised to modulate rumen fermentation favourably such as reducing protein degradation in the rumen, prevention of bloat, inhibition of methanogenesis and increasing conjugated linoleic acid concentrations in ruminant‐derived foods. The inclusion of tannins in diets has been shown to improve body weight and wool growth, milk yields and reproductive performance. However, the beneficial effects on rumen modulation and animal performance have not been consistently observed. This review discusses the effects of tannins on nitrogen metabolism in the rumen and intestine, and microbial populations (bacteria, protozoa, fungi and archaea), metabolism of tannins, microbial tolerance mechanisms to tannins, inhibition of methanogenesis, ruminal biohydrogenation processes and performance of animals. The discrepancies of responses of tannins among different studies are attributed to the different chemical structures (degree of polymerisation, procyanidins to propdelphinidins, stereochemistry and C? C bonding) and concentrations of tannins, and type of diets. An establishment of structure–activity relationship would be required to explain differences among studies and obtain consistent beneficial tannin effects. Copyright © 2010 Society of Chemical Industry     

Assessment of the effect of condensed (acacia and quebracho) and hydrolysable (chestnut and valonea) tannins on rumen fermentation and methane production in vitro

BACKGROUND: Tannins added to animal diets may have a positive effect on energy and protein utilisation in the rumen. The objective of this study was to examine the impact of different sources and concentrations (20, 50, 100, 150 and 200 g kg^?1 dry matter (DM)) of condensed (acacia and quebracho) and hydrolysable (chestnut and valonea) tannins on rumen microbial fermentation in vitro. The experiment also included a negative control with no tannins (control) and a positive control with monensin (10 mg L^?1). RESULTS: In vitro gas production and total volatile fatty acid (VFA) concentration decreased as tannin concentration increased. Addition of acacia, chestnut or valonea tannins at ≥ 50 g kg^?1 or quebracho tannins at ≥ 100 g kg^?1 resulted in a decrease (up to 40%) in methane (CH₄) production compared with the control. Valonea tannins were the only tannin source that reduced (?11%) CH₄ production at 50 g kg^?1 without affecting VFA concentration. Tannin treatments reduced ammonia (NH₃) and branched‐chain VFA concentrations, indicating a reduction in ruminal protein degradation. Monensin reduced CH₄ production (?37%) and NH₃ concentration (?20%) without affecting total VFA concentration. CONCLUSION: Supplying acacia, chestnut or valonea tannins at 50 g kg^?1 has the potential to reduce CH₄ production and ruminal protein degradation with minimum detrimental effects on efficiency of ruminal fermentation. Copyright © 2012 Crown in the right of Canada. Published by John Wiley & Sons, Ltd     

Chemistry and Biological Activities of Processed Camellia sinensis Teas: A Comprehensive Review

Tea is a typical processed beverage from the fresh leaves of Camellia sinensis [Camellia sinensis (L.) O. Kuntze] or Camellia assamica [Camellia sinensis var. assamica (Mast.) Kitamura] through different manufacturing techniques. The secondary metabolites of fresh tea leaves are mainly flavan‐3‐ols, phenolic acids, purine alkaloids, condensed tannins, hydrolysable tannins, saponins, flavonols, and their glycoside forms. During the processing, tea leaves go through several steps, such as withering, rolling, fermentation, postfermentation, and roasting (drying) to produce different types of tea. After processing, theaflavins, thearubigins, and flavan‐3‐ols derivatives emerge as the newly formed compounds with a corresponding decrease in concentrations of catechins. Each type of tea has its own critical process and presents unique chemical composition and flavor. The components among different teas also cause significant changes in their biological activities both in vitro and in vivo. In the present review, the progress of tea chemistry and the effects of individual unit operation on components were comprehensively described. The health benefits of tea were also reviewed based on the human epidemiological and clinical studies. Although there have been multiple studies about the tea chemistry and biological activities, most of existing results are related to tea polyphenols, especially (‐)‐epigallocatechin gallate. Other compounds, including the novel compounds, as well as isomers of amino acids and catechins, have not been explored in depth.     

柿果成熟过程中总酚和缩合单宁含量的变化

本实验通过Folin-Ciocalteu法、香草醛-盐酸法测定不同类型12 个柿品种果实生长发育进程中总酚和缩合单宁含量的变化,并运用正交试验法对香草醛-盐酸法进行优化。结果表明：香草醛-盐酸法优化参数为：显色液为2.0 g/100 mL香草醛甲醇与15%盐酸甲醇液,显色0.5 h。柿果实的生长发育进程中,总酚和缩合单宁含量变化规律相似,花后35～50 d达到最高水平,随后逐渐降低,但不同类型柿间总含量及变化幅度存在着较大的差异;其中,日本完全甜柿（J-PCNA）、中国完全甜柿（C-PCNA）、不完全甜柿（PVNA）、不完全涩柿（PVA）、完全涩柿（PCA）同类型各品种间总酚和缩合单宁变化趋势相似,含量相近,总酚、缩合单宁含量基本符合规律PCA＞C-PCNA＞PVA＞PVNA＞J-PCNA。     

Interrelationships between the concentrations of total condensed tannin,free condensed tannin and lignin in Lotus sp. and their possible consequences in ruminant nutrition

Interrelationships between the concentrations of total condensed tannin (TCT), free condensed tannin (FCT) and lignin were studied to gain knowledge of how to manipulate nutritive value of fresh herbages containing condensed tannins fed to ruminants. FCT was defined as condensed tannin not bound by macerates of fresh plants, with both FCT and TCT being determined with vanillin HCl. Effects of spraying lotus with polyethylene glycol (mol. wt 3350; PEG) upon the relationship between FCT and TCT was also studied. Increasing soil nutrient and climatic stress caused large and similar increases in the concentrations of TCT and of lignin. Over the range 0–90 g kg^?1 DM, 10% of TCT in Lotus sp. was detected as FCT, with increments in TCT above 90 g kg^?1 DM being released almost entirely as FCT. PEG formed much stronger chemical bonds with condensed tannins than did plant proteins, and did not release FCT; consequently PEG application reduced the concentration of condensed tannin that was detectable with vanillin HCl. After disintegration of plant material, it is proposed that most condensed tannin is bound and co-precipitated as an insoluble complex with protein, that FCT is in equilibrium with this complex, and that bound and free tannin are indices of nutritionally beneficial and detrimental effects produced by condensed tannins in fresh forages eaten by ruminants. It was concluded that growing Lotus pedunculatus under conditions of stress leads to depressions in nutritive value through simultaneously increasing concentrations of lignin and FCT, both of which depress rumen carbohydrate digestion and voluntary intake, and that treatment with PEG offers a convenient method of separating effects due to condensed tannins from other factors influencing nutritive value.     

不同皮渣浸渍发酵时间对葡萄酒中缩合单宁构成及感官品质的影响

为明确不同皮渣浸渍时间对葡萄酒中缩合单宁的影响,以赤霞珠和西拉为材料,进行不同浸渍发酵时间处理,对葡萄皮和葡萄籽以及葡萄酒中缩合单宁的含量、组成、缩合单宁以及相关口感指标等进行了分析。结果表明,不同葡萄品种中缩合单宁的初始含量、聚合度及没食子酰化率都有显著差异（P<0.05）。葡萄皮中缩合单宁的平均聚合度显著高于葡萄籽（P<0.05）,而葡萄皮缩合单宁的没食子酰化率则显著低于葡萄籽缩合单宁（P<0.05）。葡萄皮和葡萄籽中缩合单宁组成的最大差异是葡萄籽缩合单宁中不含有（?）-表棓儿茶素亚单元,而且末端单元主要是由（+）-儿茶素、（?）-表儿茶素和（?）-表儿茶素没食子酸酯组成。皮渣浸渍时间对葡萄酒中缩合单宁的组成及含量都有明显影响。随着浸渍时间的延长,葡萄酒中缩合单宁的总含量呈上升趋势,而平均聚合度则呈下降趋势。不同品种的葡萄酒之间缩合单宁含量也存在显著差异（P<0.05）,这与不同葡萄品种中酚类物质的可浸提率有关。葡萄酒中葡萄皮缩合单宁的占比一直显著高于籽粒缩合单宁的占比（P<0.05）,说明葡萄皮中缩合单宁比葡萄籽缩合单宁更容易浸提到葡萄酒中。相对于苦味和酸味,不同浸渍时间处理对葡萄酒的涩味影响更为显著（P<0.05）,综合考虑酒体的丰满度和口感的平衡,皮渣浸渍时间选择14 d左右更好一些。     

大孔吸附树脂对广西甜茶中水解鞣质吸附性能的研究

研究了8种大孔吸附树脂及聚酰胺对水解鞣质的吸附与解析性能,从中选出LSA21树脂具有较大吸附量和解吸率。动态吸附实验研究了提取液浓度、pH值以及流速等对LSA21树脂吸附量的影响,适合的上柱浓度为3mg/mL、pH为4.8、流速为1.2BV/h(本文1BV/h=50mL/h)。在此条件下,用体积分数60%乙醇洗脱得水解鞣质纯度为71.03%。