Condensed Tannin Extract Research Articles

Antioxidant, antimicrobial and cytotoxic potential of condensed tannins from Leucaena leucocephala hybrid-Rendang

Condensed tannins (CTs) are one of the promising compounds due to their potentially health-promoting qualities. In this study, CTs were extracted from a Leucaena leucocephala hybrid-Rendang and subjected to various biological studies including antioxidant (using Ferric reducing antioxidant power (FRAP), DPPH and ABTS radical scavenging assay), anti-microbial (against different pathogens) and cytotoxic activities (toward human breast adenocarcinoma (MCF-7), human colon carcinoma (HT29), human cervical carcinoma (HeLa) and human liver carcinoma (HepG2) cell lines) in cancer cells through in vitro experiments. The structural characteristics and purity of CTs extract were determined using 13C NMR. The results showed that CTs exhibited higher in vitro antioxidant activities (2257.12±80.55mgTEAC/gextract, 605.3±1.82mgTEAC/gextract and 1014.03±1.20mgTEAC/gextract in FRAP, ABTS and DPPH assay, respectively) and demonstrated anti-microbial activities toward selected Gram's positive and Gram's negative bacteria tested with MIC and MBC value at 6.25–50mg/mL. Furthermore, among other selected cancer cells, CTs also demonstrated cytotoxic activity toward human breast cancer cells (MCF-7) (IC50=38.33±2.08μg/mL). Characteristic of apoptosis such as cell shrinkage, nuclear condensation and apoptotic bodies were shown in MCF-7. These preliminary investigations have provided scientific rationale to use CTs as an alternative therapy for various oxidative and inflammatory associated diseases.

Antioxidants and Anticoccidial Potential of Aqueous Extract from Various Tree Leaves containing Condensed Tannins

The present study was conducted to determine the antioxidant and anticoccidial properties of aqueous extract from condensed tannins (CT) containing tree leaves (Acacia nilotica, Eugenia jambolana, Ficus religiosa, Leucaenea leucocephala and Psidium guajava). The CT content was estimated by using butanol-Hcl method. The CT extracted from various tree leaves in water as solvents and then lyophilized. The antioxidant potential of aqueous extract from various CT sources was evaluated by using multiple in-vitro colorimetric methods which include 1, 1-Diphenyl-2-picrylhydrazyl (DPPH), total reducing power and hydrogen peroxide assays. Ascorbic acid was used as standard antioxidant in our study. However, anticoccidial efficacy of aqueous extract at different concentration (CT: 1, 2, 3 and 4 mg/ml) from various CT sources was performed using coccidial oocysts sporulation inhibition assay. The DPPH free radical scavenging activity was significantly higher in P. guajava as compared to other sources whereas hydrogen peroxide (H2O2) and reducing power activities were significantly (P<0.05) lower in L. leucocephala compared to other CT sources. Sporulation inhibition (%) of Eimeria spp. was significantly (P<0.05) higher in E. jambolana followed by P. guajava, A. nilotica, L. leucocephla while least in F. religiosa. E. jambolana and P. guajava showed maximum sporulation inhibition activity @ 4 mg/ml. It was concluded that CT extracts of A. nilotica, E. jambolana, F. religiosa, L. leucocephala and P. guajava leaves possess the antioxidant and anti-coccidian property and may be eco-friendly sustainable alternative, natural antioxidant, anti-coccidian agent and/or natural feed additive for organic meat production.

Polymeric flavonoids processed with co-polymers as UV and thermal stabilisers for polyethylene films

Stabilisers are often required to extend the service life of polymers, however few bio-based options are available. The effect of polymeric flavonoids, processed with co-polymers, on the thermal and UV stability of polyethylene films was investigated. Condensed tannin extracts from Pinus radiata and Acacia mearnsii were compounded with a range of co-polymers into linear low density polyethylene films. Tannin compatibility with the polymer matrix was studied using confocal microscopy. The thermal and UV stability was assessed using differential scanning calorimetry, accelerated weathering, mechanical testing and infrared spectroscopy. Tannin increased the thermo-oxidative stability of the films, particularly when the compatibility was enhanced using co-polymers. Furthermore, tannin improved the UV stability during accelerated weathering, with greater strength and elongation retention. The stability provided by tannin may be attributed to radical scavenging by the chain breaking donor mechanism. These results show potential for tannin as a stabiliser for polyethylene, however further improvements in performance need to be achieved to facilitate commercial uptake.

Green chemistry preparation of superparamagnetic nanoparticles containing Fe3O4 cores in biochar

Nanotechnology is an engineering science in which the aim is to develop novel procedures and structures at the nanoscale that might offer solutions to many current problems. In this article, we describe the synthesis of superparamagnetic iron oxide (Fe3O4) nanoparticles in biochar obtained from the condensed tannin extract of Acacia mearnsii, using a single-step process that is compliant with the principles of green chemistry. Characterization of this material (acronym: SPMIOBNs) was performed using Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, and X-ray diffraction analysis. The porous particles produced contained iron oxide nanoparticles with average sizes in the range 20–35nm. The magnetic properties revealed that the SPMIOBNPs were superparamagnetic, with a saturation magnetization of 3.2memu/g at 300K.

The effects of essential oil and condensed tannin on fermentation and methane production under in vitro conditions

The potential of five different essential oils (EO) and quebracho condensed tannin extract (QCT) as antimethanogenic additives in ruminant feeds were investigated. The first experiment was conducted to screen the effects rosemary oil, sage oil, cinnamon oil (CNO), eucalyptus oil and myrrh oil at 500 mg/L of culture fluid on methane (CH4) production under in vitro conditions. Rumen contents were collected from a cannulated Holstein dairy cow and used for a 24-h batch-culture experiment. Treatments were a control (CON) or CON plus EO at 500 mg/L. Results showed that CNO decreased CH4 production and, therefore, was selected for Experiment 2. The second experiment was designed to test the effects of CNO at three different dose levels on CH4 production and fermentation in 24-h batch-culture experiments. Treatments were CON or CON plus CNO supplemented at 125, 250 and 500 mg/L. Relative to CON, CNO decreased total gas production at the 250 and 500 mg/L doses. All doses of CNO decreased CH4 production. Total volatile fatty acid production was lower in cultures incubated with CNO at the 500 mg/L. Ammonia-N concentration decreased in cultures incubated with CNO at the 500 mg/L. The third experiment was designed to test the effects of QCT on CH4 production and fermentation in 24-h batch cultures. Treatments were CON or CON plus QCT at 25, 50 and 75 g/kg of diet DM. Relative to CON, total volatile fatty acid concentration increased with the 50 g/kg QCT, but was similar to the 25 and 75 g/kg QCT. The proportions of acetate decreased, while the proportions of propionate increased with the 25 g/kg QCT compared with CON. Methane production was not affected in cultures incubated with QCT. Relative to CON, all doses of QCT decreased ammonia-N concentration. In conclusion, results from the present study showed that except for CNO, EO tested in the study had no effects on rumen CH4 production. Addition of CNO to rumen cultures at 125 and 250 mg/L reduced CH4 production without negative effects on rumen fermentation. Quebracho condensed tannin-extract supplementation had no effects on CH4 production and fermentation parameters except for ammonia-N concentration.

The effects of cinnamaldehyde, monensin and quebracho condensed tannin on rumen fermentation, biohydrogenation and bacteria in continuous culture system

Abstract The objective of this experiment was to evaluate the effects of different feed additives (cinnamaldehyde, monensin, and quebracho condensed tannin extract) on fermentation, trans fatty acids (FA) formation and selected strains of rumen bacteria. Four continuous culture systems were used in 4 × 4 Latin square designs with 4 periods of 10 days each. Treatment diets were: control diet (44:56 forage to concentrate; CON), control plus cinnamaldehyde (CIN) at 400 mg/L, control plus monensin (MON) at 12 mg/L, and control with quebracho condensed tannin extract (QTAN) at 100 g/kg of diet (DM basis). Fermenters were fed treatment diets three times daily at 120 g/day and overflow (effluent) samples were collected from each fermenter on days 8, 9 and 10 of each period to estimate nutrients digestibility and FA composition. On day 10 of each period, three samples were collected from each fermenter at 3 and 6 h post morning feeding for volatile fatty acids (VFA), ammonia-N and bacterial analyses. Compared with the CON diet, feed additives had no effects (P > 0.05) on apparent dry matter (DM), neutral detergent fiber (NDF) and organic matter (OM) digestibility but apparent protein digestibility decreased (P 0.05) on the DNA abundance of Anaerovibrio lipolytica and Butyrivibrio SA. In conclusion, results demonstrate that the feed additives used in this study affected the fermentation and biohydrogenation process. Addition of feed additives reduced the formation of C18:0 but only MON and CIN increased VA formation. MON and CIN effects on VA formation may in part be explained by their effects on B. proteoclasticum.

Biobased foams from condensed tannin extracts from Norway spruce (Picea abies) bark

Different kinds of tannin-based foams were developed in the recent past with fisetinidin/robetinidin-type tannins extracted from mimosa (Acacia mearnsii) or quebracho (Schinopsis lorentzi) bark; or procyanidin-type tannins from pine (Pinus pinaster and Pinus radiata). These biobased porous products revealed excellent properties similar to their synthetic counterparts in many applications. Norway spruce (Picea abies) bark is another large potential source of procyanidin-type tannins. In this study rigid and homogeneous foams were produced from purified tannins containing at least 80% of polyflavonoid condensed tannins. This paper deals with the study of spruce tannins reactivity for rigid foam formulations. Characterization results have point out their very good mechanical resistance (σ>0.08MPa), and low thermal conductivities (λ<0.045W/m/K) at low densities (d<50kg/m3).

Impact of variation in structure of condensed tannins from sainfoin (Onobrychis viciifolia) on invitro ruminal methane production and fermentation characteristics.

Our study investigated the effects of condensed tannins (CT) on rumen invitro methane (CH4 ) production and fermentation characteristics by incubating lucerne in buffered rumen fluid in combination with different CT extracts at 0 (control), 40, 80 and 120gCT/kgof substrate DM. Condensed tannins were extracted from four sainfoin accessions: Rees 'A', CPI63763, Cotswold Common and CPI63767. Gas production (GP) was measured using a fully automated GP apparatus with CH4 measured at distinct time points. Condensed tannins differed substantially in terms of polymer size and varied from 13 (Rees 'A') to 73 (CPI63767) mean degree of polymerization, but had relatively similar characteristics in terms of CT content, procyanidin: prodelphinidin (PC: PD) and cis:trans ratios. Compared to control, addition of CT from CPI63767 and CPI63763 at 80 and 120gCT/kgof substrate DM reduced CH4 by 43% and 65%, and by 23% and 57%, respectively, after 24-h incubation. Similarly, CT from Rees 'A' and Cotswold Common reduced CH4 by 26% and 46%, and by 28% and 46% respectively. Addition of increasing level of CT linearly reduced the maximum rates of GP and CH4 production, and the estimated invitro organic matter digestibility. There was a negative linear and quadratic (p<0.01) relation between CT concentration and total volatile fatty acid (VFA) production. Inclusion of 80 and 120gCT/kgof substrate DM reduced (p<0.001) branched-chain VFA production and acetate: propionate ratio and was lowest for CPI63767. A decrease in proteolytic activity as indirectly shown by a change in VFA composition favouring a shift towards propionate and reduction in branched-chain VFA production varied with type of CT and was highest for CPI63767. In conclusion, these results suggest that tannin polymer size is an important factor affecting invitro CH4 production which may be linked to the CT interaction with dietary substrate or microbial cells.

Condensed tannins reduce browsing and increase grazing time of free-ranging goats in semi-arid savannas

Tannin concentrations fluctuate spatially and temporally within and among plant species, with consequences for forage quality of herbivores. The extent to which these fluctuations influence foraging activities of goats is not fully understood. While accounting for the effects of the time of the day and season, we tested the hypothesis that goats exposed to high levels of condensed tannins (i) spend less of their foraging time browsing, (ii) spend more time grazing, and (iii) reduce their total foraging time, especially during the dry season when grasses dry out and deciduous trees lose leaves. We orally dosed 15 goats with (i) 20g of condensed tannins extract dissolved in 50ml of water (high tannin exposure), another 15 goats (ii) with 20g of polyethylene glycol dissolved in 50ml of water, which neutralizes the effects of tannins (low tannin exposure), and the last group of 15 goats (iii) with 50ml of water (control). We recorded the time spent on grazing, browsing and these two activities together (i.e., foraging) for 30 days in the dry and wet season. As expected, dosing goats with condensed tannins reduced their browsing time and increased the time spent grazing. Goats dosed with polyethylene glycol increased their browsing time and lowered their time spent grazing. Animals dosed with polyethylene glycol foraged for longer than other treatment groups in the dry season, whereas the goats dosed with condensed tannins increased their foraging time in the wet season. Overall, all treatment groups spent a similar amount of time foraging, indicating an instinctive drive by goats to maintain high total foraging time while avoiding over ingestion of tannin-rich forages. We concluded that tannins do not supress total foraging time for free-ranging goats. Instead, they increase the amount of time animals spend on grazing on herbaceous plants and decrease the amount of time animals spend browsing on woody plants. Comparing time spent on different foraging activities by goats is a first step towards understanding how goats utilize feed resources and how tannins influence resource utilization patterns.

Effects of Supplemental Virgin Coconut Oil and Condensed Tannin Extract from Pine Bark in Lactation Dairy Diets on Ruminal Fermentation in a Dual-flow Continuous Culture System

The objective of our study was to investigate effects of virgin coconut oil (VCO) and condensed tannin extract from pine bark (PCT), either separately or in combination, as supplements to lactation dairy diets on in vitro ruminal fermentation profiles in a completely randomized design with four independent runs of continuous cultures. Four dietary treatments included: 1) control [CONT; total mixed ration (TMR) without supplement], 2) TMR with VCO (VCOT), 3) TMR with PCT (PCTT) and 4) TMR with VCO and PCT (VPT). Results showed that culture pH was maintained at least at 6.13 across dietary treatments, and supplementing VCO and/or PBE did not influence culture pH. Total volatile fatty acid concentration was similar in response to the supplements. Supplementing PCT decreased ammonia-nitrogen concentration both in PCTT and VPT (P<0.01), while VCO supplementation resulted in no effect on ammonia-nitrogen concentration. Cultures offered VCO and PCT supplementation, either separately or in combination, showed no response on methane production. The decrease in ammonia-nitrogen concentration when PCT-containing diets (PCTT and VPT) were offered is likely attributed to condensed tannins in PCT, which indicates that PCT can affect dietary nitrogen utilization efficiency in vivo through condensed tannins on ruminal nitrogen metabolism. However, dietary concentration of VCO used in this study may have not been enough to manipulate ruminal fermentation.

In vitro ovicidal and larvicidal activity of condensed tannins on gastrointestinal nematode infestations in sheep (Ovis aries)

Infestations of gastrointestinal parasitic nematodes in sheep result in significant costs to farmers. These infestations are controlled using synthetic anthelmintic treatments, which can result in the development of anthelmintic resistance in nematodes. The use of plants rich in condensed tannins (CTs) is a promising alternative for controlling infestations of harmful parasites in sheep, and could allow reduction of the chemical products used. This study investigated the in vitro effect of CTs from Acacia mearnsii extract (AE) on egg hatching and motility of third-stage larvae. Egg-hatching rate was measured after incubation with extracts for 48 h at 27 °C. The egg hatch test was performed with dilutions of 0.09, 0.19, 0.39, 0.78, 1.56, 3.12, 6.25, 12.5, 25, 50, and 100 mg mL-1. Distilled water was used as the negative control. The corresponding egg hatching inhibition percentages were 22.3, 32.3, 39.2, 49.1, 56.7, 59.0, 62.3, 77.3, 92.7, 98.3, and 100%. The concentration required to inhibit egg hatching in 50% of eggs (LC50) was 2.85 mg mL-1. The inhibition achieved with the negative control was 7.06%. A larval migration inhibition test was carried out after incubation with the extracts for 48 h at 27 oC, with AE and distilled water used in dilutions of 3.12, 6.25, 12.5, 25, 50, and 100 mg mL-1. The corresponding percentages of migration inhibition were 16.5, 37.0, 56.3, 79.4, 91.8, and 97.1%. The concentration required to inhibit migration of 50% of larvae (LC50) was 12.45 mg mL-1. The inhibition achieved with the negative control was 8.53%. The in vitro ovicidal and larvicidal activity of CTs from AE indicate the anthelmintic effect of AE, suggesting the potential of CT extracts to be used as alternatives for controlling gastrointestinal nematode infestations in small ruminants.

Efficacy of condensed tannins against larval Hymenolepis diminuta (Cestoda) in vitro and in the intermediate host Tenebrio molitor (Coleoptera) in vivo

Natural anti-parasitic compounds in plants such as condensed tannins (CT) have anthelmintic properties against a range of gastrointestinal nematodes, but for other helminths such effects are unexplored. The aim of this study was to assess the effects of CT from three different plant extracts in a model system employing the rat tapeworm, Hymenolepis diminuta, in its intermediate host, Tenebrio molitor. An in vitro study examined infectivity of H. diminuta cysticercoids (excystation success) isolated from infected beetles exposed to different concentrations of CT extracts from pine bark (PB) (Pinus sps), hazelnut pericarp (HN) (Corylus avellana) or white clover flowers (WC) (Trifolium repens), in comparison with the anthelmintic drug praziquantel (positive control). In the in vitro study, praziquantel and CT from all three plant extracts had dose-dependent inhibitory effects on cysticercoid excystation. The HN extract was most effective at inhibiting excystation, followed by PB and WC. An in vivo study was carried out on infected beetles (measured as cysticercoid establishment) fed different doses of PB, HN and praziquantel. There was a highly significant inhibitory effect of HN on cysticercoid development (p=0.0002). Overall, CT showed a promising anti-cestodal effect against the metacestode stage of H. diminuta.

Carcass Traits in Sheep Receiving Acacia mearnsii Condensed Tannin Extract to Control Endoparasites

We evaluated carcass traits from twenty 6-month-old Santa Ines lambs under tropical grazing (Andropogon gayanus) receiving condensed tannin from Acacia mearnsii once a week for 13 weeks to control endoparasites. Ten animals were treated with tannin (TG) and the remainder (10 animals) received a diet without tannin (CG). At slaughter, the following measurements were taken: live weight, carcass weight, half-carcass weight, carcass length, fat cover, skin weight and thickness, weight of thoracic and abdominal organs, scrotum and commercial cuts. The 12 th rib was removed for determination of muscle, fat and bone percentages, as well as their chemical analysis. Skin thickness was greater and commercial cuts (loin and rib/belly) were lower in TG. Animals that received tannin had a lower percentage of ether extract and higher protein in the 12 th rib. Condensed tannin from

Digestion, ruminal fermentation and microbial nitrogen supply in sheep fed soybean meal treated with Cistus ladanifer L. tannins

Three rumen-cannulated rams were used in a 3×3 Latin square experiment to evaluate the effect of a condensed tannin (CT) extract of Cistus ladanifer L. on apparent digestibility, N balance, rumen microbial N supply, ruminal fermentation characteristics, in sacco rumen degradability and in vitro intestinal digestibility (ivID) of soybean meal. The rams were fed with diets consisting of 600g of oat straw, 300g of manioc and 100g of soybean meal treated with 0, 15 and 30g/kg of Cistus CT, resulting in three treatments: control (SC), medium (SM) and high condensed tannins (SH).Apparent digestibility of DM, organic matter (OM), crude protein (CP), neutral detergent fibre (NDF), acid detergent fibre (ADF) and gross energy (GE) was similar among experimental diets (P>0.05). In the rumen, the concentration of NH3-N and microbial N supply in g/day tended to be reduced with the inclusion of CT extract (P=0.08 and P=0.06, respectively). The pH and VFA concentrations were not affected by CT. Tannins decreased the effective degradability (P) of soybean meal protein at high levels of feeding, with faster outflow rates (k=0.08h−1) (0.53, 0.50 and 0.50 for SC, SM and SH, respectively) (P=0.02) and the ivID of rumen undegradable protein (RUP) (0.77, 0.74, 0.74 for SC, SM and SH, respectively) (P=0.04).The utilisation of soybean meal supplemented with 15g/kg of C. ladanifer condensed tannins can be a valuable approach to reduce the rumen protein effective degradability without compromising the effective dry matter degradability and the digestibility in the whole digestive tract. The reduction of the intestinal digestibility of RUP and of microbial protein synthesis seems to be balanced by an increase in protein absorption in lower digestive tract.

A new method for preparing tannin-based foams

Phenolic foams derived from natural precursors, condensed tannin extracts from mimosa trees, were prepared for the first time by curing and drying liquid foams obtained by aeration of tannin solutions containing surfactant and crosslinker. The materials derived from the new method were called tannin-based meringues in reference to the lightweight pastry made in a similar way by whipping egg whites. The new foams were compared with more standard cellular solids having very close composition but obtained by physical or chemical foaming. No significant differences were observed in terms of mechanical and thermal properties. The porous structure was also similar, except the cell sizes which were much higher in tannin-based meringues. The new method is not only easy, fast and cost-effective, but allows producing solid foams having a very broad range of bulk densities and cell sizes, which can be controlled by the concentration of tannin in the initial solution, all other things being equal.

The effect of purified condensed tannins of forage plants from Botswana on the free-living stages of gastrointestinal nematode parasites of livestock

The effect of condensed tannins (CT) extracted from forage plants from Botswana on the free-living stages of a number of species of gastrointestinal nematode parasites derived from infected sheep were investigated using in vitro assays. Fresh samples of five different plants (Viscum rotundifolium, Viscum verrucosum, Tapinanthus oleifolius, Grewia flava and Ipomoea sinensis) were collected over two summers (February 2009 and 2010). Fractionation of each crude extract on a Sephadex LH-20 column yielded low molecular weight phenolics and CT-containing fractions. The effect of each purified CT fraction on parasites was evaluated using either egg hatch, larval development or larval migration inhibition assays. Three gastrointestinal nematode species (Haemonchus contortus, Trichostrongylus colubriformis and Teladorsagia circumcincta) derived from infected sheep were evaluated in the study. CT from V. rotundifolium and I. sinensis fractions from samples collected in 2009 and 2010 did not inhibit larval development. However, CT isolated from V. verrucosum, T. oleifolius and G. flava collected in 2009 completely inhibited the development of all parasite species. These CT fractions were more potent in inhibiting larval development of H. contortus than fractions from the same plant species collected in 2010. However, a slight effect on larval migration was observed with some CT extracts. The results suggest that CT extracts of some forage plants from Botswana have anti-parasitic properties in vitro, and that further research is required to determine any in vivo efficacy from feeding the plants to goats in a field situation.

Condensed tannins from Sesbania sesban and Desmodium intortum as a means of Haemonchus contortus control in goats

Two experiments were conducted to determine whether the proanthocyanidin (condensed tannin)-containing forage legumes Desmodium intortum cv Greenleaf and Sesbania sesban (accession 15019) could be integrated into a feeding management strategy as a means of Haemonchus contortus control in goats. The anthelmintic effects of condensed tannin extracts from the two legumes on H. contortus L(3) larvae were studied in an in vitro larval migration inhibition system. The extracts inhibited larval migration in a dose-dependent manner, and at concentrations from 1,000 μg/ml condensed tannin, the extract from D. intortum caused a significantly higher inhibition of larval migration than did the corresponding concentrations of the S. sesban extract (P < 0.01). Prolonged feeding of tanniniferous forage legumes showed that animals receiving D. intortum had the lowest total worm burden, the lowest female to male parasite ratio, the lowest number of eggs in the uterus of each female worm and the lowest per capita fecundity (P < 0.01). However, there was no change in the performance (weight gain) of parasite-infected goats probably due to incomplete removal of the parasite or prolonged confinement of goats in small pens, which calls for further investigation. However, since there is no single efficient method in control of parasites, based on the obtained data from this experiment, integrated feeding of D. intortum with other suitable method of parasite control is thus suggested.

Bactericidal effect of hydrolysable and condensed tannin extracts on Campylobacter jejuni in vitro

Strategies are sought to reduce intestinal colonisation of food-producing animals by Campylobacter jejuni, a leading bacterial cause of human foodborne illness worldwide. Presently, we tested the antimicrobial activity of hydrolysable-rich blackberry, cranberry and chestnut tannin extracts and condensed tannin-rich mimosa, quebracho and sorghum tannins (each at 100mg/mL) against C. jejuni via disc diffusion assay in the presence of supplemental casamino acids. We found that when compared to non-tannin-treated controls, all tested tannins inhibited the growth of C. jejuni and that inhibition by the condensed tannin-rich mimosa and quebracho extracts was mitigated in nutrient-limited medium supplemented with casamino acids. When tested in broth culture, both chestnut and mimosa extracts inhibited growth of C. jejuni and this inhibition was much greater in nutrient-limited than in full-strength medium. Consistent with observations from the disc diffusion assay, the inhibitory activity of the condensed tannin-rich mimosa extracts but not the hydrolysable tannin-rich chestnut extracts was mitigated by casamino acid supplementation to the nutrient-limited medium, likely because the added amino acids saturated the binding potential of the condensed tannins. These results demonstrate the antimicrobial activity of various hydrolysable and condensed tannin-rich extracts against C. jejuni and reveal that condensed tannins may be less efficient than hydrolysable tannins in controlling C. jejuni in gut environments containing high concentrations of amino acids and soluble proteins.

Effects of supplementing condensed tannin extract on intake, digestion, ruminal fermentation, and milk production of lactating dairy cows

A lactation experiment was conducted to determine the influence of quebracho condensed tannin extract (CTE) on ruminal fermentation and lactational performance of dairy cows. The cows were fed a high forage (HF) or a low forage (LF) diet with a forage-to-concentrate ratio of 59:41 or 41:59 on a dry matter (DM) basis, respectively. Eight multiparous lactating Holstein cows (62±8.8 d in milk) were used. The design of the experiment was a double 4 × 4 Latin square with a 2 × 2 factorial arrangement of treatments, and each period lasted 21 d (14 d of treatment adaptation and 7 d of data collection and sampling). Four dietary treatments were tested: HF without CTE, HF with CTE (HF+CTE), LF without CTE, and LF with CTE (LF+CTE). Commercial quebracho CTE was added to the HF+CTE and the LF+CTE at a rate of 3% of dietary DM. Intake of DM averaged 26.7kg/d across treatments, and supplementing CTE decreased intakes of DM and nutrients regardless of forage level. Digestibilities of DM and nutrients were not affected by CTE supplementation. Milk yield averaged 35.3kg/d across treatments, and yields of milk and milk component were not influenced by CTE supplementation. Negative effects of CTE supplementation on feed intake resulted in increased feed efficiency (milk yield/DM intake). Although concentration of milk urea N (MUN) decreased by supplementing CTE in the diets, efficiency of N use for milk N was not affected by CTE supplementation. Feeding the LF diet decreased ruminal pH (mean of 6.47 and 6.33 in HF and LF, respectively). However, supplementation of CTE in the diets did not influence ruminal pH. Supplementing CTE decreased total volatile fatty acid concentration regardless of level of forage. With CTE supplementation, molar proportions of acetate, propionate, and butyrate increased in the HF diet, but not in the LF diet, resulting in interactions between forage level and CTE supplementation. Concentration of ammonia-N tended to decrease with supplementation of CTE. The most remarkable finding in this study was that cows fed CTE-supplemented diets had decreased ruminal ammonia-N and MUN concentrations, indicating that less ruminal N was lost as ammonia because of decreased degradation of crude protein by rumen microorganisms in response to CTE supplementation. Therefore, supplementation of CTE in lactation dairy diets may change the route of N excretion, having less excretion into urine but more into feces, as it had no effect on N utilization efficiency for milk production.

Antioxidant and Antidiabetic Properties of Condensed Tannins in Acetonic Extract of Selected Raw and Processed Indigenous Food Ingredients from Kenya

Recently, tannins have received considerable attention as health-promoting component in various plant foods and several studies have reported on its nutraceutical properties. However, no study has established the role of condensed tannins in indigenous foods of Kenya. Therefore, this study was designed to evaluate the antioxidant activity (DPPH and FRAP) and antidiabetic effects (α-amylase and α-glucosidase inhibition activities) of condensed tannins in some selected raw and traditionally processed indigenous cereals, legumes, oil seeds, and vegetables. The condensed tannin content of the grains and vegetables ranged between 2.55 and 4.35 g/100 g DM and 1.53 and 5.73 g/100 g DM, respectively. The scavenging effect of acetonic extract on DPPH radical ranged from 77% to 90% while the reducing power was found to be 31 to 574 mmol Fe(II)/g DM in all the investigated food ingredients. The condensed tannin extracts of the analyzed samples showed promising antidiabetic effects with potential α-amylase and α-glucosidase inhibition activities of 23% to 44% and 58% to 88%, respectively. Condensed tannins extracted from the amaranth grain, finger millet, field bean, sunflower seeds, drumstick, and amaranth leaves exerted significantly higher antioxidant and antidiabetic activities than other food ingredients. Among the traditional processing methods, roasting of grains and cooking of vegetables were found to be more suitable mild treatments for preserving the tannin compound and its functional properties as opposed to soaking + cooking and blanching treatments. The identified elite sources of optimally processed indigenous food ingredients with promising results could be used as health-promoting ingredients through formulation of therapeutic diets.