The Use of Tannins to Control Salmonella Typhimurium Infections in Pigs

In vitro and in vivo evaluation of tannic acid as an antibacterial agent in broilers infected with Salmonella Typhimurium

This study was conducted to evaluate tannic acid (TA) as an antibacterial agent against Salmonella Typhimurium in in vitro and in vivo chicken models. The TA formed an inhibitory zone against Salmonella enterica serotypes including S. Typhimurium, S. Enteritidis, and S. Infantis. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of TA against Salmonella Typhimurium nalidixic acid resistant strain (STNR) were determined as 40 and 700 μg/mL, respectively. Sublethal doses of TA (5, 10, and 20 μg/mL) restricted swimming and swarming motility and biofilm formation of STNR compared to the control group (0 μg/mL) (P < 0.05). The TA-bovine serum albumin (BSA) complex formed at simulated gastric pH (pH 3.75) was hydrolyzed at pH 6.75 and 7.25 (P < 0.05), and the hydrolysis of the TA-BSA complex was stronger at pH 7.25 compared to the pH 6.75 (P < 0.05). The inhibitory zone of the TA-BSA complex against STNR at pH 6.75 was lower than TA without BSA at 30 and 60 min (P < 0.05), but not at 120 min (P > 0.1). The inhibitory zone of the TA-BSA complex against STNR at pH 7.25 was not decreased at 0, 30, and 60 min compared to TA without BSA (P > 0.1). The recovery rate of TA was 83, 54.8, 10.5, and 19.6% in the gizzard, jejunum, ileum, and ceca, respectively, in broiler chickens. The STNR-infected broilers fed 0.25 g/kg of TA had significantly lower unweighted beta diversity distance compared to the sham-challenged control (SCC) and challenged controlled (CC) group on D 21. TA supplementation linearly (P < 0.05) and quadratically (tendency; P = 0.071) reduced relative abundance of the family Peptostreptococcaceae in broilers infected with STNR on D 7. TA supplementation linearly (P < 0.05) and quadratically (tendency; P = 0.06) increased the relative abundance of the family Erysipelotrichaceae in broilers infected with STNR on D 21. Therefore, TA has potential to be used as an antibacterial agent against the S. Typhimurium infection in broilers.

Supplementation with Antimicrobial Peptides or a Tannic Acid Can Effectively Replace the Pharmacological Effects of Zinc Oxide in the Early Stages of Weaning Piglets

Zinc oxide (ZnO) harms the environment and can potentially increase the number of drug-resistant bacteria. Therefore, there is an urgent need to find safe and effective alternatives to improve gut health and reduce the incidence of diarrhea in weaned piglets. This study conducted an antibacterial test of ZnO, antibacterial peptides (AMPs), and tannic acid (TA) in vitro. Thirty piglets were randomly allotted to one of the following three dietary treatments: ZnO (2000 mg/kg ZnO diet), AMPs (700 mg/kg AMPs diet), and TA (1000 mg/kg TA diet). The results showed that the minimum inhibitory concentrations of ZnO and TA against Escherichia coli and Salmonella were lower than those of AMPs, and the minimum inhibitory concentrations of ZnO, AMPs, and TA against Staphylococcus aureus were the same. Compared to ZnO, AMPs increased the digestibility of dry, organic matter and the crude fat. Additionally, TA significantly (p < 0.05) increased the digestibility of dry and organic matter. On experimental day 14, the plasma interleukin-6 (IL-6) content of piglets supplemented with AMPs and TA was increased significantly (p < 0.05). On experimental day 28, alanine aminotransferase activity in the plasma of weaned piglets in the ZnO and TA groups was significantly (p < 0.05) higher than in piglets in the AMPs group. The levels of plasma IL-6 and immunoglobulin M (IgM) were significantly higher (p < 0.05) in the ZnO and AMPs groups than in the TA group. On experimental days 14 and 28, no significant differences were observed in the antioxidant capacity among the three experimental groups. Intestinal microbial diversity analysis showed that the Chao1 and ACE indices of piglets in the AMPs group were significantly higher (p < 0.05) than those in the ZnO and TA groups. At the genus level, the relative abundance of Treponema_2 was higher in the feces of piglets fed a diet supplemented with TA than in those fed diet supplemented with ZnO (p < 0.05). The relative abundance of Lachnospiraceae was higher in the feces of piglets fed a diet supplemented with AMPs than in those fed diet supplemented with ZnO or TA. Overall, AMPs and TA could be added to feed as substitutes for ZnO to reduce diarrhea, improve nutrient digestibility and immunity, and increase the abundance of beneficial intestinal bacteria in weaned piglets.

Antimicrobial and immunomodulatory effects of tannic acid supplementation in broilers infected with Salmonella Typhimurium

Infection by Salmonella Typhimurium, a food-borne pathogen, can reduce the poultry production efficiency. The objective of this study was to investigate the effects of tannic acid (TA) supplementation on growth performance, Salmonella colonization, gut barrier integrity, serum endotoxin levels, antioxidant capacity, gut health, and immune function in broilers infected with the Salmonella enterica serovar Typhimurium nalidixic acid resistant strain (STNR). A total of 546 one-day-old broilers were arbitrarily allocated into 6 treatments including 1) Sham-challenged control (SCC; birds fed a basal diet and administrated peptone water); 2) Challenged control (CC; birds fed a basal diet and inoculated with 108 STNR); 3) Tannic acid 0.25 (TA0.25; CC + 0.25 g/kg TA); 4) TA0.5 (CC + 0.5 g/kg TA); 5) TA1 (CC + 1 g/kg TA); and 6) TA2 (CC + 2 g/kg TA). On D 7, supplemental TA linearly reduced STNR colonization in the ceca (P < 0.01), and TA1 and TA2 group had significantly lower reduced STNR colonization in the ceca (P < 0.01). On D 7 to 21, average daily gain tended to be linearly increased by supplemental TA (P = 0.097). The serum endotoxin levels were quadratically decreased by supplemental TA on D 21 (P < 0.05). Supplemental TA quadratically increased ileal villus height (VH; P < 0.05), and the TA0.25 group had higher ileal VH compared to the CC group (P < 0.05). Supplemental TA linearly increased percentage of peripheral blood CD8+ T cells on D 18 (P < 0.01). The TA0.5 group had significantly lower lymphocyte numbers compared to the CC groups (P < 0.05). The abundance of monocytes linearly increased with TA supplementation (P < 0.01). Therefore, broilers fed TA had reduced STNR colonization, increased growth performance, decreased serum endotoxin levels, enhanced gut health in the broilers, and stimulated the immune system in broilers infected with STNR. Supplementation of TA (1-2 g/kg) enhanced growth performance and gut health via antimicrobial and immunostimulatory effects in broilers infected with STNR.

Effect of Select Tannin Sources on Pathogen Control and Microbial Nitrogen Metabolism in Composted Poultry Litter Intended for Use as a Ruminant Crude Protein Feedstuff

Poultry litter is a good crude protein supplement for ruminants but must be treated to kill pathogens before feeding. Composting effectively kills pathogens but risks loss of ammonia due to uric acid degradation. The objectives of this study were to test the ability of tannins to reduce pathogens and preserve uric acid during poultry litter composting. In two experiments, poultry litter was mixed with phosphate buffer and distributed to 50-ml tubes (three tubes/treatment per sample day) amended with 1 ml buffer alone or buffer containing pine bark, quebracho, chestnut, or mimosa tannins. Treatments achieved 0.63% (wt/wt) quebracho, chestnut, or mimosa tannins in experiment 1, or 4.5% pine bark or 9% quebracho, chestnut, or mimosa tannins in experiment 2. Tubes were inoculated with a novobiocin- and nalidixic acid-resistant Salmonella typhimurium, closed with caps, and incubated at successive 3-day increments at 22, 37, and 42°C, respectively. In experiment 1, bacterial counts in contents collected on days 0, 6, and 9 revealed a treatment by day effect (p < 0.03), with the Salmonella challenge being 1.3 log₁₀ CFU/g higher in quebracho-treated composts than in untreated controls after 6 days of composting. After 9 days of composting, Salmonella, wildtype Escherichia coli, and total aerobes in untreated and all tannin-treated composts were decreased by about 2.0 log₁₀ CFU/g compared to day 0 numbers (3.06, 3.75, and 7.77 log₁₀ CFU/g, respectively). Urea and ammonia concentrations tended (p < 0.10) to be increased in chestnut-treated composts compared to controls and concentrations of uric acid, urea, and ammonia were higher (p < 0.05) after 9 days of composting than on day 0. Despite higher tannin application in experiment 2, antibacterial effects of treatment or day of composting were not observed (p > 0.05). However, treatment by time of composting interactions was observed (p < 0.05), with quebracho- and chestnut-treated composts accumulating more uric acid after 24 h and 9 days of composting and chestnut-, mimosa- or quebracho-treated composts accumulating less ammonia than untreated composts. Results demonstrate that composting may effectively control pathogens and that tannin treatment can help preserve the crude protein quality of composting poultry litter.

Coated tannin supplementation improves growth performance, nutrients digestibility, and intestinal function in weaned piglets

To explore the effect of coated tannin (CT) on the growth performance, nutrients digestibility, and intestinal function in weaned piglets, a total of 180 piglets Duroc × Landrace × Yorkshire (28 d old) weighing about 8.6 kg were randomly allotted to three treatments: 1) Con: basal diet (contains ZnSO4); 2) Tan: basal diet + 0.15% CT; and 3) ZnO: basal diet + ZnO (Zn content is 1,600 mg/kg). The results showed that 0.15% CT could highly increase the average daily gain and average daily feed intake of weaned piglets compared with the control group, especially decreasing diarrhea incidence significantly (P < 0.05). Compared with the control group, crude protein apparent digestibility and digestive enzyme activity of the piglets fed with 0.15% CT were enhanced obviously (P < 0.05). Meanwhile, the intestinal villi and microvilli arranged more densely, while the content of serum diamine oxidase was decreased, and the protein expressions of zonula occludens-1 (ZO-1) and claudin-1 were significantly upregulated (P < 0.05). In addition, CT altered the structure of intestinal microbiota and augmented some butyrate-producing bacteria such as Ruminococcaceae and Megasphaera. PICRUSt (Phylogenetic Investigation of Communities by Reconstruction of Unobserved States) analysis also showed that the abundances of pathways related to butyrate metabolism and tryptophan metabolism were increased; however, the function of lipopolysaccharide biosynthesis proteins was significantly decreased. The results demonstrated that 0.15% CT could improve growth performance, digestibility, and intestinal function of weaned piglets, and it had the potential to replace ZnO applied to farming.

Biological Function of Plant Tannin and Its Application in Animal Health

Plant tannins are widely found in plants and can be divided into hydrolyzed tannins and condensed tannins. In recent years, researchers have become more and more interested in using tannin-rich plants and plant extracts in ruminant diets to improve the quality of animal products. Some research results show that plant tannins can effectively improve the quality of meat and milk, and enhance the oxidative stability of the product. In this paper, the classification and extraction sources of plant tannins are reviewed, as well as the biological functions of plant tannins in animals. The antioxidant function of plant tannins is discussed, and the influence of their structure on antioxidation is analyzed. The effects of plant tannins against pathogenic bacteria and the mechanism of action are discussed, and the relationship between antibacterial action and antioxidant action is analyzed. The inhibitory effect of plant tannins on many kinds of pathogenic viruses and their action pathways are discussed, as are the antiparasitic properties of plant tannins. The anti-inflammatory action of tannins and its mechanism are analyzed. The function of plant tannins in antidiarrheal action and its influencing factors are discussed. In addition, the effects of plant tannins as feed additives on animals and the influencing factors are reviewed in this paper to provide a reference for further research.

Use of Tannin-Containing Plants as Antimicrobials Influencing the Animal Health

The antimicrobial effects of diverse tannin-containing plants, particularly condensed tannins (CTs) produced from various plants, are the subject of this study. CT components can be determined using CT-specific procedures such the HCl-Butanol Acetone assay, Thiolysis reaction, and HPLC/MS analysis. These methods indicate CT contents, including mean degree of polymerization, the procyanidins and prodelphinidins ratio (PC/PD%), the isomers of trans- and cis-, and CT concentration. Tannin-containing plants possess antibacterial action, which can be attributed to their protein linkage technique, and tannin-type variations, particularly CTs extract and their PC/PD%. The effects of CT components on the development of Gram-positive and Gram-negative bacteria have been documented for their relative PC/PD%; this is regarded to be a key predictor of tannin characteristics in terms of antimicrobials. In conclusion, tannins, more specific CT compositions, have significant impacts on in vivo trials of animal productions and utilization of metabolites and fermentation in vitro experiments. These findings need further investigations to fully understand how CT-types act on animal feeding in terms of enhanced nutritional quality of animal diets, which may have implications for human and animal health.

Supplementing chestnut tannins in the broiler diet mediates a metabolic phenotype of the ceca

As the demand for alternatives to antibiotic growth promoters (AGP) increases in food animal production, phytobiotic compounds gain popularity because of their ability to mimic the desirable bioactive properties of AGP. Chestnut tannins (ChT) are one of many phytobiotic compounds used as feed additives, particularly in South America, for broilers because of its favorable antimicrobial and growth promotion capabilities. Although studies have observed the microbiological and immunologic effects of ChT, there is a lack of studies evaluating the metabolic function of ChT. Therefore, the objective of this study was to characterize the cecal metabolic changes induced by ChT inclusion and how they relate to growth promotion. A total of 200 day-of-hatch broiler chicks were separated into 2 feed treatment groups: control and 1% ChT. The ceca from all the chicks in the treatment groups were collected on day 2, 4, 6, 8, and 10 after hatch. The cytokine mRNA quantitative RT-PCR was determined using TaqMan gene expression assays for IL-1B, IL-6, IL-8, IL-10, and interferon gamma quantification. The cytokine expression showed highly significant increased expressions of IL-6 and IL-10 on day 2 and 6, whereas the other proinflammatory cytokines did not have significantly increased expression. The results from the kinome array demonstrated that the ceca from birds fed with 1% ChT had significant (P < 0.05) metabolic alterations based on the number of peptides when compared with the control group across all day tested. The increased expression of IL-6 appeared to be strongly indicative of altered metabolism, whereas the increased expression of IL-10 indicated the regulatory effect against other proinflammatory cytokines other than IL-6. The ChT initiate a metabolic mechanism during the first 10 d in the broiler. For the first time, we show that a phytobiotic product initially modulates metabolism while also potentially supporting growth and feed efficiency downstream. In conclusion, a metabolic phenotype alteration in the ceca of chickens fed ChT may indicate the importance of enhanced broiler gut health.

Review: Chestnut and quebracho tannins in pig nutrition: the effects on performance and intestinal health

Natural extracts are frequently adopted as a valuable alternative to antibiotics in intensive animal farming. Their diverse bioactive constituents such as phytosterols, glucosinolates, carotenoids and polyphenols have shown antioxidant, anti-inflammatory and antibacterial effects. Tannins are the largest class of polyphenol compounds of plant extracts, which can be classified into two hydrolysable or condensed subgroups. Poultry and swine nutrition are the most important sectors in which tannins have been used, firstly adopting tannin-rich feedstuffs and more recently, using tannin extracts from different plants. Several commercial products are available containing tannins extracted from the European chestnut tree (Castanea sativa Mill.) and the American quebracho (Schinopsis spp.). Tannins extracted from these plants have been applied on intensive swine farms due to their ability to improve animal performance and health. These positive and prominent effects are frequently associated with the antinutritional effects in reducing feed palatability, digestibility and protein utilization of feed. Some criticisms and contrasting results regarding pig performance and intestinal health have been reported. This paper provides an overview of the effects of chestnut and quebracho tannins on growth performance and intestinal health of pigs in order to clarify the appropriate dosage and response in the various physiological stages.

Efficacy of chestnut and quebracho wood extracts to control Salmonella in poultry

AIMS

The study was aimed to evaluate the antibacterial activity and efficacy of chestnut and quebracho wood extracts against Salmonella by in vitro assays and in vivo trials.

METHODS AND RESULTS

The extracts showed inhibitory activity against Salmonella determined by the minimum inhibitory concentration method as well as on the adhesion and invasion of S. Gallinarum (SG) and S. Enteritidis (SE) in Caco-2 cells. Also, transmission electron microscopy revealed that extract-treated Salmonella showed disruption of cell walls and membranes, damage of the cytoplasm and tannin-protein aggregations. In addition, efficacy of the extracts to control SG and SE was evaluated in experimental infection trials in laying hens and broilers respectively. SE excretion was significantly reduced on days 5 (P < 0·01) and 12 (P < 0·025) only in the quebracho group. In the fowl typhoid infection model, hens that received the chestnut extract showed a significantly reduced mortality (P < 0·05).

CONCLUSIONS

Our results evidence that these alternative natural products may be a useful tool to control Salmonella in poultry.

SIGNIFICANCE AND IMPACT OF THE STUDY

Salmonella is a zoonotic pathogen usually associated with poultry production. This study provides information about the mechanism of antibacterial effects of chestnut and quebracho wood extracts to control Salmonella in poultry.

Dietary Application of Tannins as a Potential Mitigation Strategy for Current Challenges in Poultry Production: A Review

Simple Summary

There are diverse challenges in the poultry production industry that decrease the productivity and efficiency of poultry production, impair animal welfare, and pose issues to public health. Furthermore, the use of antibiotic growth promoters (AGP) in feed, which have been used to improve the growth performance and gut health of chickens, has been restricted in many countries. Tannins, polyphenolic compounds that precipitate proteins, are considered as alternatives for AGP in feed and provide solutions to mitigate challenges in poultry production due to their antimicrobial, antioxidant, anti-inflammatory and gut health promoting effects. However, because high dosages of tannins have antinutritional effects when fed to poultry, determining appropriate dosages of supplemental tannins is critical for their potential implementation as a solution for the challenges faced in poultry production.

Abstract

The poultry industry has an important role in producing sources of protein for the world, and the size of global poultry production continues to increase annually. However, the poultry industry is confronting diverse challenges including bacterial infection (salmonellosis), coccidiosis, oxidative stress, including that caused by heat stress, welfare issues such as food pad dermatitis (FPD) and nitrogen and greenhouse gasses emissions that cumulatively cause food safety issues, reduce the efficacy of poultry production, impair animal welfare, and induce environmental issues. Furthermore, restrictions on the use of AGP have exacerbated several of these negative effects. Tannins, polyphenolic compounds that possess a protein precipitation capacity, have been considered as antinutritional factors in the past because high dosages of tannins can decrease feed intake and negatively affect nutrient digestibility and absorption. However, tannins have been shown to have antimicrobial, antioxidant and anti-inflammatory properties, and as such, have gained interest as promising bioactive compounds to help alleviate the challenges of AGP removal in the poultry industry. In addition, the beneficial effects of tannins can be enhanced by several strategies including heat processing, combining tannins with other bioactive compounds, and encapsulation. As a result, supplementation of tannins alone or in conjunction with the above strategies could be an effective approach to decrease the need of AGP and otherwise improve poultry production efficiency.

The Effects of Tannins in Monogastric Animals with Special Reference to Alternative Feed Ingredients

Over recent years, the monogastric animal industry has witnessed an increase in feed prices due to several factors, and this trend is likely to continue. The hike in feed prices is mostly due to extreme competition over commonly used conventional ingredients. For this trend to be subdued, alternative ingredients of both plant and animal origin need to be sourced. These types of ingredients are investigated with the aim of substituting all or some of the conventional compounds. However, alternative ingredients often have a double-edged sword effect, in that they can supply animals with the necessary nutrients although they contain antinutritional factors such as tannins. Tannins are complex secondary metabolites commonly present in the plant kingdom, known to bind with protein and make it unavailable; however, recently they have been proven to have the potential to replace conventional ingredients, in addition to their health benefits, particularly the control of zoonotic pathogens such as Salmonella. Thus, the purpose of this review is to (1) classify the types of tannins present in alternative feed ingredients, and (2) outline the effects and benefits of tannins in monogastric animals. Several processing methods have been reported to reduce tannins in diets for monogastric animals; furthermore, these need to be cost-effective. It can thus be concluded that the level of inclusion of tannins in diets will depend on the type of ingredient and the animal species.

Natural Tannin Wood Extracts as a Potential Food Ingredient in the Food Industry

Wood extracts are one of the most important natural sources of industrially obtained tannins. Their use in the food industry could be one of the biggest (most important) recent innovations in food science as a result of their multiple (many) possible applications. The use of tannin wood extracts (TWEs) as additives directly added in foods or in their packaging meets an ever-increasing consumer demand for innovative approaches to sustainability. The latest research is focusing on new ways to include them directly in food, to take advantage of their specific actions to prevent individual pathological conditions. The present review begins with the biology of TWEs and then explores their chemistry, specific sensorial properties, and current application in food production. Moreover, this review is intended to cover recent studies dealing with the potential use of TWEs as a starting point for novel food ingredients.

Hydrolysable chestnut tannins for reduction of postweaning diarrhea: Efficacy on an experimental ETEC F4 model

An experimental model for postweaning diarrhea with enterotoxigenic Escherichia coli F4 (ETEC F4) was set up in piglets, and the efficacy of 1% chestnut-tannin extract in preventing diarrhea was subsequently assessed. In a first trial (infection model), 32 Swiss Large White piglets (age: 24 days; average BW: 7.8 ± 0.8 kg) were randomly assigned to two experimental groups (infected [INF], noninfected [NINF]). In a subsequent trial, 72 Swiss Large White piglets (age: 26 days; average BW: 7.4 ± 1.5 kg) were blocked by BW and assigned within block to four experimental groups: NINF-CO: not infected and fed a standard control starter diet (CO); INF-CO: infected and fed the CO diet; NINF-TA: not infected and fed the CO diet supplemented with 1% chestnut extract containing 54% of hydrolysable tannins (TA); and INF-TA: infected and fed the TA diet. Both diets (TA and CO) were formulated to be isocaloric and isoproteic and to meet or surpass the nutritional requirements. In both trials, four days after weaning, piglets assigned to the INF group received an oral suspension of ETEC F4. Fecal score, ETEC shedding in feces (only in trial 2), and growth performance traits were measured for the following 14 days post infection. In both trials, more than 50% of the INF piglets developed diarrhea within six days post infection. Tannins reduced (P < 0.05) the average fecal score, the percentage of piglets in diarrhea, and the duration of diarrhea, whereas feed intake and the average daily gain were unaffected.

Potential and challenges of tannins as an alternative to in-feed antibiotics for farm animal production

Naturally occurring plant compounds including tannins, saponins and essential oils are extensively assessed as natural alternatives to in-feed antibiotics. Tannins are a group of polyphenolic compounds that are widely present in plant region and possess various biological activities including antimicrobial, anti-parasitic, anti-viral, antioxidant, anti-inflammatory, immunomodulation, etc. Therefore, tannins are the major research subject in developing natural alternative to in-feed antibiotics. Strong protein affinity is the well-recognized property of plant tannins, which has successfully been applied to ruminant nutrition to decrease protein degradation in the rumen, and thereby improve protein utilization and animal production efficiency. Incorporations of tannin-containing forage in ruminant diets to control animal pasture bloat, intestinal parasite and pathogenic bacteria load are another 3 important applications of tannins in ruminant animals. Tannins have traditionally been regarded as "anti-nutritional factor" for monogastric animals and poultry, but recent researches have revealed some of them, when applied in appropriate manner, improved intestinal microbial ecosystem, enhanced gut health and hence increased productive performance. The applicability of plant tannins as an alternative to in-feed antibiotics depends on many factors that contribute to the great variability in their observed efficacies.

Castanea sativa Mill. bark extract exhibits chemopreventive properties triggering extrinsic apoptotic pathway in Jurkat cells

Background

Chemoprevention represents the possibility to prevent, stop or reverse the cancerogenetic process. In this context the interest towards natural extracts and botanical drugs has constantly grown due to their phytochemical content. Castanea sativa Mill. (CSM) extracts showed to exert positive effect in the prevention/counteraction of chronic/degenerative diseases, therefore, we evaluated the potential chemopreventive effect of CSM bark extract.

Methods

Flow cytometry (FCM) analyses of Jurkat cells treated with CSM bark extract (0–500 μg·mL⁻¹) for 24–72 h allowed evaluating its cytotoxicity and ability to induce apoptosis through the intrinsic or extrinsic pathways. Moreover, to evaluate CSM bark extract selectivity towards cancer cells, its cytotoxic and pro-apoptotic effect was also evaluated in human peripheral blood lymphocytes (PBL).

Results

CSM bark extract induced apoptosis in Jurkat cells in a dose- and time- dependent manner activating the extrinsic pathways as evidenced by the increase of activated caspase-8 positive cells. Moreover, IC₅₀ calculated after 24 h treatment resulted 304 and 128 μg·mL⁻¹ in PBL and Jurkat cells respectively.

Conclusions

Our data suggest that CSM bark extract might be considered an interesting potential anti-cancer agent, since it induces apoptosis in cancer cells without appreciable cytotoxic effects on non-transformed cells.

Electronic supplementary material

The online version of this article (doi:10.1186/s12906-017-1756-6) contains supplementary material, which is available to authorized users.

Cranberry extract inhibits in vitro adhesion of F4 and F18+Escherichia coli to pig intestinal epithelium and reduces in vivo excretion of pigs orally challenged with F18+ verotoxigenic E. coli

F4⁺E. coli and F18⁺E. coli infections are an important threat for pig industry worldwide. Antibiotics are commonly used to treat infected piglets, but the emerging development of resistance against antibiotics raises major concerns. Hence, alternative therapies to prevent pigs from F4⁺E. coli and F18⁺E. coli infections need to be developed. Since cranberry previously showed anti-adhesive activity against uropathogenic E. coli, we aimed to investigate whether cranberry extract could also inhibit binding of F4⁺E. coli and F18⁺E. coli to pig intestinal epithelium. Using the in vitro villus adhesion assay, we found that low concentrations of cranberry extract (20μg or 100μg/ml) have strong inhibitory activity on F4⁺E. coli (75.3%, S.D.=9.31 or 95.8%, S.D.=2.56, respectively) and F18⁺E. coli adherence (100% inhibition). This effect was not due to antimicrobial activity. Moreover, cranberry extract (10mg or 100mg) could also abolish in vivo binding of F4 and F18 fimbriae to the pig intestinal epithelium in ligated loop experiments. Finally, two challenge experiments with F18⁺E. coli were performed to address the efficacy of in-feed or water supplemented cranberry extract. No effect could be observed in piglets that received cranberry extract only in feed (1g/kg or 10g/kg). However, supplementation of feed (10g/kg) and drinking water (1g/L) significantly decreased excretion and diarrhea. The decreased infection resulted in a decreased serum antibody response indicating reduced exposure to F18⁺E. coli.

Use of Plant Extracts as an Effective Manner to Control Clostridium perfringens Induced Necrotic Enteritis in Poultry

Necrotic enteritis (NE) is an important concern in poultry industry since it causes economic losses, increased mortality, reduction of bird welfare, and contamination of chicken products for human consumption. For decades, the use of in-feed antimicrobial growth promoters (AGPs) has been the main strategy to control intestinal pathogens including Clostridium perfringens (CP), the causative agent of NE. However, the use of AGPs in animal diet has been linked to the emergence and transmission of antimicrobial resistance through food-borne microorganisms, which has led to the ban of AGPs in many countries. This scenario has challenged the poultry industry to search for safer alternative products in order to prevent NE. In this context, the utilization of natural plant extracts with antimicrobial properties appears as a promising and feasible tool to control NE in chicken. In this paper, we review the scientific studies analyzing the potential of plant extracts as alternative feed additives to reduce NE in poultry, with focus on two types of plant products that arise as promising candidates: tannins and essential oils. Some of these products showed antimicrobial activity against CP and coccidia in vitro and in vivo and are able to increase productive performance, emulating the bioactive properties of AGPs.

Perspectives in the use of tannins as alternative to antimicrobial growth promoter factors in poultry

Antibiotics have been included in the formulation of feed for livestock production for more than 40 years as a strategy to improve feed conversion rates and to reduce costs. The use of antimicrobials as growth-promoting factors (AGP) in sub-therapeutic doses for long periods is particularly favorable for the selection of antimicrobial resistant microorganisms. In the last years, global concern about development of antimicrobial resistance and transference of resistance genes from animal to human strains has been rising. Removal of AGP from animal diets involves tremendous pressure on the livestock and poultry farmers, one of the main consequences being a substantial increase in the incidence of infectious diseases with the associated increase in the use of antibiotics for therapy, and concomitantly, economic cost. Therefore, alternatives to AGP are urgently needed. The challenge is to implement new alternatives without affecting the production performances of livestock and avoiding the increase of antimicrobial resistant microorganisms. Plant extracts and purified derived substances are showing promising results for animal nutrition, either from their efficacy as well as from an economical point of view. Tannins are plant derived compounds that are being successfully used as additives in poultry feed to control diseases and to improve animal performance. Successful use of any of these extracts as feed additives must ensure a product of consistent quality in enough quantity to fulfill the actual requirements of the poultry industry. Chestnut (hydrolysable) and Quebracho (condensed) tannins are probably the most readily available commercial products that are covering those needs. The present report intends to analyze the available data supporting their use.

Antimicrobial Activity of Chestnut Extracts for Potential Use in Managing Soilborne Plant Pathogens

Chestnut extracts were studied for antimicrobial activity against selected microorganisms, including plant pathogens. Chestnut extract on paper discs was applied to an agar medium to evaluate the inhibition to multiple microorganisms or the extract was added at various concentrations to a culture medium to evaluate the growth of target microorganisms. Chestnut type, tissue of plants (shell, pellicle, and leaf), extraction methods, and physical characteristics were studied to determine antimicrobial activity. Most test microorganisms were inhibited by the extracts at different effective concentrations for 50% growth inhibition (EC₅₀). Pseudomonas fluorescens was the most sensitive (EC₅₀ = 4.4 μg/μl), Phytophthora cambivora was one of the least inhibited (EC₅₀ = 185 μg/μl), and Cryphonectria parasitica was not inhibited. Extracts of the Japanese × European chestnut (Castanea crenata × C. sativa) 'Colossal' showed a greater inhibition than those of wild trees of the Chinese species (C. mollissima). High temperature did not affect the inhibitory effect. Extracts from chestnut pellicle had the highest concentration of antimicrobial compound, compared with leaf and shell. The active fraction contained several substances with molecular masses consistent with one flavonol glycoside and several terpenoid substances. Pellicle and shell tissue reduced radish scab disease caused by Streptomyces scabies in the greenhouse.

Intracellular replication inhibitory effects of Galla Rhois ethanol extract for Brucella abortus infection

ETHNOPHARMACOLOGICAL RELEVANCE

Galla Rhois (GR) has long been applied in traditional Korean and Oriental medicine. Although GR has an anti-bacterial effect, the anti-bacterial mechanism and therapeutic efficiency of GR for intracellular parasitic Brucella infection are still unclear.

AIM OF THE STUDY

The objective of this study was to investigate the antibacterial and therapeutic effects of GR ethanol extract (GRE), which is a natural antibacterial component for the treatment of Brucella abortus infection.

MATERIALS AND METHODS

The antibacterial activity of GRE towards Brucella abortus was evaluated by incubating Brucella abortus with GRE. Following treatment with GRE, Brucella abortus adherence, uptake, intracellular growth, and intracellular trafficking in macrophages were monitored. Mice were infected intraperitoneally with Brucella abortus and treated orally with GRE for 14 days, and then the weight and CFUs from each spleen were monitored.

RESULTS

The viability of Brucella abortus was markedly decreased in a dose-dependent manner. Moreover, Brucella abortus internalization and intracellular growth within macrophages were reduced in GRE-treated cells. The number of bacteria that adhered to GRE-pretreated cells was significantly lower than that of untreated cells. With regards to intracellular trafficking, treatment with GRE augmented the colocalization of Brucella abortus-containing phagosomes with LAMP-1. GRE-treated mice showed considerably decreased weight and bacterial burdens in the spleen compared to untreated mice.

CONCLUSION

GRE exhibits antibacterial and protective effects on Brucella abortus in vitro and in vivo. These results highlight the beneficial effects of GRE in the prevention and treatment of brucellosis.