Interaction between xylanase and a proton pump inhibitor on broiler chicken performance and gut function.

Three hundred thirty-six Ross 308 male broiler chicks were used in a 21-d study to explore performance and gut function when treated with a proton pump inhibitor (PPI; 0 or 89 mg/kg) in a 2 × 2 factorial arrangement with a xylanase (Xyl; 0 or 0.1 g/kg) to determine if the beneficial activity of arabinoxylan (AX) depolymerisation, through arabinoxylo-oligosaccharides (AXOS) production, starts in the upper gastrointestinal tract. Treatment with the PPI started from d 14, and by d 21 animal performance had deteriorated (P < 0.001). An interaction was observed between PPI and Xyl for feed conversion ratio (FCR) (P < 0.05), whereby the combination reduced the negative effect of PPI on FCR. Application of PPI raised digesta pH in the gizzard and caecum (P < 0.05), increased protein concentrations in the lower gut (P < 0.05) and reduced intake of digestible nutrients (P < 0.05). Caecal concentrations of indole, p-cresol, ammonia and the ratio of total volatile fatty acid (VFA) to butyric acid were increased with PPI (P < 0.05), indicating enhanced protein fermentation. Xylanase activity in the digesta were greatest in the caeca, especially when Xyl was supplemented (P < 0.001). The concentration of total soluble AX was greater in the gizzard and ileal digesta with Xyl supplementation (P < 0.05), supporting the depolymerisation action of xylanase even under acidic conditions. These data suggest xylanase may function in the gizzard even though pH is not optimal for activity and emphasises the importance of chlorohydric acid secretions in ensuring overall optimum gut function. AX depolymerisation benefits animal performance although it is still unknown how the AXOS produced with xylanase supplementation in the upper gastrointestinal tract influence the microbial populations and overall gut functionality.

Distribution, Metabolism, and Recovery of Resin Acids in the Intestine and Tissues of Broiler Chickens in a Feeding Trial With Tall Oil Fatty Acid-Supplemented Diets.

Tall oil fatty acids (TOFA) are novel, health-improving feed ingredients which have been shown to improve the performance of broiler chickens. TOFA contains resin acids, the suggested key components for its beneficial effects. For product safety, possible accumulation of TOFA components in tissues consumed by end-users is an issue of major importance. Wheat-soy-based diets with an indigestible marker and TOFA at 0, 750 and 3,000 g/t were fed to broiler chickens for 5 weeks; 11 replicate pens/treatment. Deposition of resin acids was assessed by analyzing jejunal tissue, breast muscle, abdominal fat, blood, liver, bile, and digesta along the intestinal tract at the end of the 35-day trial. Both free and conjugated resin acids were quantified. With TOFA 3,000 g/t diet, 30% of ingested resin acids could not be recovered from jejunal digesta. Also, a proportion representing 45% of resin acids fed were in conjugated form and thus had already re-entered the intestine from the bile duct. This means that at least 75% of resin acids ingested had become absorbed in, or proximal to jejunum. Recovery of resin acids in excreta was 45 and 70% when TOFA was fed at 750 and 3,000 g/t, respectively. Based on recovery data, of the estimated 1,087 mg of resin acids ingested by birds on the high TOFA dose during their lifetime, about 330 mg was unaccounted for. In analysis of jejunal tissue, blood, liver, bile, breast muscle, and abdominal tissue, <1 mg of resin acids was found after the 35-day trial when TOFA at the 4-fold the recommended dose was fed. It is likely that the host or microbiota mineralized or converted one-third of resin acids to a form that escaped analysis. TOFA at 3,000 g/t dose caused no detectable adverse effects in broiler chickens. Based on analysis of breast meat and liver, the common edible tissues, a human consumer would ingest <100 µg of resin acids in a single meal. That is one-thousandth of the dose shown to be harmless in rodents. Thus, unintentional exposure of human consumers to resin acids is marginal, and posed no safety concerns.

Conversion of Branched-Chain Amino Acids to Corresponding Isoacids - An in vitro Tool for Estimating Ruminal Protein Degradability.

In this paper we describe a study that evaluates the applicability of an in vitro fermentation model to assess the resistance of protein supplements to rumen degradation. The protein sources used were: soybean meal (SBM); whey protein (WHEY), which was expected to be rapidly degraded, and yeast-derived microbial protein (YMP), which was proposed to be resistant to rumen degradation. The basal diet was composed of grass silage and a commercial compound feed. The protein supplements were added at three isonitrogenous doses. Fermentation was monitored for 24 h and gas production, volatile fatty acids, lactic acid, and ammonia were analyzed at three timepoints. Protein degradation was estimated by determining the extent to which branched-chain amino acids (BCAA) introduced with the protein supplement were converted to corresponding branched-chain volatile fatty acids (BCVFA). At the highest dose of WHEY, 60% of introduced valine, leucine, and isoleucine was recovered as isobutyric, 2-methylbutyric, and isovaleric acid (products of BCAA decarboxylation and deamination), respectively. The BCVFA detected represented 50% of added BCAA with SBM, but <15% with YMP. Further indications that YMP protein is resistant to degradation were provided by analysis of ammonia. With YMP, the residual ammonia concentration only marginally exceeded that of the cultures with no protein supplementation, while it increased dose-dependently when the vessels were supplemented with WHEY or SBM. This suggests that with WHEY and SBM, the rate of deamination exceeded the rate of ammonia assimilation by bacteria. Residual ammonia and BCVFA, the two indicators of protein fermentation, were strongly correlated. Overall bacterial activity was monitored as yield of gas, volatile fatty acids, and bacteria. These three correlating parameters showed that WHEY only modestly stimulated fermentation, whereas SBM and YMP stimulated fermentation extensively, possibly owing to their higher carbohydrate content. The results presented suggest that the in vitro fermentation method was suitable for detecting differences in resistance of protein supplements to rumen degradation and following a full method validation could be a useful tool for diet formulation. The data obtained suggested that YMP was the most resistant and WHEY the most susceptible to degradation.

2-Iodo-imidazolium receptor binds oxoanions via charge-assisted halogen bonding.

A detailed (1)H-NMR study of the anion binding properties of the 2-iodo-imidazolium receptor 1 in DMSO allows to fully attribute the observed affinities to strong charge-assisted C-I···X(-) halogen bonding (XB). Stronger binding was observed for oxoanions over halides. Phosphate, in particular, binds to 1 with an association constant of ca. 10(3) M(-1), which is particularly high for a single X-bond. A remarkably short C-I···O(-) contact is observed in the structure of the salt 1·H(2)PO(4)(-).

Discriminating octahedral transition metal ions: highly selective tripodal tris-(2,2'-bipyridine) functionalized piperazine cyclophane receptor for Cu2+ ions.

New tripodal transition metal ion receptors, tris(5-ethoxycarbonyl-2,2'-bipyridine) and tris(5-carboxylate-2,2'-bipyridine) substituted 27-membered trimeric piperazine cyclophanes 5 and 7 as well as tetra(5-ethoxycarbonyl-2,2'-bipyridine) substituted 36-membered tetrameric piperazine cyclophane 6, have been prepared and their transition metal ion complexing properties studied in solution by UV-vis spectroscopy and in the solid state by single-crystal X-ray diffraction. The crystal structures of [H(3)5(3+)·Fe(2+)]·4(ClO(4)(-))·CF(3)COO(-) (V), [H(3)7(2+)·Fe(2+)]·2(SO(4)(2-)) (VII) and the reference complex [tris(5,5'-bis(ethoxycarbonyl)-2,2'-bipyridine)Fe(II) perchlorate] (I) showed that the robust piperazine cyclophane is an optimal platform in preorganizing the 2,2'-bipy moieties to form a very fixed octahedral coordination site. In an acidic water solution, the highly preorganized structure of 5 gives a [5·Fe(2+)] complex, the stability of which is comparable with the classical tris(2,2'-bipy) Fe(2+)-complex but it is a significant 3.7 logK units more stable than the non-preorganized tetrameric analog [6·Fe(2+)]. Detailed studies with other similar divalent octahedral transition metal cations showed that the restricted octahedral coordination in complexes of 5 results in an unusual selectivity. The selectivity order [Zn(2+)

Tri- and tetraurea piperazine cyclophanes: synthesis and complexation studies of preorganized and folded receptor molecules.

A series of symmetrical tri- and tetrameric N-ethyl- and N-phenylurea-functionalized cyclophanes have been prepared in nearly quantitative yields (86-99 %) from the corresponding tri- and tetraamino-functionalized piperazine cyclophanes and ethyl or phenyl isocyanates. Their conformational and complexation properties have been studied by single-crystal X-ray diffraction, variable-temperature NMR spectroscopy, and ESI-MS analysis. The rigid 27-membered trimeric cyclophane skeleton assisted by a seam of intramolecular hydrogen bonds results in a preorganized ditopic recognition site with an all-syn conformation of the urea moieties that, complemented by a lipophilic cavity of the cyclophane, binds molecular and ionic guests as well as ion pairs. The all-syn conformation persists in acidic conditions and the triprotonated triurea cyclophane binds an unprecedented anion pair, H(2)PO(4)(-)⋅⋅⋅HPO(4)(2-), in the solid state. The tetra-N-ethylurea cyclophane is less rigid and demonstrates an induced-fit recognition of diisopropyl ether in the solid state. The guest was encapsulated within the lipophilic interior of a quasicapsule, formed by intramolecular hydrogen-bond-driven folding of the 36-membered cyclophane skeleton. In the gas phase, the essential role of the urea moieties in the binding was demonstrated by the formation of monomeric 1:1 complexes with K(+), TMA(+), and TMP(+) as well as the ion-pair complexes [KI+K](+), [TMABr+TMA](+) and [TMPBr+TMP](+). In the positive-mode ESI-MS analysis, ion-pair binding was found to be more pronounced with the larger tetraurea cyclophanes. In the negative mode, owing to the large size of the binding site, a general binding preference towards larger anions, such as the iodide, over smaller anions, such as the fluoride, was observed.

The subtle balance of weak supramolecular interactions: The hierarchy of halogen and hydrogen bonds in haloanilinium and halopyridinium salts.

THE SERIES OF HALOANILINIUM AND HALOPYRIDINIUM SALTS: 4-IPhNH3Cl (1), 4-IPhNH3Br (5), 4-IPhNH3H2PO4 (6), 4-ClPhNH3H2PO4 (8), 3-IPyBnCl (9), 3-IPyHCl (10) and 3-IPyH-5NIPA (3-iodopyridinium 5-nitroisophthalate, 13), where hydrogen or/and halogen bonding represents the most relevant non-covalent interactions, has been prepared and characterized by single crystal X-ray diffraction. This series was further complemented by extracting some relevant crystal structures: 4-BrPhNH3Cl (2, CCDC ref. code TAWRAL), 4-ClPhNH3Cl (3, CURGOL), 4-FPhNH3Cl (4, ANLCLA), 4-BrPhNH3H2PO4, (7, UGISEI), 3-BrPyHCl, (11, CIHBAX) and 3-ClPyHCl, (12, VOQMUJ) from Cambridge Structural Database for sake of comparison. Based on the X-ray data it was possible to highlight the balance between non-covalent forces acting in these systems, where the relative strength of the halogen bonding C-X...A⁻ (X = I, Br or Cl) and the ratio between the halogen and hydrogen bonds [C-X...A⁻ : D-H...A⁻] varied across the series.

Halogen bonding drives the self-assembly of piperazine cyclophanes into tubular structures.

Halogen bonding with 1,4-diiodotetrafluorobenzene leads to the self-assembly of piperazine cyclophanes into well-defined tubular structures with solvent inclusion.

Molecular Pacman: folding, inclusion, and X-ray structures of tri- and tetraamino piperazine cyclophanes.

Reaction of piperazine and 1,3-bis(bromomethyl)-2-nitrobenzene under high-dilution conditions yields cyclic trimeric trinitro, tetrameric tetranitro, and pentameric pentanitro piperazine cyclophanes. Reduction of the nitro groups with SnCl(2) under acidic conditions produces the corresponding triamino and tetraamino piperazine cyclophanes. The solution studies of both nitro and amino piperazine cyclophanes at 30 degrees C by (1)H NMR spectroscopy shows symmetrical structures owing to the fast conformational exchange, whereas the low temperature studies of the tetraamino piperazine cyclophane reveals interesting dynamic behavior that indicates additional intramolecular interactions. Careful crystallizations of the trimeric trinitro and triamino and the tetrameric tetraamino cyclophanes resulted in crystals suitable for X-ray diffraction studies. In the crystalline state the amino-functionalized cyclophanes manifest an extraordinary circular intramolecular hydrogen-bonding network that leads to a fixed 3D structure. Hydrogen bonding in the triamino trimer leads to orientation of all three of the amino groups on the same side of the macrocycle, namely, the rcc conformation, whereas the tetraamino tetramer folds into a more compact shell-like conformation. During the crystallization process one acetonitrile guest is enclosed into the cavity of the tetraamino cyclophane, which gives a crystalline inclusion complex with remarkable resemblance to the famous Pacman motif. The folding, which mimics the behavior of some cyclic peptides and pyrroles, is induced by intramolecular hydrogen bonding from the amino groups to the tertiary amine groups of the piperazines. The cavity of the tetraamino tetramer is markedly smaller than in the corresponding, but nonfolded, tetranitro tetramer and the guest/host volume ratio (packing coefficient) for the acetonitrile and the cavity is approximately 50 %, which indicates a good size match for acetonitrile inclusion.