J. M. García Fernández

Tuning glycosidase inhibition through aglycone interactions: pharmacological chaperones for Fabry disease and GM1 gangliosidosis.

Competitive inhibitors of either α-galactosidase (α-Gal) or β-galactosidase (β-Gal) with high affinity and selectivity have been accessed by exploiting aglycone interactions with conformationally locked sp(2)-iminosugars. Selected compounds were profiled as potent pharmacological chaperones for mutant lysosomal α- and β-Gal associated with Fabry disease and GM(1) gangliosidosis.

Correlations between changes in intestinal microbiota composition and performance parameters in broiler chickens

Growing male Cobb broiler chickens were fed on diets supplemented with additives reported as able to influence intestinal microbiota composition. The diets used were a balanced commercial diet (no additive), inulin (20 g/kg), fructose caramel (FC, 20 g/kg) and the garlic derivative PTS-O (propyl propane thiosulfonate, 45 and 90 mg/kg diet). The composition of the intestinal microbiota was analysed by qPCR at different points of the intestinal tract, and a number of nutritional parameters were also determined. The relative amounts of bacteroides (bacteroides/total bacteria) in the ileal contents correlated (p < 0.05) positively with faecal NDF, ADF, hemicellulose and cellulose digestibility. The relative amounts of Escherichia-Shigella (Escherichia-Shigella/total bacteria) in the crop contents correlated (p = 0.05) negatively with weight gain of broilers. Faecal N digestibility correlated (p < 0.05) negatively with total bacteria in the ileal contents of chickens. The relative amounts of Escherichia-Shigella (Escherichia-Shigella/total bacteria) in the caecal contents correlated (p = 0.05) negatively with faecal fat digestibility of broilers. Total bacteria in ileal or caecal contents of growing chickens correlated (p < 0.05) negatively with ileal N digestibility. The results here reported suggest that positive or negative correlations can be found between performance parameters and changes in intestinal microbiota composition of growing broiler chickens.

Effects of inulin and di-D-fructose dianhydride-enriched caramels on intestinal microbiota composition and performance of broiler chickens.

In vitro and in vivo experiments were designed to evaluate the effectiveness of laboratory-made di-d-fructose dianhydride (DFA)-enriched caramels. The DFA-enriched caramels were obtained from d-fructose (FC), d-fructose and sucrose (FSC), or d-fructose and β-cyclodextrin (FCDC). In the in vitro experiment, raftilose and all caramels increased (P<0.05) l-lactate concentration and decreased (P<0.05) pH. Total short-chain fatty acid concentration was higher (P<0.05) than controls in tubes containing raftilose, FSC, FCDC and commercial sucrose caramel (CSC). Raftilose, and all caramels tested except FSC and FC (1%), increased (P<0.01) lactobacilli log10 number of copies compared with the non-additive control. FSC, FCDC and CSC increased (P<0.01) the bifidobacteria number of copies as compared with controls. All additives, except FCDC, decreased (P<0.01) Clostridium coccoides/Eubacterium rectale log number of copies. Compared with controls, raftilose, FC and CSC led to lower (P<0.01) Escherichia-Shigella and enterobacteria. For the in vivo experiment, a total of 144 male 1-day-old broiler chickens of the Cobb strain were randomly assigned to one of the three dietary treatments for 21 days. Dietary treatments were control (commercial diet with no additive), inulin (20 g inulin/kg diet) and FC (20 g FC/kg diet). Final BW of birds fed FC diet was higher (P<0.01) than controls or inulin-fed birds, although feed: gain values were not different. Feed intake of chickens fed FC was higher (P<0.01) than that of inulin-fed birds but not statistically different from controls. Crop pH values were lower (P<0.01) in birds fed FC diet as compared with control diet, with inulin-fed chickens showing values not different from control- or FC-fed birds. Lower (P<0.05) lactobacilli number of copies was determined in the crop, ileum and caeca of birds fed the inulin diet compared with the control diet. Inulin supplementation also resulted in lower (P<0.05) C. coccoides/E. rectale, bacteroides and total bacteria in caecal contents. Addition of FC to broiler diets gave place to lower (P<0.05) enterobacteria and Escherichia-Shigella in crop and caecal contents compared with controls. The bacteroides number of copies increased (P<0.05) as compared with controls in the ileum, but decreased (P<0.05) in the caeca of chickens fed the FC diet. Energy, ADF, NDF and non-starch polysaccharides faecal digestibilities were greater (P<0.05) than controls in chickens fed diets containing inulin or FC. Fat digestibility was higher (P<0.05) in FC-fed birds compared with controls or inulin-fed chickens. In conclusion, DFA-enriched caramels tested here, particularly FC, may represent a type of new additives useful in poultry production.

Tuning of glyconanomaterial shape and size for selective bacterial cell agglutination

Multivalent glycosystems are potential candidates for anti-adhesive therapy, a non-lethal approach against the ever increasing antibiotic resistance of pathogenic bacteria. In order to fine-tune the glyconanomaterial size and shape for selective bacterial cell agglutination, herein we report the synthesis of sugar-coated dynamic and polymeric 3D-micelles and 1D-carbon nanotubes. The reported shot-gun like synthetic approach is based on the ability of diacetylenic-based neoglycolipids to self-assemble into micelles in water and hierarchically self-assemble into hemimicelles on a single-walled carbon nanotube surface. The affinity of the nanosystems was preliminarily assessed by enzyme-linked lectin assay (ELLA) using the mannose-specific Concanavalin A lectin as a model receptor. Relative binding potency enhancements, compared to methyl α-d-mannopyranoside used as control, from 10- to 25- to 2340-folds in sugar molar basis were observed when passing from 3D dynamic micelles to static micelles, to 1D-mannose coated carbon nanotubes, respectively, indicative of a significant cluster glycoside effect. Importantly, these results were confirmed in vivo showing that the 1D-glyconanoring-coated carbon nanotubes efficiently and selectively regulate the agglutination and proliferation of the enterobacteria Escherichia coli type 1 fimbriae. These findings highlight the potential of sugar coated nano-materials as novel and effective tools in the control of bacterial pathogenesis.

Effects of feed additives on ileal mucosa–associated microbiota composition of broiler chickens

The effects of dietary supplementation with 2 recently developed feed additives on the composition of the mucosa-associated microbiota of the ileum were studied in growing broiler chickens. A total of 48 male 1-d-old broiler chickens of the Cobb 500 strain were distributed in 4 treatments with 2 replicates of 6 birds each. The 2 additives tested were a di-d-fructose dianhydride–enriched caramel (FC) and the garlic derivative propyl propane thiosulfonate (PTS-O). Dietary treatments were a control (commercial diet with no additive), INU (20 g inulin/kg diet), CAR (20 g FC/kg diet), and GAR (90 mgPTS-O/kg diet). As a result of this study, inulin supplementation resulted in lower (P < 0.05) and FC feeding resulted in higher (P < 0.05) Blautia coccoides/Eubacterium rectale log10 number of copies respect to controls. Higher (P < 0.05) bifidobacteria log10 number of copies with respect to the controls was determined in the ileal mucosa of birds fed the PTS-O–supplemented diet. Denaturing gradient gel electrophoresis and PCR analysis on Bifidobacterium spp. revealed the presence of Bifidobacterium longum, Bifidobacterium pseudolongum, and Bifidobacterium pseudocatenulatum in samples from chickens fed the control and the PTS-O–supplemented diet. Bifidobacterium longum was exclusively found in poultry fed the control diet, whereas B. pseudocatenulatum was found only in poultry fed the PTS-O–supplemented diet. This study showed that both PTS-O and FC were able to modulate the composition of the ileal mucosa-associated microbiota of growing broiler chickens. Finally, in addition to B. pseudolongum, the presence of B. longum and B. pseudocatenulatum, species not previously described in intestinal samples of broilers, was also demonstrated.

Les cyclodextrines en pharmacie : perspectives pour le ciblage d’actifs thérapeutiques et le contrôle d’interactions membranaires

Resume Les proprietes de complexation des cyclomaltooligosaccharides (cyclodextrines, CDs), structures cage biocompatibles issues des biotechnologies, ont ete mises a profit dans les trente dernieres annees pour solubiliser, stabiliser et augmenter la biodisponibilite d’actifs therapeutiques. La fonctionnalisation permet d’ameliorer la solubilite et les proprietes de solubilisation et de s’affranchir des effets nephrotoxiques rencontres avec des cyclodextrines natives. De meme, les proprietes hemolytiques attribuees a des interactions membranaires sont mieux controlees. Des procedes selectifs et commercialement viables sont desormais disponibles permettant de pallier aux problemes d’heterogeneite associes aux procedes industriels existants. Ces strategies ont permis un acces commode a des structures modulaires adaptables aux caracteristiques moleculaires de la structure hote (CDs bouquets ou dimeres). Le greffage de ligands saccharidiques multivalents reconnus par des proteines membranaires constitue un autre aspect prometteur de ces resultats pour le transport et l’adressage de molecules actives vers des recepteurs d’interet pharmacologique ou encore le controle d’interactions cellulaires. Certains aspects topologiques de presentation du ligand saccharidique vis-a-vis du domaine de reconnaissance d’une lectine membranaire ont pu etre precises pour la concanavaline A et des glycodendrons mannosyles et ces resultats ont ete etendus au ciblage moleculaire vers des macrophages. Les proprietes d’auto-association des cyclodextrines et en particulier de derives amphiphiles sont par ailleurs exploitees pour l’acces a des structures nanoparticulaires d’interet pour le transport et le ciblage de systemes macromoleculaires.

CHAPTER 5:Cyclodextrins for Pharmaceutical and Biomedical Applications

Cyclodextrins have occupied a preferential position in supramolecular chemistry and pharmaceutical technology for decades. Their molecular structure provides them with unique supramolecular features that have already found a plethora of applications for numerous purposes, including innovative solutions to formerly unmet pharmaceutical and biomedical challenges. The amalgamation of chemical, supramolecular and technological knowledge and the paradigmatic correlation between cyclodextrin structure and function has facilitated an unprecedent and fluent crosstalk among formerly distant research disciplines. This chapter emphasizes the role that cyclodextrins are playing in the era of nanosciences and the recent advances in cyclodextrins chemistry and technology that are making it feasible to address a broad range of pharmaceutical and biomedical challenges. A series of examples illustrates how the knowledge gained over a century of cyclodextrin research can applied: (i) for manipulation of the bioavailability of therapeutic agents, (ii) for the rational design of intelligent systems envisioned for targeted delivery and programmed release of cargos, (iii) for devising new therapeutic strategies for known maladies, and (iv) for the engineering of biosensing devices.

Macrocyclic Sugar Thioureas: Cyclooligosaccharides Mimicking Cyclopeptides

Interactions between carbohydrates and other organic molecules, specially proteins, play a prominent role in many biological recognition processes. The complexity of such phenomena has stimulated the use of model systems to get information about their nature (lipophilic, polar, hydrogen bonds, etc.) and to evaluate their contribution to the stability and specificity of the carbohydrate-containing supramolecular entity. Among model sugar-derived hosts, the natural cyclodextrins (CDs) have been by far the most widely used for this purpose, due to their commercial availability and to the presence of a hydrophobic cavity that can accommodate a guest molecule surrounded by a hydrophilic environment.1 Contributory reasons to the popularity of CDs are the high symmetry and rigidity of the structure that facilitate the study of inclusion complexes by NMR techniques. However, this lack of conformational flexibility is a limitation regarding efficiency of complexation, since the host cannot adapt its geometry to the guest for an optimal interaction. Such ability is, in contrast, a main structural feature of polyamide receptors, from which cyclopeptides are paradigmatic examples. We have now imported this faculty into cyclic oligosaccharides by inserting thiourea spacers that would act as symmetric amide surrogates. The possibility of switching between Z and E configurations at the pseudoamide linkages allows then a restricted number of rotameric forms whose relative populations are conditioned by the strong hydrogen bond donnor character of the NH thiourea protons.2,3 In addition, these sugar-thiourea coronands may be considered as comformationally restricted glycopeptide analogues, useful as model compounds for the study of specific carbohydrate-peptide interactions, e.g. interactions involving the pseudoamide NH protons and the carbohydrate oxygen atoms.

Thiourea-Bridged ß-Cyclodextrin Conjugates

Saccharide as well as peptide antennae have been efficiently appended to the primary hydroxy 1 rim of the s-CD core through thiourea tethers. The synthetic strategy involves the coupling reaction of glycosyl or peptide isothiocyanates with amine funtionalized s-CDs and has been applied to the preparation of mono- as well as heptavalent derivatives. The new conjugates exhibited a dramatic increase in water solubility as compared to s-CD itself while retaining the inclusion properties towards the anticancer drug Taxotere®.