Immunomodulation by food: promising concept for mitigating allergic disease?

The importance of a properly functioning and well-balanced immune system for maintaining health has become strikingly evident over the past decades. Roughly since World War II, there has been an apparent decrease in the prevalence of “traditional” infectious diseases, with a concomitant increase in immune-related disorders, such as allergies. Causally, a relationship with changes in life-style-related factors such as the increasing use of hygienic practices seems likely. Diet and nutrition can affect the functioning of various immune parameters. This concept can be utilised in attempts to prevent or mitigate allergic reactions via the development of targeted food products or ingredients. This review describes recent findings with respect to food products and ingredients that show potential in this respect, with special emphasis on pro- and prebiotics, β-glucans and fungal immunomodulatory proteins. What all of these approaches have in common is that they appear to strengthen Th1-mediated immunity, thus possibly restoring defective immune maturation due to overly hygienic living conditions: a little bit of dirt does not seem bad!     

High-throughput virtual screening and microsecond MD simulations to identify potential sugar mimic of the solute-binding protein BlAXBP of the ABC transporter from Bifidobacterium animalis subsp. Lactis

Xylotetraose is a prebiotic oligosaccharide can be utilized by the ABC transporter of the gut microbiota Bifidobacteria. BlAXBP is the solute binding protein of the ABC transporter, and its complex with xylotetraose has been solved by X-ray crystallography. Here, we have identified novel sugar mimic of BlAXBP by applying a high-throughput virtual screening of ZINC database containing a huge library with ∼22 M compounds. To begin with, we identified 18,571 ligands by a ligand-based virtual screening. Further, a total of 3968 compounds were selected for molecular docking due to their Tanimoto coefficient’s value were larger than a cutoff of 0.08. The molecular mechanics-generalized born surface area was used to evaluate the binding free energies, and the top 10 ligands with free energies below an energy threshold of -35.22 kcal/mol were selected. ZINC13783511 formed the most stable complex with BlAXBP and its recognition mechanism were further explored by microsecond MD simulations in explicit solvent. Free energy landscapes were used to evaluate conformational changes of BlAXBP in its ligand free and binding states. Collectively, this work identified potential novel sugar mimics to BlAXBP, providing novel atomic-level understanding of the binding mechanism.     

Effect of the lactose source on the ultrasound-assisted enzymatic production of galactooligosaccharides and gluconic acid

It is well known that one of the main problems in galactooligosaccharide production (GOS) via tranglycosylation of lactose is the presence of monosaccharides that contribute to increasing the glycaemic index, as is the case of glucose. In this work, as well as studying the effect of ultrasound (US) on glucose oxidase (Gox) activation during gluconic acid (GA) production, we have carried out an investigation into the selective oxidation of glucose to gluconic acid in multienzymatic reactions (β-galactosidase (β-gal) and Gox) assisted by power US using different sources of lactose as substrate (lactose solution, whey permeate, cheese whey). In terms of the influence of matrix on GOS and GA production, lactose solution gave the best results, followed by cheese whey and whey permeate, salt composition being the most influential factor. The highest yields of GOS production with the lowest glucose concentration and highest GA production were obtained with lactose solution in multienzymatic systems in the presence of ultrasound (30% amplitude) when Gox was added after 1 h of treatment with β-gal. This work demonstrates the ability of US to enhance efficiently the obtainment of prebiotic mixtures of low glycaemic index.     

Stereoselective synthesis of nonsymmetrical difructose dianhydrides from xylylene-tethered d-fructose precursors

Nonsymmetrical furanose-pyranose difructose dianhydrides (DFAs), a class of cyclic disaccharides present in foodstuffs, have been prepared in high yield by connecting the reacting monosaccharide moieties through a xylylene bridge prior to triflic acid-promoted bis-spiroketalization. The reaction can then proceed either intra- or intermolecularly, both the regio- and the stereoselectivity being strongly dependent on the spacer length. Noteworthy, the longer m- and p-xylylene positional isomers led to the thermodynamic α-d-fructofuranose β-d-fructopyranose 1,2′:2,1′-dyanhydride 1, the major DFA in commercial caramel, in a stereoselective manner. The shorter o-xylylene tether afforded preferentially the elusive contra-thermodynamic β-d-fructofuranose α-d-fructopyranose diastereomer 2, a trace constituent of caramel. The results have been rationalized in terms of stereoelectronic and conformational properties and offer new perspectives for the preparation of pure DFA standards for analytical and nutritional studies.