Structural analyses of apricot pectin polysaccharides.

Apricot pectin polysaccharides' fine structure was performed using HPSEC, HPAEC-PAD, GC-MS, NMR and FTIR spectroscopies. Purified pectin fraction (F1AP) was composed of D-galacturonic acid, L-rhamnose, D-arabinose and D-galactose, Mw âˆ¼ 1588 kDa. F1AP was eluted by water and with 0.2 M NaCl from DEAE Sepharose fraction resulting in two distinct fractions, F1AP1 and F1AP6, with different structures, molecular weights, and conformations, providing insights into their structural diversity. F1AP1 neutral properties were related to its association with protein. F1AP1 had a backbone of (1 â†’ 4)-linked-D-galacturonic acid and (1 â†’ 2)-linked-L-rhamnopyranosyl residues branched with arabinogalactan including multiple glycosidic linkages of T-α-Araf, 3-α-Araf, 5-α-Araf, T-α-Arap, 2-α-Arap, t-Galp, 2-Galp, 3-Galp, 4-Galp, 6-Galp, 2,4-Galp, 3,4-Galp, 3,6-Galp and 4,6-Galp side chains, having methyl and acetylated groups, and a high molecular weight (1945 kDa). The Mark-Houwink exponent was 0.276, indicating a compact spherical conformation. While the other F1AP6 fraction consists predominately of less methylated HG regions of pectin polysaccharides. The molar mass of this fraction was 117.5 kDa, which adopted a stiffer and random coil conformation. This knowledge allows us to evaluate how the balance of chemical structure and physical properties of the two pectin domains may manifest itself in the isolated structure of apricot pectin and its applications.

Impact of Steviol Glycosides and Erythritol on the Human and Cebus apella Gut Microbiome.

Leaf extracts of Stevia rebaudiana, composed of more than 10 steviol glycosides (SGs), are used as non-nutritive, table sugar (sucrose) alternatives due to their high level of sweetness and low caloric impact. They are often combined with the sugar alcohol erythritol to increase volume and reduce aftertaste. Little is known of the impact of sugar alternatives on the human gut microbiota in terms of the diversity, composition, and metabolic products. Testing of SGs and erythritol using six representatives of the gut microbiota in vitro found no impact on bacterial growth, yet treatment with erythritol resulted in an enhancement of butyric and pentanoic acid production when tested using a human gut microbial community. Furthermore, administration of SGs and erythritol to a Cebus apella model resulted in changes to the gut microbial structure and diversity. Overall, the study did not find a negative impact of SGs and erythritol on the gut microbial community.

Triclosan has a robust, yet reversible impact on human gut microbial composition in vitro.

The recent ban of the antimicrobial compound triclosan from use in consumer soaps followed research that showcased the risk it poses to the environment and to human health. Triclosan has been found in human plasma, urine and milk, demonstrating that it is present in human tissues. Previous work has also demonstrated that consumption of triclosan disrupts the gut microbial community of mice and zebrafish. Due to the widespread use of triclosan and ubiquity in the environment, it is imperative to understand the impact this chemical has on the human body and its symbiotic resident microbes. To that end, this study is the first to explore how triclosan impacts the human gut microbial community in vitro both during and after treatment. Through our in vitro system simulating three regions of the human gut; the ascending colon, transverse colon, and descending colon regions, we found that treatment with triclosan significantly impacted the community structure in terms of reduced population, diversity, and metabolite production, most notably in the ascending colon region. Given a 2 week recovery period, most of the population levels, community structure, and diversity levels were recovered for all colon regions. Our results demonstrate that the human gut microbial community diversity and population size is significantly impacted by triclosan at a high dose in vitro, and that the community is recoverable within this system.

Biopolymer scaffolds for use in delivering antimicrobial sophorolipids to the acne-causing bacterium Propionibacterium acnes.

Sophorolipids (SLs) are known to possess antimicrobial properties towards many species (particularly Gram-positive, or Gram(+)) of bacteria. However, these properties can only be exerted if the SLs can be introduced to the bacterial cells in an acceptable manner. Propionibacterium acnes is the common bacterial cause of acne. It is a Gram(+) facultative anaerobe that is susceptible to the antimicrobial effects of SLs. In this study we demonstrated that different biopolymer matrices could be used to produce SL composite films that exert various antimicrobial efficiencies against P. acnes. Increasing SL concentrations in poly-3-hydroxybutyrate (PHB) and PHB-co-10%-3-hydroxyhexanoate (PHB/HHx) resulted in noticeably improved (PHB/HHx was best) antimicrobial activity based on the size of the zones of inhibition using an overlay plating technique on synthetic growth medium. However, increasing concentrations of SLs in PHB and PHB/HHx films also increased film opacity, which diminishes the appeal for use especially in visible (facial) areas. Pectin and alginate improved the transparent character of SL composite films while also acting as successful carriers of SLs to P. acnes. The lactone form of the SLs proved to exhibit the best antimicrobial action and in concert with either pectin or alginate biopolymers provided a comparatively transparent, successful means of utilizing SLs as a renewable, environmentally benign anti-acne solution.

Adhesion barriers of carboxymethylcellulose and polyethylene oxide composite gels.

Composite gels and films of CMC and PEO have been used to separate healing tissues and have been demonstrated to reduce postsurgical adhesions in animal models of adhesion formation. Gels of CMC/PEO were studied here to elucidate the mechanism by which the combination of PEO with CMC is effective in reducing adhesions between tissues. CMC and PEO were demonstrated to undergo micro phase separation to form a two-phase system. Protein partitioning was measured in this system for albumin, fibrinogen, and gamma globulin. All of these proteins were found to partition preferentially into the CMC phase. When gels of CMC and PEO were examined for tissue adherence, the addition of PEO reduced the adherence of CMC to tissues. To further investigate the effects of PEO on tissue adherence of the gel, the extent of thrombus formation of citrated blood initiated by calcium chloride in CMC/PEO gels was measured in vitro. The extent of thrombus formation by CMC was reduced proportionally to the content of PEO in gels of CMC/PEO. A model was developed to explain how CMC and PEO contribute to the effectiveness of CMC/PEO gels that form a barrier between healing tissues to reduce postsurgical adhesions. In an open system PEO is released from the gel faster than CMC is dissolved, resulting in a shell structure with CMC coated by PEO. The PEO-rich outer layer functions to inhibit protein deposition and thrombus formation. The CMC-rich layer functions to anchor the gel to the tissue surface.

Hyaluronate-heparin conjugate gels for the delivery of basic fibroblast growth factor (FGF-2).

The stability and activity of recombinant growth factors administered locally for the repair of damaged tissue can be directly influenced by the physical structure and chemical composition of the delivery matrix. This study describes a novel basic fibroblast growth factor-2 (FGF-2) delivery system synthesized by the conjugation of a structure-stabilizing polymer, hyaluronate (HA), with a sulfated glycosaminoglycan, heparin (HP), that has inherent specific binding sites for members of the FGF family. The biopolymers were formed via stable amine or labile imine bonds by coupling amine-modified HA with oxidized heparin. The addition of recombinant human FGF-2 resulted in the rapid binding of FGF-2 to the heparin segment of the hyaluronate-heparin (HAHP) conjugate. The FGF-2 was released in vitro from the imine-bonded (HAHPi) gels in the form of FGF-2-heparin complexes through the hydrolysis of the imine bonds. In contrast, the release of growth factor from the more stable amine-bonded (HAHPa) gels required treatment with free heparin or enzymatic digestion of the hyaluronate segment. Functional analysis of the released FGF-2 showed that the HAHP conjugate gels increased both the stability and activity of the growth factor.