Gum Tragacanth (GT): A Versatile Biocompatible Material beyond Borders.

The use of naturally occurring materials in biomedicine has been increasingly attracting the researchers' interest and, in this regard, gum tragacanth (GT) is recently showing great promise as a therapeutic substance in tissue engineering and regenerative medicine. As a polysaccharide, GT can be easily extracted from the stems and branches of various species of Astragalus. This anionic polymer is known to be a biodegradable, non-allergenic, non-toxic, and non-carcinogenic material. The stability against microbial, heat and acid degradation has made GT an attractive material not only in industrial settings (e.g., food packaging) but also in biomedical approaches (e.g., drug delivery). Over time, GT has been shown to be a useful reagent in the formation and stabilization of metal nanoparticles in the context of green chemistry. With the advent of tissue engineering, GT has also been utilized for the fabrication of three-dimensional (3D) scaffolds applied for both hard and soft tissue healing strategies. However, more research is needed for defining GT applicability in the future of biomedical engineering. On this object, the present review aims to provide a state-of-the-art overview of GT in biomedicine and tries to open new horizons in the field based on its inherent characteristics.

LC/MS detection of oligogalacturonic acids obtained from tragacanth degradation by pectinase producing bacteria.

Tragacanth, a highly branched carbohydrate polymer isolated from Astragalus, is one of the most commonly used gums in food industry. The primary structure of tragacanth is composed of galacturonic acid monomers connected with α 1-4 links, and it is very similar to the pectin. Tragacanth degradation by microorganisms is significant in two aspects: first, food preservation and microbial growth control due to too much use of tragacanth in the food industry, second, therapeutic and pharmaceutical potential of obtained oligosaccharides. In the present study, we report three new strains of bacteria, Acinetobacter guillouiae strain TD1, Kosakonia sacchari strain TD2, and Bacillus vallismortis strain PD1 with the capability of growing in tragacanth as an only source of carbon and energy. The evolutionary history of the isolated strains was analyzed based on 16S rRNA gene sequences in MEGA7 using the neighbor-joining method. The production of di and tri galacturonic acid due to pectinase activities of the strains were detected by thin layer chromatography (TLC) and liquid chromatography/Mass spectroscopy (LC/MS) analysis. Here is the first report of the ability to grow in tragacanth and pectinase activity monitoring in bacteria. Our results revealed that all of the isolated strains are capable of degrading pectin and tragacanth to oligo-galacturonic acids. The obtained products, which have different structures depending on the tragacanth structures and types of pectinolytic enzymes, would show therapeutic and pharmaceutical potentials.

Polysaccharide zeta-potentials and protein-affinity.

The ζ-potential, a parameter typically obtained by model-dependent transformation of the measured electrophoretic mobility, is frequently used to understand polysaccharide-protein complexation. We tested the hypothesis that two anionic polysaccharides with identical ζ-potentials would show equal binding affinity to the protein ß-lactoglobulin (BLG). We selected two polysaccharide polyelectrolytes (PE) with very different structures: hyaluronic acid (HA) and tragacanthin (TG). Highly precise (±0.1%) turbidimetric titrations were performed to determine critical pH values of complex formation; and PE ζ-potentials were measured for different ionic strengths I at those critical pH values. While phase boundaries (pHcvs. I) showed that HA binds to BLG more strongly (e.g. at a lower pH, for fixed I), comparisons made at fixed ζ-potential indicated that TG binds more strongly. The source of this contradiction is the effect of the bulky side chains of TG on its friction coefficient which diminishes its mobility and hence the resultant ζ-potential; while having a distinctly separate effect on the interaction between BLG and the carboxylated backbone of TG. Thus, unless the locus of the bound protein coincides with the shear plane, the ζ-potential does not directly contribute to the electrostatic PE-protein interaction.

Osteogenic differentiation of human adipose-derived mesenchymal stem cells on gum tragacanth hydrogel.

Currently, natural polymer based hydrogels has attracted great attention of orthopedic surgeons for application in bone tissue engineering. With this aim, osteoinductive capacity of Gum Tragacanth (GT) based hydrogel was compared to collagen hydrogel and tissue culture plate (TCPS). For this purpose, adipose-derived mesenchymal stem cells (AT-MSCs) was cultured on the hydrogels and TCPS and after investigating the biocompatibility of hydrogels using MTT assay, osteoinductivity of hydrogels were evaluated using pan osteogenic markers such as Alizarin red staining, alkaline phosphatase (ALP) activity, calcium content and osteo-related genes. Increasing proliferation trend of AT-MSCs on GT hydrogel demonstrated that TG has no-cytotoxicity and can even be better than the other groups i.e., highest proliferation at day 5. GT hydrogel displayed highest ALP activity and mineralization when compared to the collagen hydrogel and TCPS. Relative gene expression levels have demonstrated that highest expression of Runx2, osteonectin and osteocalcin in the cells cultured GT hydrogel but the expression of collagen type-1 remains constant in hydrogels. Above results demonstrate that GT hydrogel could be an appropriate scaffold for accelerating and supporting the adhesion, proliferation and osteogenic differentiation of stem cells which further can be used for orthopedic applications.

Optimization of de-esterified tragacanth microcapsules by computational fluid dynamic and the Taguchi design with purpose of the cell encapsulation.

This work presents the development of the new De-Esterified Tragacanth (DET) microcapsules (MCs). Co-flow extrusion method was applied for producing the MCs; the processing parameters were optimized by the Taguchi design to obtain the smallest and the most spherical MCs. Computational Fluid Dynamic (CFD) modeling was accomplished to show the formation of droplets at different airflows, and finally, ßTC3 pancreatic cells were encapsulated in the MCs. The optimum MCs had 214.58µm size and 60.75% sphericality. The air pressure and the cross-linking reaction of DET were the most influential parameter in size and the sphericality of MCs, respectively. CFD showed two velocity vortices with rotational flow formed in the chamber, which caused changing the droplet moving direction. The encapsulated cells were proliferated, and cell viability was not reduced during six days. These phenomena make DET MCs a potential candidate for the cell encapsulation.

Self-assembly of ß-lactoglobulin and the soluble fraction of gum tragacanth in aqueous medium.

Spectrophotometric and light scattering measurements, along with optical microscopy, were used to follow the complexation and coacervation process that occur when ß-lactoglobulin (BLG)/tragacanthin (T) mixed dispersions (0.3 wt.% total concentration; BLG:T ratio of 2:1) were brought from pH 6 to pH 2. In addition, the coupling of slow in situ acidification of the mixture and rheometry was utilised to gain deeper insights into pH-induced structural transitions during the assembly process. The results obtained by this multi-methodological approach allowed the associative phase separation process to be parameterised in terms of a set of characteristic pH values (~5.3, ~4.8, ~4.5, ~4.15, ~4, ~3.8, ~2.5) at which critical structural changes took place. Investigation of the absorbance profiles of complexed/coacervated systems as a function of time revealed that several transitions could occur at different time scales. Morphological changes in the assemblies and the subsequent formation of some flocculant substances during the late stage of process were clearly visualised using microscopy.

Nitrogen conversion factors for the proteinaceous content of gums permitted as food additives.

Nitrogen conversion factors for gum arabic (Acacia senegal (L.) Willd.), gum tragacanth (Asiatic Astragalus spp.), gum karaya (Sterculia spp.), guar gum (Cyamopsis spp.), locust bean (carob) gum (Ceratonia spp.), tara gum (Caesalpinia spp.), and xanthan gum (Xanthomonas campestris) have been calculated from data for the amino acid compositions of their proteinaceous components. The factors derived differ from the arbitrary values (5.7 or 6.25) at present specified by international regulatory authorities for some emulsifiers, stabilizers and thickeners.