Designing exopolysaccharide-graft-poly(3-hydroxyalkanoate) copolymers for electrospun scaffolds

Production, characterization and biological activities of exopolysaccharides from a new cold-adapted yeast: Rhodotorula mucilaginosa sp. GUMS16

Lately, it has been proved that yeast exopolysaccharides (EPS) are potentially applicable biopolymers, a fact that has led to incremental needs for their assessment. The current study is based on the biochemical and molecular level identification of the novel cold-adapted yeast Rhodotorula mucilaginosa sp. GUMS16. Possible antioxidant and antiproliferative activities, as well as extraction and characterization of the GUMS16-produced EPS, were assessed during the course of this study. The results indicated that the strain of GUMS16 is a cold-adapted yeast with growth capability at 4 °C and an approximate EPS production yield of 28.5 g/L which are characterized as highly branched beta-D-glucan having glucose and mannose residues (85:15 mol%, respectively) with an average molecular weight of 84 kDa. In comparison to hyaluronic acid, DPPH, and OH, the scavenging activity attributed to the GUMS16-produced EPS was higher alongside being dose-dependent. The biocompatibility profile of the EPS was well-recognized based on its zero-cytotoxicity rate on a normal cell model. Collectively, the favorable properties of the EPS accentuate their potential as biocompatible compound suitable for subsequent pharmaceutical and industrial applications.

Characterization and Prospective Applications of the Exopolysaccharides Produced by Rhodosporidium babjevae

Purpose: Due to the potential industrial and therapeutic applications of the yeast exopolysaccharides (EPSs), there has been an increasing demand to assess these biopolymers with improved characteristics. This study aimed to characterize the EPSs from Rhodosporidium babjevae (ATCC 90942 and IBRC-M 30088) as well as to evaluate their possible antioxidant, emulsifying and antiproliferative activities. Methods: Rhodosporidium babjevae was cultured for 5 days and following isolation of supernatant, EPSs precipitated with adding of cold absolute ethanol and freeze-dried. The EPSs chemical structure was determined by FT-IR, SEM, HPLC-SEC and GC-MS. Additionally the solubility, water holding capacity and emulsifying activity of EPSs were evaluated. In vitro, antioxidant activity was investigated against DPPH, superoxide and hydroxyl radicals. Finally the EPSs consequence on the cell proliferation of human breast adenocarcinoma (MCF-7) and Madin-Darby canine kidney (MDCK) cell lines was evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) test. Results: R. babjevae excreted 1.6±0.2 g/L of the EPSs. The EPSs had three fractions with molecular weights of 1.02 ×10⁶ , 5×10⁵ and 2×10⁵ Da. Mannose and glucose were found as the main monosaccharides of the EPSs (84:16 mol%, respectively). The EPSs exhibited emulsifying activity on sun flower oil. The scavenging activities were found to be dose-dependent and higher than hyaluronic acid. Significant difference among the EPSs treatments on the proliferation of MCF-7 and MDCK cell lines was not observed (P>0.05). Conclusion: These results show the interesting potential of the EPSs from R. babjevae as biocompatible compounds for using in food and pharmaceutical fields.

Biomedical Processing of Polyhydroxyalkanoates

The rapidly growing interest on polyhydroxyalkanoates (PHA) processing for biomedical purposes is justified by the unique combinations of characteristics of this class of polymers in terms of biocompatibility, biodegradability, processing properties, and mechanical behavior, as well as by their great potential for sustainable production. This article aims at overviewing the most exploited processing approaches employed in the biomedical area to fabricate devices and other medical products based on PHA for experimental and commercial applications. For this purpose, physical and processing properties of PHA are discussed in relationship to the requirements of conventionally-employed processing techniques (e.g., solvent casting and melt-spinning), as well as more advanced fabrication approaches (i.e., electrospinning and additive manufacturing). Key scientific investigations published in literature regarding different aspects involved in the processing of PHA homo- and copolymers, such as poly(3-hydroxybutyrate), poly(3-hydroxybutyrate-co-3-hydroxyvalerate), and poly(3-hydroxybutyrate-co-3-hydroxyhexanoate), are critically reviewed.