Abstract
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.
Highlights
Exopolysaccharides (EPSs) are high mass polymers secreted by form of microorganisms into the encompassing environment and are mainly made up of sugar residues.[1,2,3] Sometimes, organic and inorganic functional groups such as amine, acetate, succinate, phosphate and sulfate can be seen in their chemical structures.[2]
A study has been recently published on the ability of Rhodosporidium paludigenum to produce pullulan.[21]
The results showed that the EPSs were composed of mannose (84%) and glucose (16%), and three fractions with different molecular weights were observed as well; the elution profile exhibited main fraction with a molecular weight estimated as 1020 kDa, based on pullulan standards (Table 1)
Summary
Exopolysaccharides (EPSs) are high mass polymers secreted by form of microorganisms into the encompassing environment and are mainly made up of sugar residues.[1,2,3] Sometimes, organic and inorganic functional groups such as amine, acetate, succinate, phosphate and sulfate can be seen in their chemical structures.[2]. Several studies have shown a wide range of biological activities of yeast EPSs including antioxidant, antitumor, antimutant, antithrombotic, anticoagulant, immunomodulation and antiviral activities.[1,5,6,7,8] These activities are dependent on factors associated with the structure and physical characteristics of EPSs like their
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