Introduction: 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: R. 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, hydroxyl and superoxide free radicals. Finally the EPSs effect on the cell proliferation of human breast adenocarcinoma (MCF-7) and Madin-Darby Canine Kidney (MDCK) cell lines was assessed using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay.
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. No significant difference among the EPSs treatments on the proliferation of MCF-7 and MDCK cell lines was observed (P>0.05).
Conclusion: These results indicate the desirable potential of the EPSs from R. babjevae as biocompatible compounds for using in food and pharmaceutical fields.