ABSTRACT The effect on different three carbon source (i.e. glucose, fructose and sucrose) on production, chemical characterization and antioxidant activity of exopolysaccharide (EPS) produced by Phellinus vaninii Ljup was investigated in this study. Amongst carbon sources examined, glucose and sucrose were favorable for the mycelia growth, while the maximum EPS yield was achieved when sucrose was employed. The predominant carbohydrate compositions in EPSs identified were gluconic acid, glucose, mannose and galactose acid. Then, FT-IR spectral analysis revealed prominent characteristic groups in EPSs. EPSs molecule exist as nearly globular shape form in aqueous solution. The variation also affects antioxidant activities by investigated by using hydroxyl and DPPH radical scavenging assay. Sucrose was best carbon source from the viewpoint of antioxidant activity due to the relatively high contents of galactose in the EPS with moderate molecular weight and polydispersity.

Ultrasound-assisted extraction (UAE) of polysaccharide from Maryland tobacco leaves was studied by response surface methodology. Furthermore, the crude polysaccharide was purified and two components (Fr-I and Fr-II) were obtained. FT-IR spectral analysis of the purified polysaccharide revealed prominent characteristic groups. The monosaccharide composition analysis by gas chromatography-mass spectrometry (GC/MS) indicated the main composition between Fr-I and Fr-II was different. Furthermore, thermo gravimetric analysis (TGA) indicated the degradation temperature (Td) of the Fr-I (241 ºC) was higher than those of Fr-II (216 ºC). Detected by the pyrolysis gas chromatography-mass spectrometry (py-GC/MS), it was found that the main kinds of pyrolysis products from both Fr-I and Fr-II were similar. Finally, On the basis of hydroxyl and DPPH radical scavenging assay, Fr-II has stronger antioxidant activities than Fr-I. The thermal behavior and antioxidant activity might be attributed to the configuration of the chemical compositions.