Preparation and anti-tumor activity of low molecular weight exopolysaccharide from Rhizobium sp. N613

Abstract:

Exopolysaccharide from Rhizobium sp. N613 (REPS) was degraded by microwave irradiation with H2O2 to improve its physical, chemical and anti-tumor activity. Effects of REPS’s concentration, H2O2’s concentration, intensity and time of microwave irradiation on the molecular weight of degradated products were investigated by orthogonal test. Then the antitumor activities of four different molecular weight of LREPS were evaluated in mice bearing sarcoma 180. The results indicated that inhibition rate reached 52.8% when the molecular weight of LREPS reduced to 10.352 kD. LREPS(10.352 kD)’s preparation conditions were as follows: REPS’s concentration was 2 g/L, H2O2’s concentration was 6%, radiation intensity was 375 W, and irradiation time was 2 min. The molecular structure of the LREPS was analyzed by IR. The result indicated that LREPS was a β-glucan. The solubility of LREPS was increased from 8 g/L to 15.73 g/L, and the intrinsic viscosity of LREPS was reduced from 527.64 mL/g to 351.67 mL/g. The technology of preparing LREPS was established. Moreover, relevant technical parameters were obtained. Results of these study lay a certain foundation for the production and application of the polysaccharide.