Characterization and anti-tumor activities of sulfated polysaccharide SRBPS2a obtained from defatted rice bran

A novel chemically sulfated polysaccharide SRBPS2a with potent anti-tumor activity was derived from defatted rice bran by chlorosulfonic acid–pyridine (CSA–Pyr) method. The average molecular weight of SRBPS2a was 3.5 × 105 Da and the degree of sulfation (DS) was 1.29. The Fourier-transform infrared spectra (FT-IR) and 13C NMR spectroscopy analysis revealed that SRBPS2a was mainly consist of β-(1 → 3)-d-galactopyranosyl residues, the sulfate substitution site was on C-2 and C-4 while the side chains were cut off during the sulfated reaction. Furthermore, SRBPS2a exhibited evident growth inhibition on mouse mammary tumor EMT-6 cells both in vitro and in vivo.