Characterization of an.antiproliferative exopolysaccharide (LHEPS-2) from Lactobacillus helveticus MB2-1

In this study, we reported that three purified exopolysaccharides fractions (LHEPS-1, LHEPS-2 and LHEPS-3) and crude LHEPS from the Lactobacillus helveticus MB2-1 inhibited the proliferation potential of human gastric cancer BGC-823 cells. We found that all the LHEPS fractions and crude LHEPS exerted concentration and time dependent inhibitory activities in vitro on BGC-823 cells. LHEPS-2 exhibited higher antiproliferative activity against BGC-823 cells in vitro than LHEPS-1, LHEPS-3 and crude LHEPS. With the consideration of the outstanding antiproliferative effect of LHEPS-2 on BGC-823 cells, more fine structural characterization of LHEPS-2 was further identified. The structure of LHEPS-2 was elucidated by methylated analysis, GC MS, H-1 NMR and C-13 NMR spectroscopy, together with two-dimensional (2D) COSY, TOCSY, HSQC, HMBC and NOESY spectroscopy. Results showed that the LHEPS-2 was consisted of the following repeating units: alpha-D-Glc-(1 -> 4)-alpha-D-Man-(1 -> 6)-alpha-D-Glc 1 down arrow 6 (sic)4)-alpha-D-Man-(1 -> 6)-alpha-D-Man-alpha-(1 -> 4)-alpha-D-Gal-(1(sic)(n) (C) 2014 Elsevier Ltd. All rights reserved.