Antitumor activity of levan polysaccharides from selected microorganisms

Levans were isolated from the cultures of Gluconoacetobacter xylinus (G-levan; Mw = 40,000), Microbacterium laevaniformans (M; Mw = 710,000), Rahnella aquatilis (R; Mw = 380,000), and Zymomonas mobilis (Z; Mw = 570,000). The levans were composed mainly of fructose residues when analyzed by TLC and HPLC, and their main backbones were beta-(2,6)-linkages with beta-(2,1)-branches by GC-MS and NMR. In the in vitro antitumor activity test of the levans against eight different tumor cell lines, relatively stronger activity was observed from the SNU-1 and HepG2. The M- (52.54-62.05%) and R-levan (52.15-58.58%) showed the significantly high activity against SNU-1, while M-levan showed the highest (49.93-61.82%) activity against HepG2. During the in vivo analysis of inhibitory activity of the levans against Sarcoma-180 growth, M-, R- and Z-levans showed strong antitumor activity (average 66%) but G-levan (42%) had significantly lower activity.