Structure Studies of the Extracellular Polysaccharide from <Emphasis Type="Italic">Trichoderma</Emphasis> sp. KK19L1 and Its Antitumor Effect via Cell Cycle Arrest and Apoptosis

An extracellular polysaccharide TP1A was purified from the fermented broth of Trichoderma sp. KK19L1 by combination of Q Sepharose fast flow and Sephacryl S-300 chromatography. TP1A was composed of Man, Gal, and Glc in a molar ratio of about 3.0:5.1:8.1. The molar mass of TP1A was about 40.0 kDa. Methylation and NMR analysis indicated that the probable structure of TP1A was →4,6)-α-D-Glcp(1→6)-β-D-Galf(1→6)-β-D-Galf(1→2,6)-β-D-Galf(1→2,6)-β-D-Galf(1→2,6)-β-D-Galf(1→2,6)-α-D-Manp(1→2,6)-α-D-Manp(1→] with α-D-Glcp(1→] and α-D-Manp(1→6)-α-D-Glcp(1→6)-α-D-Glcp(1→] as branches. The antitumor study showed that TP1A was able to inhibit the cell viability of HeLa and MCF-7 cells. TP1A could arrest HeLa cells in G2/M phase and induce HeLa cell apoptosis. These findings suggest that fungal polysaccharides could be a potential source for antitumor agents.