Structural characterization of an acid polysaccharide from Pinellia ternata and its induction effect on apoptosis of Hep G2 cells.

In the present study, a polysaccharide fraction (PTP) was isolated and purified from the tubers of Pinellia ternata. We researched its structure and anti-tumor activity, and further studied its molecular mechanism of inducing apoptosis of Hep G2 cells. The results indicated that PTP was an acid heteropolysaccharide and the average molecular weight of PTP identified by HPGPC was 3.06 × 10⁶ Da. Ion chromatography (IC) determined that PTP was mainly composed of Ara:Gal:Glu:Man:GlcA:GalA in a molar ratio of 6.98:16.56:7.25:2.04:1:4.16. Combined with the results of FT-IR and NMR spectroscopy, it was found that PTP is a pyranose containing α-configuration and β-configuration, mainly consist of β-D-Gal, α-D-Glu, α-D-Ara and β-D-Man. By analyzing the results of MTT, cell cycle, Annexin V-FITC/PI double staining and cell morphology observation, we concluded that PTP induced dose-dependent apoptosis of Hep G2 cells via S phase arrest. In addition, mitochondrial membrane potential detection and Western blot further indicated that PTP was capable of inducing apoptosis in Hep G2 cells through an endogenous mitochondria-mediated apoptotic pathway.