Characterization and antitumor activities of polysaccharides obtained from ginger (Zingiber officinale) by different extraction methods

Three different extraction technologies including hot water extraction (HWE), enzyme assisted extraction (EAE) and ultrasonic cell grinder extraction (UCGE) were employed to extract crude ginger polysaccharides (GPs) under their respective best parameters, then crude GPs were purified by DEAE cellulose-52 and Sephadex G-200 size-exclusion chromatography in that order. Five GPs fractions (HGP, EGP1, EGP2, UGP1, and UGP2, respectively) were obtained. The differences of five GPs in chemical composition, characterization and antitumor activities were further compared. The molecular weights were different in five GPs, varying from 11.81 to 1831.75 kDa. Mannose and glucose as the main monosaccharide and the glycosidic linkage of →4)-α-D-Glc(1→ and -α-Manp-(1→ existed in both five GPs. While EGP2 and UGP1 possessed specific structure of →6)-β-D-Galp-(1→ and UGP1 contained more sulfate group. Moreover, UGP1 exhibited strong inhibitory effect on three tumor cells especially the colon cancer. The inhibition rates of UGP1 on H1975, HCT116 and MCF-7 were 23.339 ± 2.285%, 56.843 ± 2.405% and 21.061 ± 1.920% respectively. The study indicated GPs extracted by UCGE could reserve more active structure and inhibit colon cancer more significantly.