Food & Function 2018-04-06

Structural characterization and antitumor activity of a novel Se-polysaccharide from selenium-enriched Cordyceps gunnii

Yuan Zhu, Huiqing Sun, Yali Tang, Yuanyuan Ren, qiaoying song, Yun Tang, Yongmin Zhang

Index: 10.1039/C8FO00027A

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Abstract

Selenium (Se) was recognized as an essential element. Animals and humans absorb and retain more organic-Se than inorganic-Se. The bio-transformation was a major approach to transfer inorganic-Se to organic-Se. Cordyceps gunnii (C. gunnii), well known as Chinese edible and medicinal fungi, has a variety of biological functions. C. gunnii and selenium were combined through liquid-fermentation to obtain selenium-enriched C. gunnii. A novel Se-polysaccharide (SeCPS-II) was extracted from selenium-enriched C. gunnii. The molecular weight, sugar content and selenium content of SeCPS-II were 4.12×103 kDa, 17.89 μg/g and 90.75%, respectively. The structure of SeCPS-II was characterized with FT-IR, NMR, GC and GC-MS. The SeCPS-II was composed of pyranose which contained α-L-rhamnose, α-D-mannose, α-D-glucose and β-D-galactose with ratio of 4.33 : 12.62 : 27.50 : 18.99. The SeCPS-II contained α-(1→4)-D-glucose, α-(1→3)-D-glucose, β-(1→6)-D-galactose and α-(1→6)-D-mannose, α-(1→4)-L-rhamnose. And the main chain was composed of α-(1→4)-D-glucose. The MTT assay indicated that the SeCPS-II could inffluence the cell viability of SKOV-3 cells, H1299 cells and HepG2 cells in a dose-dependent and time-dependent manner. The morphologic changes (AO/EB staining and DAPI staining) and MMP assay (JC-1 staining) of SKOV-3 cells treated with SeCPS-II were performed to research the antitumor activity of SeCPS-II. The SeCPS-II could significantly induce apoptosis of SKOV-3 cells with typical apoptotic characteristics. To study the mechanism, the expressions of Caspase-3, Caspase-9, PARP, p53 and, Bax and Bcl-2 in SKOV-3 were studied with Western blotting. The SeCPS-II can stimulate the apoptosis SKOV-3 cells through the p53-Bax-Caspase pathway. The animal experiment revealed that the SeCPS-II have inhibition on the tumor with in ovarian tumor model rat modeled with SKOV-3 cells. All the results indicated that the selenium-enriched C. gunnii can be used to develop new selenium-containing additives.