Purification, structural elucidation and antitumor activity of a novel mannogalactoglucan from the fruiting bodies of Lentinus edodes.

A mannogalactoglucan, named LE-MGG, was isolated from the basidiocarps of Lentinus edodes by hot water-extraction, ethanol precipitation anion exchange chromatography, and further purified by gel-permeation chromatography (GPC). Its structural features were investigated by high performance liquid chromatography (HPLC), high performance gel-permeation chromatography (HPGPC), methylation analysis, periodate oxidation-Smith degradation, and by IR and NMR spectroscopy, including two-dimensional (2D) NMR. HPLC analysis revealed that LE-MGG contained mannose-galactose-glucose in the molar ratio of 10:18:72. GPC and HPGPC showed that LE-MGG was a homogeneous fraction (d=1.34) and its molecular weight was estimated to be 18kDa. Chemical and spectroscopic studies indicated that LE-MGG consists of (1→6)-, (1→4)- and (1→3)-linked ß-d-glucopyranosyl residues, (1→6)-linked α-d-galactopyranosyl residues, (1→3,6)- and (1→2,4)-linked α-d-mannopyranosyl residues and terminal residues of ß-d-glucopyranosyl. Cytotoxicity assay showed that LE-MGG presented higher antitumor activities against S-180 cell with a dose-dependent manner, and exhibited lower cytotoxicity to carcinoma HCT-116 and HT-29 cells. Our studies showed also that LE-MGG presented antitumor bioactivities on Sarcoma 180 solid tumor cell implanted in Kunming mice. This finding suggests that mannogalactoglucan should be explored as potential antitumor agents and could be potentially applied as a natural antitumor drug.

Neuroprotective effects of ginseng pectin through the activation of ERK/MAPK and Akt survival signaling pathways.

In this study, we investigated the neuroprotective activities of ginseng pectin (GP) against hydrogen peroxide (H2O2)-induced neuronal toxicity in different neuronal cells. GP selectively attenuated H2O2-induced damage up to 26% in primary cortical neuron cells and human glioblastoma U87 cells. Following H2O2 exposure, DAPI staining and neuron-specific ß-tubulin antibody probing indicated that GP maintained cell integrity and decreased nuclei condensation. Data from western blot analysis revealed that pre-treatment with GP increased the phosphorylation of both the extracellular signal-regulated kinases 1 and 2 (ERK1/2) and Akt in cortical neuron cells. However, the phosphorylation of ERK1/2 was increased, but that of Akt was decreased in U87 cells. These results suggest that the protective effects of GP against H2O2-induced apoptosis may be due to the activation of the phosphorylation of ERK1/2 and Akt; however, the mechanisms involved differ depending on the cell line. This neuroprotective property indicates that GP could serve as a potential therapeutic agent for neurodegenerative diseases.