Earticle

Ginseng (Panax ginseng C.A. Meyer) is a highly valued herbal medicine that has been traditionally used to prevent or treat diverse medical disorders. Polysaccharides isolated from ginseng have been shown to exhibit various biological activities, including immune modulating, anti-diabetic, anti-cancer, and anti-obesity properties. However, the ginseng-derived oligosaccharides was rarely explored. In this study, we investigated the anti-cancer activity in A549 human lung cancer cells of ginseng polysaccharides (MW. 11.605 kDa) and its lower-molecular weight oligosaccharide (GOS, MW. 2.2 kDa) prepared by enzymatic degradation. The results showed that GOS dose-dependently reduced the cell viability of the A549 cells, with an approximately 55% reduction at 500 μg/ml, while GPS did not affect the cell viability. The GOS-induced A549 cell death was mediated by induction of cell cycle arrest at the sub.G1 (apoptotic) phase. GOS treatment also induced DNA fragmentation, depolarization of MMP, and reduction in Bcl-2 and pro-caspase-3 expression levels. Moreover, the anti-cancer effects of GOS were related to the MAPK signaling pathway, as evidenced by significantly decreased phosphorylation of ERK. These results clearly demonstrated for the first time that GOS inhibits the A549 human lung cancer cell growth via induction of cell cycle arrest and stimulation of mitochondria-dependent apoptotic cell death through inhibition of MAPK pathway. These findings suggested that GOS may have a strong therapeutic potential for the treatment of human lung cancer.

In this study, we extracted water soluble polysaccharides from the defatted Korean edible nut cake by boiling for 3 h in water and purified by ethanol precipitation and DEAE-cellulose column chromatography. The monosaccharide composition analysis showed that the purified polysaccharide (NP) is a galacturonoxyloarabinan type polysaccharide consisting of xylose (7.2, molar ratio), arabinose (8.8), and galacturonic acid (4.4) as major sugars and other minor sugars like glucose, galactose, rhamnose, and glucuronic acid. It's molecular mass was shown to be 1,274 kDa by size-exclusion HPLC. Then, we investigated the immunostimulating activity of NP in murine macrophage RAW 264.7 cells. The purified water soluble polysaccharide (NP) did not show any detectable level of cytotoxicity to RAW 264.7 cells in the concentration range tested (10-200 μg/ml) and rather, it promoted the cell proliferation. The NP stimulated the RAW 264.7 cells to produce the nitric oxide (NO) and increase the mRNA expression level of inducible nitric oxide synthase (iNOS). In addition, it induced the production of pro-inflammatory cytokines (TNF-α and Interleukin-6) and chemokines (RANTES and MIP-1α), which are largely known to play an important role in immune system. Taken together, these results suggest that NP can be considered a potential immunopotentiator and thus can be a potent ingredient of health beneficial functional foods or therapeutic agents.

O-linked N-acetylglucosamine (O-GlcNAc) modification (O-GlcNAcylation) is a post translational modification, which is modulated by O-GlcNAc transferase (OGT) and O-GlcNAcase (OGA). In the present study, we determined that OGA regulates LPS-driven activation of iNOS/NO. PUGNAc, an inhibitor of OGA, suppress LPS-induced induction of iNOS/NO and the gene expression of proinflammatory mediators, indicating that O-GlcNAcase is important enzyme for LPS-mediated inflammatory response. PUGNAc did not affect the NF-κB O-GlcNAcylation in response to LPS. In addition, PUGNAc alter neither the binding of NF-κB subunits to the iNOS promoter nor the transcriptional activity of NF-κB, suggesting that inhibitory effect of PUGNAc on LPS-induced iNOS expression is not mediated by NF-κB inhibition. Instead, PUGNAc down-regulates increased phosphorylated AKT in response to LPS, suggesting that LPS-mediated AKT activation may be associate with OGA. In conclusion, our data demonstrate that LPS-mediated upregulation of iNOS/NO production via OGA regulation. Further studies should be ensued to define a possible mechanism of AKT on LPS-induced iNOS protein expression through OGA regulation.