Inhibition of Cholesterol Synthesis in HepG2 Cells by GINST-Decreasing HMG-CoA Reductase Expression Via AMP-Activated Protein Kinase.

GINST, a hydrolyzed ginseng extract, has been reported to have antidiabetic effects and to reduce hyperglycemia and hyperlipidemia. Hypercholesterolemia is caused by diet or genetic factors and can lead to atherosclerosis and coronary heart disease. Thus, the purpose of this study is to determine whether GINST and the ginsenoside metabolite, IH-901 (compound K), reduce cholesterol synthesis in HepG2 cells and the signal transduction pathways involved. Concentrations of cholesterol were measured by using an enzymatic method. Expression levels of sterol regulatory element-binding protein 2 (SREBP2), HMG-CoA reductase (HMGCR), peroxisome proliferators-activated receptor γ (PPARγ), CCAAT/enhancer-binding proteins α (C/EBPα), GAPDH, and phosphorylation of AMP-activated protein kinase α (AMPKα), protein kinase B (PKB, also known as Akt), and mechanistic target of rapamycin complex 1 (mTORC1) were measured using western blot. Total cholesterol concentration decreased after GINST treatment for 24 and 48 h. Expression of HMGCR decreased more with GINST than with the inhibitors, U18666A and atorvastatin, after 48 h in a dose-dependent manner. Phosphorylation of AMPKα increased 2.5x by GINST after 360 min of treatment, and phosphorylation of Akt decreased after 120 and 360 min. We separated compound K from GINST extracts flash chromatography. Compound K decreased cholesterol synthesis in HepG2 cells at 24 and 48 h. Therefore, we conclude that GINST inhibits cholesterol synthesis in HepG2 cells by decreasing HMGCR expression via AMPKα activation. PRACTICAL APPLICATION: GINST, a hydrolyzed ginseng extract, can inhibit cholesterol synthesis in liver cells via activation of AMPKα. IH-901 (compound K), which is the main component with bioactivity in GINST, also has anticholesterol effects. Thus, we suggest that GINST can be used to reduce hypercholesterolemia.

Antimelanogenesis Activity of Hydrolyzed Ginseng Extract (GINST) via Inhibition of JNK Mitogen-activated Protein Kinase in B16F10 Cells.

GINST is a hydrolyzed ginseng extract produced by an in vitro process that imitates the metabolic function of bacteria in the human digestive track and has approved by the Ministry of Food and Drug Safety of Korea for the management of postprandial hyperglycemia. Additionally, GINST has been reported to have other physiological functions including anti-aging and antioxidant effects. The objectives of this study are to compare the antimelanogenic effects of fresh ginseng extract (FGE) and GINST extract and to elucidate the functional mechanism. The concentration of total ginsenosides in FGE and GINST was measured using ultraperformance liquid chromatography with a C18 column. B16F10 cells were treated with FGE and GINST for 72 h to assess melanin content, tyrosinase activity, and protein levels of microphthalmia-associated transcription factor (MITF) and tyrosinase-related protein-1 (TRP-1). The activity of kinases involved in mitogen-activated protein kinase (MAPK) signaling, such as extracellular signal-regulated kinases (ERK), c-Jun N-terminal kinases (JNK), and p38 mitogen-activated protein kinases (p38), were measured using western blots. While neither FGE nor GINST inhibited the activity of mushroom tyrosinase directly, GINST decreased melanogenesis and tyrosinase activity markedly. Furthermore, our results indicate that GINST downregulated the levels of MITF and TRP-1 possibly by suppressing JNK signaling. We concluded that, when compared to FGE, GINST has a superior antimelanogenic effect mediated by the downregulation of MITF, TRP-1, and intracellular tyrosinase activity via the JNK signaling pathway. Thus, we suggest that GINST has the potential to be used as a novel skin whitening agent.

Dependency of Experimental Autoimmune Encephalomyelitis Induction on MOG35-55 Properties Modulating Matrix Metalloproteinase-9 and Interleukin-6.

Experimental autoimmune encephalomyelitis (EAE) is commonly induced with myelin oligodendrocyte glycoprotein (MOG)35-55; occasionally, EAE is not well induced despite MOG35-55 immunization. To confirm that EAE induction varies with difference in MOG35-55 properties, we compared three MOG35-55 from different commercial sources, which are MOG-A, MOG-B, and MOG-C. The peptides induced EAE disease with 100, 40, and 20 % incidence, respectively. Compared with others, MOG-A showed higher peptide purity (99.2 %) and content (92.2 %) and presented a sheet shape with additional sodium and chloride chemical elements. In MOG-A-treated group, MMP-9 activity and IL-6 levels were considerably higher than the other groups in CNS tissues, and significantly increased VCAM-1, IFN-γ, and decreased IL-4 were also shown compared to MOG-B- and/or MOG-C-treated group. In conclusion, the immunological and toxicological changes by the difference in MOG35-55 properties modulate EAE induction, and MOG35-55 which affects MMP-9 activity and IL-6 levels may be the most effective EAE-inducing antigen. This study can be potentially applied by researchers using MOG35-55 peptide and manufacturers for MOG35-55 synthesis.

Experimental autoimmune encephalomyelitis and age-related correlations of NADPH oxidase, MMP-9, and cell adhesion molecules: The increased disease severity and blood-brain barrier permeability in middle-aged mice.

The aim of the present study was to investigate effect of two different ages (6 weeks [6 W] vs. 6 months [6 M]) on blood-brain barrier (BBB) disruption in EAE and evaluate the expression and correlations of NADPH oxidase, MMP-9, ICAM-1, and VCAM-1 following increased age and EAE induction. Higher disease severity was observed in 6 M-EAE than 6 W-EAE. The four factors were significantly elevated and correlated in 6 M-EAE. BBB permeability increased with statistically significant interaction between age and EAE effects. We suggest strong correlations between NADPH oxidase and the other factors play important roles in increased BBB disruption and EAE susceptibility in middle-aged mice.