Kui-Jin Kim

Fucoidan, a sulfated polysaccharide, inhibits adipogenesis through the mitogen-activated protein kinase pathway in 3T3-L1 preadipocytes

AIMS Fucoidan, consisting of L-fucose together with xylose, galactose and mannose, is a sulfated polysaccharide from brown seaweeds, which has been reported to affect the development of adipocytes. However, the role of fucoidan in adipogenesis remains elusive. In the present study, we have investigated the inhibitory effects of fucoidan on adipocyte differentiation via mitogen-activated protein kinase (MAPK) signaling pathway in 3T3-L1 preadipocytes. MAIN METHODS Differentiation of 3T3-L1 preadipocytes was induced in the presence or absence of fucoidan. The effects of fucoidan on adipogenic gene expression and MAPK activation were investigated. KEY FINDINGS Fucoidan treatment inhibits adipocyte differentiation, evidenced by decreased lipid accumulation and down regulation of adipocyte markers. Fucoidan then inhibited the expression of both early CCAAT-enhancer-binding proteins alpha (C/EBPalpha) and peroxisome proliferator-activated receptors gamma (PPARgamma) and late activating protein 2 (aP2) adipogenic transcription factors, which is a crucial role for adipocyte development. Moreover, our results revealed that fucoidan inhibited the early activation of p38 MAPKs, extracellular signal-regulated kinases (ERK) and Jun N-terminal kinase (JNK). SIGNIFICANCE Overall, these findings are a strong indication that fucoidan might inhibit adipogenesis in 3T3-L1 preadipocytes, due to inhibition of the MAPK signaling pathway that involves adipogenic transcription factors.

A 4-week repeated oral dose toxicity study of fucoidan from the Sporophyll of Undaria pinnatifida in Sprague-Dawley rats.

Fucoidan is extracted from brown seaweeds, which can have anti-coagulant, antithrombotic, antitumor, and antiviral activities. However, detailed studies on the toxicology of fucoidan have not been performed. Here we tested the toxicity of fucoidan in Sprague-Dawley rats. Fucoidan (1350mg/kg bw/day for 4 weeks) did not induce statistically significant differences in groups matched by gender with respect to body weight, ophthalmoscopy, urinalysis, hematology, and histopathology. Fucoidan did not change prothrombin time or activated partial thromboplastin time, indicating an inability to change blood clotting. This study demonstrated that fucoidan is not toxic under this administration paradigm.

Ginsenoside Rg1 promotes glucose uptake through activated AMPK pathway in insulin-resistant muscle cells.

Ginsenoside Rg1, a protopanaxatriols saponin, is one of the major active constituents from Panax ginseng and possesses various biological activities. A recent study reported that insulin resistance in skeletal muscle is a major contributor to the development of type 2 diabetes mellitus (T2DM). We examined the effects of ginsenoside Rg1 on glucose uptake and the associated molecular mechanisms of the glucose transport system in insulin‐resistant muscle cells. The insulin resistance of the muscle cell was induced by treatment of differentiated C2C12 cells with chronic insulin. The results showed that chronic treatment of insulin resulted in reduced glucose uptake in the muscle cells. The treatment of ginsenoside Rg1 significantly enhanced glucose uptake in the differentiated muscle cells and the relative abundance of GLUT4 through the adenosine‐monophosphate‐activated protein kinase pathway. These results suggest that ginsenoside Rg1 improved the insulin resistance in C2C12 muscle cells, which might be useful for prevention of T2DM and metabolic syndromes. Copyright

Genotoxicity studies on fucoidan from Sporophyll of Undaria pinnatifida.

The sulfated seaweed extract, fucoidan, has anticoagulant, antithrombotic, and antiviral activities. Despite extensive work on the biological activities of fucoidan, detailed studies on the genotoxicity of fucoidan from Sporophyll of Undaria pinnatifida sources have not been tested before. The objective of this study was to investigate the genotoxicity effects of fucoidan extracted from Sporophyll of U. pinnatifida using a test battery of three different methods. In a reverse mutation assay using four Salmonella typhimurium strains and Escherichia coli, fucoidan did not increase the number of revertant colonies in any tester strain regardless of metabolic activation by S9 mix, and did not cause chromosomal aberration in short tests with S9 mix or in the continuous (24 h) test. A bone marrow micronucleus test in ICR mice dosed by oral gavage at doses up to 2000 mg/kg bw/day showed no significant or dose-dependent increases in the frequency of micronucleated polychromatic erythrocytes (MNPCE), and the high dose suppressed the ratio of polychromatic erythrocytes (PCE) to total erythrocytes. We conclude that fucoidan presents no significant genotoxic concern under the anticipated conditions of use.

Oleuropein Suppresses LPS-Induced Inflammatory Responses in RAW 264.7 Cell and Zebrafish

Oleuropein is one of the primary phenolic compounds present in olive leaf. In this study, the anti-inflammatory effect of oleuropein was investigated using lipopolysaccharide (LPS)-stimulated RAW 264.7 and a zebrafish model. The inhibitory effect of oleuropein on LPS-induced NO production in macrophages was supported by the suppression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2). In addition, our enzyme immunoassay showed that oleuropein suppressed the release of pro-inflammatory cytokines such as interleukin-1β (IL-1β) and interleukin-6 (IL-6). Oleuropein inhibited the translocation of p65 by suppressing phosphorylation of inhibitory kappa B-α (IκB-α). Oleuropein also decreased activation of ERK1/2 and JNK, which are associated with LPS-induced inflammation, and its downstream gene of AP-1. Furthermore, oleuropein inhibited LPS-stimulated NO generation in a zebrafish model. Taken together, our results demonstrated that oleuropein could reduce inflammatory responses by inhibiting TLR and MAPK signaling, and may be used as an anti-inflammatory agent.

Fucoidan regulate blood glucose homeostasis in C57BL/KSJ m+/+db and C57BL/KSJ db/db mice.

Type 2 diabetes mellitus is a multisystem disease that is characterized by hyperglycemia and is associated with the dysfunction and failure of various organs. The control of postprandial hyperglycemia is important in the prevention and intervention of type 2 diabetes. Fucoidan has several biological activities in vitro and in vivo. However, the effect of fucoidan on hyperglycemia in non-diabetic and diabetic mice has not been investigated. This study was undertaken to study the effects of different molecular weight forms (5 kilodalton (k), 5-30 k and crude) of fucoidan on oral glucose tolerance tests in non-diabetic mice and on food intake, weight gain, fasting blood glucose and blood biochemistry of db/db mice. Treatment with 200 mg/mL 5 k, 5-30 k and crude fucoidan substantially prevented hyperglycemia according to oral glucose tolerance tests in non-diabetic mice. In addition, fucoidan fractions significantly reduced blood glucose levels in diabetic mice.

SEAWEED EXTRACTS AS A POTENTIAL TOOL FOR THE ATTENUATION OF OXIDATIVE DAMAGE IN OBESITY-RELATED PATHOLOGIES(1).

Recent studies suggest that seaweed extracts are a significant source of bioactive compounds comparable to the dietary phytochemicals such as onion and tea extracts. The exploration of natural antioxidants that attenuate oxidative damage is important for developing strategies to treat obesity‐related pathologies. The objective of this study was to screen the effects of seaweed extracts of 49 species on adipocyte differentiation and reactive oxygen species (ROS) production during the adipogenesis in 3T3‐L1 adipocytes, and to investigate their total phenol contents and 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) radical scavenging activities. Our results show that high total phenol contents were observed in the extracts of Ecklonia cava (see Table 1 for taxonomic authors) (681.1 ± 16.0 μg gallic acid equivalents [GAE] · g−1), Dictyopteris undulata (641.3 ± 70.7 μg GAE · g−1), and Laurencia intermedia (560.9 ± 48.1 μg GAE · g−1). In addition, DPPH radical scavenging activities were markedly higher in Sargassum macrocarpum (60.2%), Polysiphonia morrowii (55.0%), and Ishige okamurae (52.9%) than those of other seaweed extracts (P < 0.05). Moreover, treatment with several seaweed extracts including D. undulata, Sargassum micracanthum, Chondrus ocellatus, Gelidium amansii, Gracilaria verrucosa, and Grateloupia lanceolata significantly inhibited adipocyte differentiation and ROS production during differentiation of 3T3‐L1 preadipocytes. Furthermore, the production of ROS was positively correlated with lipid accumulation (R2 = 0.8149). According to these preliminary results, some of the seaweed extracts can inhibit ROS generation, which may protect against oxidative stress that is linked to obesity. Further studies are required to determine the molecular mechanism between the verified seaweeds and ROS, and the resulting effects on obesity.

Caffeine prevents LPS-induced inflammatory responses in RAW264.7 cells and zebrafish.

Caffeine is a white crystalline xanthine alkaloid found in the seeds of coffee plants and leaves of the tea bush. In this study, we evaluated whether caffeine exerts anti-inflammatory effects on lipopolysaccharide (LPS)-induced inflammation both in vitro and in vivo. RAW264.7 cells were treated with various concentrations of caffeine in the presence or absence of LPS. Caffeine decreased the LPS-induced inflammatory mediator, nitric oxide (NO). Caffeine treatment also reduced the expression of pro-inflammatory genes, including inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), interleukin (IL)-3, IL-6 and IL-12, and decreased both IL-6 secretion and phosphorylated p38MAPK expression in LPS-treated RAW264.7 cells. Caffeine inhibited nuclear translocation of nuclear factor κB (NF-κB) via IκBα phosphorylation. In addition, caffeine inhibited LPS-induced NO production in zebrafish. These results suggest that caffeine may suppress LPS-induced inflammatory responses in RAW264.7 cells by regulating NF-κB activation and MAPK phosphorylation.

Effect of Pycnogenol ® on Glucose Transport in Mature 3T3-L1 Adipocytes

Pycnogenol®, a procyanidins‐enriched extract of Pinus maritima bark, possesses antidiabetic properties, which improves the altered parameters of glucose metabolism that are associated with type 2 diabetes mellitus (T2DM). Since the insulin‐stimulated antidiabetic activities of natural bioactive compounds are mediated by GLUT4 via the phosphatidylinositol‐3‐kinase (PI3K) and/or p38 mitogen activated protein kinase (p38‐MAPK) pathway, the effects of pycnogenol® were examined on the molecular mechanism of glucose uptake by the glucose transport system. 3T3‐L1 adipocytes were treated with various concentrations of pycnogenol®, and glucose uptake was examined using a non‐radioisotope enzymatic assay and by molecular events associated with the glucose transport system using semi‐quantitative reverse transcription‐polymerase chain reaction (RT‐PCR). The results show that pycnogenol® increased glucose uptake in fully differentiated 3T3‐L1 adipocytes and increased the relative abundance of both GLUT4 and Akt mRNAs through the PI3K pathway in a dose dependent manner. Furthermore, pycnogenol® restored the PI3K antagonist‐induced inhibition of glucose uptake in the presence of wartmannin, an inhibitor of the PI3K. Overall, these results indicate that pycnogenol® may stimulate glucose uptake via the PI3K dependent tyrosine kinase pathways involving Akt. Further the results suggest that pycnogenol® might be useful in maintaining blood glucose control. Copyright

Codonopsis lanceolata Extract Prevents Diet-Induced Obesity in C57BL/6 Mice

Codonopsis lanceolata extract (CLE) has been used in traditional medicine in the Asian-Pacific region for the treatment of bronchitis, cough, and inflammation. However, it is still unclear whether obesity in mice can be altered by diet supplementation with CLE. To investigate whether CLE could have preventative effects on high fat diet (HFD)-induced obesity, male C57BL/6 mice were placed on either a normal chow diet, 60% HFD, or a HFD supplemented with CLE (60, 180, and 360 mg/kg/day) for 12 weeks. CLE decreased body weight and subcutaneous and visceral fat weights in HFD-induced obese mice. CLE group mice showed lower fat accumulation and a smaller adipocyte area in the adipose tissue compared with the HFD group mice. CLE group mice exhibited lower serum levels of triglycerides, total cholesterol, low density lipoprotein (LDL), glucose, and insulin compared with the HFD group mice. In addition, CLE decreased liver weight and lowered the increase in aspartate aminotransferase (AST) and alanine transaminase (ALT) levels in HFD-induced obese mice. These results indicate that CLE can inhibit the development of diet-induced obesity and hyperlipidemia in C57BL/6 mice.