Anti-Obesity and Anti-Adipogenic Effects of Chitosan Oligosaccharide (GO2KA1) in SD Rats and in 3T3-L1 Preadipocytes Models.

Excess body weight is a major risk factor for type 2 diabetes (T2D) and associated metabolic complications, and weight loss has been shown to improve glycemic control and decrease morbidity and mortality in T2D patients. Weight-loss strategies using dietary interventions produce a significant decrease in diabetes-related metabolic disturbance. We have previously reported that the supplementation of low molecular chitosan oligosaccharide (GO2KA1) significantly inhibited blood glucose levels in both animals and humans. However, the effect of GO2KA1 on obesity still remains unclear. The aim of the study was to evaluate the anti-obesity effect of GO2KA1 on lipid accumulation and adipogenic gene expression using 3T3-L1 adipocytes in vitro and plasma lipid profiles using a Sprague-Dawley (SD) rat model. Murine 3T3-L1 preadipocytes were stimulated to differentiate under the adipogenic stimulation in the presence and absence of varying concentrations of GO2KA1. Adipocyte differentiation was confirmed by Oil Red O staining of lipids and the expression of adipogenic gene expression. Compared to control group, the cells treated with GO2KA1 significantly decreased in intracellular lipid accumulation with concomitant decreases in the expression of key transcription factors, peroxisome proliferator-activated receptor gamma (PPARγ) and CCAAT/enhancer-binding protein alpha (CEBP/α). Consistently, the mRNA expression of downstream adipogenic target genes such as fatty acid binding protein 4 (FABP4), fatty acid synthase (FAS), were significantly lower in the GO2KA1-treated group than in the control group. In vivo, male SD rats were fed a high fat diet (HFD) for 6 weeks to induced obesity, followed by oral administration of GO2KA1 at 0.1 g/kg/body weight or vehicle control in HFD. We assessed body weight, food intake, plasma lipids, levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) for liver function, and serum level of adiponectin, a marker for obesity-mediated metabolic syndrome. Compared to control group GO2KA1 significantly suppressed body weight gain (185.8 ± 8.8 g vs. 211.6 ± 20.1 g, p < 0.05) with no significant difference in food intake. The serum total cholesterol, triglyceride, and low-density lipoprotein (LDL) levels were significantly lower in the GO2KA1-treated group than in the control group, whereas the high-density lipoprotein (HDL) level was higher in the GO2KA1 group. The GO2KA1-treated group also showed a significant reduction in ALT and AST levels compared to the control. Moreover, serum adiponectin levels were significantly 1.5-folder higher than the control group. These in vivo and in vitro findings suggest that dietary supplementation of GO2KA1 may prevent diet-induced weight gain and the anti-obesity effect is mediated in part by inhibiting adipogenesis and increasing adiponectin level.

Anti-obesity potential of enzymatic fragments of hyaluronan on high-fat diet-induced obesity in C57BL/6 mice.

Hyaluronan has diverse biological activities depending on its molecular size. The hyaluronan fragments (50 kDa) can decrease adipogenic differentiation in vitro. However, in vivo anti-obesitic effects of hyaluronan fragments have not been elucidated. Therefore, we examined the anti-obesity effects of hyaluronan fragments on high-fat diet induced obesity in C57BL/6 mice. Oral administration of hyaluronan fragments (200 mg/kg for 8 weeks) decreased body weight, adipose tissues, serum lipid (low-density lipoprotein cholesterol, triglyceride), and leptin level. Hyaluronan fragments decreased the hypertrophy of adipose tissue and ameliorated liver steatosis. The mRNA expression of leptin was reduced in adipocyte by treatment with hyaluronan fragments. Additionally, hyaluronan fragments enhanced the mRNA expression of PPAR-α and its target genes UCP-2 and decreased mRNA expression of PPAR- γ and fatty acid synthase in liver. In conclusions, hyaluronan fragments had marked effects on inhibiting the development of obesity in obese mice fed the high-fat diet. It suggested that enhancing PPAR-α and suppressing PPAR-γ expression are two possible mechanisms for the anti-obesitic effect of hyaluronan fragments.

Enzymatic fragments of hyaluronan inhibit adipocyte differentiation in 3T3-L1 pre-adipocytes.

Hyaluronan has diverse biological activities depending on its molecular size. High molecular weight hyaluronan (2000 kDa) is a major component of extracellular matrix, and has been used in wounding healing, extracellular matrix regeneration, and in the treatment of osteoarthritis. Hyaluronan fragments can stimulate inflammation or induce loss of extracellular matrix. Hyaluronan is expressed during adipocyte differentiation, and down regulation of hyaluronan synthesis can reduce adipogenic differentiation. However, the direct effects of hyaluronan fragments on adipocyte differentiation have not been elucidated. Therefore, we prepared hyaluronan fragments by enzymatic digestion, and examined the inhibitory effects of these hyaluronan fragments on the accumulation of lipid droplets and on adipogenic gene mRNA expression in differentiating 3T3-L1 pre-adipocytes. Medium sized hyaluronan fragments (50 kDa) decreased lipid droplet accumulation in a dose-dependent manner. However, high molecular weight hyaluronan did not inhibit lipid droplet accumulation when used at a concentration of 600 µg/ml. Two or 4 day treatments with medium molecular weight of hyaluronan resulted in similar inhibitory levels of lipid accumulation as did treatment for 8 days. Medium sized hyaluronan inhibited the differentiation of 3T3-L1 pre-adipocytes during the early stages of adipogenesis. When 3T3-L1 cells were treated with 180 µg/ml of medium sized hyaluronan, the mRNAs for the master adipogenic transcription factors PPAR-γ and C/EBP-α were inhibited. Additionally, medium molecular weight hyaluronan suppressed mRNA expression of PPAR-γ target genes, including aP2 and FAS. This study is the first to report that medium molecular weight hyaluronan fragments can inhibit adipocyte differentiation.

Purification and Characterization of a Fucoidanase (FNase S) from a Marine Bacterium Sphingomonas paucimobilis PF-1.

The Search for enzyme activities that efficiently degrade marine polysaccharides is becoming an increasingly important area for both structural analysis and production of lower-molecular weight oligosaccharides. In this study, an endo-acting fucoidanase that degrades Miyeokgui fucoidan (MF), a sulfated galactofucan isolated from the sporophyll (called Miyeokgui in Korean) of Undaria pinnatifida, into smaller-sized galactofuco-oligosaccharides (1000-4000 Da) was purified from a marine bacterium, Sphingomonas paucimobilis PF-1, by ammonium sulfate precipitation, diethylaminoethyl (DEAE)-Sepharose column chromatography, and chromatofocusing. The specific activity of this enzyme was approximately 112-fold higher than that of the crude enzyme, and its molecular weight was approximately 130 kDa (FNase S), as determined by native gel electrophoresis and 130 (S1), 70 (S2) and 60 (S3) kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The optimum pH and temperature of FNase S were pH 6.0-7.0 and 40-45 °C, respectively. FNase S activity was enhanced by Mn2+ and Na+ (115.7% and 131.2%), but it was inhibited by Ca2+, K+, Ba2+, Cu2+ (96%, 83.7%, 84.3%, and 89.3%, respectively), each at 1 mM. The Km, Vmax and Kcat values of FNase S on MF were 1.7 mM, 0.62 mg·min-1, and 0.38·S-1, respectively. This enzyme could be a valuable tool for the structural analysis of fucoidans and production of bioactive fuco-oligosaccharides.

Potential anti-osteoporotic activity of low-molecular weight hyaluronan by attenuation of osteoclast cell differentiation and function in vitro.

Due to some severe side effects or lack of efficacy of currently used synthetic drugs, such as bisphosphonates (BPs), the search for new therapeutic agents that can more effectively prevent and treat osteoporosis (OP) has been an increasingly important topic of research. In this study, the low-molecular weight hyaluronan (LMW-HA, 50 kDa) produced by enzymatic degradation of high-molecular weight hyaluronan (HMW-HA, 1922 kDa) from Streptococcus zooepidemicus was evaluated in vitro for its anti-osteoclastogenic potentials using RAW 264.7 murine macrophage cells. LMW-HA (25-200 µg/ml) dose-dependently inhibited the receptor activator of NF-κB ligand (RANKL)-induced tartrate-resistance acid phosphatase (TRAP) activity and the formation of multinucleated osteoclasts. Western blot analysis showed that LMW-HA reduced the RANKL-induced expression of tumor necrosis factor receptor-associated factor 6 (TRAF6), gelsolin and c-Src-proline-rich tyrosine kinase 2 suggesting that it could inhibit actin ring formation of osteoclast cells. In addition, LMW-HA inhibited the bone resorption activity of osteoclastic cells by dose-dependently attenuating the RANKL-induced expression of carbonic anhydrase II and integrin ß3. RT-PCR analysis showed that LMW-HA dose-dependently decreased the expression of osteoclast-specific genes, such as matrix metalloproteinase 9 (MMP-9) and cathepsin K, suggesting that it has potential to inhibit the differentiation of osteoclastic cells. Taken collectively, these results suggested that LMW-HA (50 kDa) has significant anti-osteoporotic activity in vitro and may be used as a potent functional ingredient in health beneficial foods or as a therapeutic agent to prevent or treat OP.

Anti-Obesity Effects of SPY Fermented with Lactobacillus rhamnosus BST-L.601 via Suppression of Adipogenesis and Lipogenesis in High-Fat Diet-Induced Obese Mice.

In this research, the potential anti-obesity efficacy of Lactobacillus rhamnosus BST-L.601 and its fermented product (named SPY) with mashed sweet potato paste were investigated using 3T3-L1 preadipocytes and high-fat diet (HD)-induced obese mice. SPY (0-0.5 mg/mL) dose-dependently and significantly reduced lipid accumulation and TG content and the expression of adipogenic markers (C/EBPα, PPAR-γ, and aP2) and fatty acid synthetic pathway proteins (ACC and FAS) in 3T3-L1 adipocytes, demonstrating that SPY suppresses adipocyte differentiation and lipogenesis. Oral administration of SPY (4 × 107 CFU/kg body weight) to HD-induced obese mice for 12 weeks significantly reduced the body and liver weight, the size of adipocytes, and the weight of epididymal, visceral, and subcutaneous fat tissues. SPY was more effective in decreasing body weight gain in HD mice than in treatment with BST-L.601 alone. Administration of SPY or BST-L.601 also reduced the serum level of total cholesterol and LDL cholesterol and leptin secretion at a similar level. These results revealed that both SPY and BST-L.601 effectively suppress HD-induced adipogenesis and lipogenesis, suggesting that these materials would be useful in the functional foods industry to ameliorate and/or prevent obesity.

Fabrication of dihydroxyflavone-conjugated hyaluronic acid nanogels for targeted antitumoral effect.

We prepared hyaluronic acid (HA)-based nanogels conjugated with dihydroxyflavone (DHF) and evaluated their cellular uptake and antitumoral efficiency. 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium chloride (DMTMM) was used as a conjugation agent for esterification between DHF and HA as well as crosslinking among HA. The conjugations were confirmed by nuclear magnetic resonance spectroscopy, UV/vis spectroscopy, and high-performance liquid chromatography. The size and Zeta-potential of the DHF/HA nanogels were reduced with an increase in the concentration of DMTMM due to the involvement of more HA molecules for the conjugation reactions. The DHF/HA nanogel with a smaller size was greatly taken up by two kinds of tumor cells (HeLa and HepG2), compared to NIH3T3. The cell viabilities were reduced to approximately 60% for HeLa and HepG2 cells after 48 h post treatment with DHF/HA nanogels.

Bioconversion of compactin into pravastatin by Streptomyces sp.

Streptomyces sp. Y-110, isolated from soil, modified compactin to pravastatin, a therapeutic agent for hypercholesterolemia. In a batch culture, the highest production of pravastatin was 340 mg l(-1) from 750 mg compactin l(-1) in 24 h. By intermittent feeding of compactin into the culture medium, both the compactin concentration and its conversion increased to 2000 mg l(-1) and 1000 mg pravastatin l(-1), respectively, with the conversion rate of 10 mg l(-1) h(-1). Continuous feeding of compactin increased production of pravastatin to 15 mg l(-1) h(-1).