• Journal of Microbiology and Biotechnology
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• v.19 no.6
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• pp.629-633
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• 2009

The present study investigated the antimetastatic property of chitosan oligosaccharides (COS) by evaluating motility, invasion, and the amount and activity of MMP-9 in MDA-MB-231 human breast carcinoma cells. Treatment of MDA-MB-231 cells with increasing concentrations of COS led to a concentration-dependent decrease in cell migration. COS significantly inhibited the invasion of MDA-MB-231 cells through a Matrigel-coated membrane. The treatment of MDA-MB-231 cells with COS reduced the amounts of secreted MMP-9. The activity and amount of MMP-9 protein in MDA-MB-231 cells were decreased by treatment with COS and occurred in a concentration-dependent manner. Our data indicated that COS can serve as a potential novel therapeutic candidate for the treatment of metastatic breast cancer.

• Journal of the Korean Society of Food Science and Nutrition
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• v.33 no.2
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• pp.236-243
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• 2004

Antimicrobial effect of chitosan and its oligosaccharides was examined on Vibrios sp., Edwardsiella tarda and Streptococcus sp., which are major pathogenic bacteria inducing bacterial diseases of acquacultured flounder. Chitosan oligosaccharides (COS ) were produced by enzymatic hydrolysis of chitosan in an ultrafiltration mombrane bioreactor system which was established with three membranes with different molecular weight cut-off (MWCO) 1,000, 5,000 and 10,000, and fractionated into three kinds of COS, based on their molecular weight sizes. The three kinds of COS were as follows : relatively high molecular weight COS [HMW-COS, molecular weight distribution of 7,000 to 24,000 Da〕, medium molecular weight COS 〔MMW-COS, 1,500 to 6,000 Da〕, and low molecular weight COS 〔LMW-COS, 1,000 to 1,500 Da). Chitosan and HMW-COS effectively inhibited the growths of Vibrio sp. and Streptococcus sp. and their antimicrobial activities were superior to the others with smaller molecular weights. This result suggested that antimicrobial effect of chitosan preparations extremely depend on their molecular weight sizes. Antimicrobial effect of chitosan and HMW-COS on E. tarda was improved by longer inoculation times. Scanning electron microscopy in morphological change of E. tarda treated with chitosan preparations showed that chitosan and HMW-COS bound to the cells and suppressed the growth of the cells. This observation appears to prove the fact that positive charged amines of chitosan electrostatically bind to negative charged compounds of cell walls.

• Journal of Microbiology and Biotechnology
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• v.12 no.3
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• pp.503-507
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• 2002

Chitosan oligosaccharides (COSs) were prepared and fractionated into three groups of COS [a high molecular weight COS (HMWCOS), medium molecular weight COS (LMWCOS), and low molecular weight COS (LMWCOS)] according to their molecular weight, using an ultrafiltration membrane enzymatic bioreactor designed earlier [8]. Antitumor activity of these COSs was then examined against Sarcoma 180 solid (S180) or Uterine cervix carcinoma No. 14 (Ul4) tumor cell-bearing mice. Among these COSs, MMWCOS with molecular weight range from 1.5 to 5.5 kDa effectively inhibited the growth of both tumor cells in the mice. In addition, the administration of MMWCOS resulted in increased thymus weight among lymphoid organs. The mice treated with MMWCOS showed improved survival rate and larger number of survivors after 40 days of feeding. The most effective of MMWCOS far antitumor activity in the S180- or U14-bearing mice was 20 mg/kg/day or more.

• Journal of the Korean Society of Food Science and Nutrition
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• v.34 no.1
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• pp.36-41
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• 2005

Effect of chitosan oligo saccharides (COS) on the level of serum lipids, antioxidant enzyme activities and lipid peroxidation was investigated in rats fed with high cholesterol diet for 4 weeks, The rats were divided into three experimental groups that is, high cholesterol diet group (0.5% cholesterol; control). high cholesterol diet and 1.0% or 2.0% COS-supplemented groups (COS I , COS II). Serum total cholesterol, LDL-cholesterol and triglyceride level were significantly decreased and relative HDL-cholesterol level in total cholesterol significantly increased in COS II group. Liver TBARS level and activities of SOD and catalase of COS I were also significantly reduced. These results suggest that supplement of chitosan oligosaccharides reduce levels of serum cholesterol and reduce oxidative damage by activating hepatic antioxidative defense system in rats fed with high cholesterol diets.

• Macromolecular Research
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• v.12 no.6
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• pp.573-580
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• 2004

To prepare chitosan-based polymeric amphiphiles that can form nanosized core-shell structures (nanopar­ticles) in aqueous milieu, chitosan oligosaccharides (COSs) were modified chemically with hydrophobic cholesterol groups. The physicochemical properties of the hydrophobized COSs (COSCs) were investigated by using dynamic light scattering and fluorescence spectroscopy. The feasibility of applying the COSCs to biomedical applications was investigated by introducing them into a gene delivery system. The COSCs formed nanosized self-aggregates in aqueous environments. Furthermore, the physicochemical properties of the COSC nanoparticles were closely related to the molecular weights of the COSs and the number of hydrophobic groups per COS chain. The critical aggregation concentration values decreased upon increasing the hydrophobicity of the COSCs. The COSCs effi­ciently condensed plasmid DNA into nanosized ion-complexes, in contrast to the effect of the unmodified COSs. An investigation of gene condensation, performed using a gel retardation assay, revealed that $COS6(M_n=6,040 Da)$ containing $5\%$ of cholesteryl chloroformate (COS6C5) formed a stable DNA complex at a COS6C5/DNA weight ratio of 2. In contrast, COS6, the unmodified COS, failed to form a stable COS/DNA complex even at an elevated weight ratio of 8. Furthermore, the COS6C5/DNA complex enhanced the in vitro transfection efficiency on Human embryonic kidney 293 cells by over 100 and 3 times those of COS6 and poly(L-lysine), respectively. Therefore, hydrophobized chitosan oligosaccharide can be considered as an efficient gene carrier for gene delivery systems.

• Polymer(Korea)
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• v.31 no.6
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• pp.555-561
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• 2007

To obtain low molecular weight water soluble chitosan (LMWSC) with various molecular weights, chitosan oligosaccharides (COS) with lactic acid was separated by using ultrafilteration technique and LMWSC with a free amine group was prepared by the novel salts-removal method. The characterization of LMWSC removed the lactic acid and degree of deacetylation (DDA) were identified by FT-IR and $^1H-NMR$ spectra. Polydispersity index (PDI) was $1.278{\sim}1.499$, which indicates a relatively molecular weight distribution. To identify the potential as a gene carrier, we confirmed the transfection efficiency of COS fractioned according to molecular weight successfully and the salt-removed LMWSC using 293T cell. Also, LMWSC derivatives prepared for improvement transfection efficiency were evaluated using Balb/C mice.

• Asian-Australasian Journal of Animal Sciences
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• v.20 no.4
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• pp.556-562
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• 2007

A total of 126 crossbred weanling pigs (average body weight of $6.3{\pm}0.3$ kg) were used to investigate the effect of chito-oligosaccharide (COS) on growth performance, nutrient digestibility, pH of gastro-intestinal tract (GI), intestinal and fecal microflora of young piglets. Pigs were allocated to three dietary treatments based on body weight and gender in a single factorial arrangement. Treatments were control (No COS), T1 (0.2% COS during starter (6-13 kg) and 0.1% COS during grower (13-30 kg) phases, and T2 (0.4% COS during starter (6-13 kg) and 0.3% COS during grower (13-30 kg) phases, respectively. Each treatment had 3 replicates and 14 pigs were raised in each pen. COS is a low molecular weight water-soluble chitosan that can be obtained from chitin of the crab shell after deacetylation with concentrated sodium hydroxide at high temperature and then further decomposition by chitosanase enzyme in the presence of ascorbic acid. For the starter and grower periods, there were no significant differences (p>0.05) in average daily gain (ADG) and feed to gain ratio among treatments. However, during the overall period (6-30 kg), T2 showed better (p<0.05) feed to gain ratio than other treatments. A digestibility study was conducted at the end of grower phase which showed improvement (p<0.05) in DM and crude fat digestibility in T2 over the control. At 25 kg body weight, 6 pigs per treatment (2 per replicate) were sacrificed to determine the effect of diets on pH and microbial count at different sections of the GI tract. The pH of the cecal contents in pigs fed 0.1% COS was higher (p<0.05) than in the other treatments. Total anaerobic bacterial number increased from cecum to rectum in all treatments. The weekly total bacterial counts showed higher (p<0.05) in feces of pigs fed COS than that of untreated pigs at the $8^{th}$ week. The number of fecal E. coli in untreated pigs at $4^{th}$ wk was 7.35 log CFU/g compared to 6.71 and 6.54 log CFU/g in 0.1 and 0.3% COS-treated pigs, respectively. Similarly, at $8^{th}$ wk, fecal clostridium spp. were lower in pigs fed 0.3% COS (5.43 log CFU/g) than in untreated pigs (6.26 log CFU/g). In conclusion, these results indicated that chito-oligosaccharide could improve feed efficiency in young pigs and inhibited the growth of harmful bacteria.

• Asian-Australasian Journal of Animal Sciences
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• v.21 no.5
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• pp.723-731
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• 2008

Immunomodulatory feed additives might offer alternatives to antimicrobial growth promoters in pig production. This experiment was designed to determine the effects of dietary galacto-mannan-oligosaccharide (GMOS) and chitosan oligosaccharide (COS) supplementation on the immune response in early-weaned piglets. Forty 15-day-old piglets (Duroc$\times$Landrace$\times$Yorkshire) with an average live body weight of $5.6{\pm}0.51kg$ were weaned and randomly assigned to 4 treatment groups that were fed maize-soybean meal diets containing either basal, 110 mg/kg of lincomycin, 250 mg/kg of COS or 0.2% GMOS, respectively, over a 2-week period. Another six piglets of the same age were sacrificed on the same day at the beginning of the study for sampling, in order to obtain baseline values. Interleukin (IL)-1${\beta}$gene expression in peripheral blood monocytes, jejunal mucosa and lymph nodes, as well as serum levels of IL-1${\beta}$ IL-2 and IL-6, IgA, IgG, and IgM, were evaluated for 5 pigs from each group at 15 and 28 days of age. The results indicate that weaning stress resulted in decreases in serum antibody and cytokine levels. Dietary supplementation with GMOS or COS enhanced (p<0.05) IL-1${\beta}$gene expression in jejunal mucosa and lymph nodes, as well as serum levels of IL-1${\beta}$ IL-2, IL-6, IgA, IgG and IgM compared to supplementation with lincomycin. These findings suggest that GMOS or COS may enhance the cell-mediated immune response in early-weaned piglets by modulating the production of cytokines and antibodies, which shows that GMOS or COS have different effects than the antibiotic on animal growth and health.

• KSBB Journal
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• v.13 no.2
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• pp.147-154
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• 1998

Enzymatic hydrolysis using an immobilized enzyme was carried out to produce chitosan oligosaccharides (COSs) from chitosan effectively. Chitosanase was immobilized on eight different carriers by physical adsorption. The enzyme immobilized on chitin had higher activity than those immobilized on the other carriers in spite of its lower adsorption. The activity of chitin-immobilized enzyme was more than 90% of the original activity. Optimal temperature of the immobilized enzyme increased by about $15^{\circ}C$ and its thermostability was excellent in relatively wide range of temperature. But its effects of pH did not improve compared to the free enzyme. The immobilized enzyme produced 153 mg/g chitosan of the reducing sugar for 3hrs of hydrolytic incubation time. The total content of higher oligomers, tetramer to hexamer, among amount of total COSs obtained for 2hrs was more than 90%. In kinetic parameters for both enzymes, immobilized enzyme showed lower affinity for substrate and reaction rate than free enzyme, however, no reduction of the rate for high substrate concentrations. Consequently, chitin-immobilized could effectively hydrolyse chitosan and produce the higher COSs without activity decrease in comparison with the free enzyme.