• Journal of Microbiology and Biotechnology
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• v.11 no.2
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• pp.281-286
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• 2001

Since the number of amino groups which are exposed by deacetylation of acetyl-D-glucosamine influences antimicrobial activity, a chitosan oligosaccharide (COS) derivative by N-conjugation of COS with asparagine, an amino acid with two amino groups, was synthesized and the antimicrobial effect on E. coli growth was compared with other COS derivatives which were N-conjugated with glycine, alanine, aspartic acid, cysteins, an methionine, and unmodified COS. The structure of asparagine N-conjugated COS (Asn-COS) derivative was identified by using a FT-IR, $^{13}C\;FT-NMR$, and an elemental analyzer. The antimicrobial activity of Asn-COS against E. coli growth was significantly improved as compared to the other COS derivatives as well as COS itself. This means that Asn-COS with two positive charges strongly interacts with the carboxyl negative charges on the bacteria cell wall. The results for Asn-COS were as follows: 100% bactericidal activity, 0.002% MIC, and no growth of E. coli during 3 days of culture time, suggesting that Asn-COS may be useful as a new antibiotic agent.

• Journal of Microbiology and Biotechnology
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• v.16 no.12
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• pp.1984-1989
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• 2006

Deacetylated chitosan oligosaccharide (COS) had effective antiprotozoal activity against Trichomonas vaginalis (Minimal Inhibitory Concentration, MIC 0.25%), whereas 80% acetylated cas showed no antiprotozoal activity (MIC > 1 %). an the other hand, 80% acetylated cas showed growth stimulatory activity against the protozoa. When T. vaginalis was treated with 98% deacetylated COS at 0.25% concentration, the viability of the protozoa was rapidly decreased within 15 min, and the protozoa completely died within 40 min. Ultrastructural changes of trichomonads treated with COS included a loss of defined nuclear membrane and endoplasmic reticulum membranes, an increase in the number of free ribosome, vacuolation, and ultimately lysis of the cell membrane. These results indicate that deacetylated COS can be used as an antitrichomonal agent, although its lethal mechanism is not known.

• Korean journal of food and cookery science
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• v.18 no.6
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• pp.586-592
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• 2002

The purpose of this study was to investigate the quality characteristics of Jeung-Pyhn by the addition of chitosan-oligosaccharide (COS, Chitoligo-L). Jeung-Pyun is a traditional Korean fermented rice cake leavened by yeast. To develop a functional Jeung-Pyun, COS was added to the rice at the levels of 0, 2, 4 and 6% of the 2-hour-soaked rice. Physicochemical, sensory, rheological and inner structure characteristics of Jeung-Pyun were examined. The pH values of COS Jeung-Pyun batters were decreased with fermentation time. In sensory evaluation, the uniformity of the grain and overall quality of Jeung-Pyun added with 2% COS had the highest score among the samples. In He rheological properties measured with rheometer, the hardness of Jeung-Pyun with COS was higher than control. Cohesiveness of Jeung-Pyun added with 4% COS and gumminess, brittleness and springiness of Jeung-Pyun added with 2% COS were the highest among the samples. The inner structure observed by scanning electron microscope showed that Jeung-Pyun added with 2% COS had the largest and the most uniform air cells. In conclusion, Jeung-Pyun with 2% COS had positive effects on the qualify of Jeung-Pyun.

• Journal of Microbiology and Biotechnology
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• v.17 no.9
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• pp.1546-1549
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• 2007

Chitosan oligosaccharide (COS, 3 kDa

• 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.

• Journal of Microbiology and Biotechnology
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• v.17 no.12
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• pp.2042-2045
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• 2007

The effect of chitosan oligosaccharide (COS, 1 kDa${\gamma}$, 10 ng/ml IL-$1{\alpha}$, and 25 ng/ml TNF-${\alpha}$) in HT-29 cells. Inducible nitric oxide synthase (iNOS) expression induced by these cytokines was inhibited by COS. COS pretreatment inhibited the invasiveness of cytokines-treated HT-29 cells through Matrigel-coated membrane in a dose-dependent manner. COS also inhibited cytokines-induced matrix metalloproteinase (MMP)-2 activity. This study shows that proinflammatory cytokines induce NO production, iNOS expression, and invasiveness of human colorectal adenocarcinoma HT-29 cells. COS pretreatment inhibited cytokines-mediated NO production, iNOS expression, and invasiveness of HT-29 cells. These results provide sufficient information for the further development of COS as an antitumor metastatic agent for the treatment of colon cancer.

• Journal of the East Asian Society of Dietary Life
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• v.13 no.2
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• pp.122-129
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• 2003

This study was carried out in order to investigate the dextran formation and the internal structure of the chitosan-oligisaccharide(COS) Jeung-Pyun during the fermentation. To develop a functional Jeung-Pyun, COS was added to the rice at the level of 0, 2, 4, and 6% to the 2-hour-soaked rice. The pH, dextran and reducing sugar contents of COS batter, specific volume and the internal structure of COS were analyzed as a function of fermentation time. The specific volume of COS peaked at the 3 hour fermentation. The pH values of COS batters reduced with the fermentation time. The dextran content of the control batters peaked at the 7 hour fermentation. In contrast, the dextran contents of COS batters reduced up to 7th hour of fermentation, and then increased slowly until 20th hour of the fermentation process. From the air pore size and distribution of COS observed by SEM, the COS fermented fur 3 hour was judged as the best. It was concluded that COS prevented the fermation of dextran at the early stage of fermentation process.

• 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.

• Polymer(Korea)
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• v.32 no.3
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• pp.263-269
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• 2008

To develop carriers of hydrophobic anticancer agents based on chitosan, chitosan oligosaccharide lactate (COS) was chemically modified with lithocholic acid (LA) which is one of the bile acids as a hydrophobic group. The physicochemical properties of the lithocholic acid conjugated chitosan nanoparticles (COS-LA) were investigated using $^1H$-NMR spectroscopy, dynamic light scattering (DLS) and spectrofluorophotometer. COS-LA-paclitaxel (CLs-Tx) nanoparticles loading paclitaxel as an anticancer agent were prepared by a dialysis method and its loading efficiency was measured through HPLC. On the basis of DLS results, the estimated particle sizes of CLs-Tx were around 300 nm. Also, the critical micelle concentration (CMC) was proven to be dependent on the degree of substitution of lithocholic acid. It showed that the CLs-Tx has the superior potential for the application as a paclitaxel carrier.