Biomedical subjects

Se-Kwon Kim

Publications and source records attributed to Se-Kwon Kim.

At least 19 recordsLinked to original sources

PubMed2006

Inhibitory effect of chitooligosaccharides on matrix metalloproteinase-9 in human fibrosarcoma cells (HT1080).

Matrix metalloproteinase-9 (MMP-9) has gelatinase activity and plays an important role in cancer invasion and metastasis. Therefore, inhibition of specific types of MMPs including MMP-9 has become an attractive target for therapeutic intervention. The aim of this study was to investigate the effect of chitooligosaccharides (COS) on activity and expression of MMP-9 in HT1080 cells. The inhibitory effect of COS with different molecular masses was examined by gelatin zymography, reverse transcriptase-polymerase chain reaction (RT-PCR), gene reporter assay, and Western blot analysis. MMP-9 inhibition in the presence of COS was clearly observed in gelatin zymography. Specifically, 1- to 3-kDa COS (COS-I) exhibited the highest inhibitory effect on MMP-9 activity in HT1080 cells among tested molecular mass fractions. It was also found that COS-I was capable of inhibiting both gene and protein expression of MMP-9 (P<0.01). These results suggest that low molecular mass COS can be considered as a potent inhibitor of MMP-9.

Cell Line, Tumor↗

PubMed2006

Inhibition of free radical-mediated oxidation of cellular biomolecules by carboxylated chitooligosaccharides.

The objective of this study was to identify the cellular antioxidant effects of carboxylated chitooligosaccharides (CCOS), a chemically modified derivative of chitooligosaccharides (COS), by assessing oxidation inhibition potential on cellular biomolecules such as lipids, proteins, and direct scavenging of reactive oxygen species (ROS). Radical-mediated oxidation of cell membrane lipids and proteins was dose-dependently inhibited by CCOS, assessed by amount of lipid hydroperoxides and carbonyl carbon content in mouse macrophages, RAW264.7 cells. Further, CCOS inhibited myeloperoxidase (MPO) activity in human myeloid cells (HL60) suggesting indirect possibility of inhibiting generation of reactive oxygen species (ROS) such as superoxide radicals, H(2)O(2) and HOCl. Direct radical scavenging studies carried out with DCFH-DA fluorescence probe concluded that CCOS can act as a potent radical scavenger in cells.

Animals↗

PubMed2006

Antihypertensive activity of chitin derivatives.

To develop angiotensin I converting enzyme (ACE) inhibitory chitin derivatives based on the properties of ACE inhibitors, chitins with different degree of deacetylation were chemically modified by grafting 2-chloroethylamino hydrochloride onto chitin at the C-6 position. Three kinds of chitin derivatives were prepared and designated as aminoethyl-chitin (AEC) with 10% degree of deacetylation, aminoethyl-chitin with 50% degree of deacetylation (AEC50), and aminoethyl-chitin with 90% degree of deacetylation (AEC90). IC50 values of three chitin derivatives on ACE were 0.064 microM (AEC), 0.038 microM (AEC50), and 0.103 microM (AEC90). The results of Dixon plots revealed that AEC50 was a competitive inhibitor, and the inhibition constant (Ki) value was 0.021 microM. In addition, the antihypertensive effect of AEC50 on spontaneously hypertensive rats (SHR) was evaluated, and the result showed that it effectively decreased systolic blood pressure (SBP) in a dose-dependent manner.

Acetylation↗

PubMed2006

Anticoagulant activity of marine green and brown algae collected from Jeju Island in Korea.

Twenty-two algal species were evaluated for their potential anticoagulant activities. Hot water extracts from selected species, Codium fragile and Sargassum horneri showed high activated partial thromboplastin time (APTT). Ultraflo extract of C. fragile and S. horneri exhibited the most potent anticoagulant activity. Furthermore, in both algal species, active compounds were mainly concentrated in >30kDa faction. The crude polysaccharide fraction (>30kDa; CpoF) of C. fragile composed of approximately 80% carbohydrate and approximately 19% of protein; the crude polysaccharide fraction (>30kDa; CpoF) of S. horneri was composed of 97% of carbohydrate and approximately 2% of protein. Therefore, most probably the active compound, or compounds of the algal species were related to high molecular weight polysaccharide, or a complex form with carbohydrate and protein (proteoglycan).

Anticoagulants↗

PubMed2006

Chitosan derivatives killed bacteria by disrupting the outer and inner membrane.

Six kinds of water-soluble chitosan were prepared by grafting aminofunctionality onto chitosan at the C-6 position, and their antimicrobial activities were investigated against three Gram-negative and three Gram-positive bacteria. Among the derivatives, dimethylaminoethyl-chitosan (DMAEC) has the highest potential to suppress the growth of bacteria. To elucidate detailed antimicrobial modes of action against bacteria, cell integrity, outer membrane (OM), and inner membrane (IM) permeabilization assays were investigated. When treated with DMAEC, the release of 260 nm absorbing materials quickly increased for both Escherichia coli and Staphylococcus aureus, but the absorbance value was different due to the difference in cell structures. In OM and IM permeabilization assays, DMAEC rapidly increased 1-N-phenylnaphthylamine uptake and the release of cytoplasmic beta-galactosidase via an increase in the permeability of OM and IM. Moreover, DMAEC90 prepared from 90% deacetylated chitosan had more activity than DMAEC50 prepared from 50% deacetylated chitosan, and these results revealed that the antimicrobial action of water-soluble chitosans was dependent on the degree of deacetylation and the substituted group.

Anti-Bacterial Agents↗

PubMed2006

Carboxylated chitooligosaccharides (CCOS) inhibit MMP-9 expression in human fibrosarcoma cells via down-regulation of AP-1.

Matrix metalloproteinases (MMPs) play a fundamental role in invasion and metastasis of tumor and, recent advances in medicinal chemistry have approached designing of MMP inhibitors with desired structural properties, selectivity and bioavailability. In the present study, novel low-molecular-weight carboxylated chitooligosaccharides (CCOS) were evaluated for their MMP-9 inhibitory effect on human fibrosarcoma cell line (HT1080). In zymography experiments, a clear dose-dependent inhibition on MMP-9 mediated gelatinolytic activities were observed in HT1080 cells following treatment with CCOS. Further, transfection studies carried out with MMP-9 and AP-1 reporter constructs suggested that the observed reduction in MMP-9 expression was due to down-regulation of MMP-9 transcription that mediated via inhibition of AP-1. Moreover, expression of c-Fos protein levels in cytoplasm and nucleus confirmed that CCOS could inhibit AP-1 expression but not its translocation. However, in the presence of CCOS, NF-kappaB and TIMP-1 expression levels remained constant. More importantly, inhibition of MMP-9 expression clearly led to inhibit tumor invasiveness that was studied with reconstituted basement membrane matrix proteins coated synthetic membranes. Taken together, this study discusses MMP-9 inhibition potential of CCOS and their involvement to demote degradation and cellular invasion of extracellular matrix (ECM) and basement membrane. Thus, control of MMP-9 expression by CCOS has considerable significance for the regulation of tumor progression.

Blotting, Western↗

PubMed2006

Isolation and characterization of visceral excitatory neuropeptides from striped mullet (Mugil cephalus L.) brain.

From a brain extract of the catadromous fish, striped mullet (Mugil cephalus), two visceral excitatory neuropeptides (Mvp-1 and Mvp-2) were isolated by means of reversed phase chromatography together with bioassay on fish hindgut. The primary structure of Mvp-1 was elucidated to be SGPAGVLamide by ESI-Q-TOF mass spectrometry. The threshold concentration of Mvp-1 that changes spontaneous contraction of mullet hindgut was between 10(-9) and 10(-8) M. In addition, Mvp-1 was found to exert excitatory activities on some other smooth muscle segments (oviduct and esophagus) of mullet but it did not show any effect on body wall muscle strips. Therefore, the present study suggests that Mvp-1 and Mvp-2 peptides act as factors that control visceral contractions of mullet gastrointestinal tract.

Amino Acid Sequence↗

PubMed2006

Reactive oxygen species scavenging activity of aminoderivatized chitosan with different degree of deacetylation.

Chitosans with different degree of deacetylation were prepared from crab shell chitin in the presence of alkali. Aminoderivatized chitosan derivatives were prepared in addition of amino functional groups at a hydroxyl site in the chitosan backbone. Six kinds of aminoderivatized chitosan such as aminoethyl-chitosan (AEC90), dimethylaminoethyl-chitosan (DMAEC90), and diethylaminoethyl-chitosan (DEAEC90), which were prepared from 90% deacetylated chitosan, and AEC50, DMAEC50 and DEAEC50, which were prepared from 50% deacetylated chitosan, were prepared and their reactive oxygen species (ROS) scavenging activities were investigated against hydroxyl radical, superoxide anion radical and hydrogen peroxide. The electron spin resonance (ESR) spectrum revealed that AEC90 showed the highest scavenging effects against hydroxyl and superoxide anion radical, the effects were 91.67% and 65.34% at 0.25 and 5 mg/mL, respectively. For hydrogen peroxide scavenging effect, DEAEC90 exhibited the strongest activity. These results suggest that the scavenging effect depends on their degree of deacetylation and substituted group.

Acetylation↗

PubMed2006

Phlorotannins in Ecklonia cava extract inhibit matrix metalloproteinase activity.

Matrix metalloproteinase (MMP) inhibitors have been identified as potential therapeutic candidates for metastasis, arthritis, chronic inflammation and wrinkle formation. For the first time here we report a detailed study on the inhibitory effects of phlorotannins in brown algae, Ecklonia cava (EC) on MMP activities in cultured human cell lines. A novel gelatin digestion assay could visualize complete inhibition of bacterial collagenase-1 activity at 20 microg/ml of EC extract during preliminary screening studies. Sensitive fluorometric assay revealed that EC extract can specifically inhibit both MMP-2 and MMP-9 activities significantly (P < 0.001) at 10 microg/ml. In addition, artificially induced activities of MMP-2 and MMP-9 in human dermal fibroblasts and HT1080 cells were inhibited by EC extract in a more or less similar manner to the positive control doxycycline. Even though the expression levels of MMPs differ from one cell type to the other, gelatin zymography clearly revealed that both MMP expression and activity in cells can be inhibited by EC extract. More interestingly, EC extract did not exert any cytotoxic effect even at 100 microg/ml anticipating its potential use as a safe MMP inhibitor.

Biological Assay↗

PubMed2006

Chitooligosaccharides inhibit activation and expression of matrix metalloproteinase-2 in human dermal fibroblasts.

Recently, much attention has been given to chitosan and its hydrolyzed products due to their diverse biological activities. For the first time here we report the inhibitory effect of chitooligosaccharides (COS) on activation and expression of matrix metalloproteinase-2 (MMP-2) in primary human dermal fibroblasts (HDFs). COS with 3-5 kDa exhibited the highest inhibitory effect on MMP-2 activity in HDFs assessed by gelatin zymography. Interestingly, protein expression of MMP-2 was also inhibited by COS with same molecular weight. This inhibition was caused by the decrease of the gene expression and transcriptional activity of MMP-2. Furthermore, it was found that COS repressed the gene expression of c-fos, a part of AP-1 transcription factor. These results suggest that COS may play an important role in the prevention and treatment of MMP-2 mediated several health problems such as metastasis and wrinkle formation.

Cell Line↗

PubMed2006

Carboxy derivatized glucosamine is a potent inhibitor of matrix metalloproteinase-9 in HT1080 cells.

Experimental evidences have confirmed that matrix metalloproteinases (MMPs) play a fundamental role in a wide variety of pathologic conditions and recent advances in medicinal chemistry approach to the design of MMP inhibitors with desired structural and functional properties. Among MMPs, MMP-9 has demonstrated to play a major role in the establishment of metastases and it is substantially increased in the majority of malignant tumors. Inhibition of MMP-9 is thought to have a therapeutic benefit to cancer. Results of this study present a novel synthetic MMP-9 inhibitor that downregulates MMP-9 expression level in HT1080, human fibrosarcoma cells.

Cell Line, Tumor↗

PubMed2006

Purification and characterization of antioxidant peptide from hoki (Johnius belengerii) frame protein by gastrointestinal digestion.

To extract antioxidant peptide from hoki frame protein hydrolysate (APHPH), we employed six proteases (pepsin, trypsin, papain, alpha-chymotrypsin, Alcalase and Neutrase) for enzymatic hydrolysis, and the antioxidant activities of their hydrolysates were investigated using both lipid peroxidation inhibition assay and free radical scavenging assay by electron spin resonance spin-trapping technique. Among hydrolysates, peptic hydrolysate, having the highest antioxidant activity, further separated into four groups using ultrafiltration membranes and purified consecutive chromatographic methods. Finally, the purified peptide had a molecular mass of 1801 Da, and amino acid sequence was identified as Glu-Ser-Thr-Val-Pro-Glu-Arg-Thr-His-Pro-Ala-Cys-Pro-Asp-Phe-Asn. APHPH inhibited lipid peroxidation higher than that of alpha-tocopherol as positive control and efficiently quenched different sources of free radical: 1,1-diphenyl-2-pycryl-hydrazyl (IC(50)=41.37 microM), hydroxyl (IC(50)=17.77 microM), peroxyl (IC(50)=18.99 microM) and superoxide radicals (IC(50)=172.10 microM). Furthermore, APHPH decreased t-butylhydroperoxide-induced cytotoxicity on human embryonic lung fibroblasts and efficiently protected free-radical-induced DNA damage.

Amino Acid Sequence↗

PubMed2006

Cytotoxic activities of water-soluble chitosan derivatives with different degree of deacetylation.

Chitosans with different degree of deacetylation (DD) (90% and 50% deacetylated chitosan) were prepared by N-deacetylation followed by grafted onto chitosan to form water-soluble aminoethyl-chitosan (AE-chitosan), and dimetylaminoethyl-chitosan (DMAE-chitosan), diethylaminoethyl-chitosan (DEAE-chitosan). In the present study, cytotoxic activities of the chitosan derivatives were evaluated using three tumor cell lines and two normal cell lines, and structure-activity relationship was suggested. The cytotoxic activity was dependent on their DD and substituted group.

Acetylation↗

PubMed2006

Preparation of semi-interpenetrating polymer networks composed of chitosan and poloxamer.

Through semi-interpenetration of polymer networks with poloxamer, mechanical properties of chitosan (CS) sponge were increased for wound dressing application. Synthesis of poloxamer macromer was confirmed by proton nuclear magnetic resonance (1H NMR) spectra. Possible interactions between CS and poloxamer in semi-interpenetrating polymer networks (SIPNs), and changes in crystalline structures of both polymers were evaluated by Fourier-transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD), respectively. Swelling behavior, thermal analysis, mechanical properties, and morphology of SIPNs were studied by thermal gravimetric analysis, differential scanning calorimetry (DSC), compressive modulus measurement, and scanning electron microscopy (SEM), respectively. Preparation of poloxamer macromer, and intermolecular hydrogen bonding between CS and poloxamer were confirmed by NMR and FTIR, respectively. Melting temperature of poloxamer in SIPNs decreased due to prevention of crystallization by incorporation of CS. Formation of SIPNs with poloxamer and increasing poloxamer content in CS/poloxamer SIPNs increased mechanical strength of CS sponge compared with CS/poloxamer blend. Formation of SIPNs with poloxamer remarkably increased water content of CS due to hydrophilicity of CS and poloxamer. These results suggest CS/poloxamer sponges prepared by SIPNs method have good possibility for wound dressing application owing to rapid water adsorption, high mechanical strength, and interconnected cross-sectional morphology of SIPNs.

Adsorption↗

PubMed2006

Antioxidant activity of novel chitin derivative.

Novel water-soluble chitin derivative was prepared by chemical modification to evaluate antioxidant activities by free radical scavenging potential using electron spin resonance spin trapping technique. Aminoethyl-chitin (AEC) exhibited free radical scavenging activities against 1,1-diphenyl-2-picrylhydrazyl (DPPH), hydroxyl, superoxide, and peroxyl radicals. AEC quenched DPPH and peroxyl radical over 55% and 59% at 4mg/mL, and also suppressed superoixde radical over 58% at 2mg/mL. Especially, AEC was more active against hydroxyl radical, and scavenging ratio was 92.2% at 0.12mg/mL. These results suggested that free amino group in the -CH(2)CH(2)NH(2) plays an important role in the free radical scavenging activity. In addition, cytotoxic effect of AEC was assessed using human lung fibroblast (MRC-5) cell line, and AEC showed less toxic against MRC-5.

Antioxidants↗

PubMed2006

Isolation and characterization of collagen from brown backed toadfish (Lagocephalus gloveri) skin.

Collagen was isolated and characterized from the skin of brown backed toadfish (Lagocephalus gloveri), processing wastes. The total collagen yield extracted was 54.3% on the basis of lyophilized dry weight compared to other vertebrates. According to the electrophoretic pattern, the skin collagen of the fish consisted of heterotrimer alpha1alpha2alpha3. Moreover, the denaturation temperature was 28 degrees C, which was about 9 degrees C lower than that of collagen from porcine skin. Therefore, there is a possibility to use brown backed toadfish skin collagen as an alternative source of collagen for industrial purposes and subsequently it may maximize the economical value of the fish.

Amino Acids↗

PubMed2006

Characterization of (aminoethyl)chitin/DNA nanoparticle for gene delivery.

Nonviral gene delivery systems have been increasingly proposed as a safer alternative to viral vehicles. In the present study, we synthesized water-soluble chitin by aminoalkylating onto chitin at the C-6 position, and its transfection efficiency was investigated. Aminoethyl-chitin (AEC) was complexed with DNA, and AEC/DNA nanoparticles were characterized. AEC/DNA nanoparticles showed good DNA binding ability, high protection of DNA from nuclease and serum, and low cytotoxicity. Mean particle size decreased from 367 to 290 nm and zeta potential increased from -4.58 to 22.87 mV when the AEC/DNA charge ratio (N/P) increased from 1.15 to 18.5. The transfection efficiency of AEC/DNA nanoparticles was investigated in a human embryonic kidney cell line (HEK293), and the results showed that AEC/DNA nanoparticles were much enhanced compare with naked DNA.

Cell Line↗

PubMed2006

A new antibacterial dioxopiperazine alkaloid related to gliotoxin from a marine isolate of the fungus Pseudallescheria.

A new antibacterial dioxopiperazine, dehydroxybisdethiobis(methylthio)gliotoxin (1), and the previously described bisdethiobis(methylthio)gliotoxin (2) and gliotoxin (3), have been isolated from the broth of a marine-derived fungus of the genus Pseudallescheria. The structure and absolute stereochemistry of the new compound was assigned on the basis of NMR and CD experiments. Compounds 1 to approximately 3 exhibit potent antibacterial activity against the methicillin-resistant and multidrug-resistant Staphylococcus aureus with MIC values of 31.2, 31.2, and 1.0 microg/ml, respectively. Compound 3 also exhibited a significant radical scavenging activity against 1,1-diphenyl-2-picrylhydrazyl (DPPH) with IC50 value of 5.2 microM.

Anti-Bacterial Agents↗