• The korean journal of orthodontics
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• v.46 no.3
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• pp.146-154
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• 2016

Objective: Different methods have been utilized to prevent enamel demineralization and other complications during orthodontic treatment. However, none of these methods can offer long-lasting and effective prevention of orthodontic complications or interventions after complications occur. Considering the photocatalytic effect of $TiO_2$ on organic compounds, we hoped to synthesize a novel bracket with a $TiO_2$ thin film to develop a photocatalytic antimicrobial effect. Methods: The sol-gel dip coating method was used to prepare $TiO_2$ thin films on ceramic bracket surfaces. Twenty groups of samples were composed according to the experimental parameters. Crystalline structure and surface morphology were characterized by X-ray diffraction and scanning electron microscopy, respectively; film thickness was examined with a surface ellipsometer. The photocatalytic properties under ultraviolet (UV) light irradiation were analyzed by evaluating the degradation ratio of methylene blue (MB) at a certain time. Antibacterial activities of selected thin films were also tested against Lactobacillus acidophilus and Candida albicans. Results: Films with 5 coating layers annealed at $700^{\circ}C$ showed the greatest photocatalytic activity in terms of MB decomposition under UV light irradiation. $TiO_2$ thin films with 5 coating layers annealed at $700^{\circ}C$ exhibited the greatest antimicrobial activity under UV-A light irradiation. Conclusions: These results provide promising guidance in prevention of demineralization by increasing antimicrobial activities of film coated brackets.

• KSBB Journal
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• v.9 no.3
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• pp.266-271
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• 1994

Lipsome system composed of egg phosphatidylcholine was employed to reduce the membrane toxicity of Amphotericin B(Amp. B). Liposomal Amp. B, which showed a free drug equivalent antibiotic effect on fungi, displayed a remarkable reduction of toxicity of the drug against the membrane of red blood cell than that of fungizone which has been used in clinical treatment, and it shows conspicuously lowered toxicity on red blood cells. However liposomal Amp. B which contains cholesterol as a component of liposome lowered the antibiotic effect and toxicity than that phosphatidylcholine liposome. This due to the affinity between Amp. B and cholesterol. In addition to this, ${\beta}$-glucuronidase from snail juice crude enzyme reveals synergistic effect on liposomal Amp. B and free Amp. B. We also obtained positively raised antibiotic effect, when enzyme which is coupled with palmitic acid using NHSP inserted into liposome bilayer From these results, we suppose that the use of liposomal system in the case of Amp. B shows increasing antibiotic effect and dramatically lowered toxicity, thus, we think that we can solve the problem of Amp. B toxicity, which cause hesitate of clinical use.

• Journal of Environmental Health Sciences
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• v.34 no.3
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• pp.207-212
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• 2008

This study was performed to investigate the anti-microbial activity of extract from Korean fermented soybean paste (doen-jang) against 16 types of oral microbes, and to determine the minimum inhibition concentration (MIC) of the extract for three major microbes causing human oral diseases (Streptococcus mutans, Porphyromonas gingivalis, and Candida albicans). The extract was prepared using ethyl acetate and it was treated with the oral microbes at a concentration of 5.00 mg/ml (0.5%). The anti-microbial activity and MIC were measured using broth dilution method. Significant reduction of microbial activities of 16 types of oral microbes occurred when the soybean paste extract was added to the broth compared to the control (p<0.01), and striking inhibition (more than 99%) was observed in ten types. S. mutans, which causes dental caries, showed MIC at a concentration of 1.25 mg/ml for the extract. P. gingivalis, which causes adult periodontal disease, showed MIC at a concentration of 2.50 mg/ml for the extract. C. albicans, which causes denture stomatitis and angular stomatitis, showed MIC at a concentration of 20 mg/ml for the extract. These results indicate that ethyl acetate extract of doen-jang showed strong anti-microbial effect against 16 types of oral microbes, and the anti-microbial effect of the extract against oral microbes was stronger against bacteria than against fungi. The anti-microbial effect might be possibly enhanced by the fermentation of soybeans.

• Mycobiology
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• v.48 no.2
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• pp.122-132
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• 2020

Citric acid is a commercially valuable organic acid widely used in food, pharmaceutical, and beverage industries. In this study, 260 yeast strains were isolated from soil, bread, juices, and fruits wastes and preliminarily screened using bromocresol green agar plates for their ability to produce organic acids. Overall, 251 yeast isolates showed positive results, with yellow halos surrounding the colonies. Citric acid production by 20 promising isolates was evaluated using both free and immobilized cell techniques. Results showed that citric acid production by immobilized cells (30-40 g/L) was greater than that of freely suspended cells (8-19 g/L). Of the 20 isolates, two (KKU-L42 and KKU-L53) were selected for further analysis based on their citric acid production levels. Immobilized KKU-L42 cells had a higher citric acid production rate (62.5%), while immobilized KKU-L53 cells showed an ~52.2% increase in citric acid production compared with free cells. The two isolates were accurately identified by amplification and sequence analysis of the 26S rRNA gene D1/D2 domain, with GenBank-based sequence comparison confirming that isolates KKU-L42 and KKU-L53 were Candida tropicalis and Pichia kluyveri, respectively. Several factors, including fermentation period, pH, temperature, and carbon and nitrogen source, were optimized for enhanced production of citric acid by both isolates. Maximum production was achieved at fermentation period of 5 days at pH 5.0 with glucose as a carbon source by both isolates. The optimum incubation temperature for citric acid production by C. tropicalis was 32 ℃, with NH₄Cl the best nitrogen source, while maximum citric acid by P. kluyveri was observed at 27 ℃ with (NH₄)₂ SO₄ as the nitrogen source. Citric acid production was maintained for about four repeated batches over a period of 20 days. Our results suggest that apple and banana wastes are potential sources of novel yeast strains; C. tropicalis and P. kluyveri which could be used for commercial citric acid production.

• YAKHAK HOEJI
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• v.43 no.6
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• pp.716-728
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• 1999

Whole oil and ketonic fraction (KF) of Leptospermum scoparium have been tested for their antimicrobial activity and combination effect with several antibiotics against various bacterial strains and fungi by using microbiological assay methods. Antibacterial activities of KF against a number of test strains were 2-3 fold stronger than those of whole oil. MICs of the KF were $65~125{\;}{\mu\textrm{g}}/ml$ against seven gram positive bacterial strains, $65~250{\;}{\mu\textrm{g}}/ml$ against 19 methicillin resistance Staphylococcus aureus strains, and $65~50{\;}{\mu\textrm{g}}/ml$ against 14 quinolone resistance strains. However, KF showed little or no activity against gram negative bacteria. MICs of the KF were $16~250{\;}{\mu\textrm{g}}/ml$ against more than 50% of the anaerobic bacterial strains tested. KF showed the higher antibacterial activity than bacitracin against 10 strains of Bacteroids thetaiotaomicron, or three strains of Bacteroides ovatus, and the more active than ciprofloxacin against one strain of Bacteroides thetaiotaomicron and three strains of Bacteroids ovatus. The MICs of KF was 63 and $250{\;}{\mu\textrm{g}}/ml$ against Aspergillus niger and Candida albicans, respectively. Antibacterial activities of KF in combination with 19 antibiotics against 14 strains and with four antifungal agents against one fungal strain were determined by paper strip diffusion method. While most of combination showed additivity, KF showed synergism with bacitracin, exfadroxil, cephradin, and meropenem for 29~57% of the strains tested. However, ofloxacin, enoxacin, sparfloxacin showed antagonism with KF for 43~71% of the strains. KF alone and in combination with bacitracin, gentamycin, neomycin, itraconazole, fluconazole, terfinafine and ketoconazole against five bacterial strains or one fungus strain synergistic effect was demonstrated against 33% of strains examined with FIC index value below 0.5 by checkerboard study. Synergistic effect of KF with gentamicin against Staphylococcus epidermidis 329 (QRS) was found by time-kill study.

• YAKHAK HOEJI
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• v.54 no.2
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• pp.106-111
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• 2010

The chemical structures of eight compounds purified from two plants (Polygala tenuifolia Willdenow and Dioscorea batatas Decene) were determined and their anti-microbial activity against three microbial strains (Staphylococcus aureus, Pseudomonas aeruginosa, and Candida albicans) was tested. The three micro organisms were cultured in 96-well plates or Petri dishes without (control) or with the eight compounds added at concentrations of 100 to 0.01 ${\mu}M$ (wt/vol). The growth of the microorganisms in the medium was examined after a 24-h incubation. The inhibitory effect of each compound on the growth of the microorganisms was calculated from the optical density measured at 595 nm, turbidity, and size of the inhibition zone around the treated paper disc. The minimum inhiitory concentration (MIC) of compounds 4 to 7 against S. aureus was 0.08, 0.05, 1.3 and 0.02 ${\mu}M$, respectively, and 0.09, 0.1, 0.2 and 100 ${\mu}M$ against C. albicans. The $IC_{50}$ (50% inhibition) values of compounds 5 and 6 were 3.1 and 6.4 ${\mu}M$ against S. aureus, respectively, and 10 and 2.4 ${\mu}M$ against C. albicans. Therefore, compounds 4 to 6 were the most potent anti-microbial agents among the eight compounds tested.

• Proceedings of the Microbiological Society of Korea Conference
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• 2000.10a
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• pp.39-45
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• 2000

It hab been proposed that CHS3-mediated chitin synthesis during the vegitative cell cycle is regulated by CHS4. To investigate direct protein-protein interaction between their coding products, we used yeast two hybrid system and found that a domain of Chs3p was responsible for interaction with Chs4p. This domain, termed MIRC3-4 (maximum interacting region of chs3p with chs4p), spans from 647 to 700 residues. It is well conserved among CHS3 homologs of various fungi such as Candida albicans, Emericella nidulans, Neurospora crassa, Magnaporthe grisea, Ustilago maydis, Glomus versiforme, Exophiala dermatitidis, Rhizopus microsporus. A series of mutaion in the MIRC3-4 resulted in no appearance of chitin ring at the early G 1 phase but did not affect chitin synthesis in the cell wall after cytokinesis. Absence of chitin ring could be caused either by delocalization of Chs3p to the septum or by improper interaction with Chs4p. To discriminate those two, not mutually exclusive, alternatives, mutants cells were immunostained with Chs3p-specific antibody. Some exhibited localization of chs3p to the septum, while others failed. These results indicate that simultaneous localization and activation Chs3p by Chs4p is required for chitin ring synthesis.

• Korean Journal of Microbiology
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• v.19 no.1
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• pp.14-22
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• 1981

Protein content of cellulosic wastes, such as spent grain, hop bark, spent rye, rice straw, rice hull, saw dust and used newspaper, was increased by a mixed culture of C. utilis wastes having 66-75% moisture. Among the fungal strains tested. A.phoenicis KU175 was the most powerful to increase the protein content of A. phoenicis during the mixed culture with C. utilis in the CMC medium reached at the peak for one day culture after inoculation of the both strains at the same time, while it reached at peark from the beginning of the mixed culture, when A. phoenicis was inocultated for 12-24hours prior to the inoculation of C.utilis. To increase the protein content of the cellulosic wastes by the mixed culture of C.utilis and A.phoenicis, the inoculation of both strains at the same time was more effective than the preinoculation of A. phoenicis for 6-24 hours. Content of crude cellulose in the used newspaper, saw dust and spent grain was high relatively, and the lignin content of spent grain, spent rye, and rice strew was reduced more than half by the treatment of 2% NaOH. However, effect of alkali treatment of increase the protein content of the cellulosic wastes was not prominent in the case of mixed culture. Protein content of the cellulosic wastes was increased prominently by the mixed culture of C.utilis and A.phoenicis in semi-solid substrate, compared with the single culture of C. utilis, although the latter increased the protein content of cellulosic wastes considerably. The effect of mixed culture of C. utilis and A. phoenicis increased 4-fold the protein content of spent grain, and more than doubled crude protein in hop bark and rice straw.

• Journal of the Korean Society of Fashion and Beauty
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• v.5 no.4
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• pp.130-138
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• 2007

The aim of this study was to assess the cosmeceutical activies of four kinds of Korea herb medicine extracts using in cosmetics and related industries. The cosmeceutical activities of extracts were investigated by tyrosinase inhibition, astringent, anti-bacterial and MTT assay for cell viability. In the whitening effect, PA that the highest tyrosinase inhibition activity showed 56% at 10 ppm in ethanol extract. Also water and ethanol extract of RE showed 54%, 68% at 1,000 ppm, respectively, but LE and CA showed lower effect. Astringent effect of water and ethanol extract of PA appeared over 60% at 1,000ppm concentration but other extracts showed no astringent effect. In the anti-bacterial test, water and ethanol extract of PA showed no anti-bacterial effect against all microorganisms. But water and ethanol extract of RE showed anti-bacterial effect on Staphylococcus aureus, ethanol extract of showed on Staphylococcus aureus and Propionibacterium acnes, ethanol extract of CA showed on Candida albicans. The resUlt of stability test showed that the emulsion of containing PA were very stable at various temperature and sun-light test. Viscosity and pH of emulsion did not change. From the results of human patch test to assess the safety of cosmetics containing PA there was no negative reaction on skin was found.

• Korean Chemical Engineering Research
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• v.56 no.2
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• pp.245-251
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• 2018

In this study, Coffea arabica ethanol extract (CAE) was tested for possible functional cosmetic agent. Whitening effect was measured by tyrosinase inhibition assay, and anti-oxidant activity was checked by SOD-like activity. SOD-like activity of CAE showed $94.8{\pm}6.2%$ at $500{\mu}g/mL$. The anti-bacterial activities CAE was evaluated against three different gram-positive bacteria and six gram-negative bacteria including MRSA strains. CAE exhibited in vitro broad spectrum antimicrobial activities of gram-negative bacteria without antifungal activity. CAE was strong exhibited against MRSA CCARM3561. The tyrosinase and L-DOPA inhibitory activities of the CAE lower than those positive control arbutin. CAE reduced melanin contents of B16-F10 melanoma cell in a dose dependent manner and decrease about 89.2% at a concentration $100{\mu}g/mL$. These result highlight the potential of coffee extract as a naturally active and non-toxic antibacterial suitable for cosmetic applications.