• Journal of dental hygiene science
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• v.10 no.3
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• pp.161-165
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• 2010

The aim of this study was to investigate the antimicrobial effect of (-)-epigalocatechin on Fusobacterium nucleatum, Prevotella intermedia, and Porphyromonas gingivalis. To test the antimicrobial effect of (-)-epigalocatechin, the minimum inhibitory concentration (MIC) of against 4 strains of F. nucleatum, 2 strains of P. intermedia, and 2 strains of P. gingivalis was measured by broth dilution method. Time-kill curves were assessed for susceptible bacteria, testing $0{\times}MIC$ (control group), $0.5{\times}MIC$, $1{\times}MIC$, and $2{\times}MIC$ for (-)-epigalocatechin, by counting viable bacteria after 3, 90, 180, 360, 720, 1440 minutes. The MIC of (-)-epigalocatechin was 0.312-0.625, 0.625, and 0.625 mg/ml on the strains of F. nucleatum, P. intermedia, and P. gingivalis, respectively. Time-kill curves demonstrated (-)-epigalocatechin had bactericidal activity on P. intermedia ATCC $25611^T$, P. gingival is ATCC 53978, and F. nucleatum subsp. fusiforme ATCC $51190^T$. The results suggest that (-)-epigalocatechin can be useful in developing the oral hygiene product such as tooth past and gargling solution for the prevention of periodontal diseases.

• Archives of Pharmacal Research
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• v.19 no.4
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• pp.317-320
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• 1996

The time-kill curves of LB20304, a novel fluoroquinolone that has potent antibacterial activity against gram-positve and gram-negative bacteria, were calculated at the concentrations of 1/4-, 1/2-, 1-, 2- and 4-times the MIC against Staphylococcus aureus 77, Escherichia coli 3739E, Pseudomonas aeruginosa 1912E. The bactericidal activity of LB20304 for these strains was very rapid and comparable to that of ciprofloxacin. LB20304 produced a decrease in the $log_10$ CFU per milliliter of${\geq}$3 within 2 h at 4-times the MIC for all strains and consitently prevented regrowth of bacteria after 24 h of incubation. The MBCs (Minimal Bactericidal Concentration) of LB20304 against test organisms were equal to or at most four-times higher than the MICs.

• Biomaterials and Biomechanics in Bioengineering
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• v.2 no.3
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• pp.127-141
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• 2015

Silver-based systems activated by low intensity direct current continue to be investigated as an alternative antimicrobial for infection prophylaxis and treatment. However there has been limited research on the quantitative characterization of the antimicrobial efficacy of such systems. The objective of this study was to develop a semi-mechanistic pharmacokinetic/pharmacodynamic (PK/PD) model providing the quantitative relationship between the critical system parameters and the degree of antimicrobial efficacy. First, time-kill curves were experimentally established for a strain of Staphylococcus aureus in a nutrientrich fluid environment over 48 hours. Based on these curves, a modified PK/PD model was developed with two components: a growing silver-susceptible bacterial population and a depreciating bactericidal process. The test of goodness-of-fit showed that the model was robust and had good predictability ($R^2>0.7$). The model demonstrated that the current intensity was positively correlated to the initial killing rate and the bactericidal fatigue rate of the system while the anode surface area was negatively correlated to the fatigue rate. The model also allowed the determination of the effective range of these two parameters within which the system has significant antimicrobial efficacy. In conclusion, the modified PK/PD model successfully described bacterial growth and killing kinetics when the bacteria were exposed to the electrically activated silver-titanium implant system. This modeling approach as well as the model itself can also potentially contribute to the development of optimal design strategies for other similar antimicrobial systems.

• YAKHAK HOEJI
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• v.47 no.6
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• pp.365-368
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• 2003

The bactericidal activities of DW286, a new fluoroquinolone were investigated by comparing the minimal bactericidal concentrations (MBCs) and the time-kill curve of it against some Gram-positive and Gram-negative bacterial strains. The MBCs of DW286 for the strains tested were either equal to or two-fold higher than the MICs, as were observed for the other fluoroquinolones. And DW286 exhibited rapid killing curves against the strains. Accordingly, it could be said that DW286 has bactericidal activity comparable to other fluoroquinolones.

• Journal of dental hygiene science
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• v.11 no.1
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• pp.37-40
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• 2011

Oleanolic acid (OA) and ursolic acid (UA) are triterpenoid compound present in many plants. This study examined the antimicrobial activity of OA and UA against Streptococcus downei. The antimicrobial activity was evaluated by the minimal inhibitory concentration (MIC) and time kill curves. The MIC values of OA and UA for S. downei isolated from the Korean population were $8{\mu}g/ml$. OA and UA had a bactericidal effect on S. downei ATCC $33748^T$ above $2{\times}MIC$, $16{\mu}g/ml$ and $8{\mu}g/ml$, respectively. The results suggest that OA and UA can be used in the development of oral hygiene products for the prevention of dental caries.

• Microbiology and Biotechnology Letters
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• v.38 no.3
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• pp.289-294
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• 2010

Salvia miltiorrhiza Bunge (S. miltiorrhiza) is a traditional Korean medicine that is commonly used for the treatment of inflammatory diseases such as edema, arthritis, and hepatitis. The present study investigated the antimicrobial activity of methanol (MeOH) extract of S. miltiorrhiza roots against oral bacteria using broth the microdilution method and the checkerboard and time-kill methods evaluated the synergistic effects of treatment with antibiotics. The MeOH extract was demonstrated as a higher antibacterial activity (MICs, 8 to $64\;{\mu}g/mL$; MBCs, 16 to $64\;{\mu}g/mL$) against all tested oral bacteria. Additionally, the extract was observed to have a synergistic effect with ampicillin or gentamicin. A time-kill study evaluating the effects of the extract indicated that the extract treatment in combination with ampicillin or gentamicin showed rapid bactericidal activity. The results suggest that MeOH extract of S. miltiorrhiza could be employed as a natural antibacterial agent against dental caries.

• Korean Journal of Veterinary Research
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• v.54 no.3
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• pp.189-192
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• 2014

This study evaluated the antibacterial effects of a mixture of Sophorae radix and Glycyrrhiza uralensis Fischer (1 : 1) ethanol extracts (SGE) on mice infected with Streptococcus (S.) pyogenes. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration of SGE necessary for antibacterial effects against S. pyogenes were $20{\mu}g/mL$. Based on the time-kill curves for S. pyogenes, SGE was effective at $4{\times}$ MIC after 16 h. On Day 12 after challenge, the survival rate of mice treated with 2.0 mg/kg SGE was 60%. In conclusion, SGE had potent in vitro and in vivo antibacterial activities against S. pyogenes.

• International Journal of Oral Biology
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• v.36 no.1
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• pp.7-11
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• 2011

Ursolic acid is a triterpenoid compound present in many plants. This study examined the antimicrobial activity of ursolic acid against mutans streptococci (MS) isolated from the Korean population. The antimicrobial activity was evaluated by the minimum inhibitory concentration (MIC) and time kill curves of MS. The cytotoxicity of ursolic acid against KB cells was tested using an MTT assay. The $MIC_{90}$ values of ursolic acid for Streptococcus mutans and Streptococcus sobrinus isolated from the Korean population were $2 {\mu}g$/ml and $4 {\mu}g$/ml, respectively. Ursolic acid had a bactericidal effect on S. mutans ATCC $25175^T$ and S. sobrinus ATCC $33478^T$ at > $2 \;{\times}\; MIC (4 {\mu}g$/ml) and $4 \;{\times}\; MIC (8 {\mu}g$/ml), respectively. Ursolic acid had no cytotoxic effect on KB cells at concentrations at which it exerted antimicrobial effects. The results suggest that ursolic acid can be used in the development of oral hygiene products for the prevention of dental caries.

• International Journal of Oral Biology
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• v.35 no.4
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• pp.191-195
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• 2010

Oleanolic acid is a natural triterpenoid that exists widely in foods and some medicinal herbs. The purpose of this study was to determine the antimicrobial activity of oleanolic acid against Streptococcus mutans strains isolated from a Korean population. Antimicrobial activity against these bacteria was evaluated by minimal inhibitory concentration (MIC) and time kill curves. The tolerance of human gingival fibroblasts and human periodontal ligaments to oleanolic acid was tested using a methyl thiazolyl tetrazolium (MTT) assay. The $MIC_{90}$ value of oleanolic acid for both S. mutans and S. sobrinus isolated from Koreans was 8 ${\mu}g/ml$. Oleanolic acid showed bactericidal effects against S. mutans ATCC $25175^T$ and S. sobrinus ATCC $33478^T$ at $1\;{\times}\;MIC$ ($8{\mu}g/ml$) and had no cytotoxic effects against KB cells at this dose. The results suggest that oleanolic acid could be useful in the future development of oral hygiene products for the prevention of dental caries.