• Journal of Microbiology and Biotechnology
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• v.27 no.12
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• pp.2129-2140
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• 2017

Silibinin is the major active component of silymarin, extracted from the medicinal plant Silybum marianum. Silibinin has potent antibacterial activity; however, the exact mechanism underlying its activity has not been elucidated. Here, we investigated the novel mechanism of silibinin against Escherichia coli. Time-kill kinetic assay showed that silibinin possess a bactericidal effect at minimal inhibitory concentration (MIC) and higher concentrations (2-and 4-fold MIC). At the membrane, depolarization and increased intracellular $Ca^{2+}$ levels were observed, considered as characteristics of bacterial apoptosis. Additionally, cells treated with MIC and higher concentrations showed apoptotic features like DNA fragmentation, phosphatidylserine exposure, and caspase-like protein expression. Generally, apoptotic death is closely related with ROS generation; however, silibinin did not induce ROS generation but acted as a scavenger of intracellular ROS. These results indicate that silibinin dose-dependently induces bacterial apoptosis-like death, which was affected by ROS depletion, suggesting that silibinin is a potential candidate for controlling bacteria.

• Journal of Microbiology and Biotechnology
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• v.19 no.8
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• pp.792-802
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• 2009

Antimicrobial peptides (AMPs) are considered to be a promising alternative to conventional antibiotics for future generations. We identified four novel hexapeptides with antimicrobial activity: KCM11 (TWWRWW-$NH_2$), KCM12 (KWRWlW-$NH_2$), KCM21 (KWWWRW-$NH_2$), and KRS22 (WRWFIH-$NH_2$), through positional scanning of a synthetic peptide combinatorial library (PS-SCL). The ability of these peptides to inhibit the growth of a variety of bacteria and unicellular fungi was evaluated. KCM11 and KRS22 preferentially inhibited the normal growth of fungal strains, whereas KCM12 and KCM21 were more active against bacterial strains. Bactericidal activity was addressed in a clear zone assay against phytopathogenic bacteria, including Pectobacterium spp., Xanthomonas spp., Pseudomonas spp., etc. KCM21 showed the highest activity and was effective against a wide range of target organisms. Application of KCM21 with inoculation of Pectobacterium carotovorum subsp. carotovorum on detached cabbage leaves resulted in an immune phenotype or a significant reduction in symptom development, depending on the peptide concentration. Cytotoxicity of the four hexapeptides was evaluated in mouse and human epithelial cell lines using an MTT test. The results revealed a lack of cytotoxic effects.

• Journal of Korean society of Dental Hygiene
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• v.14 no.1
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• pp.95-100
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• 2014

Objectives : The purpose of the present study was to investigate the effect of bamboo charcoal on Streptococcus mutans which is one of the most important causative agents of dental caries. Methods : S. mutans was incubated with or without bamboo charcoal and then changes were observed in its cell viability and antibacterial effect. Oral epithelial cells viabillity(human gingival fibroblast, HGF) was performed using MTT assay. Antibacterial effect was analyzed using a dilution plating method and agar diffusion method. Results : Oral epithelial cells, human gingival fibroblast (HGF) showed a tendency to increase in bamboo charcoal treatment solution concentrations(0.5, 1, 2, 3, 5, 10%). The bamboo charcoal had an antibacterial effect on S. mutans. Antibacterial effect of bamboo charcoal for the bacterium was 58%. Charcoal concentration of 2% and 5% in the inhibition zone showed a minimal growth, but the concentration of 10% bamboo charcoal in inhibition zone revealed a conspicuous antibacterial activity. Conclusions : Overall results suggested that the bamboo charcoal proved to be bactericidal effect on S. mutans.

• International Journal of Oral Biology
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• v.40 no.2
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• pp.79-83
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• 2015

The purpose of the study was to investigate the antimicrobial activity of the methanol extract of Coptidis rhizome against the type strains of cariogenic bacteria, Streptococcus mutans and Streptococcus sobrinus, and the periodontopathogens, Porphyromonas gingivalis, Prevotella intermedia, Treponema denticola and Aggregatibacter actinomycetemcomitans. The antimicrobial activities of the crude extract and the methanol extract fractions of Coptidis rhizome separated by silica gel chromatography were evaluated by determining the minimal bactericidal concentration (MBC) values, using the microdilution method. The cell viability test of the extracts of Coptidis rhizome on the KB cells was also studied by methyl thiazolyl tetrazolium (MTT) assay. Our results showed that the 11th fraction (F11) of the methanol extract had the greatest antimicrobial activity against the tested bacteria, with no associated cytotoxicity on the KB cells, upto a concentration of $50{\mu}g/ml$. These results suggest that the silica gel chromatography fraction F11 of the methanol extract of Coptidis rhizome, could be useful in the development of oral hygiene products as an antimicrobial agent for the prevention of dental caries and periodontal diseases.

• Preventive Nutrition and Food Science
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• v.10 no.2
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• pp.130-133
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• 2005

The growth inhibitiory effect of chaff vinegar against various food-borne pathogenic bacteria was evaluated. Bacterial growth was evaluated in chaff vinegar at concentrations of 15, 30, 50, 65, 80, and $100\%$ using the paper disc diffusion method and 0.5, 1.0, 1.5, 1.8, 2.0, 2.2 and $2.5\%$ in broth. In the paper disc diffusion assay, chaff vinegar showed a clear zone on both the Gram-positive bacteria; Listeria monocytogenes, Staphylococcus aureus and Gram-negative bacteria; Escherichia coli O157:H7, Salmonella Typhimurium, and Vibrio parahaemolyticus. Chaff vinegar exhibited the greatest growth inhibition for V. parahaemolyticus. The bactericidal effect of chaff vinegar on the E. coli O157:H7 was tested at concentrations ranging from 0.5 to $2.5\%$ (v/v) in the LB broth media. Chaff vinegar retarded the lag phase time of the growth curve in proportion in a concentration-dependent manner. Chaff vinegar at $2.5\%$ completely inhibited the growth of E. coli O157:H7.

• Journal of Food Hygiene and Safety
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• v.33 no.6
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• pp.427-437
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• 2018

In this study, 23 ethanolic extracts from 20 medicinal plants were evaluated for biological activities. Results revealed that of 23 samples, seven samples have demonstrated good antimicrobial activity. Minimum inhibitory concentrations were 0.4-2.0 mg/mL, while minimum bactericidal concentrations were mostly high 0.8-2.0 mg/mL for selected seven samples. Five samples revealed > 70 mg gallic acid equivalent (GAE)/g of total phenolic contents. Among test samples, six samples exhibited > 80% inhibition of the 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical and only two samples exhibited > 80% inhibition of 2,2'-Azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) radicals. A total of five test samples revealed Trolox equivalent antioxidant capacity more than $1000{\mu}m/g$. The MTT assay indicated that eight test samples exhibited > 90% viability of murine macrophage cells (RAW 264.7) at $250{\mu}g/mL$ and suppressed iNOS mRNA expression at transcriptional level when stimulated by lipopolysaccharide (LPS). Some medicinal plants revealed promising results, and so they have prospective for further more inclusive studies.

• Biomedical Science Letters
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• v.29 no.3
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• pp.130-136
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• 2023

In this study, the anti-bacterial activity of three medicinal herbs such as Dioscorea batatas, Morus alba, and Tagetes erecta, have been applied in oriental medicine against Escherichia coli and Staphylococcus aureus. The antibacterial activity of Dioscorea batatas ethanol extract (DBEE), Morus alba ethanol extract (MAEE), and Tagetes erecta ethanol extract (TEEE) was analyzed by disk diffusion, minimum inhibitory concentration (MIC), and minimum bactericidal concentration (MBC) assays. As a result, three medicinal herbs exhibited antibacterial activity in a dose-dependent manner as well as MAEE and TEEE showed the most potent antibacterial activity followed by disk diffusion assay against E. coli and S. aureus, respectively. MIC against E. coli and S. aureus was 1.6 mg/mL of MAEE and TEEE as well as 0.2 mg/mL of TEEE. MBC against both strains was 5 mg/mL of DBEE and 2.5 mg/mL of TEEE. Consequently, three medicinal herbs in this study showed potent antibacterial activity through the inhibited growth of E. coli and S. aureus, which is considered as a potential candidate for cosmeceutic agents to attenuate the pruritus. In addition, antibacterial and antihistamine effects followed by the extraction solvents should be analyzed in future studies.

• Pediatric Infection and Vaccine
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• v.24 no.3
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• pp.125-133
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• 2017

Purpose: After the introduction of Haemophilus influenzae type b (Hib) vaccine in 1995 in Korea, it was included in the national immunization program in 2013. In the post-Hib vaccine era, some studies in other countries reported that invasive Hib disease affects adults, especially the elderly and immunocompromised persons, more often than it affects children. To evaluate disease susceptibility, quantitative and qualitative analysis of anti-polyribosylribitol phosphate (PRP) antibodies were carried out in Korean adults aged 20 to 85 years. Methods: Sera were collected from 39 healthy adults (20 to 50 years of age) and from 30 elderly adults (75 to 85 years of age) who did not have immune-compromising conditions. The concentration of anti-PRP immunoglobulin G (IgG) and serum bactericidal indices (SBIs) were measured by enzyme-linked immunosorbent assay and serum bactericidal assay. Results: Geometric mean concentrations of anti-PRP IgG and geometric mean SBIs were $0.88{\mu}g/mL$ (95% confidence interval [CI], 0.17 to 3.85) and 354 (95% CI, 50 to 2,499) in young adults and $1.67{\mu}g/mL$ (95% CI, 0.53 to 5.24) and 449 (95% CI, 146 to 1,376) in elderly adults, respectively. When the threshold of seropositivity for anti-PRP IgG was applied as 0.15 or $1.0{\mu}g/mL$, which is the protective antibody level in children, seropositive rates were 87.2% or 53.8% in young adults and 100% or 60% in elderly adults. The seropositivity rates of the SBI ($SBI{\geq}4$) were 82.1% and 100% in the groups, respectively. Conclusions: Most subjects in the adult and elderly adult groups display immunity to Hib based on quantitative and qualitative antibody levels, but not all. Because high immunization and low Hib circulation rates may reduce the natural Hib immunity in the population, monitoring Hib immunity as well as disease are needed continuously.

• Clinical and Experimental Pediatrics
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• v.50 no.5
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• pp.449-456
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• 2007

Purpose : Antibody persistence after primary series of Haemophilus influenzae type b (Hib) vaccine and responses to a boosters are little known in Korean children. We performed this study to evaluate the antibody titer in relation with a booster immunization of Hib vaccine in Korean children. Methods : One hundred forty-four children aged 12-23 months old were enrolled in three university hospitals. The immunogenicity of a boosters with Hib vaccine was assessed in children previously primed with Hib vaccine. Antibody persistence was also assessed in children who had received 3 doses of Hib vaccine without a booster. Anti-polyribosylribitol phosphate (PRP) IgG antibody levels and bactericidal titers were determined by enzyme immunoassay and bactericidal assay at the Center for Vaccine Evaluation and Study, Medical Research Institute, Ewha Womans University. Results : Prior to a booster in the second year of life, geometric mean antibody concentrations were $2.39{\mu}g/mL$ and the percent of subjects who had a anti-PRP antibody level ${\geq}1{\mu}g/mL$ was 68.6%. After boosting, antibody concentration was $19.09{\mu}g/mL$ and the percent of subjects who had a anti-PRP antibody level ${\geq}1{\mu}g/mL$ was 96.5%, which reflects previous immune priming. In subjects who had finished primary immunization only, the bactericidal titer was 3,946 and in subjects who had a booster, it was 11,205. Anti-PRP antibody level was correlated with serum bactericidal titer. Conclusion : Many children aged 12-23 month old still had protective antibodies after recommended primary immunization only. A booster dose seemed to induce good anamnestic antibody responses in Korean children.

• Microbiology and Biotechnology Letters
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• v.42 no.4
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• pp.361-366
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• 2014

In this study, Glycyrrhiza uralensis and Glycyrrhiza glabra extracts, with their countries of origin as Korea (Jecheon), Uzbekistan and China, were prepared under various extraction conditions. There were 8 extraction conditions which the licorice were subjected to, and all conditions had different extraction solvents, temperatures and times. Antimicrobial activity on skin flora was evaluated comparatively by a disc diffusion assay, broth macrodilution assay, and kill time curve assay. Based on the antimicrobial activity of their extract confirmed by disc diffusion assay, we established optimal extraction conditions. The Korean licorice extract (85% ethanol, $40^{\circ}C$, 12 h) showed the best activity amongst the samples examined. In particular, its antimicrobial activity against Propionibacterium acnes was the highest. Minimum inhibitory concentrations (MIC) and minimum bactericidal concentrations (MBC) of the licorice extracts revealed that the Korean licorice ($156{\mu}g/ml$ and $1,250{\mu}g/ml$) had better antimicrobial activity than that of the Uzbekistani licorice ($625{\mu}g/ml$ and $2,500{\mu}g/ml$) and the Chinese licorice ($625{\mu}g/ml$ and $5,000{\mu}g/ml$). Taken together, it was shown that Korean licorice extracted in group F (85% ethanol, $40^{\circ}C$, 12 h) had the highest antimicrobial activity amongst the licorices from the other countries of origin. These results also suggest that the optimal extraction conditions are 85% ethanol, $40^{\circ}C$, 12 h, and that licorice has a potential application as a natural preservative in cosmetics products, thereby replacing synthetic preservatives.