Streptococcus mutans and Streptococcus sobrinus play important roles in dental caries. Coptis chinensis is a natural product with antimicrobial activity against enterobacteria; however, its effects on oral streptococci are still unknown. Therefore, the effects of C. chinensis on the growth and biofilm formation of the representative cariogenic bacteria S. mutans and S. sobrinus were investigated for the possible use of C. chinensis as an anticaries agent. The C. chinensis extract was diluted with sterile distilled water, and 0.1–2.5% of the extract was used in the experiment. The effects of the C. chinensis extract on the growth and glucan formation of S. mutans and S. sobrinus were measured by viable cell counting and spectrophotometry at 650 nm absorbance, respectively. Crystal violet staining was also carried out to confirm the C. chinensis extract’s inhibitory effect on biofilm formation. The C. chinensis extract significantly inhibited the growth of S. mutans and S. sobrinus at concentrations of ≥ 0.3% as compared with the control group. The viable cell count of colonies decreased by 1.7-fold and 1.2-fold at 2.5% and 1.25%, respectively, compared with the control group. The biofilm formation of S. mutans and S. sobrinus was inhibited by > 20-fold at C. chinensis extract concentrations of ≥ 1.25% as compared with the control group. In summary, the C. chinensis extract inhibited the growth and biofilm and glucan formation of S. mutans and S. sobrinus . Therefore, C. chinensis might be a potential candidate for controlling dental caries.

Streptococcus mutans is one of the important bacteria that forms dental biofilm and cause dental caries. Virulence genes in S. mutans can be classified into the genes involved in bacterial adhesion, extracellular polysaccharide formation, biofilm formation, sugar uptake and metabolism, acid tolerance, and regulation. The genes involved in bacterial adhesion are gbps (gbpA, gbpB, and gbpC) and spaP. The gbp genes encode glucan-binding protein (GBP) A, GBP B, and GBP C. The spaP gene encodes cell surface antigen, SpaP. The genes involved in extracellular polysaccharide formation are gtfs (gtfB , gtfC , and gtfD ) and ftf , which encode glycosyltransferase (GTF) B, GTF C, and GTF D and fructosyltransferase, respectively. The genes involved in biofilm formation are smu630, relA , and comDE. The smu630 gene is important for biofilm formation. The relA and comDE genes contribute to quorumsensing and biofilm formation. The genes involved in sugar uptake and metabolism are eno, ldh , and relA . The eno gene encodes bacterial enolase, which catalyzes the formation of phosphoenolpyruvate. The ldh gene encodes lactic acid dehydrogenase. The relA gene contributes to the regulation of the glucose phosphotransferase system. The genes related to acid tolerance are atpD, aguD, brpA, and relA . The atpD gene encodes F1F0-ATPase, a proton pump that discharges H+ from within the bacterium to the outside. The aguD gene encodes agmatine deiminase system and produces alkali to overcome acid stress. The genes involved in regulation are vicR, brpA, and relA .

Phagocytosis is a fundamental process in which phagocytes capture and ingest foreign particles including pathogenic bacteria. Several oral pathogens have anti-phagocytic strategies, which allow them to escape from and survive in phagocytes. Impaired bacteria phagocytosis increases inflammation and contributes to inflammatory diseases. The purpose of this study is to investigate the influences of various agents on oral pathogenic phagocytosis. To determine phagocytosis, Streptococcus mutans, Fusobacterium nucleatum, Aggregatibacter actinomycetemcomitans and Porphyromonas gingivalis were stained with 5-(and-6)-carboxyfluorescein diacetate succinimidyl ester (CFSE), and was measured using flowcytometery and confocal microscopy. The influencing factors on phagocytosis were evaluated through the pretreatment of ROS inhibitor (N-acetyl-L-cysteine (NAC)), lysozyme, potassium chloride (KCI) and adenosine triphosphate (ATP) in THP-1 cells. Expression of pro-inflammatory cytokines was determined by enzyme-linked immunosorbent assay (ELISA). The phagocytosis of various bacteria increased in a MOI-dependent manner. Among the tested bacteria, phagocytosis of P. gingivalis showed the highest fluorescent intensity at same infection time. Among the tested inhibitors, the NAC treatment significantly inhibited phagocytosis in all tested bacteria. In addition, NAC treatment indicated a similar pattern under the confocal microscopy. Moreover, NAC treatment significantly increased the bacteriainduced secretion of IL-1β among the tested inhibitors. Taken together, we conclude that the phagocytosis occurs differently depending on each bacterium. Down-regulation by ROS production inhibited phagocytosis and lead increased of oral pathogens-associated inflammation.

Polyphenon 60 refers to the mixture of catechins present in green tea. The aim of this study was to investigate the antimicrobial activities of polyphenon 60 against 4 strains of Streptococcus mutans and 2 strains of Streptococcus sorbrinus, which are the major causative bacteria of dental caries. The minimum bactericidal concentration (MBC) values of polyphenon 60 for S. mutans and S. sobrinus were determined and the effect of biofilm formation inhibition of that was evaluated. The MBC value of polyphenon 60 against the bacterial strains was 2.5 mg/ml except for one particular strain, S. mutans KCOM 1128 for which the value was 1.25 mg/ml. The results of biofilm formation inhibition assay revealed that polyphenon 60 inhibited biofilm formation more than 90% at a concentration of 2.5 mg/ml. It was apparent that polyphenon exhibited biofilm formation inhibition activity along with bactericidal effect against S. mutans and S. sobrinus. Therefore, it is proposed that polyphenon 60 as one of the components of bactericidal agents could be useful in developing oral hygiene products, toothpaste or gargling solution.

It is noted that Streptococcus mutans (S. mutans) triggers dental caries establishment by two major factors: the synthesis of organic acids, which demineralize dental enamel, and the synthesis of glucans, which mediate the attachment of bacteria to the tooth surface. Therefore, it is noted that the development of a more effective, substantial and safe preventive agent that works against dental caries and periodontal disease is required at this time. For this reason, the present study was designed to investigate the effect of croton seed ethanol extracts on the growth, acid production, adhesion, and insoluble glucan synthesis of S. mutans. In this case, the ethanol extract of croton seed showed concentration dependent inhibitory activity against the growth, acid production and adhesion of S. mutans. Especially, it is important to note that it has produced significant inhibition at the concentration of 0.1 and 0.2 mg/ml as compared to the control group. Moreover, these results suggest that the application of croton seed extract may be considered to be a useful method for the prevention of dental caries.

Streptococcus mutans (S. mutans) is one of the most important bacteria in the formation of dental plaque and dental caries. S. mutans adheres to an acquired pellicle formed on the tooth surface, and aggregates with many oral bacteria. It initiates plaque formation by synthesizing glucan from sucrose, which is catalyzed by glucosyltransferases. Propolis is a resinous mixture produced by honeybees, by mixing saliva and beeswax with secretions gathered from wood sap and flower pollen. Bees prevent pathogenic invasions by coating the propolis to the outer and inner surface of the honeycomb. Propolis has traditionally been used for the treatment of allergic rhinitis, asthma and dermatitis. We investigated the inhibitory effects of propolis ethanol extract on biofilm formation and gene expression of S. mutans. The biofilm formation of S. mutans was determined by scanning electron microscopy (SEM) and safranin staining. We observed that the extract of propolis had an inhibitory effect on the formation of S. mutans biofilms at concentrations higher than 0.2 mg/ml. Real-time PCR analysis showed that the gene expression of biofilm formation, such as gbpB, spaP, brpA, relA and vicR of S. mutans, was significantly decreased in a dose dependent manner. The ethanol extract of propolis showed concentration dependent growth inhibition of S. mutans, and significant inhibition of acid production at concentrations of 0.025, 0.05, 0.1 and 0.2 mg/ml, compared to the control group. These results suggest that the ethanol extract of propolis inhibits gene expression related to biofilm formation in S. mutans.

Dental caries, the most common oral disease, is a multifactorial disease caused by interactions among bacteria within the dental plaque, food, and saliva, resulting in tooth destruction. Streptococcus mutans has been strongly implicated as the causative organism in dental caries and is frequently isolated from human dental plaque. Photodynamic therapy (PDT) is a technique that involves the activation of photosensitizer by light in the presence of tissue oxygen, resulting in the production of reactive radicals capable of inducing cell death. Postantibiotic effect (PAE) is defined as the duration of suppressed bacterial growth following brief exposure to an antibiotic. In this study, the in vitro PAE of PDT using erythrosine and light emitting diode on S. mutans ATCC 25175 was investigated. The PAE of PDT for 1 s irradiation and 3 s irradiation were 1.65 h and 2.1 h, respectively. The present study thus confirmed PAE of PDT using erythrosine on S. mutans.

Cariogenic Streptococcus mutans encounters a variety of host defense factors produced in oral cavity. Nitric oxide (NO) and NO-mediated reactive nitrogen species are potential antimicrobials of innate immunity that can threaten the fitness of S. mutans in their ecological niches. Streptococcal strategies to detoxify cytotoxic NO, which allow S. mutans to persist in caries or other environments of the oral cavity, remain unknown. In this study, we directly measured NO consumption rates of S. mutans isolated in Korea. Surprisingly, all S. mutans strains were unable to consume exogenous NO efficiently, while an intracellular parasite Salmonella enterica serovar Typhimurium expressing the NO-metabolizing enzyme flavohemoglobin consumed most of the NO. This result suggested that S. mutans has alternative detoxification systems for tolerating NO-induced nitrosative stresses.

Streptococcus mutans (S. mutans) is a facultative anaerobic bacterium mainly found in the oral cavity and is known to contribute to tooth decay and gingivitis. Recent studies on intestinal microbiota have revealed that microorganisms forming a biofilm play important roles in maintaining tissue homeostasis through their own metabolism. However, the physiological roles of oral microorganisms such as S. mutans are still unclear. In our current study, we identified that constituents released from S. mutans (CR) reduce arecoline- mediated cytotoxicity without producing toxic effects themselves. Arecoline, as a major alkaloid of areca nut, is known to mediate cytotoxicity on oral epithelial cells and induces a sustained intracellular Ca2+ ([Ca2+]i) increase that is cytotoxic. The exposure of human gingival fibroblast (HGF) cells to CR not only inhibited the sustained [Ca2+]i increase but also the initial [Ca2+]i elevation. In contrast, CR had no effects on the gene regulation mediated by arecoline. These results demonstrate that S. mutans has physiological role in reducing cytotoxicity in HGF cells and may be considered a novel pharmaceutical candidate.

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 MIC90 value of oleanolic acid for both S. mutans and S. sobrinus isolated from Koreans was 8μg/mℓ. Oleanolic acid showed bactericidal effects against S. mutans ATCC 25175T and S. sobrinus ATCC 33478T at 1 × MIC(8μg/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.

In our present study, we investigated the effects of continentalic acid on Streptococcus mutans (S. mutans) biofilm. Methanol extract of Aralia continentalis (A. continentalis) was suspended in water and sequentially partitioned with CHCl3, ethyl acetate (EtOAc), and n-butanol (n-BuOH). The CHCl3 fraction showed the highest activity and an antibacterial compound against S. mutans was isolated from this preparation through various chromatography methods by bioassay guided fractionation. MS, 1H - NMR and 13C-NMR analysis showed that the active principle was continentalic acid which was confirmed to show significant inhibitory effects against S. mutans biofilm. These results may provide some scientific rationale for the traditional use these extracts for the treatment of dental diseases.

We conducted growth inhibition tests on oral microorganisms using three strains of Lactobacillus spp. which are widely known as their probiotic properties. In these experiments, we measured the number of oral microorganisms after directly contacting lactobacillus with them. In addition, we conducted a similar study using yogurts which are well known as a p robiotic food. I n these yogurts, w e identified t he t ype o f lactobacilli by 1 6s r RN A nucleotide analysis. In o ur study, the growth of most of oral microorganisms were inhibited by lactobacilli, and we also found that yogurts had the highest effectiveness in inhibiting the growth of most of oral microorganisms. The lactobacilli contained in the yogurts were identified as Lactobacillus casei, Lactobacillus paracasei, Lactobacillus helveticus, Lactobacillus casei, and Lactobacillus helveticus

The production of insoluble glucan was affected by the concentration of ions and buffers in a mouth. In this study, the effects of ions and buffers on the mRNA expression of gtfB and gtfC gene of Streptococcus mutans which is an important causative agent of dental caries were investigated by Fluorescent in situ hybridization(FISH). The mRNA of gtfB and gtfC gene was normally expressed in the BHI broth containing 1 % sucrose. The gtfB and gtfC mRNA expression was increased at 0.25 mM and 4 mM of CaCl2, respectively. While the mRNA expression of two genes was inhibited at each concentration of KCl and MgCl2 when compared to the control. As for buffers, the gtfB and gtfC mRNA expression was lower than the control by the addition of sodium bicarbonate. The addition of sodium phosphate decreased the gtfB mRNA expression except for 100 mM in which the expression was increased, and the gtfC mRNA expression was similar to or lower than the control at each concentraion of sodium phosphate. The mRNA expression of the gtfB and gtfC was decreased at each concentration of potassium phosphate when compared to the control.

고삼에서 치아우식원인세균인 S. mutans에 대한 항세균효과와 GTase의 활성을 저해하는 물질을 탐색, 개발하여 식품 또는 치아우식예방제로 응용하기 위하여 연구를 수행하였다. 고삼 에틸 아세테이트추출물의 3차 분획의 소분획에서 S. mutans에 대한 최소억제농도가 3.13 ㎍/ml으로 나타나, 높은 항세균효과를 관찰할 수 있었다. GTase 활성은 고삼의 에틸 아세테이트 추출물에 의하여 glucan의 형성을 저해하였으며, 100 ㎍/ml의 농도에서 77%의 저해율이 나타났고, 통계학적으로 유의한 효과가 나타났다 (p<0.05). 이상의 결과로 고삼은 치아우식예방제로 개발 가능성이 있다고 기대된다.

Aloe vera peel에서 항우식 및 함염증 활성이 있는 물질로 분리, 동정한 aloe-emodin과 barbaloin에 대한 Streptococcus mutans JC-2의 항균활성 및 glucosyltransferase (GTase)활성에 대한 저해 효과를 조사하였다, Aloe-emodin과 barbaloin은 Streptococcus mutans JC-2에 대해 강한 항균활성을 나타내었으며 100ug/mL 첨가농도에서는 lag phase가 연장되고 대수기의 생육도 저하되는 뚜렷한 항균효과가 있었다. 배양액의 pH의 감소폭은 대조군에 비해 aloe-emodin과 barbaloin의 첨가로 적게 나타났다. Streptococcus mutans JC-2의 세포질 성분들은 aloe-emodin과 barbaloin의 첨가농도가 증가할수록 많은 양이 누출되었으며, aloe-emodin과 barbaloin간의 세포막 손상에 있어 큰 차이는 없었다. GTase의 활성은 aloe-emodin과 barbaloin에 의해 저해되었으며 각각 100ug/mL 첨가 농도에서 각각 99.8, 98.4%의 저해율을 나타내었다.

단백질성의 치아우식 예방제를 개발하기 위해 polylysine을 선정하고 Streptococcus mutans와 Lactobacillus acidophilus의 생육과 산생성량에 미치는 영향을 anaerobic broth system에서 미생물학적인 방법에 준하여 조사하였으며, polylysine의 항균활성에 대한 pH와 열 안정성을 조사하였다. Streptococcus mutnas와 Lactobacillus acidophilus의 생육은 polylysine의 첨가농도가 증가할수록 감소하였으며 1.0㎎/ml 이상의 첨가농도에서는 두 시험균의 lag time이 약 1시간 정도 연장되는 효과가 있었다. 시험균의 산 생성량도 polylysine에 의해 감소되었으며 특히 1.0㎎/ml의 첨가농도에서 그 효과가 뚜렷하였다. Polylysine은 pH 5.0∼8.0에서도 그 항균활성이 유지되었으며, 60℃에서 30분간, 120℃에서 15분간의 열 처리에도 그 항균활성이 소실되지 않았다.