scholarly journals A Novel Small Molecule, ZY354, Inhibits Dental Caries-Associated Oral Biofilms

2019 ◽  
Vol 63 (5) ◽  
Author(s):  
Chenzi Zhang ◽  
Xinyi Kuang ◽  
Yuanzheng Zhou ◽  
Xian Peng ◽  
Qiang Guo ◽  
...  
Keyword(s):  
Antimicrobial Activity ◽  
Dental Caries ◽  
Small Molecule ◽  
Laser Scanning Microscopy ◽  
Oral Streptococci ◽  
Biofilm Inhibition ◽  
Content Type ◽  
Small Molecule Compound ◽  
Low Cytotoxicity ◽  
Multispecies Biofilms

ABSTRACT Biofilm control is a critical approach to the better management of dental caries. Antimicrobial small molecules have shown their potential in the disruption of oral biofilm and control of dental caries. The objectives of this study were to examine the antimicrobial activity and cytotoxicity of a newly designed small-molecule compound, ZY354. ZY354 was synthesized, and its cytotoxicity was evaluated in human oral keratinocytes (HOK), human gingival epithelial cells (HGE), and macrophages (RAW) by CCK-8 assays. Minimal inhibitory concentrations (MICs), minimum bactericidal concentrations (MBCs), minimum biofilm inhibition concentrations (MBICs), and minimum biofilm reduction concentrations (MBRCs) of ZY354 against common oral streptococci (i.e., Streptococcus mutans, Streptococcus gordonii, and Streptococcus sanguinis) were determined by microdilution method. The exopolysaccharide (EPS)/bacterium ratio and the dead/live bacterium ratio in the ZY354-treated multispecies biofilms were determined by confocal laser scanning microscopy, and the microbial composition was visualized and quantified by fluorescent in situ hybridization and quantitative PCR (qPCR). The demineralizing activity of ZY354-treated biofilms was evaluated by transverse microradiography. The results showed that ZY354 exhibited low cytotoxicity in HOK, HGE, and RAW cells and exhibited potent antimicrobial activity against common oral streptococci. The EPS and the abundance of S. mutans were significantly reduced after ZY354 treatment, along with an increased dead/live microbial ratio in multispecies biofilms compared to the level with the nontreated control. The ZY354-treated multispecies biofilms exhibited reduced demineralizing activity at the biofilm/enamel interface. In conclusion, the small-molecule compound ZY354 exhibits low cytotoxicity and remarkable antimicrobial activity against oral streptococci, and it may have a great potential in anticaries clinical applications.

scholarly journals Repurposing Napabucasin as an Antimicrobial Agent against Oral Streptococcal Biofilms

2020 ◽  
Vol 2020 ◽  
pp. 1-9
Author(s):  
Xinyi Kuang ◽  
Tao Yang ◽  
Chenzi Zhang ◽  
Xian Peng ◽  
Yuan Ju ◽  
...  
Keyword(s):  
Dental Caries ◽  
Laser Scanning ◽  
Antibacterial Activities ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Oral Streptococci ◽  
Oral Keratinocytes ◽  
Microbial Composition ◽  
Biofilm Inhibition ◽  
Multispecies Biofilms

Objectives. Disruption of microbial biofilms is an effective way to control dental caries. Drug resistance and side effects of the existing antimicrobials necessitate the development of novel antibacterial agents. The current study was aimed at investigating the antibacterial activities of the repurposed natural compound napabucasin against oral streptococci. Methods. The minimum inhibitory concentration, minimum bactericidal concentration, minimum biofilm inhibition concentration, and minimum biofilm reduction concentration of Streptococcus mutans, Streptococcus gordonii, and Streptococcus sanguinis were examined by a microdilution method. Cytotoxicity of napabucasin against human oral keratinocytes, human gingival epithelia, and macrophage RAW264.7 was evaluated by CCK8 assays. The dead/live bacterium and exopolysaccharide in the napabucasin-treated multispecies biofilms were evaluated by confocal laser scanning microscopy. Microbial composition within the napabucasin-treated biofilms was further visualized by fluorescent in situ hybridization and qPCR. And the cariogenicity of napabucasin-treated biofilms was evaluated by transverse microradiography. Results. Napabucasin exhibited good antimicrobial activity against oral streptococcal planktonic cultures and biofilms but with lessened cytotoxicity as compared to chlorhexidine. Napabucasin reduced the cariogenic S. mutans and increased the proportion of the commensal S. gordonii in the multispecies biofilms. More importantly, napabucasin significantly reduced the demineralization capability of biofilms on tooth enamels. Conclusion. Napabucasin shows lessened cytotoxicity and comparable antimicrobial effects to chlorhexidine. Repurposing napabucasin may represent a promising adjuvant for the management of dental caries.

scholarly journals Genetic Analysis of Mutacin B-Ny266, a Lantibiotic Active against Caries Pathogens

2020 ◽  
Vol 202 (12) ◽  
Author(s):  
Delphine Dufour ◽  
Abdelahhad Barbour ◽  
Yuki Chan ◽  
Marcus Cheng ◽  
Taimoor Rahman ◽  
...  
Keyword(s):  
Antimicrobial Activity ◽  
Dental Caries ◽  
Streptococcus Mutans ◽  
Dental Plaque ◽  
Oral Bacteria ◽  
Oral Streptococci ◽  
Chromosomal Locus ◽  
Content Type ◽  
Genes Encoding ◽  
Plaque Biofilm

ABSTRACT Bacteriocins are ribosomally synthesized proteinaceous antibacterial peptides. They selectively interfere with the growth of other bacteria. The production and secretion of bacteriocins confer a distinct ecological advantage to the producer in competing against other bacteria that are present in the same ecological niche. Streptococcus mutans, a significant contributor to the development of dental caries, is one of the most prolific producers of bacteriocins, known as mutacins in S. mutans. In this study, we characterized the locus encoding mutacin B-Ny266, a lantibiotic with a broad spectrum of activity. The chromosomal locus is composed of six predicted operon structures encoding proteins involved in regulation, antimicrobial activity, biosynthesis, modification, transport, and immunity. Mutacin B-Ny266 was purified from semisolid cultures, and two inhibitory peptides, LanA and LanA′, were detected. Both peptides were highly modified. Such modifications include dehydration of serine and threonine and the formation of a C-terminal aminovinyl-cysteine (AviCys) ring. While LanA peptide alone is absolutely required for antimicrobial activity, the presence of LanA′ enhanced the activity of LanA, suggesting that B-Ny266 may function as a two-peptide lantibiotic. The activation of lanAA′ expression is most likely controlled by the conserved two-component system NsrRS, which is activated by LanA peptide but not by LanA′. The chromosomal locus encoding mutacin B-Ny266 was not universally conserved in all sequenced S. mutans genomes. Intriguingly, the genes encoding LanAA′ peptides were restricted to the most invasive serotypes of S. mutans. IMPORTANCE Although dental caries is largely preventable, it remains the most common and costly infectious disease worldwide. Caries is initiated by the presence of dental plaque biofilm that contains Streptococcus mutans, a species extensively characterized by its role in caries development and formation. S. mutans deploys an arsenal of strategies to establish itself within the oral cavity. One of them is the production of bacteriocins that confer a competitive advantage by targeting and killing closely related competitors. In this work, we found that mutacin B-Ny266 is a potent lantibiotic that is effective at killing a wide array of oral streptococci, including nearly all S. mutans strains tested. Lantibiotics produced by oral bacteria could represent a promising strategy to target caries pathogens embedded in dental plaque biofilm.

scholarly journals A New Small Molecule Specifically Inhibits the Cariogenic Bacterium Streptococcus mutans in Multispecies Biofilms

2011 ◽  
Vol 55 (6) ◽  
pp. 2679-2687 ◽  
Author(s):  
Chang Liu ◽  
Roberta J. Worthington ◽  
Christian Melander ◽  
Hui Wu
Keyword(s):  
Dental Caries ◽  
Small Molecules ◽  
Streptococcus Mutans ◽  
Small Molecule ◽  
Biofilm Formation ◽  
Content Type ◽  
Multispecies Biofilm ◽  
Small Molecule Library ◽  
Cariogenic Bacterium ◽  
Multispecies Biofilms

ABSTRACTStreptococcus mutansis a major cariogenic bacterium. It has adapted to the biofilm lifestyle, which is essential for pathogenesis of dental caries. We aimed to identify small molecules that can inhibit cariogenicS. mutansand to discover lead structures that could give rise to therapeutics for dental caries. In this study, we screened a focused small-molecule library of 506 compounds. Eight small molecules which inhibitedS. mutansat a concentration of 4 μM or less but did not affect cell growth or biofilm formation of commensal bacteria, represented byStreptococcus sanguinisandStreptococcus gordonii, in monospecies biofilms were identified. The active compounds share similar structural properties, which are characterized by a 2-aminoimidazole (2-AI) or 2-aminobenzimidazole (2-ABI) subunit. In multispecies biofilm models, the most active compound also inhibited cell survival and biofilm formation ofS. mutansbut did not affect commensal streptococci. This inhibitor downregulated the expression of six biofilm-associated genes,ftf,pac,relA,comDE,gbpB, andgtfB, in planktonicS. mutanscells, while it downregulated the expression of onlyftf,pac, andrelAin the biofilm cells ofS. mutans. The most potent compound also inhibited production of two key adhesins ofS. mutans, antigen I/II and glucosyltransferase (GTF). However, the compound did not alter the expression of the corresponding genes in bothS. sanguinisandS. gordonii, indicating that it possesses a selective inhibitory activity againstS. mutans.

scholarly journals Antimicrobial Effectiveness of Calcium Silicate Sealers against a Nutrient-Stressed Multispecies Biofilm

2020 ◽  
Vol 9 (9) ◽  
pp. 2722
Author(s):  
Rahul Bose ◽  
Konstantinos Ioannidis ◽  
Federico Foschi ◽  
Abdulaziz Bakhsh ◽  
Robert D. Kelly ◽  
...  
Keyword(s):  
Antimicrobial Activity ◽  
Calcium Silicate ◽  
Antimicrobial Properties ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Biofilm Inhibition ◽  
Planktonic Bacteria ◽  
Multispecies Biofilm ◽  
Significant Difference ◽  
Ah Plus

Purpose: This study compared the antimicrobial efficacy of calcium silicate sealers (BioRoot RCS and Total Fill BC) and conventional sealers (AH Plus and Tubli-seal) against planktonic bacteria and a nutrient-stressed multispecies biofilm. Methods: Antimicrobial properties of freshly mixed sealers were investigated using the direct contact test (DCT) and a nutrient-stressed multispecies biofilm comprised of five endodontic strains. Antimicrobial activity was determined using quantitative viable counts and confocal laser scanning microscopy (CLSM) analysis with live/dead staining. The pH of the sealers was analysed over a period of 28 days in Hanks Balanced Salt Solution (HBSS). Analysis of variance (ANOVA) with Tukey tests and the Kruskal–Wallis test were used for data analysis with a significance of 5%. Results: All endodontic sealers exhibited significant antimicrobial activity against planktonic bacteria (p < 0.05). BioRoot RCS caused a significant reduction in viable counts of the biofilms compared to AH Plus and the control (p < 0.05), while no significant difference could be observed compared to TotalFill BC and Tubli-seal (p > 0.05). CLSM analysis showed that BioRoot RCS and TotalFill BC exhibited significant biofilm inhibition compared to Tubli-seal, AH Plus and the control (p < 0.05). BioRoot RCS presented with the highest microbial killing, followed by TotalFill BC and Tubli-seal. Alkalizing activity was seen from the onset by BioRoot RCS, TotalFill BC and AH Plus. After 28 days, BioRoot RCS demonstrated the highest pH in HBSS (pH > 12). Conclusions: Calcium silicate sealers exhibited effective antimicrobial properties. This was demonstrated by superior biofilm inhibition capacity and microbial killing, with strong alkalizing activity compared to epoxy-based and zinc oxide-eugenol-based sealers.

ACTIVITY OF PERICARP EXTRACT OF MANGOSTEEN AGAINST ORAL STREPTOCOCCI

2017 ◽  
Vol 20 (1) ◽  
pp. 41-46
Author(s):  
Dewi Nurul Mustaqimah ◽  
Josh Erry HW
Keyword(s):  
Antimicrobial Activity ◽  
Dental Caries ◽  
Streptococcus Mutans ◽  
Antimicrobial Agents ◽  
Biological Activities ◽  
World Health ◽  
Direct Result ◽  
Oral Streptococci ◽  
Oral Pathogens

The increasing prevalence of dental caries is still as a major world health problem. Caries is the direct result of acid production by cariogenic oral pathogens, especially Streptococcus mutans. New and better antimicrobial agents active against cariogenic bacteria with minimal side effects on the oral tissues are much needed, especially natural agents derived directly from plants. Phytochemical studies have shown that the extracts from various parts of mangosteen or Garciniamangostana Linn tree contain varieties of secondary metabolites such as prenylated and oxygenated xanthones, many of which have been found in vitro to have antimicrobial properties against oral pathogens. Several studies which examined the eficacy of herbal for human health have shown that xanthones from mangosteen have remarkable biological activities such as antioxidant, antimicrobial, anticancer etc, and had no cytotoxic effects on human gingival fibroblasts. Their results showed that among these xanthone derivatives obtain from pericarp extract of mangosteen, α-mangostin has the most potent antimicrobial activity against cariogenic Streptococcus mutans. It can be concluded that the strong antimicrobial activity of the pericarp extract of mangosteen is a good drug of choice that might be helpful in preventing the dental caries.

scholarly journals Amino Sugars Enhance the Competitiveness of Beneficial Commensals with Streptococcus mutans through Multiple Mechanisms

2016 ◽  
Vol 82 (12) ◽  
pp. 3671-3682 ◽  
Author(s):  
Lin Zeng ◽  
Tanaz Farivar ◽  
Robert A. Burne
Keyword(s):  
Dental Caries ◽  
Streptococcus Mutans ◽  
Sugar Metabolism ◽  
Amino Sugar ◽  
Amino Sugars ◽  
Mrna Levels ◽  
Oral Streptococci ◽  
Streptococcus Gordonii ◽  
Carbohydrate Source ◽  
Content Type

ABSTRACTBiochemical and genetic aspects of the metabolism of the amino sugarsN-acetylglucosamine (GlcNAc) and glucosamine (GlcN) by commensal oral streptococci and the effects of these sugars on interspecies competition with the dental caries pathogenStreptococcus mutanswere explored. MultipleS. mutanswild-type isolates displayed long lag phases when transferred from glucose-containing medium to medium with GlcNAc as the primary carbohydrate source, but commensal streptococci did not. Competition in liquid coculture or dual-species biofilms betweenS. mutansandStreptococcus gordoniishowed thatS. gordoniiwas particularly dominant when the primary carbohydrate was GlcN or GlcNAc. Transcriptional and enzymatic assays showed that the catabolic pathway for GlcNAc was less highly induced inS. mutansthan inS. gordonii. Exposure to H2O2, which is produced byS. gordoniiand antagonizes the growth ofS. mutans, led to reduced mRNA levels ofnagAandnagBinS. mutans. When the gene for the transcriptional regulatory NagR was deleted inS. gordonii, the strain produced constitutively high levels ofnagA(GlcNAc-6-P deacetylase),nagB(GlcN-6-P deaminase), andglmS(GlcN-6-P synthase) mRNA. Similar to NagR ofS. mutans(NagRSm), theS. gordoniiNagR protein (NagRSg) could bind to consensus binding sites (dre) in thenagA,nagB, andglmSpromoter regions ofS. gordonii. Notably, NagRSgbinding was inhibited by GlcN-6-P, but G-6-P had no effect, unlike for NagRSm. This study expands the understanding of amino sugar metabolism and NagR-dependent gene regulation in streptococci and highlights the potential for therapeutic applications of amino sugars to prevent dental caries.IMPORTANCEAmino sugars are abundant in the biosphere, so the relative efficiency of particular bacteria in a given microbiota to metabolize these sources of carbon and nitrogen might have a profound impact on the ecology of the community. Our investigation reveals that several oral commensal bacteria have a much greater capacity to utilize amino sugars than the dental pathogenStreptococcus mutansand that the ability of the model commensalStreptococcus gordoniito compete againstS. mutansis substantively enhanced by the presence of amino sugars commonly found in the oral cavity. The mechanisms underlying the greater capacity and competitive enhancements of the commensal are shown to depend on how the genes for the catabolic enzymes are regulated, the role of the allosteric modulators affecting such regulation, and the ability of amino sugars to enhance certain activities of the commensal that are antagonistic toS. mutans.

scholarly journals Novel Model for Multispecies Biofilms That Uses Rigid Gas-Permeable Lenses

2011 ◽  
Vol 77 (10) ◽  
pp. 3413-3421 ◽  
Author(s):  
Rebecca Peyyala ◽  
Sreenatha S. Kirakodu ◽  
Jeffrey L. Ebersole ◽  
Karen F. Novak
Keyword(s):  
Laser Scanning ◽  
Bacterial Species ◽  
Disease Process ◽  
Laser Scanning Microscopy ◽  
Host Cells ◽  
Confocal Laser ◽  
Content Type ◽  
Oral Biofilms ◽  
Multispecies Biofilms

ABSTRACTOral biofilms comprise complex multispecies consortia aided by specific inter- and intraspecies interactions occurring among commensals and pathogenic bacterial species. Oral biofilms are primary initiating factors of periodontal disease, although complex multifactorial biological influences, including host cell responses, contribute to the individual outcome of the disease. To provide a system to study initial stages of interaction between oral biofilms and the host cells that contribute to the disease process, we developed a novelin vitromodel system to grow biofilms on rigid gas-permeable contact lenses (RGPLs), which enable oxygen to permeate through the lens material. Bacterial species belonging to early- and late-colonizing groups were successfully established as single- or three-species biofilms, with each group comprisingStreptococcus gordonii,Streptococcus oralis, andStreptococcus sanguinis;S. gordonii,Actinomyces naeslundii, andFusobacterium nucleatum; orS. gordonii,F. nucleatum, andPorphyromonas gingivalis. Quantification of biofilm numbers by quantitative PCR (qPCR) revealed substantial differences in the magnitude of bacterial numbers in single-species and multispecies biofilms. We evaluated cell-permeable conventional nucleic acid stains acridine orange, hexidium iodide, and Hoechst 33258 and novel SYTO red, blue, and green fluorochromes for their effect on bacterial viability and fluorescence yield to allow visualization of the aggregates of individual bacterial species by confocal laser scanning microscopy (CLSM). Substantial differences in the quantity and distribution of the species in the multispecies biofilms were identified. The specific features of these biofilms may help us better understand the role of various bacteria in local challenge of oral tissues.

scholarly journals Antimicrobial Peptide CMA3 Derived from the CA-MA Hybrid Peptide: Antibacterial and Anti-inflammatory Activities with Low Cytotoxicity and Mechanism of Action in Escherichia coli

2015 ◽  
Vol 60 (1) ◽  
pp. 495-506 ◽  
Author(s):  
Jong-kook Lee ◽  
Chang Ho Seo ◽  
Tudor Luchian ◽  
Yoonkyung Park
Keyword(s):  
Escherichia Coli ◽  
Antimicrobial Activity ◽  
Antimicrobial Peptide ◽  
Blood Cells ◽  
Mammalian Cells ◽  
White Blood Cells ◽  
Raw 264.7 Cells ◽  
Content Type ◽  
Anti Inflammatory ◽  
Low Cytotoxicity

ABSTRACTCA-MA is a hybrid antimicrobial peptide (AMP) derived from two naturally occurring AMPs, cecropin A and magainin 2. CA-MA shows strong antimicrobial activity against Gram-negative and Gram-positive bacteria but also exhibits cytotoxicity toward mammalian cells. Our objective was to identify CA-MA analogues with reduced cytotoxicity by systematic replacement of amino acids with positively charged R groups (His and Lys), aliphatic R groups (Leu), or polar R groups (Glu). Among the CA-MA analogues studied (CMA1 to -6), CMA3 showed the strongest antimicrobial activity, including against drug-resistantEscherichia coliandPseudomonas aeruginosastrains isolated from hospital patients. CMA3 appeared to act by inducing pore formation (toroidal model) in the bacterial membrane. In cytotoxicity assays, CMA3 showed little cytotoxicity toward human red blood cells (hRBCs) or HaCaT cells. Additionally, no fluorescence was released from small or giant unilamellar vesicles exposed to 60 μM CMA3 for 80 s, whereas fluorescence was released within 35 s upon exposure to CA-MA. CMA3 also exerted strong lipopolysaccharide (LPS)-neutralizing activity in RAW 264.7 cells, and BALB/c mice exposed to LPS after infection byEscherichia colishowed improved survival after administration of one 0.5-mg/kg of body weight or 1-mg/kg dose of CMA3. Finally, in a mouse model of septic shock, CMA3 reduced the levels of proinflammatory factors, including both nitric oxide and white blood cells, and correspondingly reduced lung tissue damage. This study suggests that CMA3 is an antimicrobial/antiendotoxin peptide that could serve as the basis for the development of anti-inflammatory and/or antimicrobial agents with low cytotoxicity.

scholarly journals Small-Molecule Compound SYG-180-2-2 to Effectively Prevent the Biofilm Formation of Methicillin-Resistant Staphylococcus aureus

2022 ◽  
Vol 12 ◽  
Author(s):  
Lulin Rao ◽  
Yaoguang Sheng ◽  
Jiao Zhang ◽  
Yanlei Xu ◽  
Jingyi Yu ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Small Molecule ◽  
Biofilm Formation ◽  
Bacterial Biofilm ◽  
Alveolar Epithelial Cells ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Antibiofilm Activity ◽  
Methicillin Resistant ◽  
Small Molecule Compound

The resistance of methicillin-resistant Staphylococcus aureus (MRSA) has augmented due to the abuse of antibiotics, bringing about difficulties in the treatment of infection especially with the formation of biofilm. Thus, it is essential to develop antimicrobials. Here we synthesized a novel small-molecule compound, which we termed SYG-180-2-2 (C21H16N2OSe), that had antibiofilm activity. The aim of this study was to demonstrate the antibiofilm effect of SYG-180-2-2 against clinical MRSA isolates at a subinhibitory concentration (4 μg/ml). In this study, it was showed that significant suppression in biofilm formation occurred with SYG-180-2-2 treatment, the inhibition ranged between 65.0 and 85.2%. Subsequently, confocal laser scanning microscopy and a bacterial biofilm metabolism activity assay further demonstrated that SYG-180-2-2 could suppress biofilm. Additionally, SYG-180-2-2 reduced bacterial adhesion and polysaccharide intercellular adhesin (PIA) production. It was found that the expression of icaA and other biofilm-related genes were downregulated as evaluated by RT-qPCR. At the same time, icaR and codY were upregulated when biofilms were treated with SYG-180-2-2. Based on the above results, we speculate that SYG-180-2-2 inhibits the formation of biofilm by affecting cell adhesion and the expression of genes related to PIA production. Above all, SYG-180-2-2 had no toxic effects on human normal alveolar epithelial cells BEAS-2B. Collectively, the small-molecule compound SYG-180-2-2 is a safe and effective antibacterial agent for inhibiting MRSA biofilm.

scholarly journals A Novel Small Molecule, LCG-N25, Inhibits Oral Streptococcal Biofilm

2021 ◽  
Vol 12 ◽  
Author(s):  
Xiaoying Lyu ◽  
Chungen Li ◽  
Jin Zhang ◽  
Liang Wang ◽  
Qingsong Jiang ◽  
...  
Keyword(s):  
Antimicrobial Activity ◽  
Drug Resistance ◽  
Dental Caries ◽  
Antimicrobial Agent ◽  
Small Molecule ◽  
Cell Counting ◽  
Tooth Surface ◽  
Extracellular Polysaccharides ◽  
Fluorescent Staining ◽  
Microbial Composition

Dental caries is a chronic oral infectious disease caused by cariogenic biofilm adhered on the tooth surface. Our previous study demonstrated that a repurposed natural compound napabucasin (NAP) showed good antimicrobial activity against oral streptococcal biofilms. The current study designed a novel small molecule, namely LCG-N25, using NAP as a lead compound, and aimed to investigate its potential as an antimicrobial agent in the control of dental caries. LCG-N25 was designed and synthesized with reference to the structure of NAP. The minimal inhibitory concentrations and the minimal bactericidal concentrations of LCG-N25 against Streptococcus mutans, Streptococcus sanguinis, and Streptococcus gordonii were evaluated by microdilution method. The antimicrobial activity of LCG-N25 was further evaluated by crystal violet staining, colony forming units counting, biofilm metabolism assay, dead/live fluorescent staining, and scanning electron microscopy. The effect of LCG-N25 on the extracellular polysaccharides of biofilms was determined by both anthrone-sulfuric acid method and fluorescent staining. The microbial composition of streptococcal biofilms after LCG-N25 treatment was further visualized and quantified by fluorescence in situ hybridization. Besides, the cytotoxicity of LCG-N25 was evaluated by Cell Counting Kit-8 assay, and repeated exposure of S. mutans to LCG-N25 treatment was performed to assess if this novel compound could induce drug resistance of this cariogenic bacterium. We found that LCG-N25 exhibited a good antibacterial activity, low-cytotoxicity, and did not induce drug resistance of cariogenic S. mutans. These findings suggest that LCG-N25 may represent a promising antimicrobial agent that can be used as an adjuvant to the management of dental caries.

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