A Novel Small Molecule, ZY354, Inhibits Dental Caries-Associated Oral 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.

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

“…CHX as a broad-spectrum antimicrobial agent can effectively inhibit most of oral microbes but with poor selectivity, which might impose adverse effects on the oral microbial ecology after long-term use ( Tokajuk et al, 2017 ; Sakaue et al, 2018 ). A multispecies biofilm model consisting of S. mutans , S. sanguinis , and S. gordonii was reported previously that could be used to evaluate the ecological impact of the tested compounds on oral biofilms ( Zhang et al, 2019 ; Yu et al, 2020 ). In the current study, although S. mutans was less sensitive to LCG-N25 (MIC = 0.5 μg/mL) relative to the other 2 streptococci (MICs = 0.125 μg/mL) in the planktonic culture, data obtained from FISH showed that treatment with LCG-N25 led to a decreased proportion of S. mutans and an elevation of other commensal streptococci within mixed biofilms.…”

Antibacterial and Antibiofilm Studies of Synthetic Copper(I)-containing Small Molecule Complexes Against Streptococcus Mutans in Vitro

“…EPS production, which directly mediates microbial adherence to a surface, forms a polymeric matrix that enhance mechanical stability of bio lm [7]. Hence, EPS is recognized as one of key virulence factors of oral bio lm in terms of caries development [37,38]. Both the CLSM and the SEM were used to assess the bio lm microstructure, the EPS production was strikingly reduced.…”

Antimicrobial activities of a small molecule compound II-6s against oral streptococci

“…The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of II-6s against S. mutans, S. gordonii , and S. sanguinis were measured by a microdilution method in BHI as described previously [ 23 , 27 ]. The bacterial inoculum for the experiment was adjusted to 1 × 10 7 colony-forming units (CFU)/ml for S. mutans, S. gordonii , and S. sanguinis based on the optical density at 600 nm (OD 600 ) versus a CFU/ml graph of each bacterium.…”

“…Antimicrobial small molecules are promising for the control of microbial biofilm due to their structural versatility, relatively low cost, and ease of control and use [21,22]. Previous studies have reported various synthetic small molecules which display moderate efficacy against cariogenic bacteria and biofilms [23][24][25]. Reasonable structural design and scientific screening are important for the development of novel antimicrobial small molecules.…”