title: [Inhibitory effect of quercetin on the biofilm formation of Streptococcus mutans].
abstract: OBJECTIVE
  To observe the inhibitory effect of quercetin on the biofilm formation of Streptococcus mutans(Sm), to preliminarily reveal the possible underlying mechanisms, and to evaluate the cytotoxicity of quercetion to human dental pulp cells so as to provide the theoretical basis for the application of quercetin in oral biomaterials.
  
  
  METHODS
  Quercetin storage solution was diluted to 0, 3.125, 6.25, 12.5, 25, 50, 100, 200, 400 and 800 mg/L, and added into Sm medium for 4 h and 24 h, crystal violet staining was used to evaluate the biofilm volume. In subsequent detections, three groups were set: control(0 mg/L), 200 mg/L quercetin and 400 mg/L quercetin. Confocal laser scanning microscopy was used to observe the morphology of the biofilm; qPCR for gtfB, gtfC, comD, comE, and luxS were assessed to preliminarily investigate the mechanisms. Finally, the methyl thiazolyl tetrazolium(MTT)test using human dental pulp cells was used to investigate cytotoxicity.
  
  
  RESULTS
  Quercetin could significantly inhibit up to(86.16±0.45)% of the biofilm formation of Sm(Compared with the control group P=0.00)and effectively removed(43.04±0.53)% of the mature biofilm(Compared with the control group P=0.00). Confocal laser scanning microscopy photographs showed that after co-incubated for 24 h, the dense biofilm structures of the experimental group were destroyed by quercetin both at 200 mg/L and 400 mg/L. Quercetin suppressedover 50% of the expression of gtfB, gtfC, comD, comE(compared with the control group P<0.05)and promoted the expression of luxS up to 2.18 ± 0.24 and 2.84 ± 0.26 after 4 h and 24 h, respectively(compared with the control group P<0.05). Quercetin also exhibited acceptable compatibility for human dental pulp cells.
  
  
  CONCLUSIONS
  Quercetin could effectively reduce the biofilm formation of Sm by inhibiting the expression of the related genes, and exhibited no cytotoxicity for human dental pulp cells. Quercetin has good potential to be applied in oral biological materials.
authors.affiliation: The State Key Laboratory Breeding Base of Basic Science of Stomatology & Key Laboratory of Oral Biomedicine Ministry of Education, School of Stomatology, Wuhan University, Wuhan 430079, China.
authors.forename: J X
authors.initials: JX
authors.lastname: Yue
authors.affiliation: The State Key Laboratory Breeding Base of Basic Science of Stomatology & Key Laboratory of Oral Biomedicine Ministry of Education, School of Stomatology, Wuhan University, Wuhan 430079, China.
authors.forename: H Y
authors.initials: HY
authors.lastname: Yang
authors.affiliation: Department of Dermatology, China Resources & Wisco General Hospital, Wuhan 430080, China.
authors.forename: L
authors.initials: L
authors.lastname: Han
authors.affiliation: Teaching and Researching Office of Chinese Traditional Medicine, School of Chinese Medicine, Hubei University for Nationalities, Enshi Hubei 445000, China.
authors.forename: M Y
authors.initials: MY
authors.lastname: Zhu
authors.affiliation: The State Key Laboratory Breeding Base of Basic Science of Stomatology & Key Laboratory of Oral Biomedicine Ministry of Education, School of Stomatology, Wuhan University, Wuhan 430079, China.
authors.forename: F F
authors.initials: FF
authors.lastname: Song
authors.affiliation: Department of Prosthodontics, School of Stomatology, Wuhan University, Wuhan 430079, China.
authors.forename: C
authors.initials: C
authors.lastname: Huang
mesh_terms: D000975:Antioxidants / Q000494:pharmacology*; D018441:Biofilms / Q000187:drug effects*; D003782:Dental Pulp / Q000166:cytology; D006801:Humans; D018613:Microscopy, Confocal; D011794:Quercetin / Q000008:administration & dosage / Q000494:pharmacology*; D060888:Real-Time Polymerase Chain Reaction; D013194:Staining and Labeling; D013295:Streptococcus mutans / Q000502:physiology*; D013778:Tetrazolium Salts; D013997:Time Factors
chemical_list: D000975:Antioxidants; D013778:Tetrazolium Salts; D011794:Quercetin