title: Inhibition of major virulence pathways of Streptococcus mutans by quercitrin and deoxynojirimycin: a synergistic approach of infection control.
abstract: OBJECTIVE
  To evaluate the synergistic effect of Quercitrin and Deoxynojirimycin (DNJ) together with their individual inhibitory effect against virulence pathways of Streptococcus mutans.
  
  
  METHODS
  MICs of both the compounds were determined by the microdilution method, followed by their in vitrosynergy using checkerboard and time kill assay. The nature of interaction was classified as synergistic on the basis of fractional inhibitory concentration index (FICI) value of ≤0.5. Furthermore, the activity of Quercitrin and DNJ was evaluated individually and in combination against various cariogenic properties of S. mutans UA159 such as acidogenesis, aciduracity, glucan production, hydrophobicity, biofilm and adherence. Moreover, expression of virulent genes in S. mutans was analysed by quantitative RT- PCR (qRT-PCR) and inhibition of F1F0-ATPase, lactate dehydrogenase and enolase was also evaluated. Finally, scanning electron microscopy (SEM) was used to investigate structural obliteration of biofilm.
  
  
  RESULTS
  The in vitro synergism between Quercitrin and DNJ was observed, with a FICI of 0.313. Their MIC values were found to be 64 μg/ml and 16 μg/ml respectively. The synergistic combination consistently showed best activity against all the virulence factors as compared to Quercitrin and DNJ individually. A reduction in glucan synthesis and biofilm formation was observed at different phases of growth. The qRT-PCR revealed significant downregulation of various virulent genes. Electron micrographs depicted the obliteration of biofilm as compared to control and the activity of cariogenic enzymes was also inhibited.
  
  
  CONCLUSIONS
  The whole study reflects a prospective role of Quercitrin and DNJ in combination as a potent anticariogenic agent against S. mutans.
authors.affiliation: Medical Microbiology and Molecular Biology Lab, Interdisciplinary Biotechnology Unit, Aligarh Muslim University, Aligarh, India.
authors.forename: Sadaf
authors.initials: S
authors.lastname: Hasan
authors.affiliation: National Institute of Plant Genome Research, Aruna Asaf Ali Marg, New Delhi, India.
authors.forename: Kunal
authors.initials: K
authors.lastname: Singh
authors.affiliation: Medical Microbiology and Molecular Biology Lab, Interdisciplinary Biotechnology Unit, Aligarh Muslim University, Aligarh, India.
authors.forename: Mohd
authors.initials: M
authors.lastname: Danisuddin
authors.affiliation: National Institute of Plant Genome Research, Aruna Asaf Ali Marg, New Delhi, India.
authors.forename: Praveen K
authors.initials: PK
authors.lastname: Verma
authors.affiliation: Medical Microbiology and Molecular Biology Lab, Interdisciplinary Biotechnology Unit, Aligarh Muslim University, Aligarh, India.
authors.forename: Asad U
authors.initials: AU
authors.lastname: Khan
mesh_terms: D017485:1-Deoxynojirimycin / Q000494:pharmacology; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D000942:Antigens, Bacterial / Q000378:metabolism; D001422:Bacterial Adhesion / Q000187:drug effects; D018441:Biofilms / Q000187:drug effects / Q000254:growth & development; D004357:Drug Synergism; D005110:Extracellular Space / Q000187:drug effects / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects; D005936:Glucans / Q000378:metabolism; D005944:Glucosamine / Q000031:analogs & derivatives* / Q000494:pharmacology; D057927:Hydrophobic and Hydrophilic Interactions; D017053:Infection Control; D008826:Microbial Sensitivity Tests; D050296:Microbial Viability / Q000187:drug effects; D011135:Polysaccharides, Bacterial / Q000378:metabolism; D011794:Quercetin / Q000031:analogs & derivatives* / Q000494:pharmacology; D013295:Streptococcus mutans / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism / Q000472:pathogenicity*; D013312:Stress, Physiological / Q000187:drug effects; D014774:Virulence / Q000187:drug effects
chemical_list: D000900:Anti-Bacterial Agents; D000942:Antigens, Bacterial; D005936:Glucans; D011135:Polysaccharides, Bacterial; C501633:deoxynojirimycine; D017485:1-Deoxynojirimycin; C012526:quercitrin; D011794:Quercetin; D005944:Glucosamine