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In Vitro Study on Cariostatic Effect of Poly (L-glutamic acid)

Objectives: Previously published studies have shown that the salivary protein statherin (StN43) and a truncated peptide comprising its N-terminal 21 amino acids (StN21) inhibit demineralisation of enamel and calcium hydroxyapatite (HAp) under artificial cariogenic challenges in vitro by ~45%. Further studies and mathematical modelling suggest the acidic residues glutamate, aspartate and phosphoserine are required in the binding of such peptides to hydroxyapatite surfaces required for their cariostatic function.  Poly-L-glutamic acid (PLE20) is a similar length peptide to StN21 containing 20 glutamic acid residues. The aim of this in vitro study was to investigate the cariostatic efficacy of PLE20 using scanning microradiography (SMR).

Method: PLE20 (Alamanda Polymers, Inc., Huntsville, AL, U.S.A) was dissolved in phosphate buffered saline at a concentration of 0.94mM. HAp discs (20% porosity) used as enamel analogues were located in SMR environmental cells and treated with 0.1M acetic acid at pH 4.0 for 48h. The discs were then washed, and exposed to PLE20 peptide solution for 24h. Demineralisation was then continued for a further 48h. The rate of demineralisation (RDHAp) before and after peptide treatment was measured using SMR.

Results: RDHAp before peptide treatment was 2.18(4) ×10-4gm cm-2h-1 (r2=0.729) and after peptide treatment was 1.57(1) ×10-4gm cm-2 h-1 (r2=0.943). This result demonstrates a significant reduction in RDHAp of ~27% following PLE20 treatment.

Conclusion: This study demonstrates that poly-L-glutamic acid at a concentration of 0.94mM can inhibit the demineralisation of hydroxyapatite (HAp), confirming the role of glutamic acid in HAp demineralisation inhibition, and suggesting its cariostatic potential.

Division: British Division Meeting
Meeting: 2013 British Division Meeting (Bath, England)
Location: Bath England
Year: 2013
Final Presentation ID: 145
Abstract Category|Abstract Category(s): Scientific Groups
Authors
  • Joseph, Neera  ( Queen Mary University of London, London, N/A, England )
  • Williams, R.  ( Queen Mary University of London, London, N/A, England )
  • Al-jawad, Maisoon  ( Queen Mary University of London, London, N/A, England )
  • Anderson, Paul  ( Queen Mary University of London, London, N/A, England )
    • SESSION INFORMATION
    Oral Session
    Dentine, Enamel and Pulp
    09/11/2013