title: Proanthocyanidins' efficacy in stabilizing dentin collagen against enzymatic degradation: MALDI-TOF and FTIR analyses.
abstract: OBJECTIVE
  To investigate grape seed extract proanthocyanidins' (PA) capability in improving dentin collagen's sustainability in an enzymatic environment, given that the size and shape of the collagen samples, and the manner to apply PA are both clinically relevant.
  
  
  METHODS
  Human dentin was sectioned into 6-μm-thick films. After demineralisation in 35wt% phosphoric acid for 15s, the films were subject to 30s of treatment at PA concentrations of 0% (control), 0.5%, 1%, 2%, 3.75%, 7.5% and 15% (w/w), respectively. The films were then digested in 0.1wt% collagenase for 1h and 24h. The amount of degraded collagen in the liquid digests was determined by MALDI-TOF mass spectroscopy. The trend of PA's incorporation into dentin collagen was analysed by ATR-FTIR.
  
  
  RESULTS
  The control exhibited complete digestion in 1h. In contrast, collagen treated with 0.5% and 1% PA afforded 13.84±4.69% and an undetectable level of degradation, respectively in the first 1h of digestion, and additional 17.48±4.38% and 4.50±1.68%, respectively in the following 23h. Collagen treated with ≥2wt% PA was not significantly digested regardless of digestion time. FTIR spectroscopy revealed that PA incorporation was saturated at ≥2wt% PA.
  
  
  CONCLUSIONS
  Thirty seconds of PA treatment at 2wt% and above could provide optimal protection for dentin collagen against collagenase digestion.
  
  
  CONCLUSIONS
  This study demonstrated PA's extraordinary efficiency in stabilizing demineralised dentin collagen when it is applied in a clinical relevant manner, and identified the optimal conditions for its utilization.
authors.affiliation: University of Missouri-Kansas City School of Dentistry, Kansas City, MO 64108, USA.
authors.forename: Yi
authors.initials: Y
authors.lastname: Liu
authors.forename: Yong
authors.initials: Y
authors.lastname: Wang
mesh_terms: D000595:Amino Acid Sequence; D003094:Collagen / Q000032:analysis / Q000187:drug effects*; D017364:Collagenases / Q000494:pharmacology; D003804:Dentin / Q000187:drug effects*; D056604:Grape Seed Extract / Q000494:pharmacology*; D006801:Humans; D061965:Matrix Metalloproteinase Inhibitors / Q000494:pharmacology*; D009842:Oligopeptides / Q000032:analysis; D010756:Phosphoric Acids / Q000494:pharmacology; D044945:Proanthocyanidins / Q000494:pharmacology*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D017550:Spectroscopy, Fourier Transform Infrared; D013997:Time Factors; D017001:Tooth Demineralization / Q000503:physiopathology; D027843:Vitis
chemical_list: D056604:Grape Seed Extract; C511402:Grape Seed Proanthocyanidins; D061965:Matrix Metalloproteinase Inhibitors; D009842:Oligopeptides; D010756:Phosphoric Acids; D044945:Proanthocyanidins; C035024:glycyl-prolyl-arginine; C047981:arginyl-glycyl-aspartic acid; D003094:Collagen; C030242:phosphoric acid; D017364:Collagenases