title: Molecular weight and galloylation affect grape seed extract constituents' ability to cross-link dentin collagen in clinically relevant time.
abstract: OBJECTIVE
  To investigate the relationship between the structures of polyphenolic compounds found in grape seed extract (GSE) and their activity in cross-linking dentin collagen in clinically relevant settings.
  
  
  METHODS
  Representative monomeric and dimeric GSE constituents including (+)-catechin (pCT), (-)-catechin (CT), (-)-epicatechin (EC), (-)-epigallocatechin (EGC), (-)-epicatechin gallate (ECG), (-)-epigallocatechin gallate (EGCG), procyanidin B2 and a pCT-pCT dimer were purchased or synthesized. GSE was separated into low (PALM) and high molecular weight (PAHM) fractions. Human molars were processed into dentin films and beams. After demineralization, 11 groups of films (n=5) were treated for 1min with the aforementioned reagents (1wt% in 50/50 ethanol/water) and 1 group remained untreated. The films were studied by Fourier transform infrared spectroscopy (FTIR) followed by a quantitative mass spectroscopy-based digestion assay. Tensile properties of demineralized dentin beams were evaluated (n=7) after treatments (2h and 24h) with selective GSE species that were found to protect dentin collagen from collagenase.
  
  
  RESULTS
  Efficacy of GSE constituents in cross-linking dentin collagen was dependent on molecular size and galloylation. Non-galloylated species with degree of polymerization up to two, including pCT, CT, EC, EGC, procyanidin B2 and pCT-pCT dimer were not active. Galloylated species were active starting from monomeric form, including ECG, EGCG, PALM, GSE and PAHM. PALM induced the best overall improvement in tensile properties of dentin collagen.
  
  
  CONCLUSIONS
  Identification under clinically relevant settings of structural features that contribute to GSE constituents' efficacy in stabilizing demineralized dentin matrix has immediate impact on optimizing GSE's use in dentin bonding.
authors.affiliation: School of Dentistry, University of Missouri-Kansas City, Kansas City, MO 64108, USA.
authors.forename: Yi
authors.initials: Y
authors.lastname: Liu
authors.affiliation: School of Dentistry, University of Missouri-Kansas City, Kansas City, MO 64108, USA.
authors.forename: Xinyan
authors.initials: X
authors.lastname: Bai
authors.affiliation: School of Dentistry, University of Missouri-Kansas City, Kansas City, MO 64108, USA.
authors.forename: Shaohua
authors.initials: S
authors.lastname: Li
authors.affiliation: School of Dentistry, University of Missouri-Kansas City, Kansas City, MO 64108, USA.
authors.forename: Ying
authors.initials: Y
authors.lastname: Liu
authors.affiliation: School of Biological Sciences, University of Missouri-Kansas City, Kansas City, MO 64110, USA.
authors.forename: Andrew
authors.initials: A
authors.lastname: Keightley
authors.affiliation: School of Dentistry, University of Missouri-Kansas City, Kansas City, MO 64108, USA. Electronic address: Wangyo@umkc.edu.
authors.forename: Yong
authors.initials: Y
authors.lastname: Wang
mesh_terms: D044946:Biflavonoids / Q000737:chemistry; D002392:Catechin / Q000031:analogs & derivatives / Q000737:chemistry; D003094:Collagen / Q000737:chemistry*; D003432:Cross-Linking Reagents / Q000737:chemistry; D003804:Dentin / Q000737:chemistry*; D056604:Grape Seed Extract / Q000737:chemistry*; D006801:Humans; D066298:In Vitro Techniques; D013058:Mass Spectrometry; D008422:Materials Testing; D008963:Molar; D015394:Molecular Structure; D008970:Molecular Weight; D058105:Polymerization; D044945:Proanthocyanidins / Q000737:chemistry; D017550:Spectroscopy, Fourier Transform Infrared; D013499:Surface Properties; D013718:Tensile Strength; D013997:Time Factors
chemical_list: D044946:Biflavonoids; D003432:Cross-Linking Reagents; D056604:Grape Seed Extract; D044945:Proanthocyanidins; C017674:procyanidin; D002392:Catechin; D003094:Collagen; C062669:epicatechin gallate; C045651:epigallocatechin gallate
keywords: Collagenase digestion; Cross-linking; Dentin collagen; Grape seed extract; Proanthocyanidins; Tensile properties