Functional Co-monomers from Grape Seed Extract Rendering Collagen Cross-linking Ability

Objectives: This study evaluated synthesized functional co-monomers derived from grape seed extract (GSE) on collagen cross-linking ability by Fourier-transform infrared spectroscopy (FTIR), weight loss (WL), hydroxyproline (HYP), and SEM analyses.
Methods: Functional co-monomers were synthesized from GSE and methacryloyl chloride through a simple one-step reaction, changing the quantity of methacrylate groups (MAPA-1, -2 and -3). Twenty human sound third molars were sectioned and processed into 8-µm-thick dentin films. The films were completely demineralized and treated (30 s) with 1% MAPA-1, -2, -3 or GSE in ethanol solution (n=6 x 10 films, each experimental group). Untreated films were used as a control group (CT). After rinsing (ethanol 30 min) and FTIR-characterization, WL was performed by weigthing before and after 0.1% collagenase digestion-1h. The digestion solution was subjected to HYP-assay to quantify the hydroxyproline released from each micro-gram of demineralized dentin. In-situ SEM evaluation was performed on additional etched dentin slabs (n=3), which were treated and rinsed, before and after digestion as previously described. The quantitative data were statistically analyzed (ANOVA and Tukey’s, a=5%).
Results: FTIR spectra demonstrated changes in collagen peaks (Amide I, II, III and CH₂) for all the treatment groups in comparison to CT. For WL(%), CT was completely digested after 1 h-collagenase (100%) and statistically higher HYP-release 102.7±15.9 µg/mg (p<0.0001). MAPA-1, -2 and GSE demonstrated statistically similar WL% (8.0±1.9; 5.9±2.6; 8.7±2.3, respectively) and for HYP-release (13.5±3; 11±2.3; 13.7±4.5 µg/mg, respectively), (p>0.05). MAPA-3 showed intermediate performance (WL% 38.4± 4.9; HYP 29.5±9.6 µg/mg), (p<0.0001). The SEM revealed after digestion, remaining demineralized dentin layer for all the treatment groups especially for GSE and MAPA-2, while for CT this layer completely disappeared.
Conclusions: The functionalized co-monomers from GSE exert cross-linking ability, render protection against collagen degradation, and become very promising for inclusion in methacrylate solutions.