Methacrylation of epigallocatechin-gallate for covalent attachment with a dental polymer.

OBJECTIVE: Synthesize novel epigallocatechin-gallate (EGCG) methacrylate monomers with the ability to copolymerize with dental methacrylate resins. METHODS: EGCG was reacted with 1/3 (E33), 2/3 (E67) and 1 (E100) molar equivalents of methacyloyl chloride introducing three degrees of polymerizablility. EGCG-methacrylates were characterized by Fourier Transform Infrared Spectroscopy (FTIR) and Nuclear Magnetic Resonance (NMR). E33, E67, E100 and neat EGCG were incorporated into TEGDMA at 0.5-20% ratios (m/m). Copolymers were tested for degree of conversion (%DC), EGCG release, gel content (%GC), degree of swelling (%DS), flexural properties and bacterial viability (Streptococcus mutans, baseline/30-days). Neat TEGDMA and TEGDMA passively loaded with EGCG (E0) were used as controls. Data were analysed by one-way ANOVA, Tukey, and Dunnett's method (α=5%). Two-way ANOVA and Bonferroni were used to investigate factor interaction. RESULTS: FTIR/NMR confirmed synthesis of desired compounds. All of E100 incorporated ratios had %DC similar to TEGDMA. Remaining groups had reduction in %DC at 2% in E0, 10% in E33 and 20% in E67 ratios. EGCG was stable within ECGC-methacrylate copolymers. Release of EGCG from E0 significantly increased with higher EGCG ratios. Except for E100, higher EGCG or EGCG-methacrylate ratios led to decreased %CG and %DS. At baseline, E0 had the lowest bacterial survival rates (1-10% survival) at all ratios compared to E33, E67, E100, and neat TEGDMA. However, E33, E67 and E100 still had statistically lower survival rates (7-53%) compared with neat TEGDMA. After 30-days, all compounds had similar survival rates for all ratios, which were lower than that of neat TEGDMA. SIGNIFICANCE: Demonstration of methacrylate functionalized EGCG- with inherited antibacterial activity for improved restoration longevity.

Placental autophagy regulation by the BOK-MCL1 rheostat.

Autophagy is the catabolic degradation of cellular cytoplasmic constituents via the lysosomal pathway that physiologically elicits a primarily cytoprotective function, but can rapidly be upregulated in response to stressors thereby inducing cell death. We have reported that the balance between the BCL2 family proteins BOK and MCL1 regulates human trophoblast cell fate and its alteration toward cell death typifies preeclampsia. Here we demonstrate that BOK is a potent inducer of autophagy as shown by increased LC3B-II production, autophagosomal formation and lysosomal activation in HEK 293. In contrast, using JEG3 cells we showed that prosurvival MCL1 acts as a repressor of autophagy via an interaction with BECN1, which is abrogated by BOK. We found that MCL1-cleaved products, specifically MCL1c157, trigger autophagy while the splicing variant MCL1S has no effect. Treatment of JEG3 cells with nitric oxide donor SNP resulted in BOK-MCL1 rheostat dysregulation, favoring BOK accumulation, thereby inducing autophagy. Overexpression of MCL1 rescued oxidative stress-induced autophagy. Of clinical relevance, we report aberrant autophagy levels in the preeclamptic placenta due to impaired recruitment of BECN1 to MCL1. Our data provided the first evidence for a key role of the BOK-MCL1 system in regulating autophagy in the human placenta, whereby an adverse environment as seen in preeclampsia tilts the BOK-MCL1 balance toward the build-up of isoforms that triggers placental autophagy.