Effect of Pomegranate Extract on Dentin Protease Activity

Objectives: Punica granatum L. contains ellagic acid, a phenol antioxidant that might have potential for preventing the degradation of dentin collagen. This study evaluated the effect of dentin pretreatment with Punica granatum L. extract (PGE) on matrix metalloproteinase (MMP) activity on demineralized dentin.
Methods: Dentin beams (1 mm × 2 mm × 6 mm) were demineralized in 10% H₃PO₄ for 24 h. After baseline measurements of dry mass, beams were divided into 4 groups (n = 10/group) and, were pretreated for 5 min with 1µg/mL pomegranate (PGE1); 2µg/mL (PGE2); 4µg/ml pomegranate (PGE4) and control (no pretreatment). After pretreatment, the beams were rinsed, blot-dried and incubated in 1 mL calcium and zinc-containing medium (CM, pH 7.2) at 37 °C for 1 day, and 1 week. After incubation, dry mass was reassessed. The reduction in the total activity was measured using generic MMP activity assay. The direct MMP inhibitory effect of PGE was tested using rhMMP-9 assay. Data were analyzed by repeated-measures ANOVA.
Results: After 1 week incubation, the dry mass loss was significantly low for all PGE treated groups (p < 0.05) compared to control. The lowest 1 week mean dry mass loss was 2.54% ± 0.9 in the PGE4 group compared to control loss of dry mass at 7.4% ± 3.3, p < 0.05. The relative MMP activity of PGE treated groups ranged between 23.9 ± 7.9 and 52.8 ± 8.6. The inhibition of rhMMP -9 activity was significant for PGE treated groups compared to kit inhibitor and control (p < 0.05).
Conclusions: The result of this work indicated that the effect of PGE is dose-dependent. The use of PGE on demineralized dentin can inactivate the endogenous protease activity of dentin matrices.