Characterization, Antimicrobial Activity, and Antioxidant Efficacy of a Pomegranate Peel Solution Against Persistent Root Canal Pathogens

Background: The limitations of dental irrigation solutions reinforce the need to explore novel bioactive compounds that are safer and biodegradable. This study aimed to prepare a 10% pomegranate peel solution (Punica granatum extract - PGE) and evaluate its antimicrobial and antioxidant effects for root canal treatment. Methods: Lyophilized extracts (1g/10 mL) from pomegranate peels were prepared, and the punicalagin content was assessed by ultra-performance liquid chromatography using pure punicalagin (standard). The antimicrobial activity was tested against common persistent root canal pathogens by the agar diffusion method, minimum inhibitory concentration (MIC), and minimum bactericidal/fungicide concentration (MCB/MFC). The antioxidant activity (%AA) was assessed by the DPPH radical scavenging method. Data were analyzed by ANOVA and Tukey's test (α = 0.05). Results: The total phenolic content of the PGEextract was 6.55 µg/mL. Differences were found among the inhibition zone of PGE (23.32 ± 3.65), 1% NaOCl (30.76 ± 4.73), and 50% ethanol (without inhibition) (p < 0.05). The MIC values of PGE ranged between 6.25 and 75 mg/ml, and PGE was effective against the tested pathogens. PGE had antioxidant potential (IC50 = 3.52 µg/mL); however, the mean values were inferior to that of the quercetin (positive control) (IC50 = 0.95 µg/mL). The DPPH scavenging effect (%AA) of PGE (70.98 ± 2.3) had no difference from the positive control (72.94 ± 2.1) (p = 0.253). Conclusion: The PGE extract was successfully biosynthesized and exhibited antimicrobial and antioxidant activity, suggesting its potential use as an adjuvant therapy during root canal treatment.