Effects of Korean Propolis Extracts on <i>Porphyromonas gingivalis</i> Lipopolysaccharide-Induced Inflammatory Responses in RAW 264.7 Cells

Background: Porphyromonas gingivalis is a primary etiological agent of chronic periodontitis in adults, and its lipopolysaccharide (LPS) elicits a strong inflammatory response that contributes to periodontal tissue destruction.Propolis has been reported to exhibit multiple pharmacological activities, including anti-inflammatory, antibacterial, and antioxidant effects.This study aimed to evaluate the effects of propolis extracts (PEs) collected from different regions of South Korea on LPS from P. gingivalis (LPS-PG)-induced inflammatory responses.Methods: Inflammatory responses were induced in RAW 264.7 macrophages using LPS-PG, followed by treatment with PEs from eight different regions of South Korea at varying concentrations.Cell viability was assessed using the Cell Counting Kit-8 assay, and the production of nitric oxide (NO) and prostaglandin E2 (PGE2), key inflammatory mediators, was quantified using the Griess reaction and enzyme-linked immunosorbent assay, respectively.Protein expression levels of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) were assessed by Western blot analysis.Results: All PEs dose-dependently inhibited LPS-PG-induced NO and PGE2 production within nontoxic concentration ranges in RAW 264.7 cells (p0.05).Furthermore, PEs at a concentration of 20 g/ml markedly reduced the protein expression of iNOS and COX-2, which regulate the production of NO and PGE2.Conclusion: Korean propolis effectively suppresses LPS-PG-induced inflammatory responses, with comparable inhibitory effects observed across all regional extracts.These findings suggest that Korean propolis may serve as a natural anti-inflammatory agent for adjunctive prevention and treatment of periodontitis.