Antibacterial and Anti-inflammatory Potential of Morus alba Stem Extract

Periodontitis, a chronic inflammatory disease, is the leading cause of tooth loss in adults. Evidence for the anti inflammatory activity of M. alba Stem Extract (MSE) in periodontal disease is limited.

The study aimed to investigate the inhibitory effect of MSE on the growth of periodontopathic bacteria and expression of interleukin (IL)-6 and IL-8 in Porphyromonas gingivalis Lipopolysaccharide (LPS)-stimulated human Periodontal Ligament (hPDL) fibroblasts.

The antimicrobial activities of MSE were tested against P. gingivalis and Actinobacillus actinomycetemcomitans by the disk diffusion, the minimum inhibitory concentration and the minimal bactericidal concentration methods. Cytotoxicity of P. gingivalis LPS and MSE on hPDL fibroblasts was determined by MTS assay. The expression of cytokines (IL-6 and IL-8) mRNA and proteins in hPDL fibroblasts was measured using the reverse transcription-qPCR and enzyme-linked immunosorbent assay, respectively.

MSE exhibited antibacterial activities against P. gingivalis and A. actinomycetemcomitans with the zones of inhibition of 10.00 ± 0.33 mm and 17.33 ± 0.58 mm, respectively. MIC and MBC values for MSE against P. gingivalis were 62.5 μg/ml. The MIC and MBC values against A. actinomycetemcomitans were 250 μg/mL and 500 μg/ml, respectively. P. gingivalis LPS was shown to mediate the expression of pro-inflammatory cytokines in hPDL fibroblasts. However, treatment with MSE concentrations of 2.5 and 5.0 μg/ml significantly suppressed P. gingivalis LPS-induced IL-6 and IL-8 mRNA and protein expression (p< 0.05).

The present study demonstrates that MSE has antibacterial activity against two putative periodontal pathogens. MSE suppressed IL-6 and IL-8 expression in P. gingivalis LPS-stimulated hPDL fibroblasts, indicating a possible anti-inflammatory effect. Thus, it is a potential adjunctive agent for the treatment of periodontitis.