IADR Abstract Archives
Bismuth Inhibits Porphyromonas gingivalis through Replacing Ferrous Ion in Hemin
Objectives: Porphyromonas gingivalis is regarded as a ‘keystone’ periodontopathogen, preferentially acquiring iron-based metabolism for its growth. Bismuth as a classical drug against Helicobacter pylori is able to replace the iron in transferrin, while its effects on P. gingivalis remains unknown. This study explored the potential effects of bismuth on P. gingivalis and the underlying molecular mechanisms.
Methods: The MICs of ranitidine bismuth citrate and metronidazole for P. gingivalis were determined with its initial CFU at 106/ml. The UV-vis spectra of 10 µM of hemin was scanned from 700-200 nm, and the bismuth nitrilotriacetic acid was titrated in aliquots to monitor the replacement of ferrous ion in hemin. At the early log phase of P. gingivalis culture, 25 µM of ranitidine bismuth citrate was added for 24 h treatment.
Results: The MIC of ranitidine bismuth citrate for P. gingivalis was 50 µM, and the MIC of metronidazole was 0.25 µg/ml. Initial data showed that the combination of bismuth compounds with metronidazole could decrease the dosages of both drugs against P. gingivalis by over 4 folds, indicating the synergistic effects of bismuth on metronidazole. Titration of bismuth compound into hemin solution led to the decrease of the intensity of the characteristic peak at 388 nm for hemin (iron-bound) on UV-vis spectra and the increase of the peak at 425 nm, suggesting that bismuth could successfully extract ferrous ion from hemin. Moreover, P. gingivalis accumulated 523 µg of bismuth per gram of dry cells after 24 h treatment with ranitidine bismuth citrate.
Conclusions: This novel study suggests that the absorbed bismuth could inhibit the growth of P. gingivalis by replacing ferrous ion in hemin and other iron-containing compounds and proteins. Further study is highly warranted to determine the clinical implications of the current findings.
Methods: The MICs of ranitidine bismuth citrate and metronidazole for P. gingivalis were determined with its initial CFU at 106/ml. The UV-vis spectra of 10 µM of hemin was scanned from 700-200 nm, and the bismuth nitrilotriacetic acid was titrated in aliquots to monitor the replacement of ferrous ion in hemin. At the early log phase of P. gingivalis culture, 25 µM of ranitidine bismuth citrate was added for 24 h treatment.
Results: The MIC of ranitidine bismuth citrate for P. gingivalis was 50 µM, and the MIC of metronidazole was 0.25 µg/ml. Initial data showed that the combination of bismuth compounds with metronidazole could decrease the dosages of both drugs against P. gingivalis by over 4 folds, indicating the synergistic effects of bismuth on metronidazole. Titration of bismuth compound into hemin solution led to the decrease of the intensity of the characteristic peak at 388 nm for hemin (iron-bound) on UV-vis spectra and the increase of the peak at 425 nm, suggesting that bismuth could successfully extract ferrous ion from hemin. Moreover, P. gingivalis accumulated 523 µg of bismuth per gram of dry cells after 24 h treatment with ranitidine bismuth citrate.
Conclusions: This novel study suggests that the absorbed bismuth could inhibit the growth of P. gingivalis by replacing ferrous ion in hemin and other iron-containing compounds and proteins. Further study is highly warranted to determine the clinical implications of the current findings.