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Maillard reaction products inhibit the periodontal pathogen Aggregatibacter actinomycetemcomitans by chelating iron
Mrinal K Bhattacharjee1, Binal S Mehta2, Bernadine Akukwe1
1Department of Chemistry and Biochemistry, Long Island University, Brooklyn, NY, USA.
Objective:
To determine the mechanism of growth inhibition of Aggregatibacter actinomycetemcomitans by Maillard reaction products (MRP).
Design:
Growth and cell viabilities in the presence or absence of MRP were measured for both the rough and smooth variants of the bacteria. Effects of addition of ferrous and ferric ions on the inhibition of the bacteria by MRP were determined.
Results:
MRPs decreased the extent of complex formation of Chrome Azurol S with iron suggesting that MRPs can chelate iron effectively. The chelation causes growth inhibition of both the rough and smooth strains. At low concentrations of the inhibitor, lag time was extended by approximately 12 h while at high concentrations, cells were killed, decreasing cell viability by up to 8 orders of magnitude. Growth of both the rough and smooth strains could be restored to original level by addition of iron. For the rough strain, both ferrous and ferric ions could relieve the inhibition by MRP while for the smooth strain only ferrous ion was effective.
Conclusion:
MRPs inhibit the growth of A. actinomycetemcomitans by chelating iron and the inhibition can be relieved by addition of iron.
Insights
Maillard reaction products (MRPs) inhibit Aggregatibacter actinomycetemcomitans growth by chelating iron. Adding iron reverses this growth inhibition, restoring bacterial viability.
Area of Science:
- Microbiology
- Bacterial Pathogenesis
- Food Chemistry
Background:
- Aggregatibacter actinomycetemcomitans is a significant oral pathogen.
- Maillard reaction products (MRPs) are formed during food processing and can have biological effects.
- The antimicrobial mechanisms of MRPs are not fully understood.
Purpose of the Study:
- To elucidate the mechanism by which Maillard reaction products (MRPs) inhibit the growth of Aggregatibacter actinomycetemcomitans.
- To investigate the role of iron chelation in MRP-mediated bacterial growth inhibition.
Main Methods:
- Assessing bacterial growth and viability of Aggregatibacter actinomycetemcomitans (rough and smooth variants) with and without MRPs.
- Evaluating the effect of ferrous and ferric ions on MRP-induced growth inhibition.
- Measuring the interaction between MRPs and iron using Chrome Azurol S.
Main Results:
- MRPs effectively chelate iron, indicated by reduced complex formation with Chrome Azurol S.
- Iron chelation by MRPs leads to significant growth inhibition and cell death in both rough and smooth strains.
- Bacterial growth inhibition was dose-dependent, extending lag phase at low concentrations and causing cell death at high concentrations.
- Addition of iron, particularly ferrous ions for the smooth strain, reversed the inhibitory effects of MRPs.
Conclusions:
- Maillard reaction products inhibit Aggregatibacter actinomycetemcomitans growth primarily through iron chelation.
- The iron-chelating activity of MRPs is the key mechanism for growth inhibition.
- Iron supplementation can overcome the bacteriostatic and bactericidal effects of MRPs on this pathogen.
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