Antibacterial activity of melatonin against prime periodontal pathogens: An in vitro study

Abstract

Aim: Accumulated data make it clear that by introducing large amount of antibiotics into the ecosystem, we have provided an environment conducive to antibiotic resistance and periodontal microbes are no different. Therefore, in the quest of finding a suitable drug as an alternate to antibiotic, we investigated the antibacterial activity of melatonin against predominantly Gram-negative periodontal pathogens in vitro. Melatonin with varied functions has driven its usage enormously; therefore, identifying its action against periodontal pathogens has driven this laboratory investigation. Materials and Methods: American type culture collection (ATCC) strains of Porphyromonas gingivalis, Fusobacterium nucleatum, and Aggregatibacter actinomycetemcomitans were used to determine minimum inhibitory and bactericidal concentrations (MIC and MBC) of melatonin using macro broth dilution method. MIC values were determined at 24, 48, and 72 h and sensitive MIC values were sub-cultured to determine MBC value at 24 h. Qualitative data were obtained and it was recorded as “sensitive” or “resistant” at respective concentrations. Results: When tested over a dilution range of 0.2–100 µg/mL, melatonin significantly inhibited microbial growth. At 48 h, the MIC value against A. actinomycetemcomitans, P. gingivalis, and F. nucleatum was 6.25, 0.8, and ≤0.2 µg/mL, respectively. The MBC value determined at 24 h demonstrated significant bactericidal activity against the pathogens. Conclusion: Melatonin exhibited bactericidal activity against prime periodontal pathogens even at low concentrations in comparison to previously documented evidences suggesting greater potency of the drug. Hence, renewed effort to find and develop new class of drug which can inhibit periodontal pathogens, rather than just improvements on already-existing drugs can potentially prevent the development of resistant strains in periodontal microenvironment.