Abstract
Background: Micro-organisms resistant to most of the commercial antibiotics are rapidly
expanding and there is an urgent need for detection of novel antimicrobial compounds.
Tooth decay is a dental infection with bacterial sources such as Streptococcus mutans and
Streptococcus sanguis.
Objectives: The present study aimed to evaluate the in vitro antibacterial effects of different
concentrations of Citrus limon peel, pineapple fruit, and pineapple peel extracts on oral
pathogens such as S. mutants and S. sanguis.
Materials and Methods: In this experimental study, the hydroethanolic extracts of the selected
plants were prepared by maceration method and their antibacterial effects were evaluated by
agar well diffusion method.
Results: Two-fold dilutions of plant extract solutions were tested to determine the minimum
inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) against each
selected microorganism. The results of the current study revealed that pineapple peel extracts
had the highest antibacterial effect on S. sanguis (MIC: 1.56 mg/mL and MBC: 3.12 mg/mL).
Pineapple fruit had the lowest antibacterial activity against S. mutans (MIC: 25 mg/mL and MBC:
100 mg/mL). C. limon peel had significant antibacterial activity against S. mutans and S. sanguis.
Conclusion: The peel of C. limon and pineapple had significant antibacterial activity against
cariogenic microorganisms such as S. mutans and S. sanguinis.