In Vitro Synergistic Antibacterial Effects of Extract and Honey Derived from Nigella Sativa on Streptococcus Mutans : Antibacterial Effects of Nigella Sativa Extract and Honey.

Background: This study aimed to assess the synergistic antibacterial effects of Nigella sativa extract and honey on Streptococcus mutans. Materials and Methods: In this in vitro study, the minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) of extract and honey derived from N.sativa were determined. The antibacterial activity of 1%, 2%, 3%, 4% and 5% extract and honey derived from N.Sativa was then evaluated against S. mutans by the agar disc diffusion method. Data were analyzed by ANOVA followed by pairwise comparisons by the Tukey's test and paired sample t-test. Results: N. sativa extract showed inhibitory effects on S. mutans. The MIC was 250 mg/mL for 1% and 2% concentrations and 125 mg/mL for 3%, 4%, and 5% concentrations of the mixture against S. mutans. In addition, the MBC was determined to be 500 mg/mL for the 1% and 2% concentrations, while it was 250 mg/mL for the 3%, 4%, and 5% concentrations. However, N. sativa honey did not have any antibacterial activity against S. mutans. Combination of N. sativa extract and honey had a significant inhibitory effect on S. mutans. Amount of 1000 mg/mL concentration of 5% honey and N. sativa caused the largest growth inhibition zone (13 mm) with no significant difference with 0.2% chlorhexidine as control (12 mm) (P=0.74). Conclusion: N. sativa honey alone did not demonstrate any significant effect on inhibiting the growth of S. mutans. The combination of N. sativa and honey had an inhibitory effect on the growth of S. mutans. Increased concentration of N. sativa result in a greater inhibition of S. mutans growth.