Background and Aims: To prevent dental caries, investigations have focused on finding new antibacterial and anti-biofilm agents without the drawbacks of the currently used synthetic agents. This study aimed to assess the effect of methanolic extract of Zingiber officinale (Z. officinale) on expression of virulence genes of Streptococcus mutans (S. mutans) using real-time polymerase chain reaction (PCR).
Materials and Methods: In this in vitro study, which was conducted in the year 1402, at the Microbiology Department of the Faculty of Medicine and the Faculty of Dentistry at Shahid Beheshti University of Medical Sciences, the methanolic extract of Z. officinale was obtained by the maceration technique. 10 clinical isolates of S. mutans were obtained from the patients with dental infection. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of the extract against S. mutans were determined by the microtiter plate technique. The effect of extract on the expression of relA, comDE, brpA, gtfC, and spaP virulence genes by the clinical isolates was evaluated by the real-time polymerase chain reaction (PCR) technique. Data were analyzed by the Wilcoxon and Mann-Whitney tests (alpha=0.05).
Results: The mean MIC and MBC of the methanolic extract of Z. officinale against S. mutans were 32±11.8 and 64±26.12 mg/mL, respectively. The extract caused down-regulation of relA, comDE, brpA, and gtfC by 50%, 40%, 70%, and 70%, respectively. It also caused 4 times reduction in expression of spaP gene.
Conclusion: The methanolic extract of Z. officinale caused significant down-regulation of gtfC, brpA, relA, comDE, and spaP genes, indicating its optimal efficacy to control the virulence of S. mutans.
