Antimicrobial activity and time-kill kinetics of Boesenbergia rotunda essential oil and geraniol alcohol against oral bacterial pathogens

Abstract

Boesenbergia rotunda (L.) Mansf. demonstrates remarkable antimicrobial activity against various pathogenic bacteria. However, there have been no reports on the bactericidal activity of the essential oils from B. rotunda (BREO) with active components against oral pathogenic bacteria. In this investigation, the antibacterial potency of BREO against oral pathogenic bacteria was comprehensively assessed. The evaluation of antibacterial activities was performed using agar disc diffusion, broth microdilution, and time-kill kinetics assays. Active antibacterial compounds were determined by thin-layer chromatography (TLC)-bioautography. The chemical composition was determined through gas chromatography-mass spectrometry. Inhibition zones against Streptococcus pyogenes, Streptococcus mutans, and Streptococcus sobrinus ranged between 19.81 ± 0.62 mm and 22.22 ± 5.59 mm. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were found to be between 6.25 and 12.5 mg/ml. A bactericidal effect was indicated by the MIC/MBC ratio. The time-kill assay revealed that a concentration of 4 × MIC could kill 99.99% of the tested bacteria after 1 minute of treatment. The major constituents of BREO were beta-ocimene (40.82%), followed by geraniol (16.79%) and camphor (16.01%). The TLC-bioautography of the bacteria identified geraniol as an active antibacterial compound. These results suggest that BREO is a viable ingredient for the development of natural oral care products.