Evaluation of Plant Essential Oils as Natural Alternatives for Alcohol-based Mouthwashes: Spotlight—Lemongrass and Citronella Java

Objective The purpose of our study was to evaluate plant-derived essential oils (EOs) as natural alternatives to commercial alcohol-based mouthwashes in the prevention of dental caries since several recent studies have linked high incidence of oral cancer among users with a history of prolonged use of alcohol-based mouthwashes. Materials and Methods Lemongrass, Citronella Java, Gingergrass, and Caraway seed EOs were tested against commonly occurring multidrug-resistant (MDR) oral bacteria namely Micrococcus luteus, Enterococcus faecalis, Streptococcus oralis, and Streptococcus salivarius. Agar well diffusion method was used to determine the antibacterial effectiveness of these EOs. Samples of Citronella Java and Lemongrass EO were also analyzed by gas chromatography (GC). Results Lemongrass and Citronella Java exhibited the highest antibacterial activity against all four bacterial strains. Inhibition zones of Lemongrass were 12, 21.3, 28.3, and 32 mm in diameter against E. faecalis, M. luteus, S. oralis, and S. salivarius, respectively. In comparison, inhibition zones of Citronella Java were 11.5, 17, 20.7, and 20.2 mm in diameter against E. faecalis, M. luteus, S. oralis, and S. salivarius, respectively. A significant finding in our study was that antibacterial activity of Lemongrass was much higher than that of tetracycline, a broad-spectrum antibiotic, against S. oralis and S. salivarius, while the inhibitory effects of Citronella Java against these two oral streptococci were comparable to tetracycline. The major components of Citronella Java identified by GC were citronellal, citronellol, and geraniol, whereas Lemongrass was primarily composed of cis and trans forms of citral. Conclusion Our results suggest that Lemongrass and Citronella Java could be promising natural alternatives to alcohol-based mouthwashes against MDR oral bacteria in the prevention of dental caries.