Comparison of Antibacterial Activity of Cymbopogon citratus Ethanol Extract and Essential Oil against Streptococcus mutans

This study examined the antibacterial effects of a lemongrass (Cymbopogon citratus) ethanol extract (LGEE) and essential oil (LGEO) against Streptococcus mutans. The antibacterial effects of LGEE were tested at concentrations of 125 mg/mL, 250 mg/mL, and 500 mg/mL. LGEO was analyzed at doses of 5%, 10%, 20%, and 30%. The results were obtained using the disc diffusion method, minimum inhibitory concentration (MIC), and minimum bactericidal concentration (MBC). The growth inhibition effect was measured 3, 6, 12, 24, and 48 hr after treatment. The growth inhibition effect of LGEE and LGEO was 14.89 mm at 125 mg/mL and 18.56 mm at 5%, respectively. Hence, the antibacterial effect of LGEO was stronger than that of LGEE. The MIC values of LGEE and LGEO were 0.8 mg/mL and 0.6-1.2% (v/v), respectively. The MBCs in LGEE and LGEO were 1.6 mg/mL and 1.2% (v/v), respectively. The growth inhibitory effects after 48 hr of incubation were 0.144 at 125 mg/mL, 0.132 at 250 mg/mL, and 0.123 at 500 mg/mL for LGEE compared to 0.603 for the positive control. In contrast, LGEO was 0.128 at 5%, 0.117 at 10%, 0.108 at 20%, and 0.105 at 30% compared to 0.628 for the positive control. As a result, the LGEE and LGEO exhibited significant antibacterial activity against S. mutans. A comparison of both agents revealed LGEO to have more potent antibacterial activity than LGEO. Lemongrass has been used as a tea and a spice in food, especially lemongrass oil, which has diverse uses because of its versatility. Future studies should examine the antibacterial effects of a lemongrass water extract, a lemon-like flavoring ingredient that can be easily added to children’s beverages, and different approaches to prevent dental caries.