Chemical Composition and Antibacterial Activity of the Essential Oil from Qiancao (Rubia cordifolia Linn.) Roots against Selected Foodborne Pathogens

Chemical composition of the essential oil from Qiancao roots was analyzed by gas chromatography-mass spectrometry (GC-MS), and 43 components were identified in the paper. Mollugin (30.58%) was found to be the major component, followed by 3-methyl-2-cyclopenten-1-one (10.55%), 4-tert-butyl-2-phenyl-phenol (8.64%) and eugenol (6.30%). The antibacterial activity of essential oil against selected food-borne pathogens was evaluated. The results showed that the sensitivity to essential oil were different for different tested bacteria and the essential oil had a strong antibacterial activity against B. cereus with the lowest minimum inhibitory concentration (MIC) and minimum bactericide concentration (MBC) values of 0.0625 and 0.125 mg/mL, respectively. In addition, microbial growth curve assay also showed that the essential oil had a significant effect on the growth rate of surviving B. cereus. The data of this study suggests that the essential oil from Qiancao roots has great potential for application as a natural antimicrobial agent to preserve food.