Chemical Composition, Antimicrobial Activity and Mechanism of Action of Essential Oil from the Leaves of M acleaya Cordata (Willd.) R. Br

Abstract

The essential oil from the leaves of Macleaya cordata R. Br. obtained by hydrodistillation was analyzed by gas chromatography/mass spectrometry (GC/MS). Sixty-eight compounds consisting up to 92.53% of the essential oil were identified by GC and GC/MS analysis. The antibacterial activity and minimum inhibitory concentration (MIC) of the essential oil against several pathogens were evaluated. The results showed that bacteria had different sensitivities to essential oil of M. cordata with diameters of inhibition zones ranging from 8.5 ± 0.6 to 18.6 ± 1.9 mm and MIC values from 125 to 500 μg/mL. Among these bacteria, Ralstonia solanacearum was the most sensitive to essential oil. In addition, kill-time assay also showed that the essential oil had a significant effect on the growth rate of surviving R. solanacearum. We concluded that the mechanism of action of the essential oil against R. solanacearum might be described as essential oil acting on membrane integrity according to the results of the leakage of electrolytes, the losses of content (proteins and reducing sugars) assays and electron microscopy observation. The treated cell membranes were severely damaged. The results presented here indicate that the essential oil of M. cordata may be a potential source of antimicrobial agents in the future. Practical Applications Crop diseases, food poisoning and food spoilage caused by microorganisms are still the most important issues facing the food industry and consumers. Today, essential oils with antioxidant and antimicrobial activities are ideal resources in the field of research on food and feed additives. The chemical composition of the essential oil from the leaves of Macleaya cordata was analyzed. The essential oil showed antimicrobial activities. In addition, kill-time assay also showed that the essential oil had a significant effect on the growth rate of surviving Ralstonia solanacearum. We concluded that the mechanism of action of the essential oil against R. solanacearum might be described as essential oil acting on membrane integrity according to the results of the leakage of electrolytes, the losses of proteins and reducing sugars, and electron microscopy observation. Hence, the essential oil of M. cordata may be suggested as a new potential source of natural antimicrobial agent.