Abstract:The compositions and possible mechanism of industrial hemp (Cannabis sativa L.) leaves against Staphylococcus aureus (S. aureus) were evaluated to provide a theoretical basis for the development of promising alternatives for natural preservatives based on the components of industrial hemp leaves. The main active components were extracted by ethanol and ethyl acetate sequentially, and then separated through silica gel column. The minimum inhibitory concentration (MIC) was determined using micro-dilution method to obtain components with high activity, and the antimicrobial components were analyzed by GC-MS. Furthermore, changes in cell wall integrity, cell membrane permeability, energy metabolism as well as oxidative damage before and after the treatment were measured to explore the antibacterial mechanism. Results showed that Fr5 (petroleum ether : ethyl acetate=1:1) exhibited a better effect on S. aureus with the MIC of 31.25 μg/mL, and 24 compounds were totally identified. After bacteria are treated with Fr5, apparent deformation was observed on the surface of bacteria, extracellular alkaline phosphatase (AKP) content increased, while the electric conductivity, nucleic acid content, and soluble protein content rose. Meanwhile, the concentration of adenosine triphosphate (ATP) and the activity of superoxide dismutase (SOD) in bacteria were firstly increased and then decreased. Therefore, Fr5 fractions could damage the structure of cell wall and cell membrane of S. aureus, leading to the increase of membrane permeability and thus releasing cell contents, which affected bacterial metabolism and caused oxidative damage to plasma membrane, and finally inhibited the cell growth and metabolism.
