title: Aspidin BB, a phloroglucinol derivative, exerts its antibacterial activity against Staphylococcus aureus by inducing the generation of reactive oxygen species.
abstract: Aspidin BB, a phloroglucinol derivative extracted from Dryopteris fragrans (L.) Schott, has been previously reported to exert high biological activities. In the present study, antibacterial activities and mechanisms of aspidin BB against Staphylococcus aureus were investigated. Aspidin BB exhibited strong antibacterial activity against standard and three clinical S. aureus, with minimal inhibition concentration (MIC) values ranging from 15.63 μg/mL to 62.5 μg/mL. After treatment with aspidin BB for 72 h using the MTT assay, the IC50 value was 48.14 μM (22.11 μg/mL). The time-kill assay indicated that aspidin BB could kill S. aureus completely at 2 MIC (MBC) within 4 h. Aspidin BB was capable to induce an increase in NADPH oxidase activity from 4.03 U/mg to 7.48 U/mg when the concentrations were increased from 1/2 MIC to 4 MIC. Simultaneously, aspidin BB attenuated antioxidant defense by decreasing superoxide dismutase (SOD) activity and glutathione (GSH) levels. The level of reactive oxygen species (ROS) was apparently elevated when measuring OD575. This phenomenon was blocked by pretreatment of S. aureus with the antioxidant compound catalase (200 U/mL) and the survival rate of S. aureus increased from 3.95% to 73.04%. These results showed that ROS was indeed an important mediator in the antibacterial action of aspidin BB. In addition, aspidin-BB-induced peroxidation of membranes, DNA damage and protein degradation of S. aureus were all verified in a dose-dependent manner. In conclusion, aspidin BB induced generation of ROS by activating NADPH oxidase activity and inhibiting SOD activity and GSH levels, damaging the membrane, DNA and proteins and finally led to cell death.
authors.affiliation: Engineering Research Center of Forest Bio-Preparation, Ministry of Education, Northeast Forestry University, Harbin 150040, PR China.
authors.forename: Na
authors.initials: N
authors.lastname: Li
authors.affiliation: College of Basic Medical Science, Peking University Health Science Center, Beijing 100083, PR China.
authors.forename: Chang
authors.initials: C
authors.lastname: Gao
authors.affiliation: Engineering Research Center of Forest Bio-Preparation, Ministry of Education, Northeast Forestry University, Harbin 150040, PR China.
authors.forename: Xiao
authors.initials: X
authors.lastname: Peng
authors.affiliation: Engineering Research Center of Forest Bio-Preparation, Ministry of Education, Northeast Forestry University, Harbin 150040, PR China.
authors.forename: Wei
authors.initials: W
authors.lastname: Wang
authors.affiliation: Engineering Research Center of Forest Bio-Preparation, Ministry of Education, Northeast Forestry University, Harbin 150040, PR China.
authors.forename: Meng
authors.initials: M
authors.lastname: Luo
authors.affiliation: Engineering Research Center of Forest Bio-Preparation, Ministry of Education, Northeast Forestry University, Harbin 150040, PR China. Electronic address: yujie_fu@163.com.
authors.forename: Yu-jie
authors.initials: YJ
authors.lastname: Fu
authors.affiliation: Engineering Research Center of Forest Bio-Preparation, Ministry of Education, Northeast Forestry University, Harbin 150040, PR China. Electronic address: zygorl@126.com.
authors.forename: Yuan-gang
authors.initials: YG
authors.lastname: Zu
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000494:pharmacology*; D002460:Cell Line; D006801:Humans; D008826:Microbial Sensitivity Tests; D010696:Phloroglucinol / Q000031:analogs & derivatives* / Q000737:chemistry / Q000494:pharmacology; D017382:Reactive Oxygen Species / Q000378:metabolism*; D013203:Staphylococcal Infections / Q000382:microbiology; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism*
chemical_list: D000900:Anti-Bacterial Agents; D017382:Reactive Oxygen Species; D010696:Phloroglucinol; C010302:aspidin BB
keywords: Aspidin BB; DNA; Dryopteris fragrans; Membrane; Protein; Reactive oxygen species