The antibacterial mechanism of oridonin against methicillin-resistant Staphylococcus aureus (MRSA)

Abstract

Context: Methicillin-resistant Staphylococcus aureus (MRSA) is a very harmful bacterium. Oridonin, a component in Rabdosia rubescens (Hemsl.) Hara (Lamiaceae), is widely used against bacterial infections in China. Objective: We evaluated oridonin effects on MRSA cell membrane and wall, protein metabolism, lactate dehydrogenase (LDH), DNA and microscopic structure. Materials and methods: Broth microdilution and flat colony counting methods were used to measure oridonin minimal inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) against USA300 strain. Electrical conductivity and DNA exosmosis were analysed to study oridonin effects (128 lg/mL) on cell membrane and wall for 0, 1, 2, 4 and 6 h. Sodium dodecyl sulphate polyacrylamide gel electrophoresis was used to detect effects on soluble protein synthesis after 6, 10 and 16 h. LDH activity was examined with an enzyme-linked immunosorbent assay. Effects of oridonin on USA300 DNA were investigated with DAPI staining. Morphological changes in MRSA following oridonin treatment were determined with scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Results: Oridonin MIC and MBC values against USA300 were 64 and 512 lg/mL, respectively. The conductivity and DNA exosmosis level of oridonin-treated USA300 improved by 3.20±0.84% and increased by 58.63 ± 1.78 lg/mL, respectively. LDH and soluble protein levels decreased by 30.85±7.69% and 27.51 ± 1.39%, respectively. A decrease in fluorescence intensity was reported with time. Oridonin affected the morphology of USA300. Conclusions: Oridonin antibacterial mechanism was related to changes in cell membrane and cell wall permeability, disturbance in protein and DNA metabolism, and influence on bacterial morphology. Thus, oridonin may help in treating MRSA infection.

Thymol Inhibits Biofilm Formation, Eliminates Pre-Existing Biofilms, and Enhances Clearance of Methicillin-Resistant Staphylococcus aureus (MRSA) in a Mouse Peritoneal Implant Infection Model

“…When the OD 600 of the cultures reached 0.3, the bacteria were sub-cultured, and thymol was added at final concentrations of 0, 8, 16, 32 and 64 µg/mL. These subcultures were incubated with continuous shaking (190 rpm), or under static conditions at 37 • C. At various time points, the OD 600 of a 0.5 mL aliquot was measured on an ultraviolet-visible (UV-VIS) spectrophotometer (UNICO, Shanghai, China) [51].…”

“…It is a component of the essential oils extracted from various plants in the Lamiaceae, Verbenaceae, and Scrophulariaceae families, and it exhibits anti-inflammatory, antioxidant and potent antimicrobial properties [22][23][24]. In our previous studies [25] we showed the potent effects of thymol against MRSA infections. Thymol inhibits bacterial growth by altering the membrane permeability and disturbing both protein synthesis and binary fission.…”

“…Thymol inhibits bacterial growth by altering the membrane permeability and disturbing both protein synthesis and binary fission. At subinhibitory concentrations, thymol also reduces biofilm formation [25]. Therefore, in this study, we first investigated the ability of thymol to inhibit biofilm formation and to eliminate mature biofilms in vitro.…”

Oridonin: A Review of Its Pharmacology, Pharmacokinetics and Toxicity

“…Oridonin could also decrease the OVA-induced airway hyper-responsiveness and eosinophil number, and suppress the eosinophilia and mucus production, which confirms its great prospect in the treatment of asthma ( Wang S. et al, 2016 ). In addition, oridonin could effectively ameliorate inflammation-induced bone loss in the model of mice by inhibiting DC-STAMP expression ( Zou et al, 2020 ), halt the growth of methicillin-resistant Staphylococcus aureus (MRSA) ( Yuan et al, 2019 ), mitigate visceral hyperalgesia in a rat model of postinflammatory irritable bowel syndrome ( Zang et al, 2016 ), and augment gamma-globin expression in erythroid precursors from patients ( Guo et al, 2020 ).…”

Determination of Antibacterial Activity of Film Coatings against Four Clinically Relevant Bacterial Strains

“…Lastly, the presence of extracellular DNA was studied as an indicator of cell membrane disruption. To perform this determination we modified the previous protocols from Chen and Cooper (2002) and from Yuan et al (2019).…”