Antibacterial Mechanism of Dihydrotanshinone I

2021 ◽  
Vol 16 (2) ◽  
pp. 1934578X2199615
Author(s):  
Lin Zhao ◽  
Yingying Zhao ◽  
Jinfeng Wei ◽  
Zhenhua Liu ◽  
Changqin Li ◽  
...  

The antimicrobial activity and the underlying action mechanisms of dihydrotanshinone I against Staphylococcus aureus, methicillin-resistant Staphylococcus aureus, extended-spectrum beta-lactamases Staphylococcus aureus were investigated with Kleihauer-Betke (K-B) test. The antibacterial mechanisms of dihydrotanshinone I were investigated by monitoring the changes in electric conductivity, concentration of AKP, protein content, and patterns of protein electrophoretic bands in sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The antibacterial rings showed that antimicrobial activity of dihydrotanshinone I at 18 mM was stronger to Staphylococcus aureus than to methicillin-resistant Staphylococcus aureus and extended-spectrum beta-lactamases Staphylococcus aureus. The minimum inhibitory concentration (MIC) and IC50 values showed that dihydrotanshinone I had the strongest inhibitory activity against S. aureus (MIC = 280 µM, IC50 = 874 ± 0.01 µM, respectively). Dihydrotanshinone I could increase the electric conductivity, concentration of alkaline phosphatase (AKP) and protein content. The patterns of protein bands in SDS-PAGE were changed obviously. Dihydrotanshinone I also significantly inhibited S. aureus, methicillin-resistant S. aureus, and extended-spectrum beta-lactamases S. aureus, indicating that dihydrotanshinone I can damage the structures of cell wall and cell membrane to increase permeability of cell membrane and release of cell components. Dihydrotanshinone I could influence the synthesis of bacterial protein, destroy the protein, or reject the anabolism or expression of the protein, and finally lead to the loss of normal physiological function of bacteria.

Antibiotics ◽  
2021 ◽  
Vol 10 (5) ◽  
pp. 543
Author(s):  
Ozioma F. Nwabor ◽  
Sukanlaya Leejae ◽  
Supayang P. Voravuthikunchai

As the burden of antibacterial resistance worsens and treatment options become narrower, rhodomyrtone—a novel natural antibiotic agent with a new antibacterial mechanism—could replace existing antibiotics for the treatment of infections caused by multi-drug resistant Gram-positive bacteria. In this study, rhodomyrtone was detected within the cell by means of an easy an inexpensive method. The antibacterial effects of rhodomyrtone were investigated on epidemic methicillin-resistant Staphylococcus aureus. Thin-layer chromatography demonstrated the entrapment and accumulation of rhodomyrtone within the bacterial cell wall and cell membrane. The incorporation of radiolabelled precursors revealed that rhodomyrtone inhibited the synthesis of macromolecules including DNA, RNA, proteins, the cell wall, and lipids. Following the treatment with rhodomyrtone at MIC (0.5–1 µg/mL), the synthesis of all macromolecules was significantly inhibited (p ≤ 0.05) after 4 h. Inhibition of macromolecule synthesis was demonstrated after 30 min at a higher concentration of rhodomyrtone (4× MIC), comparable to standard inhibitor compounds. In contrast, rhodomyrtone did not affect lipase activity in staphylococci—both epidemic methicillin-resistant S. aureus and S. aureus ATCC 29213. Interfering with the synthesis of multiple macromolecules is thought to be one of the antibacterial mechanisms of rhodomyrtone.


Molecules ◽  
2021 ◽  
Vol 26 (4) ◽  
pp. 1094
Author(s):  
Melissa M. Cadelis ◽  
Soeren Geese ◽  
Benedict B. Uy ◽  
Daniel R. Mulholland ◽  
Shara J. van de Pas ◽  
...  

Antimicrobial bioassay-guided fractionation of the endophytic fungi Neofusicoccum australe led to the isolation of a new unsymmetrical naphthoquinone dimer, neofusnaphthoquinone B (1), along with four known natural products (2–5). Structure elucidation was conducted by nuclear magnetic resonance (NMR) spectroscopic methods, and the antimicrobial activity of all the natural products was investigated, revealing 1 to be moderately active towards methicillin-resistant Staphylococcus aureus (MRSA) with a minimum inhibitory concentration (MIC) of 16 µg/mL.


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