Insight Into the Anti-staphylococcal Activity of JBC 1847 at Sub-Inhibitory Concentration

Abstract

Multidrug-resistant pathogens constitute a serious global issue and, therefore, novel antimicrobials with new modes of action are urgently needed. Here, we investigated the effect of a phenothiazine derivative (JBC 1847) with high antimicrobial activity on Staphylococcus aureus, using a wide range of in vitro assays, flow cytometry, and RNA transcriptomics. The flow cytometry results showed that JBC 1847 rapidly caused depolarization of the cell membrane, while the macromolecule synthesis inhibition assay showed that the synthesis rates of DNA, RNA, cell wall, and proteins, respectively, were strongly decreased. Transcriptome analysis of S. aureus exposed to sub-inhibitory concentrations of JBC 1847 identified a total of 78 downregulated genes, whereas not a single gene was found to be significantly upregulated. Most importantly, there was downregulation of genes involved in adenosintrifosfat (ATP)-dependent pathways, including histidine biosynthesis, which is likely to correlate with the observed lower level of intracellular ATP in JBC 1847–treated cells. Furthermore, we showed that JBC 1847 is bactericidal against both exponentially growing cells and cells in a stationary growth phase. In conclusion, our results showed that the antimicrobial properties of JBC 1847 were primarily caused by depolarization of the cell membrane resulting in dissipation of the proton motive force (PMF), whereby many essential bacterial processes are affected. JBC 1847 resulted in lowered intracellular levels of ATP followed by decreased macromolecule synthesis rate and downregulation of genes essential for the amino acid metabolism in S. aureus. Bacterial compensatory mechanisms for this proposed multi-target activity of JBC 1847 seem to be limited based on the observed very low frequency of resistance toward the compound.

Bacterial proton motive force as an unprecedented target to control antimicrobial resistance

“…Furthermore, the emergence of some synthesized compounds aimed at disrupting ΔΨ is also exciting. JBC 1847, a phenothiazine derivative, is a positively charged cationic amphiphilic compound exhibiting significantly improved antistaphylococcal activity through membrane depolarization 47 . Likewise, oritavancin is a semisynthetic lipoglycopeptide effective in eliminating S. aureus cells in an exponential growth state 48 .…”

“…JBC 1847, a phenothiazine derivative, is a positively charged cationic amphiphilic compound exhibiting significantly improved antistaphylococcal activity through membrane depolarization. 47 Likewise, oritavancin is a semisynthetic lipoglycopeptide effective in eliminating S. aureus cells in an exponential growth state. 48 The underlying mechanisms include cell wall injury and membrane potential disruption.…”

Unveiling the critical roles of cellular metabolism suppression in antibiotic tolerance

“…Compounds that disrupt PMF have the potential to combat bacterial infections, as demonstrated by certain FDA-approved drugs like daptomycin and telavancin, which disrupt the ΔΨ component 47,48 . Moreover, synthetic compounds such as JBC 1847 and oritavancin, along with antimicrobial peptides like WRK-12 and WW307, have shown antibacterial activities by disrupting ΔΨ through membrane depolarization [49][50][51][52] . Natural products like flavones and synthetic compounds like halicin, on the other hand, have been found to dissipate ΔpH 53,54 .…”

A natural inhibitor of diapophytoene desaturase attenuates methicillin‐resistant Staphylococcus aureus (MRSA) pathogenicity and overcomes drug‐resistance

“…Additionally, alnustone demonstrated a pronounced down‐regulatory effect on histidine genes. Histidine, an essential amino acid crucial for bacterial growth, plays a fundamental role in synthesizing and repairing cell membranes, ensuring their stability (Ronco et al, 2022). It also actively contributes to bacterial division and reproduction and is integral to the immune response, safeguarding bacteria from the external environment (Leijten et al, 2022).…”