Bolaamphiphile Analogues of 12-bis-THA Cl2 Are Potent Antimicrobial Therapeutics with Distinct Mechanisms of Action against Bacterial, Mycobacterial, and Fungal Pathogens

Simona Di Blasio, Maria Clarke, Charlotte K. Hind, Masanori Asai, Louis Laurence, Angelica Benvenuti, Mahnoor Hassan, Dorothy Semenya, De De Kwun Wai Man, Victoria Horrocks, Giorgia Manzo, Sarah Van Der Lith, Carolyn Lam, Eugenio Gentile, Callum Annette, Janine Bosse, Yanwen Li, Barry Panaretou, Paul R. Langford, Brian D. RobertsonJenny K.W. Lam, J. Mark Sutton, Michael McArthur, A. James Mason*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

2 Citations (Scopus)

Abstract

12-Bis-THA Cl2 [12,129-(dodecane-1,12-diyl)-bis-(9-amino-1,2,3,4-tetrahydroacri-dinium) chloride] is a cationic bolalipid adapted from dequalinium chloride (DQC), a bactericidal anti-infective indicated for bacterial vaginosis (BV). Here, we used a structure-activity-relationship study to show that the factors that determine effective killing of bacterial, fungal, and mycobacterial pathogens differ, to generate new analogues with a broader spectrum of activity, and to identify synergistic relationships, most notably with aminoglycosides against Acinetobacter baumannii and Pseudomonas aeruginosa, where the bactericidal killing rate was substantially increased. Like DQC, 12-bis-THA Cl2 and its analogues accumulate within bacteria and fungi. More hydrophobic analogues with larger headgroups show reduced potential for DNA binding but increased and broader spectrum antibacterial activity. In contrast, analogues with less bulky headgroups and stronger DNA binding affinity were more active against Candida spp. Shortening the interconnecting chain, from the most lipophilic twelve-carbon chain to six, improved the selectivity index against Mycobacterium tuberculosis in vitro, but only the longer chain analogue was therapeutic in a Galleria mellonella infection model, with the shorter chain analogue exacerbating the infection. In vivo therapy of Escherichia coli ATCC 25922 and epidemic methicillin-resistant Staphylococcus aureus 15 (EMRSA-15) infections in Galleria mellonella was also achieved with longer-chain analogues, as was therapy for an A. baumannii 17978 burn wound infection with a synergistic combination of bolaamphiphile and gentamicin. The present study shows how this class of bolalipids may be adapted further to enable a wider range of potential applications. IMPORTANCE While we face an acute threat from antibiotic resistant bacteria and a lack of new classes of antibiotic, there are many effective antimicrobials which have limited application due to concerns regarding their toxicity and which could be more useful if such risks are reduced or eliminated. We modified a bolalipid antiseptic used in throat lozenges to see if it could be made more effective against some of the highest-priority bacteria and less toxic. We found that structural modifications that rendered the lipid more toxic against human cells made it less toxic in infection models and we could effectively treat caterpillars infected with either Mycobacterium tuberculosis, methicillin resistant Staphylococcus aureus, or Acinetobacter baumannii. The study provides a rationale for further adaptation toward diversifying the range of indications in which this class of antimicrobial may be used.

Original languageEnglish
JournalmSphere
Volume8
Issue number1
DOIs
Publication statusPublished - Jan 2023
Externally publishedYes

Bibliographical note

Funding Information:
This work was supported by a BBSRC CASE studentship (BB/L013576/1) for S.D.B. awarded to A.J.M., an NC3Rs Skills & Knowledge Transfer grant (NC/T001240/1), a joint HKU-KCl studentship for D.K.-W.M. awarded to J.K.W.L., Public Health England, and Procarta Biosystems Ltd. and by the King’s Together Multi and Interdisciplinary Research Scheme (Wellcome Trust Institutional Strategic Support Fund; grant reference [204823/Z/16/Z]).

Publisher Copyright:
Copyright © 2022 Di Blasio et al.

Keywords

  • Galleria mellonella
  • aminoglycosides
  • dequalinium chloride
  • synergy

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