Title

Natural products show diverse mechanisms of action against Clostridium difficile

Document Type

Journal Article

Publication Title

Journal of Applied Microbiology

ISSN

1365-2672

Volume

126

Issue

2

First Page

468

Last Page

479

PubMed ID

30412324

Publisher

Blackwell Publishing Ltd

School

School of Medical and Health Sciences

RAS ID

29588

Comments

Originally published as: Roshan, N., Riley, T. V., Knight, D. R., Steer, J. H., & Hammer, K. A. (2019). Natural products show diverse mechanisms of action against clostridium difficile. Journal of Applied Microbiology, 126(2), 468-479. Original article available here

Abstract

AIMS: To investigate the mechanisms of action of natural products with bactericidal (cinnamon root powder, peppermint oil, trans-cinnamaldehyde, menthol and zingerone) or bacteriostatic (fresh garlic bulb extract, garlic clove powder, Leptospermum honey and allicin) activity against two Clostridium difficile strains.

METHODS AND RESULTS: Bactericidal products significantly reduced intracellular ATP after 1 h (P ≤ 0·01), quantified using the BacTiter-Glo reagent, and damaged the cell membrane, shown by the leakage of both 260-nm-absorbing materials and protein, and the uptake of propidium iodide. Bacteriolysis was not observed, determined by measuring optical density of treated cell suspensions at 620-nm. The effect of three bacteriostatic products on protein synthesis was quantified using an Escherichia coli S30 extract system, with Leptospermum honey (16% w/v) showing significant inhibition (P < 0·01). Lastly, no products showed elevated minimum inhibitory concentrations against antimicrobial-resistant C. difficile, determined by broth microdilution.

CONCLUSIONS: Cytoplasmic membrane damage was identified as a mechanism of action that may contribute to the activity of several natural products against C. difficile.

SIGNIFICANCE AND IMPACT OF THE STUDY: This study describes the possible mechanisms of action of natural products against C. difficile, yet the efficacy in vivo to be determined.

DOI

10.1111/jam.14152

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