Investigation on the Antibacterial Activity of Electronic Cigarette Liquids (ECLs): A Proof of Concept Study

Author(s): Virginia Fuochi, Massimo Caruso, Rosalia Emma, Aldo Stivala, Riccardo Polosa, Alfio Distefano, Pio M. Furneri*

Journal Name: Current Pharmaceutical Biotechnology

Volume 22 , Issue 7 , 2021


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Abstract:

Background: The key ingredients of e-cigarettes liquid are commonly propane-1,2-diol (also called propylene glycol) and propane-1,2,3-triol (vegetal glycerol) and their antimicrobial effects are already established. The nicotine and flavors which are often present in e-liquids can interfere with the growth of some microorganisms. Objective: The effect of combining these elements in e-liquids is unknown. The aim of the study was to investigate the possible effects of these liquids on bacterial growth in the presence or absence of nicotine and flavors.

Methods: Susceptibilities of pathogenic strains (Klebsiella pneumoniae, Staphylococcus aureus, Pseudomonas aeruginosa, Acinetobacter baumannii, Escherichia coli, Enterococcus faecalis and Sarcina lutea) were studied by means of a multidisciplinary approach. Cell viability and antioxidant assays were also evaluated.

Results: All e-liquids investigated showed antibacterial activity against at least one pathogenic strain. Higher activity was correlated to the presence of flavors and nicotine.

Discussion: In most cases, the value of minimal bactericidal concentration is equal to the value of minimal inhibitory concentration showing that these substances have a bactericidal effect. This effect was observed in concentrations up to 6.25% v/v. Antioxidant activity was also correlated to the presence of flavors. Over time, the viability assay in human epithelial lung A549 cells showed a dose-dependent inhibition of cell growth.

Conclusion: Our results have shown that flavors considerably enhance the antibacterial activity of propane-1,2-diol and propane-1,2,3-triol. This study provides important evidence that should be taken into consideration in further investigative approaches, to clarify the different sensitivity of the various bacterial species to e-liquids, including the respiratory microbiota, to highlight the possible role of flavors and nicotine.

Keywords: Electronic cigarettes, e-liquids, flavors, nicotine, propane-1, 2-diol, propane-1, 2, 3-triol, antibacterial activity.

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Article Details

VOLUME: 22
ISSUE: 7
Year: 2021
Published on: 03 September, 2020
Page: [983 - 994]
Pages: 12
DOI: 10.2174/1389201021666200903121624

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