https://pubmed.ncbi.nlm.nih.gov/37716416/
The cosmetics industry faces a significant challenge with the potential for microbial contamination. Consequently, the utilization of preservatives or other preservation methods holds immense importance and is an absolute necessity. In the contemporary context, numerous preservatives have garnered unfavorable associations due to their propensity to trigger allergic reactions, as well as irritate the skin, eyes, and lungs. Nonetheless, there is an ongoing systematic quest for fresh preservatives tailored to various applications.
Within the cosmetic industry, there is a distinct emphasis on plant extracts and substances derived from plants. The research published on Chemistry and Physics of Lipids aims to validate the antibacterial properties of a commercially available natural preservative, Leucidal® Liquid (Leucidal), obtained from radishes, on specific pathogenic bacterial species, as well as to delve into the impact of this formulation on simulated bacterial lipid membranes.
To gain insights into the mechanism of action of this formulation, lipid Langmuir monolayers mimicking the membranes of Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) was prepared. Subsequently, the influence of Leucidal on these model systems was analysed by conducting surface pressure/area measurements, penetration studies, and visualizing the results using Brewster Angle Microscopy (BAM). Similar experiments on monolayers composed of individual model membrane lipids were also performed. In vitro tests were conducted on five distinct bacterial species (E. coli, Enterococcus faecalis, S. aureus, Salmonella enterica, Pseudomonas aeruginosa).
The study revealed that Leucidal led to a reduction in the tightness of the monolayers, but at higher concentrations, it was excluded from the films. Model membrane experiments also exhibited a stronger affinity of the components of this eco-preservative for E. coli membranes as opposed to S. aureus membranes. Among the single-component films, those comprised of phosphatidylglycerols and cardiolipins were more susceptible to the presence of Leucidal. However, in vitro tests demonstrated that Leucidal had a more potent inhibitory effect on S. aureus bacteria in comparison to the E. coli strain.
These discoveries were subject to discussion from the perspective of the role of Leucidal’s components and the properties of the lipid membranes in elucidating the mechanism of action of this preservative.
The results imply that the bacterial membrane may not be the primary target of Leucidal’s action. Furthermore, given that high concentrations of the tested preparation exhibited antibacterial activity against all the tested bacteria, it is conceivable that Leucidal lacks selectivity, which could potentially pose a challenge concerning its impact on the skin microbiome.
