Physico-Chemical Investigation and Antimicrobial Efficacy of Ozonated Oils: The Case Study of Commercial Ozonated Olive and Sunflower Seed Refined Oils

Background: why researchers looked at ozonated oils as antimicrobials

Rising resistance to conventional antibiotics and antifungals has renewed interest in older, non-pharmaceutical antimicrobial agents. Ozonated vegetable oils, made by bubbling ozone through oils such as olive or sunflower oil, are one such candidate. The reaction converts unsaturated fatty acids into ozonides, peroxides and related oxygen-rich compounds that are thought to disrupt microbial cells. Although ozonated oils are already sold commercially for topical use, the authors noted that the physico-chemical make-up and antimicrobial performance of off-the-shelf products are not always well characterised. This study set out to profile two commercial ozonated oils and test how effectively they killed a panel of clinically relevant microorganisms.

Study design: two commercial oils tested against six microbial species

This was a laboratory study. The researchers examined two commercial ozonated oils, one based on refined olive oil and one on refined sunflower seed oil. They first characterised each oil physically and chemically, measuring markers of ozonation such as peroxide and iodine values and using spectroscopic analysis to describe the chemical changes ozonation had produced. They then tested antimicrobial activity against six species: the yeast Candida albicans, the Gram-positive bacteria Enterococcus faecalis and Staphylococcus aureus, and the Gram-negative bacteria Klebsiella pneumoniae, Pseudomonas aeruginosa and Escherichia coli. To gauge safety for skin contact, the oils were also applied to cultured human keratinocytes and epithelial cells in a cell viability assay. All testing was carried out in vitro, in culture, rather than in animals or people.

Findings: strong activity against yeast and some bacteria, no cell toxicity

Both ozonated oils showed high microbicidal effects against Candida albicans and Enterococcus faecalis, and were also active against Staphylococcus aureus and Escherichia coli. Activity against the other two Gram-negative species, Klebsiella pneumoniae and Pseudomonas aeruginosa, was more limited. The physico-chemical analysis confirmed that ozonation had introduced the expected oxygen-rich reactive species into both oils. In the cell viability assay, neither oil reduced the viability of the cultured keratinocytes or epithelial cells at the concentrations tested, which the authors read as an absence of cytotoxicity in these cell models.

What the authors concluded

The authors concluded that treating vegetable oils with ozone creates a reservoir of antimicrobial species active against a range of microorganisms, and that the two commercial oils they tested were promising candidates for topical antimicrobial applications, including against organisms where drug resistance is a concern. They stressed that their work was a physico-chemical and in vitro characterisation, and pointed to future studies on how the oils might best be delivered through different pharmaceutical formulations.

Limitations of this study

This was an in vitro laboratory study of two commercial ozonated oils. It measured antimicrobial activity against isolated microbial cultures and tested safety only in cultured human cells; it did not involve animals or patients, so it does not show whether the oils prevent or treat infection in real-world use. Activity was uneven across species, being weaker against some Gram-negative bacteria. The results describe two specific commercial products and may not apply to ozonated oils made by other methods or held under different storage conditions, and the study did not track how the oils' activity changes over time. These findings characterise a topical antimicrobial material in the laboratory; they are not clinical evidence and should not be read as showing that ozonated oil treats any human disease.