Antibacterial Properties of Ozonated Sunflower (Helianthus Annuus l.) and Sesame (Sesamum Indicum L.) Oils on Staphylococcus Aureus

Background

Staphylococcus aureus is a common bacterium responsible for a wide range of skin, wound and burn infections, and growing antibiotic resistance has pushed researchers to look for natural alternatives that can support wound care. Ozonated plant oils - vegetable oils bubbled with ozone gas until they thicken and take on antimicrobial properties - have been studied as one such option. This 2019 study from researchers at the Islamic Azad University and Urmia University in Iran set out to test whether ozonated sunflower oil and ozonated sesame oil could inhibit the growth of S. aureus in laboratory conditions.

Study design

This was an in vitro laboratory study - conducted in test tubes and petri dishes rather than in animals or people. Sunflower oil (Helianthus annuus L.) and sesame oil (Sesamum indicum L.) were exposed to ozone gas for 72 hours to produce ozonated versions of each oil. The researchers then used an antibiogram (disc diffusion) test to measure how well the ozonated oils inhibited S. aureus growth, comparing four groups: the ozonated sunflower oil, the ozonated sesame oil, the same oils in their pure (non-ozonated) form, the antibiotic ciprofloxacin, and a distilled water negative control. Inhibition zones - the clear area around a sample where bacterial growth is stopped - were measured after 24 and 48 hours. The researchers also calculated the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) for each ozonated oil, which describe the lowest concentration needed to stop bacterial growth and to kill the bacteria outright.

Findings

Both ozonated oils produced measurable zones of inhibition against S. aureus, though these were smaller than the ciprofloxacin antibiotic and the ozonated water comparison. At 24 hours, the antibiotic produced roughly a 12mm inhibition zone, ozonated water around 8mm, ozonated sesame oil around 4mm and ozonated sunflower oil around 3mm. The researchers reported statistically significant differences (p ≤ 0.05) between the ozonated oils and both the pure, non-ozonated oils and the distilled water negative control at 24 and 48 hours. Both ozonated oils also showed measurable MIC and MBC values, in the low hundredths-of-a-milligram-per-millilitre range, indicating that only small concentrations were needed to inhibit and kill the bacteria in this laboratory setting.

What the authors concluded

The authors concluded that ozonated sunflower and sesame oils showed genuine antibacterial activity against S. aureus in vitro, and suggested that both oils could be considered as inhibitors of S. aureus growth in pharmaceutical formulations such as wound and burn healing ointments.

Limitations of this study

This was a small, single-laboratory in vitro study using standard antibiogram, MIC and MBC testing - it did not involve animals or human participants, so the results describe what happened to bacteria in a controlled laboratory setting rather than what would happen on real skin, wounds or in clinical use. The inhibition zones produced by the ozonated oils were notably smaller than those produced by the antibiotic comparison, and the study did not test the oils in a finished wound-care formulation, at different ozonation times, or against other bacterial species. Larger studies, including clinical trials on real wounds, would be needed before firm conclusions could be drawn about how these oils perform in practice.