There have been increased demands by consumers for natural compounds able to enhancing food quality and safety. In consequence, many have proposed the substitution of synthetic antioxidants with plant extracts.

Bioactive tea tree oil (TTO) and hemp seed oil (HSO) are of particular interest as a consequence of their antioxidant and antimicrobial properties.

Study: The Biological Activity of Tea Tree Oil and Hemp Seed Oil. Image Credit: ronstik / Shutterstock.com

Background

TTO is obtained from the Melaleuca alternifolia plant of the Myrtle family and is well-known for its antimicrobial properties.

A tea tree is a tree or shrub that constitutes a papery bark and may grow as much as 14 meters in height. This plant originated from Australia and may thrive in mostly warm temperatures. Steam distillation is often used for the extraction of energetic components of the tea tree plant, most of that are terpenes.

Following harvest, cold pressing of hemp seeds allows for the extraction of HSO. Cannabidiol (CBD) content in HSO will be either low or high; nevertheless, no comparison regarding the bioactivity of HSOs with different CBD contents with that of TTO has been made.

Together with the antibacterial properties related to many plant oils, these extracts are also related to anti-fungal properties. In reality, some plant oils can resist the antagonistic impact of harsh chemicals used to sanitize food-processing areas.

This has led to an increased demand for improved antimicrobials utilized in the food industry. Subsequently, discovering natural antimicrobials that are usually not related to toxic effects is very important.

Antioxidants are synthetic or natural substances that aid within the neutralization of harmful reactive oxygen species (ROS). These agents help to avoid oxidative stress that arises as a consequence of an imbalance between oxidants and antioxidants.

Oxidative stress will be brought on by external aspects equivalent to smoking, exposure to the sun without protection, or alcohol consumption. High levels of ROS for long periods can even result in aging and plenty of chronic diseases. Two plant extracts which can be known for his or her antioxidant properties include sesame oil and vetiver oil.

A latest Applied Microbiology study compares the antimicrobial activity of HSO and TTO products against pathogenic bacteria equivalent to Salmonella enteritidis (S. enteritidis), Escherichia coli (E. coli), and Staphylococcus aureus (S. aureus). The researchers also assessed the antioxidant properties of those agents, in addition to the existence of any interrelationship between their antimicrobial and antioxidant properties.

In regards to the study

The present study utilized antimicrobial and antioxidant assays. The antimicrobial assays included time-kill studies, minimum inhibition concentration (MIC) evaluation, and the Kirby–Bauer disk diffusion method for evaluation of antimicrobial properties of the samples.

Comparatively, the antioxidant assay was used to find out the concentration of antioxidants within the sample. This assay was done using the two,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH) radical-scavenging activity method.

The antimicrobial and antioxidant activity of seven oils, including tea tree, sesame, rosehip, vetiver, pure hemp, organic hemp, and 5% CBD oil, were assessed.

The measurement of the inhibition zone of tea tree oil on different bacteria: (a) S. aureus and (b) E. coli.

Study findings

The onset of bacteria was reported to be six hours, while the very best concentration was observed at 24 hours. The variety of bacteria within the TTO group was lower than within the HSO groups.

The MIC and disk diffusion method results indicated that out of all oils, TTO exhibited significant antimicrobial activity against all three pathogens. The MIC range for TTO was reported to be 8, 2, and eight mg/mL for S. aureus, S. enteritidis, and E.coli, respectively. The inhibition zones were reported to be 2.19, 1.87, and a pair of.02 cm against S. enteritidis, S. aureus, and E.coli, respectively.

Conversely, 5% CBD oil was found to provide the very best antioxidant activity that was 5.7 times stronger as in comparison with that of TTO. Pure hemp and organic hemp also showed promising antioxidant properties. 

IC50 values of the antioxidant activities of the several oils.

Conclusions

The present study determined TTO to be probably the most effective antimicrobial agent against E.coli, S. aureus, and S. enteritidis. Moreover, the CBD content of HSOs was found to play a very important role of their antioxidant properties. Substances with higher CBD exhibited higher antioxidant properties.

Subsequently, each TTO and CBD plants will be useful in food science studies to make food products protected for consumers. Further research is required to optimize the antimicrobial and antioxidant properties of those oils for his or her use within the food and medical industries.

Journal reference:

• Lakatos, M., Apori, S. O., Dunne, J., & Tian, F. (2022). The Biological Activity of Tea Tree Oil and Hemp Seed Oil. Applied Microbiology. doi:10.3390/applmicrobiol2030041.