Oregano: What the Science Says

Today oregano is used in oil extract form to treat multiple ailments. As a result of its antimicrobial properties oil of oregano is commonly used to treat cold and flu infections. Furthermore, it continues to be used externally to treat sore muscles and joints (Wild Oil of Oregano, 2010). Other external applications of oil of oregano take advantage of its antiseptic properties to treat wounds, burns, cuts, and resulting infections (Joy of the Mountains, 2010). It can also treat fungal infections like athletes foot (Wild Oil of Oregano, 2010). Although oil of oregano and other oregano preparations continue to be used to treat the aforementioned ailments, the focus of modern research has shifted to further consider the preventative properties of the herb.

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Bacteria  Beware!

Most recently the uses of essential oils like oregano have been considered as food preservatives to prevent the development of foodborne bacteria. Bacteria such as S.aureus, salmonella typhimurium and E.coli, can cause various foodborne illnesses in humans upon ingestion.  Souza et al. (2010) demonstrate that Origanum vulgare essential oil extract is effective at inhibiting the growth of S.aureus bacteria. The extract is also able to suppress the synthesis of enterotoxins, protein toxins that cause food poisoning, by the S.aureus cell.  They conduct an experiment to examine the growth of a test strain S.aureus in the presence of oregano extract. An assay of enterotoxin production was run using a control culture, a culture grown with 0.5 µL/mL or 0.15 µL/mL concentrations of oil of oregano. Furthermore, scanning electron microscopy was used to determine cell morphology in the three cultures. The results indicated that, at both concentrations, oil of oregano inhibited the production of enterotoxins by the S.aureus bacteria. On the other hand, the control assay was positive for enterotoxin production. Scanning electron microscopy determined that the oregano extract disrupted the cell structure of the S.aureus bacteria. The results of the study are significant because they determine that exposure of S.aureus cells to Origanum vulgare oil disrupts the cell membrane causing cytoplasmic leakage, thus killing the bacteria. The results also demonstrate that the active compounds of oil of oregano disrupt cellular mechanisms to suppress enterotoxin synthesis. These findings are proof positive that Origanum vulgare essential oil could be an effective candidate for use as an antimicrobial food preservative.

Magical Oregano: Free Radicals Vanish

Perhaps one of the most groundbreaking discovers related to oregano are its antioxidant properties. Reactive oxygen species in the body cause a variety of disease. Oregano is of interest to the food industry because it presents a natural alternative to synthetic antioxidants. Merchergui et al. (2010) conduct an experiment to evaluate the antioxidant activity of oil of oregano extracts from different locations in Tunisia. Gas chromatography analysis was performed to determine the percent composition of the oil extract. Next a phenol assay was conducted to determine the total phenol content of each extract sample. Finally, the antiradical activity of the oregano extract was determine using a 2,2-Diphenyl-1-picryhydrazil radical assay. It was determined that the observed antioxidant activity of the extract was due to the presence of thymol and carvacrol. The findings of this study were relevant because they establish that in a comparison of oregano extracts from different regions of Tunisia demonstrated that samples of higher level of phenolic compounds, specifically thymol and carvacrol as found in oregano, acted as more powerful antioxidants, trapping free radicals.

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It is important to realize that both studies used solid methodologies. They demonstrate that oregano may be a practical solution to the problems associate with synthetic food preservatives and antioxidants. Oregano is likely to provide a suitable natural alternative as it has been found to be effective at reasonable concentration. Furthermore, one must note that in both studies it is specified that the leaves of the oregano plant were used to develop the essential oil extract. This is significant because as previously noted, the leaves of the oregano plant contain both romarinic and caffeic acid and therefore include the active compounds of oregano, thymol and carvacrol.