Oregano’s history as a culinary and medicinal herb stretches back into antiquity; people from the Mediterranean region, the Middle East, China, Mexico, Europe, and the Americas have included oregano in their diets or phyto-pharmacopeia. Oregano’s distinctive flavor and aroma derive from an amalgam of monoterpenes, sesquiterpenes, phenols and aromatic hydrocarbons. Among the herb’s more important constituents are carvacrol, thymol, and eugenol (phenols); pinene, limonene, and sabinene (monoterpenes); and caryophyllene (a sesquiterpene). These compounds, among others, also account for oregano’s antibacterial, antifungal, antioxidant, antispasmodic, carminative, diaphoretic and analgesic properties – properties that were exploited by the ancients but have largely been overshadowed by the herb’s gustatory attributes.(1) However, as valuable as oregano is in the kitchen, it has recently enjoyed a renascence among scientists from disciplines as disparate as human and veterinary medicine, pest control, and food and archival document preservation.
In an age of increasing bacterial resistance to antibiotics, researchers are looking to phytochemicals in the hope of discovering alternatives for dealing with potentially lethal infections. A number of studies have demonstrated oregano’s activity against a wide array of bacteria, including many, such as Staph aureus, E. coli, and Bacillus cereus, that play prominent roles in human disease. (2, 3) In 2013, scientists at India’s Guru Jambheshwer University of Science and Technology demonstrated that oregano oil, when combined with the antibiotic ciprofloxacin, not only intensified the antibiotic’s ability to eradicate multidrug-resistant Salmonella typhi (the organism that causes typhoid fever), but may allow patients to be treated with lower, less toxic doses of the drug. (4)
Viruses, which do not respond to antibiotics, are a major cause of human disease. While antiviral drugs are available for some pathogens, many viral illnesses simply have to run their course because no effective treatment is available. In 2011, a team of investigators at Brazil’s Universidade Federal de Santa Maria showed that carvacrol, one of oregano’s principal constituents, exerts antiviral activity against herpes simplex virus type 1 (including acyclovir-resistant strains), human rotavirus, and respiratory syncytial virus. (5) Oregano’s essential oil also inactivates yellow fever virus in vitro. (6) It isn’t clear how such studies will ultimately impact human health, but the observation that oregano exhibits antiviral activity at relatively low concentrations suggests that many viral infections may respond to orally or topically administered oregano preparations.
One of the oldest applications for herbs is in food preservation. Indeed, it is likely that early humans learned to appreciate the flavoring properties of herbs only after they had discovered how these plants retarded spoilage in valuable foodstuffs. In 2014, a team of scientists in Belgium found that the essential oils of several herbs, including oregano, inhibited the growth of common food spoilage bacteria, such as Brochothrix thermosphacta and Pseudomonas fluorescens. Moreover, the growth of several bacteria responsible for food-borne illnesses – S. typhimurium, Listeria monocytogenes, and enterohemorrhagic E. coli, for example – was suppressed by oregano oil. (7)
Nowadays, since most data is stored electronically, people give little thought to the need for document preservation. However, protecting historical documents and archives that have not been converted to electronic formats is of utmost concern. While controlling the environment around such documents is the most important means of preventing their degradation, floods, power outages, and other catastrophes can negate all efforts at environmental modification. In 2012, experts at the National Archive of the Republic of Cuba showed that oregano oil, when used as a vapor or when combined with a solvent, prevents the growth of bacteria and fungi that contribute to biodeterioration in valuable archived documents. (8)
Finally, it is important to remember that essential oils, as valuable as they may be to the human condition, are intended to serve the plants that synthesize them. The alchemy that spawns an essential oil and determines its composition is orchestrated by evolution and shaped by foraging insects, grazing animals, bacteria, fungi, viruses, soil conditions, and climate. Essential oils serve as a defense against diseases and predation, as an attractant for pollinating insects, as a deterrent to neighboring plants, or even as a means for manipulating the environment to the plants’ advantage. In the July 2015 edition of Proceedings of the Royal Society B: Biological Sciences, European scientists elucidated the complex relationship among Origanum vulgare, Myrmica ants (which have developed a tolerance for oregano’s oil), and Maculinea arion (a large blue butterfly whose larvae initially feed on oregano flowers but then drop into the soil to prey on ants). When oregano plants are stressed by Myrmica ants feeding upon their roots, they emit higher levels of carvacrol into the surrounding air. The carvacrol attracts gravid female butterflies, which lay a larger proportion of their eggs on those plants where more ants can be found, thereby ensuring an adequate food supply for the growing butterfly larvae. (9)
Human perspectives seem so much less relevant when compared to the intricacies of nature.
1. De Falco E, Mancini E, Roscigno G, et al. Chemical composition and biological activity of essential oils of Origanum vulgare L. subsp. vulgare L. under different growth conditions. Molceules. 2013;18(12):14948-60
2. Saeed S, Tariq P. Antibacterial activity of oregano (Origanum vulgare Linn.) against gram positive bacteria. Pak J Pharm Sci. 2009;22(4):421-4
3. Si H, Hu J, Liu Z, Zeng ZL. Antibacterial effect of oregano essential oil alone and in combination with antibiotics against extended-spectrum beta-lactamase-producing Escherichia coli. FEMS Immunol Med Microbiol. 2008;53(2):190-4
4. Bharti V, Vasudeva N, Sharma S, Duhan JS. Antibacterial activities of Origanum vulgare alone and in combination with different antimicrobials against clinical isolates of Salmonella typhi. Anc Sci Life. 2013;32(4):212-16
5. Pilau MR, Alves SH, Weiblen R, et al. Antiviral activity of the Lippia graveolens (Mexican oregano) essential oil and its main compound carvacrol against human and animal viruses. Braz J Microbiol. 2011;42(4):1616-24
6. Meneses R, Ocazionez RE, Martínez JR, Stashenko EE. Inhibitory effect of essential oils obtained from plants grown in Colombia on yellow fever virus replication in vitro. Ann Clin Microbiol Antimicrob. 2009 Mar 6;8:8
7. Mith H, Duré Rémi, Delcenserie V, et al. Antimicrobial activities of commercial essential oils and their components against food-borne pathogens and food spoilage bacteria. Food Sci Nutr. 2014;2(4):403–416
8. Borrego S, Valdés O, Vivar I, et al. Essential oils of plants as biocides against microorganisms isolated from Cuban and Argentine documentary heritage. ISRN Microbiol. 2012;2012:826786
9. Patricelli D, Barbero F, Occhipinti A, et al. Plant defences against ants provide a pathway to social parasitism in butterflies. Proc Biol Sci. 2015 Jul 22; 282(1811): 20151111