Oregano Essential Oil

Oregano Essential Oil – Uses And Benefits – image to repin / share
Background pic – Wikipedia – lic. under CC 3.0
Essential oil pic – amazon.com (click here to buy)

Oregano Essential Oil – General Description

Oregano(Origanum vulgare, O. onites, O. minutiflorum, O. majorana) is a perennial herb with pinkish to purplish flowers and opposite, spade-shaped, olive-green leaves, which have an aromatic, warm, and slightly bitter but flavorful taste that has earned this herb its culinary reputation in different Italian-American, Asian, European, and Middle East cuisines. The herb has been used medicinally since the time of Hippocrates in ancient Greece where it was employed as an antiseptic to treat wounds and bacterial infections as well as a remedy for respiratory and gastrointestinal maladies. ^[1]

Oregano essential oil is considered as one of the most powerful and versatile essential oils, possessing strong immunity-enhancing, antimicrobial, antiviral, and anti-inflammatory properties. ^[2] Steam distillation method is utilized to extract the essential oil from oregano leaves. Oregano essential oil has a light yellow to reddish yellow color, a thin consistency, and strong, spicy, camphor-like aroma with a middle perfumery note. ^[3]

Oregano Essential Oil – Uses and Reported Benefits

Aside from the aforementioned attributes of oregano essential oil, this essential oil has also been purported to exert the following therapeutically beneficial properties: analgesic, antirheumatic, antispasmodic, antitoxic, carminative, choleretic, diaphoretic, diuretic, emmenagogue, expectorant, febrifuge, rubefacient, stimulant, and tonic. ^[3] Moreover, oregano essential oil has been orally administered to deal with intestinal parasites, allergies, sinus pain, arthritis, cold and flu, swine flu, earaches, and fatigue and is applied on the skin as an alternative remedy for acne, athlete’s foot, oily skin, dandruff, canker sores, warts, ringworm, psoriasis, and insect bites. ^[4] While this broad spectrum of effects apparently is promising, more positive findings and data from studies need to be provided to scientifically support these claims.

Oregano Essential Oil – Contraindications and Safety

Oregano essential oil is generally safe and nontoxic, especially when taken or applied in prescribed medicinal amounts. Mild effects such as stomach upset and allergic reaction in those with hypersensitivity to plants belonging to the mint family may occur though, so caution is still recommended. As not enough is known regarding the safety of oregano when taken by mouth during pregnancy and breast-feeding, pregnant and lactating women are advised to avoid its use. ^[4]

Oregano Essential Oil – Scientific Studies And Research

Oregano as antimicrobial against food borne pathogens: The potent antimicrobial effect of oregano essential oil has been associated principally with its volatile compound content, and a broad array of researches have been devoted to the investigation of the activities of oregano essential oil in various concentrations so as to produce products with a wider range of applications. In a 2012 Polish study that explored the antibacterial attributes of oregano essential oil, results from the study’s experiments revealed that oregano essential oil was active against clinical strains of Escherichia coli and Pseudomonas aeruginosa obtained from patients with different clinical conditions, the strains of E. coli being more sensitive to the tested oil. ^[5]
A similar finding was obtained from a 2002 study conducted by the U.S. Department of Agriculture, California, which evaluated the bactericidal activity levels of 96 essential oils and 23 oil compounds against four bacterial species. According to this study, oregano essential oil was most active against not only E. coli O157:H7 but also Listeria monocytogenes and Salmonella enterica, which are notorious food-borne pathogens. ^[6] Furthermore, Si, Hu, Liu, and Zeng (2008) from South China Agricultural University, China, reported for the first time the antibacterial effectiveness of oregano essential oil against antibiotic-resistant variants of E. coli that are capable of producing extended-spectrum beta-lactamases, enzymes that grant resistance to these E. coli strains against common antibiotics such as penicillins and cephalosporins, which hence makes infections difficult to treat. According to this Chinese study, oregano essential oil deters the growth of multiple drug-resistant E. coli at a minimal inhibitory concentration value of 0.5 microL. In addition, the antibacterial effects of oregano essential oil in combination with kanamycin were independent against E. coli. When used together with amoxicillin, polymyxin, and lincomycin, oregano essential oil displayed an additive antibacterial effect against E. coli, with a fractional inhibitory concentration (FIC) index of 0.625–0.750. ^[7]

More on Oregano as antibacterial: Becerril, Nerin, and Gomez-Lus (2012) investigated the susceptibility of 48 clinical isolates and 12 reference strains of Gram-negative bacilli to oregano essential oil, cinnamon essential oil, and the combination of both essential oils as well as the predisposition of these bacterial strains to develop resistance against these essential oils. The results of their study demonstrated that indeed these Gram-negative bacilli are susceptible to both oregano essential oil and cinnamon essential oil, with only Serratia marcescens, Morganella morganii, and Proteus mirabilis being capable of either altering their antibiotic resistance profile or increasing their resistance to the two essential oils. ^[8] In a 2007 study from Shiraz University, Iran, oregano essential oil exhibited a negative effect on the growth and survival of Yersinia enterocolitica (the causative agent of yersiniosis)—and to a lesser extent L. monocytogenes—in a broth culture system. ^[9] Correspondingly, Elgayyar, Draughon, Golden, and Mount (2001), utilizing paper disc agar diffusion method to test growth inhibition and antibiotic susceptibility discs as control, studied the action of selected herb and essential oils with respect to the growth and survival of a variety of microorganisms. They had determined that oregano essential oil completely hampered the growth and survival of each of the test strains, which include L. monocytogenes, Staphylococcus aureus, E. coli O:157:H7, Y. enterocolitica, P. aeruginosa, Lactobacillus plantarum, Aspergillus niger, Geotrichum, and Rhodotorula, and displayed the greatest inhibition among the essential oils tested. ^[10]

Oregano as antifungal: Aside from being antibacterial, oregano essential oil also exerts antifungal effects, as demonstrated by a 2008 Brazilian study that examined the antifungal activities of selected essential oils against Candida species resistant and susceptible to fluconazole, a triazole antifungal drug used for treating vaginal, oral, and esophageal Candida infections. In this study, oregano essential oil was evidenced to be the most efficient when it comes to being an antifungal agent among the tested essential oils. Moreover, the results of this study suggested that the susceptibility of fluconazole-resistant Candida albicans, C. dubliniensis, C. tropicalis, C. glabrata, and C. krusei to oregano essential oil was higher than that of the fluconazole-susceptible yeasts. ^[11]

Oregano as anticancer agent: El Babili et al. (2011) examined the antioxidant and antimalarial activities of oregano essential oil as well as the essential oil’s action against human breast cancer cells. From their study, oregano essential oil manifested a higher antioxidant activity with an IC50=2±0.1 mg/L and an antimalarial activity of IC50=34 mg/mL; oregano extracts also exhibited activity against human breast cancer cells (MCF7). ^[12]

Oregano Essential Oil – Molecular Components and Chemistry

Analyses from gas chromatography with flame ionization detector (GC-FID) and gas chromatography–mass spectrometry (GC–MS), as conducted by El Babili et al. (2011), have identified carvacrol as the predominant compound (36.46%) in oregano essential oil, followed by thymol (29.74%) and p-cymene (24.31%). Extracts from the aerial parts of oregano have also been determined to be characterized by various chemical families, namely polyphenols (such as gallic acid), tannins (such as catechin), anthocyanins (such as cyanidin), and flavonoids (such as quercetin). ^[12] High Carvacrol content is considered a “quality marker” for oregano oil; note that Origanum vulgare
is often higher in carvacrol than other Origanum species.