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Oregano

Scientific Name(s): Origanum onites L., Origanum syriacum L., Origanum vulgare L.
Common Name(s): Kekik, Mediterranean oregano, Mexican oregano, Mountain mint, Wild marjoram, Winter marjoram, Wintersweet

Medically reviewed by Drugs.com. Last updated on Jul 19, 2022.

Clinical Overview

Use

Aside from its culinary application, oregano exhibits antimicrobial and antioxidant actions and has possible activity as an antispasmodic and in diabetes. However, there is limited clinical trial evidence to support the use of oregano for any indication.

Dosing

There is no clinical evidence to support specific therapeutic doses of oregano; however, due to its wide use in foods, it has been designated GRAS (generally recognized as safe) status by the FDA. In a small study, 200 mg/day emulsified O. vulgare oil was administered for 6 weeks.

Contraindications

Contraindications have not been identified.

Pregnancy/Lactation

Information regarding safety and efficacy in pregnancy and lactation is lacking. GRAS status when used as food. Ingestion in excess of amounts found in food should be avoided because safety and efficacy are unproven. Some studies indicate hormonal effects.

Interactions

None well documented.

Adverse Reactions

Oregano has caused allergic contact dermatitis when applied topically. When oregano is ingested, eczematous rash and, rarely, anaphylactic reactions can occur.

Toxicology

Information in humans is lacking.

Scientific Family

Botany

Common or wild oregano is a perennial plant native to the Mediterranean region and Asia and cultivated in the United States. Its creeping rootstock produces a square, downy, purplish stem with opposite ovate leaves. Stems can grow up to 76 cm tall and are dotted with small depressions. Purple, 2-lipped flowers grow in terminal clusters from July to October.(1, 2, 3)

O. vulgare subspecies hirtum has a spicy flavor, furry leaves on stems that grow up to 45.7 cm tall, and floppy white flowers.(1) Several Turkish species of Origanum are also found in commerce, including O. onites L. and O. syriacum L.(4) Other taxa in the genera Coridothymus, Thymbra, and Satureja have similar chemistry.(4) Lippia graveolens Kunth. (Verbenaceae) is known as Mexican oregano.

Molecular techniques to distinguish these related species for purposes of quality control have been developed.(5, 6, 7, 8)

History

Oregano has been a common ingredient in Spanish, Mexican, and Italian dishes as a spice and flavoring agent for hundreds of years. Its initial purpose was as a warming digestive and circulatory stimulant. It has been used in perfumery for its volatile oil contents, especially in scenting soaps.

The antiseptic qualities of aromatic and medicinal plants and their extracts, including oregano, have been recognized since ancient times.9 Attempts to characterize these properties in the laboratory date back to the early 1900s.

Antispasmodic, calmative, carminative, diaphoretic, expectorant, stomachic, and tonic actions have been reported. It has been suggested that an infusion of the fresh herb is beneficial in treating an upset stomach and indigestion, headache, colic, and nervous complaints, as well as for coughs and other respiratory ailments. An infusion of the flowers has been used to prevent seasickness. The oil has been used externally in liniments and lotions and to ease toothache. It has also been used as an ant repellent.10, 11, 12

Chemistry

The monoterpenoid phenols carvacrol and thymol are responsible for many of the properties of the essential oil, as well as p-cymene and terpinene.2, 13, 14, 15, 16, 17, 18 Of the numerous species considered as oregano, all have carvacrol as the major component of their essential oils.4 Phenolic compounds may represent more than 70% of the total oil. Biosynthetic pathways of O. vulgare, which produce monoterpenoids, have been elucidated in the glandular hairs of the plant.19, 20 The essential oil may play a role in deterring herbivores, such as snails, from feeding on the plant.21

Analytical methods for determining the constituents of oregano oil include thermal desorption gas chromatography-mass spectral and liquid chromatographic-mass spectral methods.22, 23 Using gas chromatography, 4 chemotypes of Italian O. vulgare were identified in the wild.24 Infrared and Raman spectroscopy have been used to distinguish chemotypes as well.25 In addition to classical steam distillation, supercritical fluid extraction with carbon dioxide has been studied.26, 27 The effect of drying methods on essential oil content has been defined.28

Oregano also contains oleanolic and ursolic acids; flavonoids29 and hydroquinones; caffeic, rosmarinic, and lithospermic acids; tannins; and phenolic glycosides.30, 31, 32, 33

The metabolism and pharmacokinetics of oregano phenolics have been defined in rats34 and humans.35

Uses and Pharmacology

Some of oregano's pharmacologic actions may be connected to activation of the transient receptor potential (TRP) channel V3, which mediates warm sensations, by carvacrol and thymol.(36) In addition, carvacrol and thymol rapidly activate and desensitize TRPA1, another similar receptor.(36) These are distinct from the action of capsaicin, the pungent principle of chili pepper, which activates TRPV1, and menthol, the cooling principle of mint, which activates TRPM8. There are few clinical studies on the medicinal effects of oregano, despite its widespread culinary use.

Analgesic effects

Clinical data

Possible oral analgesic applications of carvacrol were supported by data in a human experiment (n=25) that documented the desensitizing properties of carvacrol to oral irritation and innocuous heat application.(96)

Antibacterial activity

The volatile oil of oregano has demonstrated in vitro antibacterial activity against a wide range of gram-positive and gram-negative microorganisms, including Listeria, Pseudomonas, Proteus, Salmonella, and Clostridium species(11, 15, 16, 53, 54, 55, 56, 57, 58, 59) as well as some methicillin-resistant Staphylococci.(15, 60) An ointment formulation targeting methicillin-resistant Staphylococcus aureus (MRSA) has been developed.(61) Low to moderate activity against Helicobacter pylori has been demonstrated.(62, 63, 64) Oregano oil appears to inhibit organisms at relatively low concentrations(65) and its activity is primarily due to the phenolic components thymol and carvacrol.(15, 60) Functional changes in bacterial cell membrane potential and permeability have been linked to oregano oil treatment.(66) The effect of oregano oil on foodborne bacterial pathogens has been widely studied.(16, 38, 56, 57, 58, 59) Some methods of essential oil extraction appear to yield oil with poor antibacterial properties.(67)

Antifungal activity

Oregano inhibited aflatoxin production and prevented growth of Aspergillus at concentrations as low as 0.1%.(47, 48, 49) Further studies have compared the effects of oregano essential oil, thymol, and carvacrol, which all completely inhibited fungal growth of Aspergillus and Penicillium species.(50) Oregano oil has exhibited some antifungal activity against Candida species, possibly because of its carvacrol content.(14, 18, 51) Synergism of oregano oil antifungal effects with nystatin has been observed in vitro.(52)

Antiinflammatory effects

A supercritical fluid extract of O. vulgare reduced proinflammatory cytokines, while increasing antiinflammatory interleukin (IL)-10.(27) Rosmarinic acid, oleanolic acid, and ursolic acid were identified as the antiinflammatory constituents.(23) A combination of thyme and oregano oils were found to reduce the expression of proinflammatory cytokines in a mouse model of colitis. Protein levels of IL-1beta and IL-6 were also reduced.(75)

Antioxidant activity

Many experiments have demonstrated that in vitro antioxidant activity of oregano essential oil and its constituent compounds rosmarinic acid, carvacrol, and thymol are similar to or better than alpha tocopherol.(3, 15, 37, 38, 39, 40) Accelerated solvent extraction was proposed to yield higher antioxidant activity than room temperature extraction.(41) Vanillin, vanillic acid, and protocatechuic acid from O. vulgare showed both antioxidant activity and inhibition of cellular melanogenesis(42, 43) while a novel phenolic glycoside from oregano also inhibited melanogenesis.(44) Long-term dietary administration of oregano to rats reduced carbon tetrachloride-induced oxidative stress.(45) The clinical importance of these effects is not yet established. In a double-blind, placebo-controlled trial among healthy adult men, no differences in biomarkers of lipid peroxidation were found with oregano extract supplementation.(46)

Antiparasitic action

In 1 study, 14 patients with known parasites were administered 200 mg emulsified O. vulgare oil for 6 weeks. Entamoeba hartmanni, Endolimax nana, and Blastocystis hominis were eradicated from 13 patients.(68) Several oils, including oregano, were shown to inhibit Giardia trophozoite growth and viability.(69) The oil of O. vulgare has been shown to eradicate common parasites in chickens and pheasants. In vitro experiments showed activity against Trypanosoma cruzi.(68, 70)

Antispasmodic effects

Origanum compactum has been used in Morocco as a spasmolytic, prepared as a tea from flowers and leaves of the plant. The rapid spasmolytic action of O. compactum was demonstrated in in vitro experiments after using acetylcholine on smooth muscle preparations to produce contractions. It is suspected that the herb stabilizes the muscle membrane by interfering with the influx of calcium and its regulatory proteins.(2) The active components in the O. compactum essential oil appear to be thymol and carvacrol.(71)

Cancer

Essential oils of O. syriacum and O. vulgare inhibited growth of breast cancer cells in vitro; however, they were not cytotoxic.(79) Oregano ethanolic extract induced apoptosis in human colon cancer cells.(80) In rats, whole oregano given orally markedly inhibited dimethylhydrazine-induced colon cancer at 40 mg/kg.(81) Galangin and quercetin from oregano were shown to be antimutagenic in an Ames test with Salmonella typhimurium TA98.(82) Thymol had genotoxic activity in a Drosophila model; however, this activity was antagonized by carvacrol.(83)

Diabetes

Researchers have demonstrated a hypoglycemic effect of oregano in rats with induced diabetes, providing some supportive evidence for the use of oregano leaves in diabetic patients. The effect was independent of insulin and occurred after a single dose, as well as with repeated daily dosing.(72)

Other researchers have demonstrated an aldose reductase inhibitory effect by lithospermic and rosmarinic acid extracted from oregano. Some researchers have suggested that inhibiting the accumulation of sorbitol may contribute to the prevention of chronic complications, such as retinopathy and peripheral neuropathy in diabetic patients.(13, 73)

Another group reported constituents with both antagonistic and agonist effects at the peroxisome proliferator-activated receptor gamma, which could be of use in metabolic syndrome.(74)

Hyperlipidemia

Both oregano essential oil and aqueous infusions showed inhibitory activity against low-density lipoprotein (LDL) oxidation, with different constituents responsible for the activity in the 2 preparations.(76) In hyperlipidemic patients, 25 mL of an aqueous distillate of O. onites (oregano water) taken daily enhanced the effects of altered lifestyle and low-fat diet interventions in modulating mild hyperlipidemia.(77)

Oral analgesic

Possible oral analgesic applications of carvacrol were supported by data in a human experiment (n=25) that documented the desensitizing properties of carvacrol to oral irritation and innocuous heat application.(93)

Wound healing

The effect of 3% oregano ointment (free of potentially irritating essential oils) on wound healing was investigated in a small double-blind, randomized, controlled trial (n=40) conducted in adults undergoing dermatological excisions. Oregano in petrolatum or petrolatum only was applied twice daily for a mean of 12 days. Although 1 patient (6%) in the oregano group and none in control tested positive for MRSA, fewer patients in the oregano group tested positive for S. aureus (19%) or were treated for cellulitis (6%) compared to controls (41% and 16%, respectively). Additionally, both patient- and physician-scored scar assessments were significantly better in the oregano group compared to controls. No significant adverse reactions were noted in either group.(94)

Other

Monoamine reuptake inhibition in the rat brain by an oregano extract was observed, and serotonin levels, as measured by microdialysis, were elevated by the same extract.(78)

Dosing

There is no clinical evidence to support specific therapeutic doses of oregano. Due to its wide use in foods, it has been designated GRAS by the FDA.84 A study evaluating the antiparasitic effect of oregano used 200 mg emulsified O. vulgare oil daily for 6 weeks.68

Pregnancy / Lactation

Information regarding safety and efficacy in pregnancy and lactation is lacking. GRAS status when used as food.

A retrospective review of poison center data in Uruguay from 1986 to 1999 analyzed an over-the-counter herbal preparation (Carachipita) containing oregano and other herbs commonly used to induce abortion. GI symptoms, genital hemorrhage, and multiple organ system failure, resulting in 4 abortions, occurred in 13 women who received this preparation.85 Dried oregano herb (1 g) contains approximately 4 mcg of phytoprogestins, which bind to progestin-binding sites.86

In a study of natural herbs as alternatives to antimicrobials, a decrease in sow and litter mortality occurred in an experiment in which sows were fed oregano leaf, flower, and essential oil-enriched food. No apparent ill effect was reported.87 Another study found that mice fed oregano essential oil showed an increase in the proportion of dead cells in preimplantation embryos.88

Interactions

None well documented.

Progestins: Herbs (progestogenic properties) may enhance the adverse/toxic effect of progestins. Monitor therapy.Zava 1998

Adverse Reactions

Allergic contact dermatitis caused by spices, including oregano, is well documented.88 Although oregano is frequently consumed, there are a few reports of adverse or systemic reactions. One report of anaphylaxis exists, and cross-sensitivity with other members of the Lamiaceae family has been noted.89 An additional case report of an eczematous reaction to ingestion of large quantities of oregano has been published.90

Data collected between 2004 and 2013 from 8 US centers in the Drug-induced Liver Injury Network revealed that 15.5% (130) of hepatotoxicity cases were caused by herbals and dietary supplements, whereas 85% (709) of cases were related to prescription medications. Of the 130 cases of liver injury related to supplements, 65% were from non-bodybuilding supplements and occurred most often in Hispanics/Latinos compared with non-Hispanic whites and non-Hispanic blacks. Liver transplant was also more frequent with toxicity from non-bodybuilding supplements (13%) than with conventional medications (3%) (P<0.001). Overall, the proportion of severe liver injury cases was significantly higher for supplements than for conventional medications (P=0.02). Of the 217 supplement products implicated in liver injury, 175 had identifiable ingredients, of which oregano was among the 32 (18%) single-ingredient products.92

Toxicology

In a study investigating the effect of oregano on growth and development of mouse embryos, an increase in the proportion of dead cells in preimplantation embryos was observed.88 The isolation of toxic aristolochic acids from Russian O. vulgare has been reported in one investigation.91

Index Terms

References

Disclaimer

This information relates to an herbal, vitamin, mineral or other dietary supplement. This product has not been reviewed by the FDA to determine whether it is safe or effective and is not subject to the quality standards and safety information collection standards that are applicable to most prescription drugs. This information should not be used to decide whether or not to take this product. This information does not endorse this product as safe, effective, or approved for treating any patient or health condition. This is only a brief summary of general information about this product. It does NOT include all information about the possible uses, directions, warnings, precautions, interactions, adverse effects, or risks that may apply to this product. This information is not specific medical advice and does not replace information you receive from your health care provider. You should talk with your health care provider for complete information about the risks and benefits of using this product.

This product may adversely interact with certain health and medical conditions, other prescription and over-the-counter drugs, foods, or other dietary supplements. This product may be unsafe when used before surgery or other medical procedures. It is important to fully inform your doctor about the herbal, vitamins, mineral or any other supplements you are taking before any kind of surgery or medical procedure. With the exception of certain products that are generally recognized as safe in normal quantities, including use of folic acid and prenatal vitamins during pregnancy, this product has not been sufficiently studied to determine whether it is safe to use during pregnancy or nursing or by persons younger than 2 years of age.

More about oregano

Related treatment guides

1. Origanum vulgare L. USDA, NRCS. 2007. The PLANTS database (http://plants.usda.gov, 13 February 2007). National Plant Data Team, Greensboro, NC 27401-4901 USA.
2. Van Den Broucke CO, Lemli JA. Antispasmodic activity of Origanum compactum. Planta Med. 1980;38(4):317-331.6445067
3. Lagouri V, Boskou D. Nutrient antioxidants in oregano. Int J Food Sci Nutr. 1996;47(6):493-497.8933203
4. Baser KH. Biological and pharmacological activities of carvacrol and carvacrol bearing essential oils. Curr Pharm Des. 2008;14(29):3106-3119.19075694
5. Marieschi M, Torelli A, Poli F, Sacchetti G, Bruni R. RAPD-based method for the quality control of Mediterranean oregano and its contribution to pharmacognostic techniques. J Agric Food Chem. 2009;57(5):1835-1840.19216531
6. Marieschi M, Torelli A, Poli F, Bianchi A, Bruni R. Quality control of commercial Mediterranean oregano: development of SCAR markers for the detection of the adulterants Cistus incanus L., Rubus caesius L. and Rhus coriaria L. Food Control. 2010;21(7):998-1003.
7. Marieschi M, Torelli A, Bianchi A, Bruni R. Detecting Satureja montana L. and Origanum majorana L. by means of SCAR-PCR in commercial samples of Mediterranean oregano. Food Control. 2011;22(3-4):542-548.
8. Marieschi M, Torelli A, Bianchi A, Bruni R. Development of a SCAR marker for the identification of Olea europaea L.: a newly detected adulterant in commercial Mediterranean oregano. Food Chem. 2011;126(2):705-709.
9. Fleisher A, Fleisher Z. Identification of biblical hyssop and origin of the traditional use of oregano-group herbs in the Mediterranean region. Econ Bot. 1988;42(2):232-241.
10. Assaf MH, Ali AA, Makboul MA, Beck JP, Anton R. Preliminary study of phenolic glycosides from Origanum majorana; quantitative estimation of arbutin; cytotoxic activity of hydroquinone. Planta Med. 1987;53(4):343-345.3671554
11. Dorman HJ, Deans SG. Antimicrobial agents from plants: antibacterial activity of plant volatile oils. J Appl Microbiol. 2000;88(2):308-316.10736000
12. Lust JB. The Herb Book. New York, NY: Bantam Books; 1980.
13. Koukoulitsa C, Zika C, Geromichalos GD, Demopoulos VJ, Skaltsa H. Evaluation of aldose reductase inhibition and docking studies of some secondary metabolites, isolated from Origanum vulgare L. ssp. hirtum. Bioorg Med Chem. 2006;14(5):1653-1659.16249088
14. Giordani R, Regli P, Kaloustian J, Mikaïl C, Abou L, Portugal H. Antifungal effect of various essential oils against Candida albicans. Potentiation of antifungal action of amphotericin B by essential oil from Thymus vulgaris. Phytother Res. 2004;18(12):990-995.15742351
15. Bozin B, Mimica-Dukic N, Simin N, Anackov G. Characterization of the volatile composition of essential oils of some Lamiaceae spices and the antimicrobial and antioxidant activities of the entire oils. J Agric Food Chem. 2006;54(5):1822-1828.16506839
16. Dadalioglu I, Evrendilek GA. Chemical compositions and antibacterial effects of essential oils of Turkish oregano (Origanum minutiflorum ), bay laurel (Laurus nobilis), Spanish lavender (Lavandula stoechas L.), and fennel (Foeniculum vulgare) on common foodborne pathogens. J Agric Food Chem. 2004;52(26):8255-8260.15612826
17. Daferera DJ, Ziogas BN, Polissiou MG. GC-MS analysis of essential oils from some Greek aromatic plants and their fungitoxicity on Penicillium digitatum. J Agric Food Chem. 2000;48(6):2576-2581.10888587
18. Tampieri MP, Galuppi R, Macchioni F, et al. The inhibition of Candida albicans by selected essential oils and their major components. Mycopathologia. 2005;159(3):339-345.15883716
19. Crocoll C, Asbach J, Novak J, Gershenzon J, Degenhardt J. Terpene synthases of oregano (Origanum vulgare L.) and their roles in the pathway and regulation of terpene biosynthesis. Plant Mol Biol. 2010;73(6):587-603.20419468
20. Szabó K, Sárosi S, Cserháti B, Ferenczy A. Can glandular hair density be a breeding marker for Origanum vulgare subsp. hirtum with high essential oil content? Nat Prod Commun. 2010;5(9):1437-1440.20923004
21. Vokou D, Tziolas M, Bailey SE. Essential-oil-mediated interactions between oregano plants and Helicidae grazers. J Chem Ecol. 1998;24(7):1187-1202.
22. García MA, Sanz J. Analysis of Origanum vulgare volatiles by direct thermal desorption coupled to gas chromatography-mass spectrometry. J Chromatogr A. 2001;918(1):189-194.11403447
23. Shen D, Pan MH, Wu QL, et al. LC-MS method for the simultaneous quantitation of the anti-inflammatory constituents in oregano (Origanum species). J Agric Food Chem. 2010;58(12):7119-7125.20496910
24. Russo M, Galletti GC, Bocchini P, Carnacini A. Essential oil chemical composition of wild populations of Italian oregano spice (Origanum vulgare ssp. hirtum Ietswaart): a preliminary evaluation of their use in chemotaxonomy by cluster analysis. 1. Inflorescences. J Agric Food Chem. 1998;46(9):3741-3746.
25. Baranska M, Schulz H, Krüger H, Quilitzsch R. Chemotaxonomy of aromatic plants of the genus Origanum via vibrational spectroscopy. Anal Bioanal Chem. 2005;381(6):1241-1247.15711962
26. Gaspar F, Santos R, King MB. Disruption of glandular trichomes with compressed CO2: alternative matrix pre-treatment for CO2 extraction of essential oils. J Supercrit Fluids. 2001;21(1):11-22.
27. Ocaña-Fuentes A, Arranz-Gutiérrez E, Señorans FJ, Reglero G. Supercritical fluid extraction of oregano (Origanum vulgare) essentials oils: anti-inflammatory properties based on cytokine response on THP-1 macrophages. Food Chem Toxicol. 2010;48(6):1568-1575.20332013
28. Figiel A, Szumny A, Gutiérrez-Ortíz A, Carbonell-Barrachina AA. Composition of oregano essential oil (Origanum vulgare) as affected by drying method. J Food Eng. 2010;98(2):240.
29. Hawas UW, El-Desoky SK, Kawashty SA, Sharaf M. Two new flavonoids from Origanum vulgare. Nat Prod Res. 2008;22(17):1540-1543.19023817
30. Milos M, Mastelic J, Jerkovic I. Chemical composition and antioxidant effect of glycosidically bound volatile compounds from oregano (Origanum vulgare L. ssp. hirtum). Food Chem. 2000;71(1):79-83.
31. Nakatani N, Kikuzaki H. A new antioxidative glucoside isolated from oregano (Origanum vulgare L.). Agric Biol Chem. 1987;51(10):2727-2732.
32. Kikuzaki H, Nakatani N. Structure of a new antioxidative phenolic acid from oregano (Origanum vulgare L.). Agric Biol Chem. 1989;53(2):519-524.
33. Lukas B, Schmiderer C, Mitteregger U, Novak J. Arbutin in marjoram and oregano. Food Chem. 2010;121(1):185-190.
34. Lin SP, Tsai SY, Lin YL, Kuo SC, Hou YC, Chao PD. Biotransformation and pharmacokinetics of 4-(3,4-dihydroxybenzoyloxymethyl)phenyl-O-beta-D-glucopyranoside, an antioxidant isolated from Origanum vulgare. J Agric Food Chem. 2008;56(8):2852-2856.18376843
35. Nurmi A, Nurmi T, Mursu J, Hiltunen R, Voutilainen S. Ingestion of oregano extract increases excretion of urinary phenolic metabolites in humans. J Agric Food Chem. 2006;54(18):6916-6923.16939358
36. Xu H, Delling M, Jun JC, Clapham DE. Oregano, thyme and clove-derived flavors and skin sensitizers activate specific TRP channels. Nat Neurosci. 2006;9(5):628-635.16617338
37. Vichi S, Zitterl-Eglseer K, Jugl M, Franz C. Determination of the presence of antioxidants deriving from sage and oregano extracts added to animal fat by means of assessment of the radical scavenging capacity by photochemiluminescence analysis. Nahrung. 2001;45(2):101-104.11379280
38. Faleiro L, Miguel G, Gomes S, et al. Antibacterial and antioxidant activities of essential oils isolated from Thymbra capitata L. (Cav.) and Origanum vulgare L. J Agric Food Chem. 2005;53(21):8162-1868.16218659
39. Zheng W, Wang SY. Antioxidant activity and phenolic compounds in selected herbs. J Agric Food Chem. 2001;49(11):5165-5170.11714298
40. Ivanova D, Gerova D, Chervenkov T, Yankova T. Polyphenols and antioxidant capacity of Bulgarian medicinal plants. J Ethnopharmacol. 2005;96(1-2):145-150.15588663
41. Hossain MB, Barry-Ryan C, Martin-Diana AB, Brunton NP. Optimization of accelerated solvent extraction of antioxidant compounds from rosemary (Rosmarinus officinalis L.), marjoram (Origanum majorana L.) and oregano (Origanum vulgare L.) using response surface methodology. Food Chem. 2011;126(1):339-346.
42. Chou TH, Ding HY, Hung WJ, Liang CH. Antioxidative characteristics and inhibition of alpha-melanocyte-stimulating hormone-stimulated melanogenesis of vanillin and vanillic acid from Origanum vulgare. Exp Dermatol. 2010;19(8):742-750.20482617
43. Chou TH, Ding HY, Lin RJ, Liang JY, Liang CH. Inhibition of melanogenesis and oxidation by protocatechuic acid from Origanum vulgare (oregano). J Nat Prod. 2010;73(11):1767-1774.20973550
44. Liang CH, Chou TH, Ding HY. Inhibition of melanogensis by a novel origanoside from Origanum vulgare. J Dermatol Sci. 2010;57(3):170-177.20071152
45. Botsoglou NA, Taitzoglou IA, Botsoglou E, Lavrentiadou SN, Kokoli AN, Roubies N. Effect of long-term dietary administration of oregano on the alleviation of carbon tetrachloride-induced oxidative stress in rats. J Agric Food Chem. 2008;56(15):6287-6293.
46. Nurmi A, Mursu J, Nurmi T, et al. Consumption of juice fortified with oregano extract markedly increases excretion of phenolic acids but lacks short- and long-term effects on lipid peroxidation in healthy nonsmoking men. J Agric Food Chem. 2006;54(16):5790-5796.
47. Basílico MZ, Basílico JC. Inhibitory effects of some spice essential oils on Aspergillus ochraceus NRRL 3174 growth and ochratoxin A production. Lett Appl Microbiol. 1999;29(4):238-241.10583751
48. Llewellyn GC, Burkett ML, Eadie T. Potential mold growth, aflatoxin production, and antimycotic activity of selected natural spices and herbs. J Assoc Off Anal Chem. 1981;64(4):955-960.7275911
49. Tantaoui-Elaraki A, Beraoud L. Inhibition of growth and aflatoxin production in Aspergillus parasiticus by essential oils of selected plant materials. J Environ Pathol Toxicol Oncol. 1994;13(1):67-72.7823297
50. Akgül A, Kivanç M. Inhibitory effects of selected Turkish spices and oregano components on some foodborne fungi. Int J Food Microbiol. 1988;6(3):263-268.2978951
51. Manohar V, Ingram C, Gray J, et al. Antifungal activities of origanum oil against Candida albicans. Mol Cell Biochem. 2001;228(1-2):111-117.11855736
52. Rosato A, Vitali C, Piarulli M, Mazzotta M, Argentieri MP, Mallamaci R. In vitro synergic efficacy of the combination of Nystatin with the essential oils of Origanum vulgare and Pelargonium graveolens against some Candida species. Phytomedicine. 2009;16(10):972-975.19616925
53. Elgayyar M, Draughon FA, Golden DA, Mount JR. Antimicrobial activity of essential oils from plants against selected pathogenic and saprophytic microorganisms. J Food Prot. 2001;64(7):1019-1024.11456186
54. Kivanç M, Akgül A, Doğan A. Inhibitory and stimulatory effects of cumin, oregano and their essential oils on growth and acid production of Lactobacillus plantarum and Leuconostoc mesenteroides. Int J Food Microbiol. 1991;13(1):81-85.1863531
55. Marino M, Bersani C, Comi G. Impedance measurements to study the antimicrobial activity of essential oils from Lamiaceae and Compositae. Int J Food Microbiol. 2001;67(3):187-195.11518428
56. Tsigarida E, Skandamis P, Nychas GJ. Behaviour of Listeria monocytogenes and autochthonous flora on meat stored under aerobic, vacuum and modified atmosphere packaging conditions with or without the presence of oregano essential oil at 5 degrees C. J Appl Microbiol. 2000;89(6):901-909.11123463
57. Ultee A, Gorris LG, Smid EJ. Bactericidal activity of carvacrol towards the food-borne pathogen Bacillus cereus. J Appl Microbiol. 1998;85(2):211-218.9750293
58. Chorianopoulos N, Kalpoutzakis E, Aligiannis N, Mitaku S, Nychas GJ, Haroutounian SA. Essential oils of Satureja, Origanum, and Thymus species: chemical composition and antibacterial activities against foodborne pathogens. J Agric Food Chem. 2004;52(26):8261-8267.15612827
59. Burt SA, Reinders RD. Antibacterial activity of selected plant essential oils against Escherichia coli O157:H7. Lett Appl Microbiol. 2003;36(3):162-167.12581376
60. Nostro A, Blanco AR, Cannatelli MA, et al. Susceptibility of methicillin-resistant staphylococci to oregano essential oil, carvacrol and thymol. FEMS Microbiol Lett. 2004;230(2):191-195.14757239
61. Eng W, Norman R. Development of an oregano-based ointment with anti-microbial activity including activity against methicillin-resistant Staphlococcus aureus. J Drugs Dermatol. 2010;9(4):377-380.20514796
62. Stamatis G, Kyriazopoulos P, Golegou S, Basayiannis A, Skaltsas S, Skaltsa H. In vitro anti-Helicobacter pylori activity of Greek herbal medicines. J Ethnopharmacol. 2003;88(2-3):175-179.12963139
63. Mahady GB, Pendland SL, Stoia A, et al. In vitro susceptibility of Helicobacter pylori to botanical extracts used traditionally for the treatment of gastrointestinal disorders. Phytother Res. 2005;19(11):988-991.16317658
64. Lin YT, Kwon YI, Labbe RG, Shetty K. Inhibition of Helicobacter pylori and associated urease by oregano and cranberry phytochemical synergies. Appl Environ Microbiol. 2005;71(12):8558-8564.16332847
65. Hammer KA, Carson CF, Riley TV. Antimicrobial activity of essential oils and other plant extracts. J Appl Microbiol. 1999;86(6):985-990.10438227
66. Bouhdid S, Abrini J, Zhiri A, Espuny MJ, Manresa A. Investigation of functional and morphological changes in Pseudomonas aeruginosa and Staphylococcus aureus cells induced by Origanum compactum essential oil. J Appl Microbiol. 2009;106(5):1558-1568.19226402
67. Karakaya S, El SN, Karagözlü N, Sahin S. Antioxidant and antimicrobial activities of essential oils obtained from oregano (Origanum vulgare ssp. hirtum) by using different extraction methods. J Med Food. 2011;14(6):645-652.21314366
68. Force M, Sparks WS, Ronzio RA. Inhibition of enteric parasites by emulsified oil of oregano in vivo. Phytother Res. 2000;14(3):213-214.10815019
69. Machado M, Dinis AM, Salgueiro L, Cavaleiro C, Custódio JB, Sousa Mdo C. Anti-Giardia activity of phenolic-rich essential oils: effects of Thymbra capitata, Origanum virens, Thymus zygis subsp. sylvestris, and Lippia graveolens on trophozoites growth, viability, adherence, and ultrastructure. Parasitol Res. 2010;106(5):1205-1215.20217133
70. Santoro GF, das Graças Cardoso M, Guimarães LG, Salgado AP, Menna-Barreto RF, Soares MJ. Effect of oregano (Origanum vulgare L.) and thyme (Thymus vulgaris L.) essential oils on Trypanosoma cruzi (Protozoa: Kinetoplastida) growth and ultrastructure. Parasitol Res. 2007;100(4):783-790.17024354
71. Van Den Broucke CO, Lemli JA. Antispasmodic activity of Origanum compactum. Part 2: antagonistic effect of thymol and carvacrol. Planta Med. 1982;45(3):188-190.6213969
72. Lemhadri A, Zeggwagh NA, Maghrani M, Jouad H, Eddouks M. Anti-hyperglycaemic activity of the aqueous extract of Origanum vulgare growing wild in Tafilalet region. J Ethnopharmacol. 2004;92(2-3):251-256.15138008
73. Koukoulitsa C, Zika C, Hadjipavlou-Litina D, Demopoulos VJ, Skaltsa H. Inhibitory effect of polar oregano extracts on aldose reductase and soybean lipoxygenase in vitro. Phytother Res. 2006;20(7):605-606.16691547
74. Mueller M, Lukas B, Novak J, Simoncini T, Genazzani AR, Jungbauer A. Oregano: a source for peroxisome proliferator-activated receptor gamma antagonists. J Agric Food Chem. 2008;56(24):11621-11630.
75. Bukovská A, Cikos S, Juhás S, Il'ková G, Rehák P, Koppel J. Effects of a combination of thyme and oregano essential oils on TNBS-induced colitis in mice. Mediators Inflamm. 2007;2007:23296.18288268
76. Kulisić T, Krisko A, Dragović-Uzelac V, Milos M, Pifat G. The effects of essential oils and aqueous tea infusions of oregano (Origanum vulgare L. spp. hirtum), thyme (Thymus vulgaris L.) and wild thyme (Thymus serpyllum L.) on the copper-induced oxidation of human low-density lipoproteins. Int J Food Sci Nutr. 2007;58(2):87-93.17469764
77. Ozdemir B, Ekbul A, Topal NB, et al. Effects of Origanum onites on endothelial function and serum biochemical markers in hyperlipidaemic patients. J Int Med Res. 2008;36(6):1326-1334.19094443
78. Mechan AO, Fowler A, Seifert N, et al. Monoamine reuptake inhibition and mood-enhancing potential of a specified oregano extract. Br J Nutr. 2011;105(8):1150-1163.21205415
79. Al-Kalaldeh JZ, Abu-Dahab R, Afifi FU. Volatile oil composition and antiproliferative activity of Laurus nobilis, Origanum syriacum, Origanum vulgare, and Salvia triloba against human breast adenocarcinoma cells. Nutr Res. 2010;30(4):271-278.20534330
80. Savini I, Arnone R, Catani MV, Avigliano L. Origanum vulgare induces apoptosis in human colon cancer caco2 cells. Nutr Cancer. 2009;61(3):381-389.19373612
81. Srihari T, Balasubramaniyan V, Nalini N. Role of oregano on bacterial enzymes in 1,2-dimethylhydrazine-induced experimental colon carcinogenesis. Can J Physiol Pharmacol. 2008;86(10):667-674.18841171
82. Kanazawa K, Kawasaki H, Samejima K, Ashida H, Danno G. Specific desmutagens (antimutagens) in oregano against a dietary carcinogen, Trp-P-2, are galangin and quercetin. J Agric Food Chem. 1995;43(2):404-409.
83. Karpouhtsis I, Pardali E, Feggou E, Kokkini S, Scouras ZG, Mavragani-Tsipidou P. Insecticidal and genotoxic activities of oregano essential oils. J Agric Food Chem. 1998;46(3):1111-1115.
84. Food. Listing of Food Additive Status Part II. US Food and Drug Administration Web Site. http://www.fda.gov/Food/FoodIngredientsPackaging/FoodAdditives/ ucm191033.htm#ftnO. Accessed October 7, 2011. Last updated May 5, 2010.
85. Ciganda C, Laborde A. Herbal infusions used for induced abortion. J Toxicol Clin Toxicol. 2003;41(3):235-239.12807304
86. Zava DT, Dollbaum CM, Blen M. Estrogen and progestin bioactivity of foods, herbs, and spices. Proc Soc Exp Biol Med. 1998;217(3):369-378.9492350
87. Allan P, Bilkei G. Oregano improves reproductive performance of sows. Theriogenology. 2005;63(3):716-721.15629791
88. Domaracký M, Rehák P, Juhás S, Koppel J. Effects of selected plant essential oils on the growth and development of mouse preimplantation embryos in vivo. Physiol Res. 2007;56(1):97-104.16497088
89. Futrell JM, Rietschel RL. Spice allergy evaluated by results of patch tests. Cutis. 1993;52(5):288-290.8299390
90. Benito M, Jorro G, Morales C, Peláez A, Fernández A. Labiatae allergy: systemic reactions due to ingestion of oregano and thyme. Ann Allergy Asthma Immunol. 1996;76(5):416-418.8630713
91. Goun E, Cunningham G, Solodnikov S, Krasnykch O, Miles H. Antithrombin activity of some constituents from Origanum vulgare. Fitoterapia. 2002;73(7-8):692-694.12490231
92. Navarro VJ, Barnhart H, Bonkovsky HL, et al. Liver injury from herbals and dietary supplements in the U.S. drug-induced liver injury network. Hepatology. 2014;60(4):1399-1408.25043597
93. Klein AH, Carstens MI, Carstens E. Eugenol and carvacrol induce temporally desensitizing patterns of oral irritation and enhance innocuous warmth and noxious heat sensation on the tongue. Pain. 2013;154(10):2078-2087.23791894
94. Ragi J, Pappert A, Rao B, Havkin-Frenkel D, Milgraum S. Oregano extract ointment for wound healing: a randomized, double-blind, petrolatum-controlled study evaluating efficacy. J Drugs Dermatol. 2011;10(10):1168-1172.21968667
95. Zava DT, Dollbaum CM, Blen M. Estrogen and progestin bioactivity of foods, herbs, and spices. Proc Soc Exp Biol Med. 1998;217(3):369-378.9492350
96. Ghitea TC, El-Kharoubi A, Ganea M, et al. The antimicrobial activity of Origanum vulgare L. correlated with the gastrointestinal perturbation in patients with metabolic syndrome. Molecules. 2021;26(2):283. doi:10.3390/molecules2602028333429991

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