Dried Oregano Fact Sheet

WHAT IS 'OREGANO' ?-It is fair to say there is still a lot of confusion with both the name given to dried herbs and with the living plants. Many confusions are carried forward by gardeners and even garden writers, not being helped by the botanists re-assigning species into sub-species of a different name!

'Oregano' is a term used in North America covering the dried herb of the two 'hotter' Origanum species  - Origanum vulgare and Origanum onites ('pot marjoram'). It also covers several sub-species (the abbreviation is 'ssp.') of Origanum vulgare, particularly the very widespread and common sub-species Origanum vulgare ssp. vulgare, as well as the much less common O. vulgare ssp. viride, and the one that we are concerned with, the relatively localised Greek and Turkish sub-species - Origanum vulgare ssp. hirtum, the 'true Greek' form of oregano, a form very high in essential oils.

'Oregano' is also used for a Mexican sage bush which is increasingly used as an 'oregano substitute', but labelled as being a form of oregano, usually being described as 'Mexican oregano'. All Origanum species are, in fact, native only to Europe, Africa and Southwest Asia. To confuse matters further, the 'flavoring' known in the trade as 'oregano' can also be extracted from Coleus amboinicus and several other totally unrelated species, and then used in products and described as 'oregano flavored'!

In UK and Australasia 'oregano' is usually called 'oreganum', and is occasionally known (confusingly) as 'wild marjoram'.

To eliminate confusion, all 'hotter' Origanum species should be referred to by the generic term 'Oregano'.

The oregano you buy in the shops is almost always the dried leaves of the common purple flowered 'wild oreganum' O.vulgare of Southern Europe, or the sub-species vulgare very widespread in the Mediterranean region and further East, or perhaps even the rather mild O.onites, 'pot marjoram'.

True 'Greek' oregano, Origanum vulgare ssp. hirtum, the strongest and most pungent form of the species, is of much more limited geographic spread and is rarely available.

Most importantly, the peasant practice of selecting and drying only the especially rich and powerful flowering stems is quite simply uneconomic, and therefore the customary 'true' Greek oregano is not often commercially available. Where the Greek origanum is grown commercially for the flower stems it is usually to distill the immensely valuable oregano oil from them. They are so potent that the dried flower stems are worth more distilled for oil than rubbed into culinary oregano for sale in supermarkets - even when 220lbs/100 kilos of dried 'true Greek oregano' only yields 9lbs/4kgs to 13lbs/6 kilos of pure oil.

As seems the pattern with this genus, even the oil is not safe from confusion. One commercial 'oregano' oil is actually produced from the so-called 'Spanish oregano', actually a species of thyme, Thymus capitatus!

Origanum vulgare subspecies hirtum  - Greek Oregano, Wild Oregano.
This is a subspecies of the widespread wild oregano, and is found only in Greece, Turkey, and the islands of the Aegean Sea (it is sometimes incorrectly referred to as Origanum heracleoticum), and is the essential herb for pizza. Known as 'origini' in Greece, it is only the summer flower heads that are dried and used. The flowers are always white. The leaves are fuzzy, oval and somewhat coarse in relation to the other species.

The flavor is strong, austerely and hotly aromatic, penetrating and slightly bitter. This is the strongest flavored 'oregano'. It is the species used for extraction of essential oils, the dried foliage having around 3% of oils, depending on growing conditions and seedling variability. The concentration of oils is so high that lengthy handling of large amounts of the dried product can cause irritation to sensitive skins.

Biologically active compounds
As with many plant compounds, the minute (usually only relatively low parts per million) amounts of chemicals are helpful and protective at the tiny doses naturally present, and sometimes harmful and dangerous when taken in concentrated and very high amounts.

According to Ecopharm Hellas, who grow selections of Origanum vulgare ssp. hirtum for oil, the following compounds are found in oregano oil (bearing in mind that activity found in the test tube is not necessarily active in the complex milieu of the human body AND some of the activity is only present at rather high levels, levels that in many cases are not reached in the natural oil. The activity is reported for the isolated compound at certain dose levels in the laboratory, it is not reflecting the activity of the compound in any particular plant, including oregano, as the concentration present in the plant may be much lower than that used in the laboratory. Not all reported activity - from the Duke database mentioned below - is mentioned here) :

6-methyl-3-heptanol;
alpha-pinene, antibacterial, cancer preventative, antinflammatory;
beta-bisabolene, antiviral, antiulcer, abortifacent;
beta-caryophyllene, antiacne, antiasthmatic, antibacterial, anticarcinogenic, antitumor, antiinflammatory, termitifuge;
beta-pinene, antiinflammatory, antiseptic, candidacide, pesticide, spasmogenic, allergenic;
calemene, no reported activity;
camphene, antioxidant, spasmogenic;
carvacrol, see below;
carvacrol acetate;
cineole, antiallergenic, allergenic (!), antibronchitic, antifatigue, antihalitosic, candidicide, hypotensive, expectorant, neurotoxic, nematicide;
cis-dihydrocarvone;
cis-sabinene hydrate, no reported activity;
cymene, analgesic, antibacterial, antiflu, antiviral, herbicide, fungicide, trichomonicide;
gamma-terpinene, antioxidant, pesticide;
germacrene D, pesticide, pheromone;
hexanal;
limonene, antibacterial, anticancer, antiviral, antitumor,  flavor, fungistat, irritant, pesticide,allergenic;
linalol, no reported activity;
linalyl acetate, motor depressant, sedative, antispasmodic;
methylcarvacrol;
myrcene, antimutagenic, antibacterial, antioxidant, pesticide, allergenic;
p-cymene, analgesic, antibacterial, antiviral, fungicide, trichomonicide;
p-cymene-8-ol;
phellandrene, irritant, laxative, emetic;
sabinene, perfumery use;
terpinen-4-ol, antiallergenic, antiasthmatic, antiseptic, bacteriostatic, antibacterial, diuretic, fungicide, herbicide, irritant, pesticide, spermicide;
terpinolene, deoderant, perfumery use, pesticide, fungicide, flavor;
thymol, antiacne, antiartheriosclerotic, antibacterial, antiinflammatory, antioxidant, antimelanomic, antiplaque, antifreeradicular, antimutagenic, antirheumatic, candidicide, urinary antiseptic, vermicide, pesticide, irritant, fungicide;
trans-dihydrocarvone;

The USDA's Agriculture Research Service has a Phytochemical and Ethnobotanical database compiled by Dr. James Duke. His entry is for Origanum vulgare, without distinguishing whether it is the species or one of the subspecies, or a mix. However, the constituents are probably closely similar, if not identical; the concentration of the constituents will vary according to whether it is the species or one of the sub species that was analysed. The data additionally identifies, amongst the 119 or so chemical compounds listed:

alpha-humulene, antitumor activity;
low amounts of beta-elemene, anti cervix cancer activity;
caffeic acid, antiviral, anticarcinogen, antioxidant, antiinflammatory, anti sunburn, hepatoprotectant, immunostimulant;
delta cadinene, antiacne, antibacterial, testosterone inducer;
rosmarinic acid, antianaphylactic, antibacterial, antioedemic, antihepatotoxic, antiherpetic, antiinflammatory, antilipo-peroxidant, antifreeradicular, antishock, antiviral, cancer preventive, pesticide;
ursolic acid, anti-HIV, antiarthritic, antidiabetic, antihepatotoxic, antihistaminic, antiinflammatory, antimutagenic, antioxidant, antitumor, antiulcer, antiviral, cancer preventive, hepatoprotective, pesticide, piscicide

Carvacrol is one of the most important and characteristic components of oregano essential oils. It has been noted as having antibacterial, antiinflammatory, antimelanomic, antioxidant, antiplaque, anti free radicular, antiseptic, antifungal and anti worm activity in greater or lesser concentrations, along with other positive, and some negative, activity. Some activities are only demonstrated when concentrated in the laboratory to an un-natural degree.

Oregano oil distilled from the leaves and flowers has been shown to be active against both fungi and bacteria. The phenolic compounds carvacol and thymol have well known antiseptic properties, and both oregano and thyme (which also contains thymol) have been used for millenia as effective herbal remedies (Theophrastos, who lived from 372-287 B.C., described oregano and its use ). The activity of some compounds is uncertain, as is the effect of all the compounds working together, but may well play an important part in the protectant and medicinal effect of true Greek oregano. When the leaves are dried in controlled optimal conditions, the health giving benefits are conserved in the dried kitchen herb.

In Turkey, 'Novaday', a clonally propagated variety, is used by meat and poultry processors in extract form to reduce surface bacterial levels on their products. Turkish researchers have found that water extracts of oreganum were effective in killing Escherichia coli O157 (H7), Listeria monocytogenes 4b, Staphylococcus aureus and Yersinia enterocolitica O3 "after direct contact application". These extracts are "edible, safe, and possibly cheaper than commerciallly available synthetic food antimicrobials and decontaminating agents" (Gülmez.et al ND). One test subject was a commercially available 'oreganum water', the other was tea made from 100 grams of "commercial crumbled native oregano spice bought from a local retailer in Kars-Turkey added to 1 liter boiled distilled water in a sterile erlenmayer flask, then the flask left for 30 min". (While both were very effective, the commercial water extract was more quickly effective than the tea, but no analysis was done to see if the commercial product had additional antibacterial chemicals added to it.)

General antioxidant effects
A recent study (Zheng and Wang 2002) of culinary and medicinal herbs identified oregano as the the herb with the greatest antioxidant activity. It scored higher than any fruit or vegetable previously tested. Oreganum had higher antioxidant activity than even vitamin E.

Propagation
This species of Origanum is a creeping rhizomatous perennial, and needs sandy or well drained soil, is hardy, and will stand a little frost. As long as it gets good snow cover, it has survived as far north as Alberta, Canada. True Greek oregano can easily be grown from seeds sown inside in late winter or spring (depending on your climate), or from cuttings in Autumn or Spring.It also easily propogates  from rooted portions of the creeping stem. Transplant the seedlings after danger from frost has passed.
 
Greek scientists have selected 3 plants of Origanum vulgare ssp. hirtum with an essential oil content close to double that of the normal oregano. This is unlikely to be available at nurseries for some years. Experience with growing a mixed seedlot suggests it would not be too difficult to select 'hotter' plants at home. There is no particular reason to do this, as normal true Greek origini, at the peak of the season, will 'blow your head off'. At seasons end, it has almost no 'heat' at all, and tastes of very little.

Origanum vulgare - Oregano, Wild Oregano, Wild Marjoram.
The leaves are only mildly pungent, certainly not as strong as Origanum vulgare ssp. hirtum, the true Greek oreganum (some writers claim it has hardly any flavor at all, but we must be aware of the possiblity that they may be confused with other Origanum species.). A creeping perennial, around 12 inches/30 cm in the selected garden forms, and 3 feet/90 cm high in the wild. The tall heads of small purple flowers are in green or violet purple bracts. It is native to the Southern part of Europe.

It is possibly the most winter hardy Origanum species, but still needs winter protection in temperate areas. Likes the sun and a free draining soil. There are some ornamental varieties grown primarily as garden plants. A few examples are-
'Album' a compact small bushy mound with white flowers and light green foliage
'Aureum' golden foliage, lavender flowers, spreading, often used as a ground cover
'Aureum crispum' as for 'Aureum', but with curled leaves
'Compactum'  very compact (6 inches/15cm), profuse pinkish flowers
'Compactum nanum' even smaller, less than 4inches/10cm, but with lilac purple flowers
'Variegatum' small creamy white variagated leaves
'White Anniversary' Lime green leaves edged with white

Wild oregano can easily be grown from seeds sown inside in late winter, or from cuttings in autumn or spring. Transplant the seedlings after danger from frost has passed.

A form of Origanum vulgare that has pink flowers, and ranges from the mainland Mediterranean, the Middle East into Iran and the approaches to the Himalayas. It has been introduced and naturalised in Southern China. It is regarded as a sub-species, and is known as Origanum vulgare ssp. vulgare. The dried plant has, variably, around .5% essential oils.

Another sub species, Origanum vulgare ssp. viride, is confined to Northern and Central Turkey. It is superficially similar to true Greek oreganum, but the flowers may be pale pink as well as white.

Lippia graveolens. Mexican Oregano, Origan, Oregamon, Wild Marjoram, Mexican sage, or Mexican wild sage
also known as  is Lippia graveolens. It is not an Oreganum species, and isn't even in the same family (the botanical family of true oreganum is 'Labiatiae', a family that includes many of the aromatic herbs - thyme, basil, rosemary as well, of course, as oreganum itself).

Origanum majorana MARJORAM Sweet Marjoram, Knotted Marjoram. (formerly Majorana hortensis)
Marjoram is a fairly small slightly sprawling, soft grey-green leafed plant, to 2 feet/60cm (smaller if grown as an annual), with 'knots' of fairly insignificant pink or white flowers on wiry erect stems in mid summer.

This is the most delicately flavored Origanum species, the small, oval grey-green leaves being vaguely 'sweet' and spicy, and often used with thyme as a meat flavoring, or with vegetables where the flavoring needs to be subtle, not overpowering.

Amongst other compounds, the essential oil from steam distillation contains various terpenes, terpineol, cis-sabinene hydrate, linalol, ocimene, cadinene, and other compounds. Marjoram has some antioxidant and antifungal properties.

Marjoram is the preferred species for fresh use. The flavor is best when the flower buds first appear. Used fresh, it is an important part of  'fines herbes' (bundled fresh herbs thrown into the pot to flavor), or as a flavoring in salads, in egg dishes, incorporated in sausages and stuffings, and sprinkled on vegetables. Marjoram shouldn't be cut too hard, and it is best to take only about a third or so of the newest growth. Harvest the leafy stems at full bloom and dry in a shady place out of direct sunlight.

Native to the Mediterranean and Turkey, now widely naturalised in Southern Europe. While it is actually a perennial, it is not winter hardy, and is usually grown as an annual in temperate regions. It is easily grown from seed. Like all Origanum species, it needs well drained soil and lots of sun. Slugs and snails love tender young marjoram seedlings, so they need protection until they are well established.

Origanum onites Pot Marjoram, Italian oregano (wasMajorana onites)
Pot marjoram is a creeping perennial eventually forming a mound of bright green leaves about 2 feet/60cm high, with off-white or purple flowers on hairy stems late in summer. Like 'Greek oregano', the lanky flower stalks need cutting back after flowering, if they haven't already been harvested for drying.

.This Origanum species has a flavor intermediate between 'Marjoram' and 'Oregano'.It is not as sweet as 'Marjoram', is slightly bitter, but not as hot as common commercial 'Oregano' (Origanum vulgare), being sometimes described as 'delicately warm'.  This Origanum also grows well as a potted herb on the patio or kitchen window ledge.

Native to southeast Europe, Turkey, and Syria.

Confusingly, 'Pot Marjoram' is sometimes called Mediterranean or Greek oregano!!

O. Dictamnus, Dittany of Crete (formerly Amaracus dictamnus or Amaracus tomentosus.)
Native of Crete, a wiry, sprawling 12 inch high (30 cm) wooly stemmed and velvety grey leafed perennial plant sometimes grown for its attractive spikes of pink to purplish pink flowers. It has been used as a herbal remedy for thousands of years (a picture on the walls of the Cretian palace of Minos is believed to be dittany of Crete), and is regarded as safe for human consumption, but has little flavor.

O. laevigatum
Also a low-growing, spreading plant with small leaves. The flowers are variably colored, from pink to mauve to violet purple. There are many garden varieties of  O. laevigatum.
'Herrenhausen', has large clusters of pale lilac purple flowers and purple tinged foliage which deepens in the fall.
'Hopley's' has particularly rich pink flowers in relatively profuse blooms on a fairly large plant.
'Rosenkuppel', dark pink flowers and contrasting maroon purple flower bracts, compact at about a foot/30 cm high
'Rotkugel', similar to 'Rosenkuppel' but larger and with more rounded foliage.

Other wild origanum species that are very rarely grown in garden collections have little or no culinary or ornamental merit, and include-
O. acutidens, white or tinged pink flowers; O. amanum, pink flowers, highly colored bracts; O. calcaratum, pink flowers; O. xhybridum, relatively large pink flowers; O. leptocladum, pink flowers; O. libanoticum, pink flowers and bracts; O. majoricum, pink flowers, sterile, probably a hybrid; O. microphyllum, purple flowers; O. rotundifolium, pink flowers, odd; O. scabrum, purple flowers; O. sipyleum, pink flowers, O. syriacum var bevanii.

Species with names of dubious standing
Some of the following will be synonyms for some of the species already mentioned above or listed below. Some confusion still remains.
O. glandulosum said to be an African (? North African) species sometimes used for oil extraction
O. virens said to be a Moroccan species also used for oil extraction
O. maru said to be a Syrian species used for oil extraction

Full species list of accepted Origanum species (http://www.theplantlist.org/browse/A/Lamiaceae/Origanum/)
Origanum acutidens (Hand.-Mazz.) Ietsw.
Origanum × adanense Baser & H.Duman
Origanum × adonidis Mouterde
Origanum akhdarense Ietsw. & Boulos
Origanum amanum Post
Origanum × barbarae Bornm.
Origanum bargyli Mouterde
Origanum bastetanum Socorro, Arrebola & Espinar
Origanum bilgeri P.H.Davis
Origanum boissieri Ietsw.
Origanum brevidens (Bornm.) Dinsm.
Origanum calcaratum Juss.
Origanum compactum Benth.
Origanum cordifolium (Montbret & Aucher ex Benth.)
Origanum cyrenaicum Bég. & Vacc.
Origanum dayi Post
Origanum dictamnus L.
Origanum × dolichosiphon P.H.Davis
Origanum ehrenbergii Boiss.
Origanum elongatum (Bonnet) Emb. & Maire
Origanum floribundum Munby
Origanum × haradjanii Rech.f.
Origanum haussknechtii Boiss.
Origanum humile Poir.
Origanum husnucan-baseri H.Duman, Aytac & A.Duran
Origanum hypericifolium O.Schwarz & P.H.Davis
Origanum × intercedens Rech.f.
Origanum × intermedium P.H.Davis
Origanum isthmicum Danin
Origanum jordanicum Danin & Kunne
Origanum laevigatum Boiss.
Origanum leptocladum Boiss.
Origanum libanoticum Boiss.
Origanum × lirium Heldr. ex Halácsy
Origanum majorana L.
Origanum × majoricum Cambess.
Origanum microphyllum (Benth.) Vogel
Origanum × minoanum P.H.Davis
Origanum minutiflorum O.Schwarz & P.H.Davis
Origanum munzurense Kit Tan & Sorger
Origanum × nebrodense Tineo ex Lojac.
Origanum onites L.
Origanum × pabotii Mouterde
Origanum pampaninii (Brullo & Furnari) Ietsw.
Origanum petraeum Danin
Origanum punonense Danin
Origanum ramonense Danin
Origanum rotundifolium Boiss.
Origanum saccatum P.H.Davis
Origanum scabrum Boiss. & Heldr.
Origanum sipyleum L.
Origanum solymicum P.H.Davis
Origanum symes Carlström
Origanum syriacum L.
Origanum vetteri Briq. & Barbey
Origanum vogelii Greuter & Burdet
Origanum vulgare L.   

References and further reading
Gülmez M, Oral N, Güven A, et al. ND 'Antibacterial activity of oregano tea and a commercial oregano water against Escherichia coli O157:H7, Listeria monocytogenes 4b, Staphylococcus aureus and Yersinia enterocolitica 03.'
Internet Journal of Food Safety V (８): ７-１3

Alma, M.H., Mavi, A., Yildirim, A., Digrak, M., Hirata, T., 2003. Screening chemical composition and in vitro antioxidant and antimicrobial activities of the essential oils from Origanum syriacum L. growing in Turkey.
Biol. Pharm. Bull. 26, 1725-1729.

Aridogan, B.C., Baydar, H., Kaya, S., Demirci, M., Ozbasar, D., Mumcu, E., 2002. Antimicrobial activity and chemical composition of some essential oils.
Arch. Pharm. Res. 25, 860-864.

Burt, S., 2004. Essential oils: their antibacterial properties and potential applications in foods- a review.
Int. J. Food Microbiol. 94, 223-253.

Capecka, E., A. Mareczek, and M. Leja. 2005. Antioxidant activity of fresh and dry herbs of some Lamiaceae species.
Food Chem. 93:223-226.

Chorianopoulos, N., Kalpoutzakis, E., Aligiannis, N., Mitaku, S., Nychas, G.J., Haroutounian, S.A., 2004. Essential oils of Satureja, Origanum, and Thymus species: chemical composition and antibacterial activities against foodborne pathogens.
J. Agric. Food Chem. 52, 8261-8267.

Dadalioglu, I., Evrendilek, G.A., 2004. 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. 52, 8255-8260.

Friedman, M., Henika, P.R., Mandrell, R.E., 2002. Bactericidal activities of plant essential oils and some of their isolated constituents against Campylobacter jejuni, Escherichia coli, Listeria monocytogenes, and Salmonella enterica.
J. Food Prot. 65, 1545-1560

Hara-kudo, Y., Kobayashi, A., Sugita-konishi, Y., Kondo, K., 2004. Antibacterial activity of plants used in cooking for aroma and taste.
J. Food Prot. 67, 2820-2824.

Kessel, A.S., Gillespie, I.A., O'Brien, S.J., Adak, G.K., Humphrey, T.J., Ward, L.R, 2001. General outbreaks of infectious intestinal disease linked with poultry, England and Wales, 1992-1999.
Commun Dis Public Health. 4, 171-177.

Kim, S., Ruengwilysup, C., Fung, D.Y.C., 2004. Antibacterial effect of water soluble tea extracts on foodborne pathogens in laboratory Medium and food model.
J. Food Prot. 67, 2608-2612.

Lin, Y.T., Labbe, R.G., Shetty, K., 2004. Inhibition of Listeria monocytogenes in fish and meat systems by use of Oregano and Cranberry phytochemical synergies.
Appl. Environ. Microbiol. 70, 5672-5678.

Nostro, A., Blanco, A.R., Cannatelli, M.A., Enea, V., Flamini, G., Morelli, I., Sudano Roccaro, A., Alonzo, V., 2004. Susceptibility of methicillin-resistant staphylococci to oregano essential oil, carvacrol and thymol.
FEMS Microbiol. Lett. 230, 191-195.

Zhao, C., Ge, B., De Villena, J., Sudler, R., Yeh, E., Zhao, S., White, D.G., Wagner, D., Meng, J., 2001. Prevalence of Campylobacter spp., Escherichia coli, and Salmonella serovars in retail chicken, turkey, pork, and beef from the greater Washington, D.C., area.
Appl. Environ.Microbiol. 67, 5431-5436.

Zheng W, Wang SY. Antioxidant activity and phenolic compounds in selected herbs.
J Agric Food Chem 2002;49:5165-70.