A February 1966 study from Weber State University's Microbiology
Department subjected the bacteria Pseudomonas aeruginosa as one of the
bacteria exposed to 74 different single oils to determine antimicrobial
activity. The microbial agents didn't respond to many of the oils, but
some had an interesting zone of inhibition. The zone in millimeters was:

Mountain Savory (Satureja Montana) 8 mm
Cinnamon Bark 6 mm
Marjoram and Tea Tree each had 5 mm
Oregano 4 mm

Other bacteria tested included:

E coli, Alcaligenes faecalis, Enterobactercioacae, Staphylococcus,
Streptococcus faecalis, Micrococcus luteus, and Bacillus cereus, as well
as some viruses and fungi.

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From Harvard Medical School .. Consumer Health Information .. and ..
InteliHealth / Home to Johns Hopkins Health.

Oregano destroys Streptococcus pneumoniae in lab.

ATLANTA (Reuters) -- In several new experiments, researchers have found
that some essential oils -- in particular, those derived from oregano,
thyme and rosewood -- create a lytic reaction (cell death/disruption) in
microorganisms, including Streptococcus pneumoniae.

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From a past edition of Natural Health magazine.

"The essential oils, thyme, rosewood, and oregano, may kill certain
bacteria, including those that cause pneumonia, reported researchers at
a recent American Society of Microbiology meetng. According to professor
of microbiology and lead researcher Diane Home, Ph.D., in these
preliminary studies, the oils caused the microorganism cells to "go to
pieces" and die.

-----------------------------------------

From the Knoxville News-Sentinel: A report of a study done at U. of
Tennessee at Knoxville by a skeptical Ph.D. looked at the ability of
essential oils to control pathogens. Says she reran the tests several
times because it wasn't at all what she expected or wanted to believe.
Marinated fresh fish in eo's of angelica, basil, carrot, celery,
cardamom, coriander, dill weed, fennel, oregano, parsley, rosemary.
Checked for 9 food-borne microbes which I will not spell out. Oil of
oregano killed ALL pathogens followed by coriander and basil. "Anise
oil was effective against molds but did little against various bacteria,
".... a second study .. found eo of black cumin moderately effective at
limiting the growth of those microbes. Meats marinated 40 minutes
showed the same reduction in HCA's (high cooking temp carcinogenics)
that 2-day marination showed. The professor is busy trying to return "a
tremendous number of calls" from seasoning companies."

----------------------------------------------------

Below are but one of the many studies on the Origanums.

Stiles J.C., Sparks W., Ronzio R.A.. The inhibition of Candida Albicans
by Oregano. 1995. Submitted for publication. (My Note: This study
shows, without the shadow of a doubt, the anti-fungal effectiveness, in
even very low concentrations, of Turkish Oregano. Turkish Wild Grown
Oregano is specifically mentioned.

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Inhibition of enteric parasites by emulsified oil of oregano in vivo.
Reported by Force M, Sparks WS, Ronzio RA

Health Explorations Trust, Scottsdale, AZ, USA (M.F.) and Biotics
Research Corporation, P.O. Box 36888, Houston, Texas 77236, USA.

Oil of Mediterranean oregano Oreganum vulgare was orally administered to
14 adult patients whose stools tested positive for enteric parasites,
Blastocystis hominis, Entamoeba hartmanni and Endolimax nana. After 6
weeks of supplementation with 600 mg emulsified oil of oregano daily,
there was complete disappearance of Entamoeba hartmanni (four cases),
Endolimax nana (one case), and Blastocystis hominis in eight cases.
Also, Blastocystis hominis scores declined in three additional cases.
Gastrointestinal symptoms improved in seven of the 11 patients who had
tested positive for Blastocystis hominis.

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Aromatic and Medicinal Plant Group, Scottish Agricultural College,
Auchincruive, South Ayrshire, UK. Dorman HJ, Deans SG

The volatile oils of black pepper [Piper nigrum L. (Piperaceae)], clove
[Syzygium aromaticum (L.) Merr. & Perry (Myrtaceae)], geranium
[Pelargonium graveolens L'Herit (Geraniaceae)], nutmeg [Myristica
fragrans Houtt. (Myristicaceae), oregano [Origanum vulgare ssp. hirtum
(Link) Letsw. (Lamiaceae)] and thyme [Thymus vulgaris L. (Lamiaceae)]
were assessed for antibacterial activity against 25 different genera of
bacteria. These included animal and plant pathogens, food poisoning and
spoilage bacteria. The volatile oils exhibited considerable inhibitory
effects against all the organisms under test while their major
components demonstrated various degrees of growth inhibition.

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Agrotechnological Research Institute, 6700 AA Wageningen, The
Netherlands. A.Ultee@... Ultee A, Kets EP, Smid EJ

Carvacrol, a naturally occurring compound mainly present in the
essential oil fraction of oregano and thyme, was studied for its effect
on bioenergetic parameters of vegetative cells of the food-borne
pathogen Bacillus cereus. Incubation for 30 min in the presence of 1 to
3 mM carvacrol reduced the viable cell numbers exponentially. Carvacrol
(2 mM) significantly depleted the intracellular ATP pool to values close
to 0 within 7 min. No proportional increase of the extracellular ATP
pool was observed. Depletion of the internal ATP pool was associated
with a change of the membrane potential (Deltapsi). At concentrations of
0.01 mM carvacrol and above, a significant reduction of Deltapsi was
observed, leading to full dissipation of Deltapsi at concentrations of
0.15 mM and higher. Finally, an increase of the permeability of the
cytoplasmic membrane for protons and potassium ions was observed (at
0.25 and 1 mM carvacrol, respectively). From this study, it could be
concluded that carvacrol interacts with the membranes of B. cereus by
changing its permeability for cations like H(+) and K(+). The
dissipation of ion gradients leads to impairment of essential processes
in the cell and finally to cell death.

-------------------------------------------------------

Basilico MZ, Basilico JC

Dpto. Biotechnologia, Facultad Ingenieria Quimica, Universidad Nacional
del Litoral, Santiago del Estero, Santa Fe, Argentina.

Inhibitory effects of essential oils of oregano (Origanum vulgare), mint
(Menta arvensis), basil (Ocimum basilicum), sage (Salvia officinalis)
and coriander (Coriandrum sativum), on the mycelial growth and
ochratoxin A production by Aspergillus ochraceus NRRL 3174 were studied.
Cultures were incubated on yeast extract-sucrose (YES) broth, at
concentrations of 0, 500, 750 and 1000 p.p.m. of essential oils during
7, 14 and 21 d at 25 degrees C. At 1000 p.p.m., oregano and mint
completely inhibited the fungal growth and ochratoxin A production up to
21 d, while basil was only effective up to 7 d. At 750 p.p.m., oregano
was completely effective up to 14 d, whereas mint allowed fungal growth
but no ocratoxin A production up to 14 d. At 500 p.p.m., no evident
inhibition could be in observed with any of the essential oils under
analysis. Sage and coriander showed no important effect at any of the
concentrations studied. These inhibitory effects are interesting in
connection with the prevention of mycotoxin contamination in many foods
and they could be used instead of synthetic antifungal products.

---------------------------------------------

Inhibitory effects of selected Turkish spices and oregano components on
some foodborne fungi.

Akgul A, Kivanc M

Ziraat Fak., TUT Bol, Erzurum, Turkey.

The inhibitory effects of 10 selected Turkish spices, oregano essential
oil, thymol and carvacrol towards growth of 9 foodborne fungi were
investigated in culture media with pH 3.5 and 5.5. The antifungal
effects of sodium chloride, sorbic acid and sodium benzoate and the
combined use of oregano with sodium chloride were also tested under the
same conditions for comparison. Of the spices tested, only sodium
chloride were also tested under the same conditions for comparison. Of
the spices tested, only oregano at 1.0, 1.5, 2.0% (w/v) levels showed
effect on all fungi. 8% (w/v) sodium chloride was less effective than
oregano. Oregano essential oil, thymol or carvacrol at concentrations of
0.025% and 0.05% completely inhibited the growth of all fungi, showing
greater inhibition than sorbic acid at the same concentrations. The
combined use of oregano and sodium chloride exhibited a synergistic
antifungal effect.

-------------------------------------------------

Sensitivity of heat-stressed yeasts to essential oils of plants.

Conner DE, Beuchat LR

Eight strains of yeasts (Candida lipolytica, Debaryomyces hansenii,
Hansenula anomala, Kloeckera apiculata, Lodderomyces elongisporus,
Rhodotorula rubra, Saccharomyces cerevisiae, and Torulopsis glabrata)
were examined for changes in sensitivity to eight essential oils of
plants (allspice, cinnamon, clove, garlic, onion, oregano, savory, and
thyme) after being sublethally heat stressed. With the exception of
garlic oil for all test yeasts, onion oil for S. cerevisiae, and oregano
oil for R. rubra, the essential oils at concentrations of up to 200 ppm
in recovery media did not interfere with colony formation by unheated
cells. However, some oils, at concentrations as low as 25 ppm in
recovery media, reduced populations of sublethally heat-stressed cells
compared to populations recovered in media containing no test oils. This
demonstrates that the yeasts were either metabolically or structurally
damaged as a result of being exposed to elevated temperatures and that
essential oils prohibited repair of injury. The size (diameter) of
colonies produced on oil-supplemented recovery agar by heat-stressed
cells was reduced compared to that observed on unsupplemented agar.
Pigment production by heated R. rubra was inhibited by oils of oregano,
savory, and thyme, but enhanced by garlic and onion oils. The influence
of essential oils on survival of yeasts in thermally processed foods and
in the enumeration of stressed cells in these foods should not be
minimized.

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Lermioglu F, Bagci S, Onderoglu S, Ortac R, Tugrul L

Ege University, Faculty of Pharmacy, Department of Toxicology, Turkey.
lermiogluf@...

Oleum origani, the essential oil of Origanum onites L., is a traditional
plant material used in Turkey for the treatment of several diseases,
including diabetes mellitus. This study has evaluated the effect of
oleum origani on streptozotocin-induced tissue injury and haematological
changes. The effect of oleum origani on glycaemia was also studied.
Long-term administration of oleum origani resulted in significant
improvement of tissue injury induced by streptozotocin treatment. No
effect on blood glucose levels was detected. In addition, any visible
toxicity or disturbance of haematological parameters and tissue
structure attributable to the long-term use of oleum origani were not
established in normal rats. The data indicate that long-term use of
oleum origani might be effective in preventing or at least in retarding
the development of some complications of diabetes mellitus. Further
investigation is required to determine the underlying mechanism(s) of
the protective effect against tissue injury induced by
streptozotocin-treatment of rats.

--------------------------------------------------------

Didry N, Dubreuil L, Pinkas M

Laboratoires de Pharmacognosie, Faculte des Sciences pharmaceutiques et
biologiques, Lille, France.

The antimicrobial activity of thymol, carvacrol and cinnamaldehyde was
tested by several methods on bacteria involved in upper respiratory
tract infections. Their combinations were investigated too. The broad
spectrum of activity and the synergistic effect observed with some
combinations (specially thymol and carvacrol) could allow the use of
the three compounds alone or, like thymol an carvacrol, combined during
the treatment of respiratory infections.