Tea Tree Oil and Biofilms

by Robert Tisserand (www.roberttisserand.com)

One of the outstanding properties of many essential oils, including tea tree (Melaleuca alternifolia), is that they can be effective even against bacterial biofilms.

A biofilm is a layered matrix, consisting mainly of polysaccharide and protein, that bacteria or fungi create on a surface as a secure habitat. In this form they are more difficult to kill, because the biofilm structure affords protection from the environment. Plaque on teeth is an example of a biofilm and the success of ‘essential oil’ mouthwashes such as Listerine compared to others is partly due to their ability to break down and inhibit plaque formation (Oyanagi et al 2012). (Listerine contains four essential oil constituents: thymol, menthol, 1,8-cineole and methyl salicylate. It was originally developed and used as a surgical antiseptic.)

In a biofilm, the outer layer consists of more or less dormant cells that are also especially resistant. Medical implants, such as heart valves, catheters, stents etc, are becoming more common. They are subject to colonization by bacterial biofilms, and if this occurs the result can be fatal, as antibiotics have great difficulty penetrating the outer layer of resistant bacteria (Hoiby et al 2010). Consequently, implant-related fatalities are on the rise.

S. aureus on a catheter

Carvacrol and cinnamaldehyde (major constituents of oregano oil and cinnamon bark oil respectively) inhibited biofilm formation on a polymer coating. It is proposed that medical devices coated with such compounds would be much less susceptible to bacterial colonization. Cinnamaldehyde significantly reduced Pseudomonas aeruginosa biofilm at 1%, and most bacteria were inhibited by either compound at 0.1% (Zodrow et al 2012). P. aeruginosa is one of the most difficult bacteria to kill. It forms mucosal biofilms in the lungs in cystic fibrosis, and it can be a problem in wound healing.

Biofilm may be found on contact lenses, chronic wounds and ulcers, vaginal mucous membrane, in fact on any surface where there is moisture and nutrients. It is constantly forming on our skin, in addition to the usual mix of dirt, sebum, sweat and cosmetics. Biofilms are also found on surfaces outside the body. Because of a combination of grease-cutting and antibiofilm properties, pine oil and orange oil are common ingredients in household disinfectants. More on biofilms here.

In vitro testing often shows antibiotics to be more effective than essential oils. Conversely, some essential oils are more effective at killing bacteria in biofilm, because they can penetrate it more effectively, and because they are less susceptible to resistant mechanisms. Essential oils that have shown good antibiofilm action in in vitro testing include:

Cinnamon bark: Staphylococcus epidermis biofilm (Nuryastuti et al 2009)

Oregano: S. aureus and S. epidermis biofilm (Nostro et al 2007)

Thyme: Listeria monocytogenes biofilm on stainless steel and polystyrene (Desai et al 2012)

Rosemary: Candida albicans and C. tropicalis biofilm (Chifiriuc et al 2012)

Tea tree: S. aureus, MRSA and C.albicans biofilm (Kwiecinski et al 2009, Park et al 2007, Sudjana et al 2012)

Some of these essential oils are now being considered for use in food preservation, another situation where biofilm formation is a challenge.

M. alternifolia in flower *

Staphylococcus aureus is a ubiquitous bacterium, notably found on the skin. In vitro research shows that tea tree oil dose-dependently eradicates S. aureus biofilm (Kwiecinski et al 2009) and that it is effective against MRSA and MSSA biofilm (Brady et al 2006). A 50% concentration of tea tree oil was as effective as vancomycin in vitro in eradicating MRSA biofilm on typanostomy tubes (Park et al 2007). S. aureus biofilm, in an infected cochlear implant, was found to be resistant to all conventional antimicrobials, but 5% tea tree oil completely eradicated it in one hour (Brady et al 2010). Tea tree oil has shown good effect in eradicating MRSA on the skin, used at 5% in a body wash, in addition to either 4% in an ointment (Caelli et al 2000) or 10% in a cream (Dryden et al 2004).

Candida albicans forms biofilms that cause disease and are difficult to treat with conventional antifungal agents. At 0.031% in vitro, tea tree oil significantly reduced biofilm formation for all of 10 C. albicans isolates tested (Sudjana et al 2012). Further in vitro work suggests that tea tree oil may be effective in oral hygiene products for the prevention and control of oral candidosis in cancer patients (Bagg et al 2006, Ramage et al 2012). In 25 AIDS patients with oral candidosis who had not responded to fluconazole treatment, 7 were cured and 8 improved after four weeks using oral solutions containing tea tree oil (Vazquez et al 2002).

These studies suggest promising uses for essential oils, notably tea tree, in the prevention and eradication of biofilm-related medical problems that may be resistant to conventional treatment, as well as in surface cleaning, hand hygiene and skin cleansing products.
 

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References

Bagg J, Jackson MS, Sweeney MP et al 2006 Susceptibility to Melaleuca alternifolia (tea tree) oil of yeasts isolated from the mouths of patients with advanced cancer. Oral Oncology 42:487-492
Brady A, Loughlin R, Gilpin D et al 2006 In vitro activity of tea-tree oil against clinical skin isolates of meticillin-resistant and -sensitive Staphylococcus aureus and coagulase-negative staphylococci growing planktonically and as biofilms. Journal of Medical Microbiology 55:1375-1380 http://jmm.sgmjournals.org/content/55/10/1375.full.pdf+html
Brady AJ, Farnan TB, Toner JG et al 2010 Treatment of a cochlear implant biofilm infection: a potential role for alternative antimicrobial agents. Journal of Laryngology, Rhinology &Otology 124:729-738
Caelli M, Porteous J, Carson CF et al 2000 Tea tree oil as an alternative topical decolonization agent for methicillin-resistant Staphylococcus aureus. Journal of Hospital Infection  46:236-237
Chifiriuc C, Grumezescu V, Grumezescu AM et al 2012 Hybrid magnetite nanoparticles/Rosmarinus officinalis essential oil nanobiosystem with antibiofilm activity. Nanoscale Research Letters 7:209 http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3368737/
Desai MA, Soni KA, Nannapaneni R et al 2012 Reduction of Listeria monocytogenes biofilms on stainless steel and polystyrene surfaces by essential oils. Journal of Food Protection 75:1332-1337
Dryden MS, Dailly S, Crouch M 2004 A randomized, controlled trial of tea tree topical preparations versus a standard topical regimen for the clearance of MRSA colonization.   Journal of Hospital Infection 56:283-286
Hoiby N, Bjarnsholt T, Givskov M et al 2010 Antibiotic resistance of bacterial biofilms.  International Journal of Antimicrobial Agents 35:322-332
Kwiecinski J, Eick S, Wojcik K 2009 Effects of tea tree (Melaleuca alternifolia) oil on Staphylococcus aureus in biofilms and stationary growth phase. International Journal of Antimicrobial Agents   33:343-347
Nostro A, Sudano Roccaro A et al 2007 Effects of oregano, carvacrol and thymol on Staphylococcus aureus and Staphylococcus epidermidis biofilms. Journal of Medical Microbiology 56:519-523 http://jmm.sgmjournals.org/content/56/4/519.long
Nuryastuti T, van der Mei HC et al 2009 Effect of cinnamon oil on icaA expression and biofilm formation by Staphylococcus epidermidis. Applied & Environmental Microbiology 75:6850-6855 http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2772433/

Oyanagi T, Tagami J, Matin K et al 2012 Potentials of mouthwashes in disinfecting cariogenic bacteria and biofilms leading to inhibition of caries. The Open Dentistry Journal 6:23-30http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3269010/
Park H, Jang CH, Cho YB et al 2007Antibacterial effect of tea-tree oil on methicillin-resistant Staphylococcus aureus biofilm formation of the tympanostomy tube: an in vitro study. In Vivo 21:1027-1030 http://iv.iiarjournals.org/content/21/6/1027.long
Ramage G, Milligan S, Lappin DF et al 2012 Antifungal, cytotoxic, and immunomodulatory properties of tea tree oil and its derivative components: potential role in management of oral candidosis in cancer patients. Frontiers in Microbiology 3:22

Sudjana AN, Carson CF, Carson KC et al 2012 Candida albicans adhesion to human epithelial cells and polystyrene and formation of biofilm is reduced by sub-inhibitory Melaleuca alternifolia (tea tree) essential oil. Medical Mycology 50:863-870
Vazquez JA, Zawawi AA 2002 Efficacy of alcohol-based and alcohol-free melaleuca oral solution for the treatment of fluconazole-refractory oropharyngeal candidiasis in patients   with AIDS. HIV Clinical Trials 3:379-385

Zodrow KR, Schiffman JD, Elimelech M 2012 Biodegradable polymer (PLGA) coatings featuring cinnamaldehyde and carvacrol mitigate biofilm formation. Langmuir 28:13993-13999

*Melaleuca alternifolia photo from The Australian Tea Tree industry Foundation

ROOTS: German Chamomile and other moderate climate oils

Many of the oils we use on a daily basis in aromatherapy are somehow associated with dry and hot climates or with poor soil. Apparently these stresses induce the plants to produce more powerful essential oils to ensure survival. Examples are Citrus, Lavender and Rosemary oils. The EO’s from these plants employ a chemical vocabulary that is heavily centered on simple monoterpenoid components, such as cineol, terpineol or linalool.

Quite distinct from those are essential oils from many species that belong to the Asteraceae and Apiaceae families. Often these oils find their highest degree of finesse not so much in the hotter subtropical climates but in the moderate and moist climates encountered in Central and Eastern Europe. In the case of German Chamomile the relation between the plant and a specific geography has even become a part of the common name of the species.

For aromatherapy this is quite interesting. These latter plant families thriving in the more moderate climates have evolved to display a more diverse array of components than the essential oils from plant species that developed before them. Lactones and en-yn ethers are just two examples.

In this post I would therefore like to share some thoughts about some classic oils of the daisy (Asteraceae) and the parsley (Apiaceae) family.

German Chamomile
German Chamomile (Matricaria recutita) is one of the best researched medicinal plants. Much of the abundant modern research, dating from the late seventies and early eighties, is ‘pre-internet’ and hence not so easy to locate.

Summing up for the purposes of aromatherapy: Depending on a variety of factors, most importantly genotypes, the Chamomile plant produces chemotypes of essential oil. Some oils have high concentrations of bisabolone and others have high concentrations of bisabolol oxide. However, only a third type, with (-) alpha bisabolol, truly has the full powerful antiinflammative qualities associated with this essential oil. It is a more powerful antiinflammative component than the characterisically blue Chamazulene.

The oil we offer is from an estate in southern Germany specializing in the cultivation and distillation of German Chamomile essential oil. As this is the climate and also the cultural environment where Chamomile has been a part of life for at least a thousand years (Odo Magdunensis, 11. Jh.) it reaches its greatest finesse in the moderate climates of central Europe. Oils from other parts of the world with subtropical climates invariably are of lesser quality.

Yarrow
Yarrow essential oil is distilled in a variety of places, however, demand for it and consequently its production seem irregular. The most relevant quantities on the market are from Eastern Europe with Bulgaria being the main supplier, and to a lesser degree Serbia and Bosnia and Herzegovina.

Wild oils are described as having a concentration of approximately 1% chamazulene and cultivated oils as having a somewhat higher percentage. The wild oils have a light blue tinge whereas the cultivated oils are a darker color blue. Whether the oil with the higher Chamazulene content is really of higher value – therapeutically – remains questionable.

The appreciation of Yarrow essential oil in aromatherapy is probably fueled to a large degree by its traditional popularity in herbalism. As such Yarrow is popular in different ethnopharmacological traditions, even Bedouins in desert areas of the Middle East value Achillea millefolium as an anti-allergy agent and for the treatment of high fever.

In modern aromatherapy Yarrow (Achillea millefolium) essential oil is described as a powerful antiinflammatory agent with particular affinity for rheumatic pain. It is ‘the’ oil to alleviate neuralgic pain and Franchomme and Pénoël even list prostatitis and kidney stones under the indications for Yarrow essential oil.

Some of the components found in Yarrow essential oil are quite special, i.e. the sesquiterpene lactone achilline or its isoartemisia ketone. Considering the appreciation Yarrow has had throughout history it is quite likely that some of its best therapeutic qualities are still to be explored.

Angelica
Angelica (Angelica archangelica) root essential oil is precious and unique. Unique for its content of musk lactone and musk ketone which give its aroma the much desired exalting fragrance quality. The novice can easily explore this particular quality by creating a simple blend of equal parts of Bergamot, Jasmine absolute, and Angelica.

Therapeutically,  Angelica is an essential oil with great benefits for those who are weakened or asthenic.

Angelica Root essential oil contains a variety of coumarines and furocoumarines which render the oil photosensitizing if used externally, but make it effective to ease anxiety, insomnia and nervous exhaustion and to ease digestive cramping that goes along with these stresses.
Angelica Seed oil has generally similar qualities as the root oil and its musk fragrance is a bit more nuanced than that of the seed oil.

Lovage Root
Lovage Root essential oil is apparently somewhat difficult to produce. The specific gravity of the oil is very near that of water so it rises to the top very slowly. But the unique composition of this essential oil makes it worth the effort to separate this oil from the hydrosol.

Lovage Root essential oil contains a variety of components called phtalides. In a simplified way one could say that the phtalides from Lovage Root remove toxins from the body by chelating them. In the French literature Lovage Root essential oil is recommended for liver congestion, and food, chemical or drug poisoning. Franchome and Pénöel consider it to be one of the most effective agents to treat Psoriasis. The oil  is very powerful and should be explored cautiously.

Hops
Hops, being from the Cannabinaceae family do not fit perfectly into this post’s Apiaceae and Asteraceae theme. However, its cultural coordinates are classically central European. Its main actions are quickly described: it is estrogen-mimicking and it is a very fast acting sedative and de-stressing oil. It is especially effective to calm irregular heartbeat and heart arythmia.

Carrot Seed (Daucus carota)
The outstanding therapeutic qualities of Carrot Seed essential oil have been explored in different environments. Recently, however, a study of Anne-Marie Giraud-Robert established the therapeutic value of this essential oil (in combination with some others) for conditions of the liver. The French literature attributes the capacity to regenerate hepatocytes to Carrot Seed oil. The oil’s ability to improve liver metabolism also seems to be the origin of its skin regenerating qualities.

The qualities of Carrot Seed on the market are often uneven as well as in essential oil is distilled from cultivated plants and from plants gathered in the wild. Although their therapeutic properties seem to be more or less identical the wild Carrot Seed oils often have a most appealing and complex fragrance, almost being a perfume in themselves!

Celery Seed 
Celery Seed essential oil (Apium graveolens) is next to Lovage Root the only common essential oil with a sizeable content of detoxifying phtalides. Similarily it drains toxins from the liver. It also acts as a forceful tonic.

From Dr. Kurt Schnaubelt’s blog. Posted in February 2013.

How Plant Oils Contribute to the Smell of Rain

A recent article in Smithsonian.com illustrates one more way that plants use volatile oils. The story also highlights the connections between plants and humans and how we've co-evolved for our mutual benefit. In our Biology of Essential Oils module, we talk about three reasons that plants make essential oils: 1) To repel predators, bugs, and anything that may do them harm 2) As signalling mechanisms to attract pollinators, warm other plants of impending danger (such as an herbivore that just chomped on one of the plant's leaves), and to appeal to humans who will cultivate them more 3) To protect the plant when it's stressed, such as during drought (plant oils conserve moisture). Read the article below and see if you can pick out another reason plants make essential oils.

What Makes Rain Smell So Good?

A mixture of plant oils, bacterial spores and ozone is responsible for the powerful scent of fresh rain. Image via Wikimedia Commons/Juni

Step outside after the first storm after a dry spell and it invariably hits you: the sweet, fresh, powerfully evocative smell of fresh rain.

If you’ve ever noticed this mysterious scent and wondered what’s responsible for it, you’re not alone.

Back in 1964, a pair of Australian scientists (Isabel Joy Bear and R. G. Thomas) began the scientific study of rain’s aroma in earnest with an article in Nature titled “Nature of Agrillaceous Odor.” In it, they coined the term petrichor to help explain the phenomenon, combining a pair of Greek roots: petra (stone) and ichor (the blood of gods in ancient myth).

In that study and subsequent research, they determined that one of the main causes of this distinctive smell is a blend of oils secreted by some plants during arid periods. When a rainstorm comes after a drought, compounds from the oils—which accumulate over time in dry rocks and soil—are mixed and released into the air. The duo also observed that the oils inhibit seed germination, and speculated that plants produce them to limit competition for scarce water supplies during dry times.

These airborne oils combine with other compounds to produce the smell. In moist, forested areas in particular, a common substance is geosmin, a chemical produced by a soil-dwelling bacteria known as actinomycetes. The bacteria secrete the compound when they produce spores, then the force of rain landing on the ground sends these spores up into the air, and the moist air conveys the chemical into our noses.

“It’s a very pleasant aroma, sort of a musky smell,” soil specialist Bill Ypsilantis told NPR during an interview on the topic. “You’ll also smell that when you are in your garden and you’re turning over your soil.”

Because these bacteria thrive in wet conditions and produce spores during dry spells, the smell of geosmin is often most pronounced when it rains for the first time in a while, because the largest supply of spores has collected in the soil. Studies have revealed that the human nose is extremely sensitive to geosmin in particular—some people can detect it at concentrations as low as 5 parts per trillion. (Coincidentally, it’s also responsible for the distinctively earthy taste in beets.)

Ozone—O_3, the molecule made up of three oxygen atoms bonded together—also plays a role in the smell, especially after thunderstorms. A lightning bolt’s electrical charge can split oxygen and nitrogen molecules in the atmosphere, and they often recombine into nitric oxide (NO), which then interacts with other chemicals in the atmosphere to produce ozone. Sometimes, you can even smell ozone in the air (it has a sharp scent reminiscent of chlorine) before a storm arrives because it can be carried over long distances from high altitudes.

But apart from the specific chemicals responsible, there’s also the deeper question of why we find the smell of rain pleasant in the first place. Some scientists have speculated that it’s a product of evolution.

Anthropologist Diana Young of the University of Queensland in Australia, for example, who studied the culture of Western Australia’s Pitjantjatjara people, has observed that they associate the smell of rain with the color green, hinting at the deep-seated link between a season’s first rain and the expectation of growth and associated game animals, both crucial for their diet. She calls this “cultural synesthesia”—the blending of different sensory experiences on a society-wide scale due to evolutionary history.

It’s not a major leap to imagine how other cultures might similarly have positive associations of rain embedded in their collective consciousness—humans around the world, after all, require either plants or animals to eat, and both are more plentiful in rainy times than during drought. If this hypothesis is correct, then the next time you relish the scent of fresh rain, think of it as a cultural imprint, derived from your ancestors.

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Did you see it? Another reason for plants to secrete essential oils: "the oils inhibit seed germination, and speculated that plants produce them to limit competition for scarce water supplies during dry times." And one more. The compound called geosmin lets us humans know that Spring is coming and soon we will have more plant and animal food available to us. Another evolutionary link between plants and humans. Thank you, plants!

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Above article from Smithsonian.com, Surprising Science, posted April 2nd by Joseph Stromberg.