Essential Oil Chemistry

Essential Oil Constituents

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A Synopsis of the Chemical Constituents in Essential Oils

In general, pure essential oils can be subdivided into two distinct groups of chemical constituents; the hydrocarbons which are made up almost exclusively of terpenes (monoterpenes, sesquiterpenes, and diterpenes), and the oxygenated compounds which ar mainly esters, aldehydes, ketones, alcohols, phenols, and oxides.

Terpenes - inhibit the accumulation of toxins and help discharge existing toxins from the liver and kidneys.

• Sesquiterpenes are antiseptic and anti-inflammatory. They work as a liver and gland stimulant and contain caryophyllene and valencene. Research from the universities of Berlin and Vienna show increased oxygenation around the pineal and pituitary glands. Further research has shown that sesquiterpenes have the ability to surpass the blood-brain barrier and enter the brain tissue. other sesquiterpenes, like chamazulene and farnesol, are very high in anti-inflammatory and anti-bacterial activity. Chamazulene may be found in chamomile, tansy, and yarrow.
• Farnesene is anti-viral in action.
• Limonene has strong anti-viral properties and has been found in 90% of the citrus oils.
• Pinene has strong antiseptic properties and may be found in high proportions in the conifer oils such as pine, fir, spruce, and juniper.
• Other terpenes include camphene, cadinene, cedrene, dipentene, phellandrene, terpinene, sabinene, and myrcene.

Esters - are the compounds resulting from the reaction of an alcohol with an acid (known as esterification). Esters are very common and are found in a large number of essential oils. They are anti-fungal, calming and relaxing.

• Linalyl acetate may be found in bergamot, Clary sage, and lavender
• Geraniol acetate may be found in sweet marjoram.
• Other esters include bornyl acetate, eugenol acetate, and lavendulyl acetate.

Aldehydes - are highly reactive and characterized by the group C-H-O (Carbon, Hydrogen, Oxygen). In general, they are anti-infectious with a sedative effect on the central nervous system. They can be quite irritating when applied topically (citral being one example), but may have a profound calming effect when inhaled.

• Citral is very common with a distinctive antiseptic action. It also has an anti-viral application as with melissa oil when applied topically on herpes simplex.
• Citronellal is also very common and has the same lemony scent as citral. Along with citral and neral, citronellas may be found in the oils of melissa, lemongrass, lemon, mandarin, lemon-scented eucalyptus, and citronella.
• Elements of aldehydes have also been found in lavender and myrrh. Other aldehydes include benzaldehyde, cinnamic aldehyde, cuminic aldehyde, and perillaldehyde.

Ketones - are sometimes mucolytic and neuro-toxic when isolated from other constituents. However, all recorded toxic effects come from laboratory testing on guinea pigs and rats. No documented cases exist where oils with a high concentration of ketones (such as mugwort, tansy, sage, and wormwood) have ever caused a toxic effect on a human being. Also, large amounts of these oils would have to be consumed for them to result in a toxic neurological effect. Ketones stimulate cell regeneration, promote the formation of tissue, and liquefy mucous. They are helpful with such conditions as dry asthma, colds, flu and dry cough and are largely found in oils used for the upper respiratory system, such as hyssop, Clary sage, and sage.

• Thujone is one of the most toxic members of the ketone family. It can be an irritant and upsetting to the central nervous system and mey be neuro-toxic when taken internally as in the banned drink Absinthe. Although it may be inhaled to relieve respiratory distress and my stimulate the immune system, it should only be administered by an educated and professional aromatherapist.
• Jasmone (found in jasmine) and fenchone (found in fennel) are both non-toxic.
• Other ketones include camphor, carvone, menthone, methyl nonyl ketone, and pinacamphone.

Alcohols - are commonly recognized for their antiseptic and anti-viral activities. They create an uplifting quality and are regarded as non-toxic.

• Terpene Alcohols stimulate the immune system, work as a diuretic and a general tonic, and are anti-bacterial as well.
  
  
• Linalol can help relieve discomfort. It may be found in rosewood and lavender.
• Citronellol may be found in rose, lemon, eucalyptus, geranium, and others.
• Geraniol may be found in geranium as well as palmarosa.
• Farnesol may be found in chamomile. It is also good for the mucous.
• Other terpene alcohols include borneol, menthol, nerol, terpineol, (which Dr. Gattefosse considered to be a decongestant), vetiverol, benzyl alcohol, and cedrol.
  
  
• Sesquiterpene Alcohols are anti-inflammatory, anti-bacterial, anti-mycotic, and ulcer-protective (preventative).
  
  
• Bisabolol is one of the the strongest sesquiterpene alcohols. It may be found in chamomile oils where it also functions well as a fixative.

Phenols - are responsible for the fregrance of an oil. They are antiseptic, anti-bacterial, and strongly stimulating but can also be quite caustic to the skin. They contain high levels of oxygenating molecules and have anioxidant properties.

• Eugenol may be found in clove and cinnamon oil.
• Thymol is found in thyme and may not be as caustic as other phenols.
• Carvacrol may be found in oregano and savory. Researchers believe it may possibly contain some anti-cancerous properties.
• Others in the phenol family include methyl eugenol, methyl chavicol anethole, safrole, myristicin, and apiol.

Oxides - According to The American Heritage™ Dictionary of the English Language, an oxide is "a binary compound of an element or a radical with oxygen".

• Cineol (or eucalyptol) is by far the most important member of the family and virtually exists in a class of its own. It is anesthetic, antiseptic, and works as an expectorant. Cineol is well known as the principal constituent of eucalyptus oil. It may also be found in rosemary, cinnamon, melissa, basil, and ravensara.
• Other oxides include linalol oxide, ascaridol, bisabolol oxide, and bisabolone oxide.

All pure essential oils have some anti-bacterial properties. They increase the production of white blood cells, which help fight infectious illnesses. It is through these properties that aromatic herbs have been esteemed so highly throughout the ages and so widely used during the onsets of malaria, typhoid, and of course, the epidemic plagues during the 16th century. Research has found that people who consistently use pure essential oils have a higher level of resistance to illnesses, colds, flues, and diseases than the average person. Further indications show that such individuals, after contracting a cold, flu, or other illness, will recover 60-70 percent faster than those who do not use essential oils.

The information on this page is from the Reference Guide for Essential Oils by Connie and Alan Higley. For more information on this subject, see also the book, The Chemistry of Essential Oils Made Simple, by David Stewart.

This Month's Essential Oils

Fennel (Foeniculum vulgare)

Fennel is native to the Mediterranean area and is now grown in the United States, India, Japan, Asia, and Central Europe. There are two types, sweet and bitter. Bitter is usually used for commercial essential oil production, but the sweet variety is recommended for therapeutic purposes.

Historically, Romans consumed fresh fennel shoots as a vegetable and it is still considered to be an edible plant in Europe and the United States. The Romans also cultivated fennel for its fruits: Pliny, the elder, recorded at least 22 medicinal uses for it. The ancient Greeks Dioscorides and Hippocrates both recommended fennel to promote the flow of breast milk and it is still used for this today.

Historical records indicate that fennel shoots, fennel water, and fennel seed were all used as far back as 961AD. Charlemagne encouraged the cultivation of fennel in Europe. In medieval times, fennel was among the many herbs used against witchcraft. It often hung over the door to ward off evil spirits.

Margaret Maury, the Austrian who brought essential oils from France to England in the 20th Century, mentions the therapeutic benefits of fennel oil for rheumatism, gout, and kidney disorders, especially kidney stones.

Ways to Use Fennel Essential Oil Today:

Fennel is excellent for digestive issues such as bloating and gas, constipation, irritable bowel, and loss of appetite, or for babies with colic (rub a little on their feet and/or tummy, mixed with warm olive oil). Fennel water is also effective for colicky babies. Fennel has been shown to stimulate the production of breast milk and assist in balancing blood sugar. Because it reportedly repels fleas, powdered fennel may be sprinkled around animal bedding, in stables and kennels, or the essential oil may be mixed with water and sprayed.

Suggested recipe for breast congestion and soreness:

Fennel Foeniculum vulgare oil: 8 drops
Geranium Pelargonium graveolens or P. Odorantissimum oil: 4 drops
Peppermint Mentha piperita oil: 2 drops
Jojoba oil: 1/2 cup

Blend all the oils and pour into an amber bottle (use a funnel if necessary). Wash the breast well before breast-feeding. Fresh fennel leaves can also be used as a poultice, applied directly to the breasts.

Source: American College of Health Sciences, Aroma 201 manual.

Scientifically Proven

(This is a great article about the fallacy of the empirical supremacy of the double blind, placebo controlled study, especially in the field of aromatherapy, and the "myth" of objectivity.)

Written by Kurt Schnaubelt on 20 July 2010

Over three decades ago American philosopher and author Theodore Roszak formulated his ideas about, what he termed, the “Myth of Objective Consciousness.” (Theodore Roszak, The Making of a Counter Culture, Chicago, 1967) It is worth to step back in time to recall Roszak’s argument as it illuminates so many of the predicaments we find ourselves trapped in today:

Objective Consciousness in this context implies that if only we, or the tireless and unselfish scientist, stepped back from her or his emotions and subjective impressions and instead use the incorruptible tools of experimental laboratory science, that then, and only then, an objective – or in other words a truly true – glance at reality is possible. In the context of treating disease this has led to the perception that testing medicines in a process aptly termed “double blind” is best to determine the efficacy of a (new) drug objectively, because it removes the subjective perceptions of patient and doctor.

This idea of objectivity has solidly taken hold in American and most other Western societies. But in his book, Roszak goes on to contemplate how this state of objectivity is neither possible nor desirable. He calls our unchecked belief in scientific objectivity the “Myth” of our time, being the underlying belief of our cultural period that is never checked. It is considered to be self evidently true, needing no further proof.

So we believe that medicines whose efficacy has been demonstrated by the cost intensive double blind testing, must be ‘working.’ That is, if the patient is within the statistical segment of the population, for which the drug was shown to work.

The paradigm of corporate drug research depends on the assumption that there are close to perfect medicines, which treat a specific symptom as perfectly as possible and which provide the desired effect for all people, all of the time. Of course neither of these assumptions has ever been objectively established to be true. Instead, it is not so difficult to see that the “one drug fits all” idea arises from adherence to the economic model of the mass market. To sell as much as possible of one product to as many people as possible.

This is why the efficacy of drugs is demonstrated by means of statistics. If the double blind test shows that the drug is working for 89% of the test group we conclude it is working. But what if you are in the non responsive 11%?

In aromatherapy we accommodate our desire to rationalize the effects of essential oils by invoking the pharmacological effects of their components, which is often convenient since often some of the main components found in essential oils have been researched. But by focusing on the few investigated standard molecules we ignore that the full spectrum of activity of essential oils has remained hidden from the tools of reductionist laboratory science.

And this is the point of departure where the exploration of aromatherapy becomes an exercise much more involved and rewarding than the sometimes drab recitation of the “proven” effects of cineol or linalool, complex as they may be. In future installments I will discuss some of the approaches which are beyond the parameters of orthodox science.

(Reprinted with permission from the author)