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Edition 102: New Year 1 January 2018

Edition 102: New Year 1 January 2018

Essential Oil Chemistry

Making Scents of the Chemistry

Give me odorous at sunrise a garden of beautiful flowers where I can walk undisturbed. - Walt Whitman

A plant’s communication

THE MAIN task of an essential oil in a plant is to organise the flow of information within the organism itself and to enable communication between the organism and other systems.
The essential oils then activate the metabolism of the system involved; they enable communications with neighbouring plants, repelling enemies and attracting pollinating insects.
These characteristics closely resemble the ways that we humans put smells and perfumes to use, whether our own or in the form of perfume.
With the help of essential oils we can activate the metabolism, kill off bacteria and, with some species, repel insects too.
We can also signal certain messages, repel other organisms such as viruses and stimulate our own sexuality and that of others.

Product of the plant’s metabolism
Volatile plant essential oils function as secondary metabolites (produced by the plant’s metabolism.)
Primary metabolites are the compounds needed for the plant to live and include the food substances produced in photosynthesis.
The secondary metabolites vary widely in chemical structure and serve a variety of purposes within the plant. They include protective, survival and reproductive roles.
However, they are responsible for giving a plant its aroma and flavour and have significant physiological and psychological effects on people and animals.

Smell is an invisible chemical world
Smell is an invisible chemical world that carries with it vital information for animal and plant survival. Smell allows plants to communicate; they have receptors that respond to volatile chemicals, whereas humans have sensors in the nose that recognise and bind with molecules in the air.
The human nose is a remarkably sensitive analytical instrument, capable in some cases of picking up substances in concentrations of parts per billion.
The human nose can sometimes do better than a gas chromatograph and detect components present in amounts too small to register on such a machine.
Nonetheless, humans have a relatively poor sense of smell compared to animals. (Incidentally, women are generally better at detecting smells than are men.)

It’s all in the shape
Essential oil molecules that we can’t see are branched and rigid chemical structures that enable them to interact with specific olfactory receptors in our nasal cavity, which means that we can smell them. We can only faintly smell fixed vegetable oils because their molecules are flexible and unbranched and do not interact specifically with the olfactory receptors, unlike a volatile essential oil.
We humans are not immune to these biological survival signals that affect us both viscerally and emotionally, triggering memories from our primordial history.
How a plant smelt had direct bearing, to our ancestors, about how to use the plant in a beneficial way for overall health.
The very smell of a plant conjures up different feelings and physical reactions in people, all of which have psychological and physiological significance.
The ancients believed that strong-smelling plants such as cinnamon; clove, frankincense and myrrh would drive away evil spirits and so employed these aromatics as fumigants.

Found in all parts of the plant
We can look to the different parts of each plant or tree from which the essential oil was distilled to understand the energetic nature of the essential oils and how they work on the subtler bodies of the human organism.
Essential oils are to be found in all parts of a plant, which indicates how intensively a plant combines itself with light and heat energy and how deeply it incorporates those within itself.
In many cases it is has not been possible to determine where the essential oil is actually produced; it quite suddenly makes an appearance in the cell plasma and is then transported to certain organs.
Both the content and the transfer of oil to and from these organs are influenced by cosmic rhythms.

The magic of synergy
Nature has created a perfect balance in essential oils for the survival of the plants in the wild with all constituents working in harmony with each other.
Even the components found in tiniest amounts all play an equally vital role in the life-support system of the plant.
This harmony or wholeness is an important characteristic in the essential oils effectiveness on the human body.
It is thought that some constituents might counteract or quench an irritating effect brought on by another or enhance the action of other components synergistically.
The sum of all these separate parts creates a natural synergy, whereby it becomes more powerful than the expected outcome of the individual components.
The art of aromatherapy, or the application of essential oils without any knowledge of chemistry, has been an efficacious practice long before scientists learned to identify and isolate the active components in the oils.
Modern research into the complex chemistry of plants can only validate and augment an already successful field of holistic healing.

Everything is made of chemicals
Many people feel that if something contains “chemicals” it must be bad.
There is no escaping the fact that every substance we encounter in life is made up of chemicals.
Your favourite lavender oil even if organically grown, is composed of a mixture of up to 300 different plant chemicals.
A basic understanding of chemistry can enhance our use of plants and their essential oils.
Essential oils have healing properties that reflect their chemical composition and the range and amounts of constituents are used for evaluation of qualities such as criteria for purity in determining extraction methods and in defining aspects such as chemo types.
An essential oil does not need to be chemically altered in any way for it be effective.
A true oil is a very complex combination of hundreds of compounds that vary due to environmental factors.
The unidentified compounds contribute to the overall synergistic effect of the oil, as significantly as the known substances.
With very few exceptions, these individual compounds are covalently bonded volatile liquids that contribute their individual properties to the oil.
An individual component may be harmful on its own but, when naturally diluted and with its sibling ingredients, it can have additional and beneficial effects; this is an example of synergy.

The varying building blocks of aromatics
Variations occur of the same essential oil from the different environments where the plants are grown, which causes different compositions of constituents and thus its overall characteristics will vary.
These differences are called chemo types; the composition may also vary depending on the plant species and subspecies and such variations are genetically determined.
Individual components or groups of components that occur naturally in an essential oil can be separated by physical methods such as dissolving or distilling.
The removal of a particular useful compound from an essential oil is done on a large scale in the cosmetics, pharmaceutical, food and perfumery industries; exploiting physical properties such as boiling point or solubility.
This has a minimal effect on the chemical properties of the compound removed.
In most situations, aromatherapy-grade oil should have no components removed, added or enhanced: this would constitute adulteration.
An example of such an adulteration would be adding the blue compound chamazulene from the more expensive German chamomile, (Matricaria recutita) to Moroccan chamomile (Anthemis nobilis).  

Taking it apart has consequences
Scientists began to pull apart essential oils and isolate the constituents with specifically potent properties, such as the aldehyde citral, which is found in lemongrass.
This isolated citral molecule was then added to synthetic medicines or sometimes used alone as a strong antiseptic.
It is now understood that citral alone is very toxic and irritating to the skin. However when it is used in the context of the whole oil of the lemongrass plant, it has proved to be a very beneficial antiseptic for the human body with significantly less toxic and irritating side effects.
It is clear that all the other components are needed to work harmoniously in synchrony for human safety and healing.
Essential oils are volatile because their molecule size is so small, the larger the molecule, the lower its ability to evaporate.
Almost all of the molecules in essential oils are composed of carbon and hydrogen; or carbon, hydrogen and oxygen. Most of them have ten or fifteen carbon atoms.
The chemistry of the constituents of essential oils is determined by two factors, one mechanical (the steam distillation process) and the other intrinsic to the plant (the biosynthesis of the constituent molecules).
By steam distillation, only volatile and water-insoluble constituents are isolated from the plant. The main types of chemical compounds that are isolated are terpenes and terpenoid compounds and phenylpropane-derived compounds.

The magic components
Alcohols are considered the most therapeutically beneficial essential oil components, with low toxicity and pleasant fragrances.
Alcohols are usually hazardous free and non-skin irritating and essential oils high in alcohols are generally safe for use on children and the elderly.
The alcohol functional group is _OH and the name ends in –ol; for example geraniol and linalool (found in geranium and lavender respectively).
Esters form the most widespread group of compounds in plant essences and fragrances. They are formed by reaction of acids with alcohols. They are generally safe to use with low toxicity.
Their properties are gentle in action, characteristically sweet, fruity smell, antifungal, anti-inflammatory, antispasmodic, calming and tonic to the nervous system, as well as effective for skin rashes.

The intense parts
Oxides are found in a wide range of essential oils, especially those of a camphoraceous nature - for example eucalyptus, rosemary, tea tree and cajeput.
Eucalyptol is the most commonly encountered oxide in aromatherapy and is found in eucalyptus and cajeput essential oils.
It is a very chemically stable molecule and has a camphor-like smell. Oxides can be skin irritants and must be well diluted in application.
Essential oils that are high in phenols must be handled with extra care. They can be toxic to the liver and irritant to the skin and mucous membranes.
Essential oils high in phenols that are skin irritants include cinnamon, clove, aniseed, basil, tarragon, red thyme and oregano.
Thyme and oregano are widely used in the pharmaceutical field, mainly due to the germicidal and antiseptic properties of phenolic components
There are many other constituents in plants (often valuable) that do not find their way into essential oils.
Among them are all the molecules that are soluble in water (such as acids or sugars) or that are too large or too high in polarity to evaporate with steam, such as tannins, flavonoids, carotenoids and polysaccharides.


Vitality and beauty are gifts of Nature for those who live according to its laws. - Leonardo Da Vinci


Terminology of Extracts

Plant extracts contain all compounds that are soluble in both the solvent used and alcohol; not all of them are necessarily volatile.
Distilled oils contain only volatile compounds (these are only a limited number within the plant.)
Expressed oils contain compounds of all molecular sizes.
Macerated oils contain compounds of all molecular sizes (not necessarily all the volatiles) that are soluble in vegetable oil.
Absolutes contain compounds of all molecular sizes that are soluble in both solvent and alcohol (not necessarily all the volatiles).
Resinoids contain compounds of all molecular sizes that are soluble in the solvent used (not necessarily all the volatiles).
Concretes are the waxy or fatty extracts produced by solvent extraction of plant material with an organic solvent, after the solvent has been recovered. They contain compounds of all molecular sizes and are usually solids containing natural wax essential oil and pigments from the plant.
Pomades are the product of enfleurage, whereby all substances of all molecular sizes are dissolved in the extracting fat.


 

Essential Oil Profile: Honey Myrtle

HONEY myrtle brings you the warm, rich aroma of a hot, honey lemon drink on a cold winter’s day - complete with joyful citrus notes, sweet honey tones and spicy depths that are almost like the bush fragrance of a comforting log fire.
Add honey myrtle to massage blends at one per cent dilution for its anti-inflammatory and analgesic assistance.
 The body feels restored after a massage with this tonic oil as it calms the central nervous system, helps to reduce spasms and lowers blood pressure.  
Honey myrtle has the highest Citral content of all the Melaleucas, which means that to avoid sensitisation, other mucous membrane nourishing oils should be added within a blend; as is the case with such oils so high in citral. (Geranial and Neral).


Useful Applications
Diffusers: clear the head and quieten the 'monkey' mind.
Massage and bath blends: use as a relaxant when highly stressed.


Honey Myrtle essential oil is distinctly anti-infectious and research has shown it to be effective in concentrations of 0.25% against bacteria such as Candida albicans, Staphylococcus aureus, and Escherichia coli (E. coli). Such a fine antimicrobial, antiviral, anti-fungal oil belongs in the first aid box to ward against common colds and flu.
Use in a diffuser/oil burner around the home to add a deodorising scent as well as kill germs. Brings an invigorating yet grounding balance for the wellbeing of the family, expelling bad smells and calming frenetic children.
Honey myrtle enhances the health of the mind, psyche and spirit because it is naturally sedative and quells anxiety.
A helpful antidepressant, this uplifting essential oil relaxes and calms, yet still maintains an alert mind with the ability to focus. Include honey myrtle in study blends to assist concentration.
The oil helps to dissolve stressful emotions bringing us to a more grounded sense of presence.
It opens the second chakra to enhance our relationships and creative energy and also our third eye Chakra for clarity and perspective.


Fact File

Name: Honey Myrtle
Botanical name: Melaleuca teretifolia
Family: Myrtaceae
The Plant: Honey Myrtle trees naturally occur in the south west of Western Australia and grow to a height of 2-5 metres in the wild. It grows in the sandy Western Australian soils and typically like other Melaleucas, it is most at home in amongst wetlands.
The Oil: is extracted by steam distillation of the leaves and terminal branches. The  oil  has  the  highest known citral  content (neral  and  geranial) of any Melaleuca
Scent:  Honey Myrtle has a fresh and lively citrus character that is beautifully rounded with warm honey notes including a herbaceous twist, that mellows into unusual spicy depths. Its bright personality is friendly and quite similar to lemon myrtle essential oil; however it does differs with its own unique sweet honey note that leaves no sharp edges.
Blends well with:  vetivert, geranium, myrrh, cedarwood, juniper.
Indications: anti-bacterial, anti-infectious, sedative, anti-inflammatory, analgesic, germacide, deodoriser, anti-fungal, anti-microbial, anti-vital.
Precautions: Use diluted on the skin. Can cause mucous membrane irritation if not diluted.


 

Essential Oil Profile: Kunzea

ANIMALS, humans and the land have all taken advantage of the kunzea bush.  
Early settlers witnessed native animals sleeping under wild Kunzea bushes for protection from ticks and other parasites, so they called this understory plant ‘Tick Bush’.
The Australian native plant has also been associated with a group of unrelated plants unflattering nicknamed ‘Poverty Bush’, due to its ability to grow in overgrazed and degraded lands. Today kunzea is often used by modern coastal gardeners for sand dune stabilisation.
The essential oil, however, is still in the discovery stage.
Kunzea possesses similar qualities to eucalyptus and other conifer oils in that it is very helpful for treating respiratory problems by calming inflammation and dissolving congestion.


Useful applications

Diffusers: use while doing household chores to bring inspiration to mundane tasks

Steam inhalations: clears congestion and mucous from the nasal passages

Kunzea’s admirable ability in fighting infections means it may be employed in chest rub blends or used in a warm compress for pulmonary infections. Inhale this oil to clear mucous from the nasal passages. Kunzea oil is soft and gentle and can be applied directly to the skin to be readily absorbed.
Add Kunzea to a massage blend to ease sore muscles or massage into the temples and neck to sooth a headache, especially a sinus headache from allergies. Put 2-10 drops of Kunzea in baths or a foot bath for its antiseptic and anti-inflammatory action. Diffuse kunzea to effectively repel insects.
Restorative, calming and relaxing for the mind, encouraging it to stay inspired and delighted in every day concerns.
The scent that is reminiscent of a band-aid indeed acts like a comforting aromatic bandage that assuages the woes of the tired battler to disengage from the stress of life’s dramas.


Fact File

Name: Kunzea
Botanical name: Kunzea ambigua
Family: Myrtaceae
The Plant: Kunzea is an Australasian shrub or small tree with small, crowded aromatic leaves.
The Oil: is extracted by steam distillation of the leaves and terminal branches.
Scent:  The top note is brisk and medicinal like eucalyptus but with a softer edge and mellows into a herbaceous heart that resembles resinous pine
Blends well with:  thyme, oregano, manuka, lemon, lavender.
Indications: anti-inflammatory, decongestant, antiseptic, relaxant.
Precautions: Is non-irritant and can be used undiluted on most skin types.

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