More on the Complex Chemistry & Constituents of Essential Oils

Common Constituents Found in Essential Oils:


Esters

Gentle in action, esters are generally found in the mildest essential oils and are mostly free of toxicity and irritants. They tend to be the most relaxing, soothing, and balancing of all the essential oil constituents. Esters exert a normalizing effect on imbalances in emotional and physical conditions. They often exude a fruity aroma. The names of esters usually end in -yl, -ate, or -ester.

Names of Common Esters:

linalyl acetate
geranyl acetate
methyl salicylate

Main Effects:

Some are antispasmodic and calming to the nervous system. Others tend to be antifungal. When applied topically, some esters exhibit comforting properties to skin and are soothing for inflamed tissue.

Found in:

lavender, clary sage, bergamot, Roman chamomile (85%), fir, and wintergreen.
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Aldehydes


Key ingredient to the scent of a plant, aldehydes exert powerful aromas. Aldehydes are often calming to the emotions. Essential oils with high aldehyde content must be used correctly when applied to the skin as they can cause irritation. The names of aldehydes usually end in -al, or -aldehyde.

Names of Common Aldehydes:

geranial
citral
neral

Main Effects:

Calming, antiseptic, antimicrobial; some are antifungal, and some act as vasodilators.

Found in:

neroli, lemongrass, lemon eucalyptus, lemon verbena, valerian, and cinnamon bark.
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Ketones

Many ketones are good for the skin and scars. They are often found in skin care products. Particular ketones encourage normal cell growth. The pest-deterring action of marigolds is due to the ketone, "tagetone." Since various ketones are resistant to digestion, excessive usage may cause a buildup in the liver when taken orally. When used in the context of a natural, whole essential oil, however, ketones may be utilized safely. The names of ketones normally end in -one, but other components found in essential oils may have the same last three letters, such as asarone, which is a phenolic ether, not a ketone.

Names of Common Ketones:

d-pulegone
jasmone
fenchone
isomethone

Main Effects:

Some ketones are soothing to cuts, abrasions, and irritated tissue; others have lipolytic (breaks down fat) actions; several ketones are mucolytic (thins the mucous); while others are sedative. A number of ketones are analgesic (for pain). One major action of certain ketones is that they act as expectorants. Note that while some ketones are sedative, others are stimulating.

Found in:

Neroli, Idaho tansy, Eucalyptus dives, spearmint, hyssop, Western red cedar, and sage.
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Sesquiterpenes

Sesquiterpenes (as well as a few other constituents) increase blood flow to the capillaries throughout the body. They pass the blood brain barrier, having a positive effect on blood flow to the brain. They exert a helpful effect on the endocrine system. Like aldehydes, sesquiterpenes possess a strong aroma. Though from the same family of terpenes, sesquiterpenes are larger molecules than monoterpenes. The names of sesquiterpenes generally end in -ene.

Names of Common Sesquiterpenes:

b-caryophyllene
germacrene D
aromadendrene
chamazulene

Main Effects:

Antiseptic, antimicrobial, soothing to irritated skin and tissue, calming; some are analgesic.

Found in:

patchouli, ginger, helichrysum, sandalwood, cedarwood, and German chamomile.
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Oxides

Oxides are found in a number of essential oils, mainly those that have a camphor-like nature. The most common oxide in aromatherapy is l,8-cineole-a strong expectorant. For example, the smell of fresh-baked bread is due to an oxide. The names of oxides generally end in -oxide.

Names of Common Oxides

1,8-cineole
bisabolol oxide
linalool oxide
sclareol oxide

Main effects:

Expectorant; mildly stimulating.

Found in:

Eucalyptus globulus, rosemary, ravensara, and German chamomile.
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Monoterpenes

Monoterpenes make up the largest single class of compounds found in essential oils (see chart). They generally possess antibacterial agents. Monoterpenes in general have a stimulating effect.

Terpenes are light molecules that normally evaporate quickly. A terpene is insoluble in water and is often removed from perfume since it causes cloudiness. The names of all terpenes end in -ene.

Names of Common Terpenes:

d-limonene
myrcene
p-cymene

Main effects:

Antiseptic; soothing to irritated tissue; limonene is believed to be antitumerol; some monoterpenes are analgesic.

Found In:

Lemon, grapefruit, frankincense, orange, thyme, and balsam fir.
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Alcohols

Not to be confused with grain alcohols, this plant constituent is somewhat stimulating and helps to increase blood circulation. Some alcohols decrease blood thickness without being over-thinning. Alcohols are very resistant to oxidation and have a very low toxicity. Non-phenolic alcohols are mild and possess pleasant floral odors. Phenolic alcohols, on the other hand, are very strong and aggressive and can be irritating to the skin. The names of alcohols usually end in –ol.

Names of Common Alcohols:


borneol
terpineol
geraniol

Main effects:

Strongly antimicrobial; some are uplifting, while others are sedative; used in animal studies to revert cells to normal function and activity.

Found in:

rosewood, coriander, geranium, rose, and lavender.
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Phenols

Phenols are a type of alcohol. Phenols are highly subject to oxidation and darken or redden with age. Only four common phenols are found in essential oils: thymol, carvacrol, eugenol, and chavicol. They are typically considered medicinal in character. Phenols often smell pungent and spicy. They are helpful for poor moods and for healing.

Many are irritating to the skin when used incorrectly.

The names of most phenols end in -ol, which may be confusing since alcohols also end in –ol.

Names of Common Phenols:

thymol
eugenol
chavicol

Main Effects:

Antiseptic, powerful anti-microbial; stimulating to the nervous and the immune systems; uplifting; many are irritating to the skin, but some have an opposite effect.

Found In:

wintergreen, clove, cinnamon, thyme, oregano, and peppermint.

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Hope this helps in finding you answers to your essential oil questions :)