The simplicity of a single flower disguises the complexity of its fragrant aroma. Looking past its structural beauty, we are awed by thousands of individual constituents, or ingredients, as they whirl in perfect order to form a fragrance that elicits physical, emotional, and even spiritual responses. Such is the intricate beauty of a single flower; such is the intricacy of its essential oils.

Essential oils are very complex in chemical compounds. Their chemistry, when charted on paper, boggles the imagination and often leaves all but the most advanced chemist with feelings of stupor. One single oil may contain thousands of individual constituents that exert specific actions. Take one substance from its normal surroundings, and combine it with a different component, and it acts in an entirely different manner. This makes it quite difficult to define any constituent's action, for its true action is often determined by the relationship it has with all the substances around it. In nature, no constituent ever works alone, but instead works in perfect harmony with all the other ingredients to create a perfect, whole essential oil.

Nevertheless, for the sake of simplicity, scientists isolate, observe, and report single actions and try to identity, name, and categorize individual components. The essential oils that share a high proportion of similar constituents are grouped together and are said to have similar actions. To help one understand the actions of the oils, scientists divide the oils' identified constituents into family units and assign them names like esters, aldehydes, and phenols.

Oils with a high number of common constituents tend to mix well with each other when creating aromatic blends. The effect of essential oils may be predicted according to the major constituents present. The identified chemical make-up helps one discover the potential properties that are exerted on the physical and mental body. But once again, this may all change when the single constituent is blended with new components. The action of the component may also change depending on how it is used. Is it inhaled, rubbed on, or taken internally? How it is taken helps determine the action of the main constituent.

When mingling with other essential oil users, you may hear the following terminology. This chart and glossary will prove useful for the beginning oil enthusiast, with descriptions and simplified keys to assist you in peeking into the complex world of essential oil chemistry.

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.

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:

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

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:

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

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.

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.

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:

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

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.

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.

Main Chemical Constituents of Young Living's Single Oils

You may find some discrepancies caused by growing conditions, amount of water the plant received, when it was harvested, etc. For each oil, the three main constituents are marked by a colored check. The means there is more of, or a significant amount of that particular substance. The indicates a lesser but still significant amount of that particular constituent.

Oil Common Name	Botanical Name	Esters	Alde- hydes	Ketones	Sesqui- terpenes	Oxides	Monoter- penes	Alcohols	Phenols
Basil	Ocimum basilicum
Bergamot	Citrus bergamia
Cedarwood	Cedrus atlantica
Chamomile, Roman	Chamaemelum nobile
Cinnamon Bark	Cinnamomum verum
Cistus	Cistus ladanifer
Clary Sage	Salvia sclarea
Clove	Syzgium aromaticum
Coriander	Coriandrum sativum
Cypress	Cupressus sempervirens
Dill	Anethum graveolens
Elemi	Canarium luzonicum
Eucalyptus Dives	Eucalyptus Dives
Eucalyptus Globulus	Eucalyptus Globulus
Eucalyptus Polybractea	Eucalyptus Polybractea
Eucalyptus Radiata	Eucalyptus Radiata
Fennel	Foeniculum vulgare
Fir, Balsam (Idaho)	Abies balsamea
Fir, Douglas	Pseudotsuga menziesii
Fir, White	Abies concolor
Frankincense	Boswellia carteri
Galbanum	Ferula gummosa
Geranium	Pelargonium graveolens
Ginger	Zingiber officinale
Goldenrod	Solidago canadensis
Grapefruit	Citrus paradisi
Helichrysum	Helichrysum officinalis
Hyssop	Hyssopus officinalis
Jasmine	Jasminum officinale
Juniper	Juniperus osteosperma & Juniperus scopulorum
Laurus Nobilis	Laurus Nobilis
Lavender	Lavandula angustifolia
Ledum	Ledum groenlandicum
Lemon	Citrus limon
Lemongrass	Cymbopogon flexuosus
Marjoram	Origanum majorana
Melaleuca Alternifolia (Tea Tree Oil)	Melaleuca alternifolia
Melaleuca Ericifolia (Australian Rosalina)	Melaleuca ericifolia
Melissa	Melissa officinalis
Mountain Savory	Satureja montana
Myrrh	Commiphora myrrha
Myrtle	Myrtus communis
Nutmeg	Myristica fragrans
Orange	Citrus sinensis
Oregano	Origanum compactum
Patchouli	Pogostemon cablin
Pepper	Piper nigrum
Peppermint	Mentha peperita
Petitgrain	Citrus sinensis
Pine	Pinus sylvestris
Ravensara	Ravensara aromatica
Rose	Rosa damascena
Rosemary	Rosmarinus officinalis CT cineol
Rosewood	Aniba rosaeodora
Sage	Salvia officinalis
Sandalwood	Santalum album
Spearmint	Mentha spicata
Spikenard	Nardostachys jatamansi
Spruce	Picea mariana
Tangerine	Citrus reticulata
Tansy, Idaho	Tanacetum vulgare
Tarragon	Artemisia dracunculus
Thyme	Thymus vulgaris
Tsuga	Tsuga canadensis
Valerian	Valerian officinalis
Vetiver	Vetiveria zizanoides
Western Red Cedar	Thuja plicata
Wintergreen	Gaultheria procumbens
Ylang Ylang	Cananga odorata

Great care was taken to accurately create this table of essential oil constituents. Sources of information include:

Advanced Aromatherapy by Kurt Schnaubelt, Ph.D.
Aromatherapy by Julia Lawless
Aromatherapy for Health Professionals by Shirley Price, Len Price
The Chemistry of Essential Oils by David Stewart, Ph.D., D.N.M.