Monoterpenes, Sesquiterpenes, and Phenols

Monoterpenes, Sesquiterpenes, and Phenols

Monoterpenes, Sesquiterpenes, and Phenols

This being a chemistry made simple class, I’m going to go over the 3 most commonly seen constituents: Monoterpenes, Sesquiterpenes and Phenols and talk about some of the favorite oils that contain large amounts of those constituents. This is nowhere near an exhaustive list, but perhaps we can do a part 2 class sometime, where we learn even more.


These monoterpene compounds are found in nearly all essential oils and have a structure of 10 carbon atoms and at least one double bond. The 10 carbon atoms are derived from two isoprene units. Umm, say what? Yeah, it’s like learning another language for me, too.
Let’s try English 😉
They react readily to air and heat sources. For this reason citrus oils do not last well, since they are high in monoterpene hydrocarbons and have a quick reaction to air, and are readily oxidized.
Although some quarters may simply state that these components have anti- inflammatory, antiseptic, antiviral and antibacterial therapeutic properties while some can be analgesic or stimulating with a tonic effect, it could be seen as a very broad generalization, since this large group of chemicals vary greatly. Since some have a stimulating effect on the mucus membranes they are also often used as decongestants.
A common monoterpene found in essential oils is d-limonene, in most citrus oils – hey, a word we recognize, limonene!!
PROPERTIES of Monoterpenes:
Airborne antimicrobials
Dermal penetration enhancers
Drying/dehydrating effect on skin and mucous membranes
Energizing/Uplifting/General Stimulant
Supports Breathing Space
OILS High in Monoterpenes:
Citrus essential oils
Black pepper
Black Spruce
Myrtle (Myrtus communis)
Nutmeg (Myristica fragrans)
Rosemary ct. camphor/cineole
Tea Tree (Mel-A)

Sesquiterpenes – these are REALLY COOL.
Sesquiterpenes are the principal constituents of Cedarwood (98%), Vetiver (97%), Spikenard (93%), Sandalwood (Aloes) 90%, Black Pepper (74%), Patchouli (71%), Myrrh (62%), and Ginger (59%). They are also found in Galbanum, Onycha, and Frankincense (8%).
Sesquiterpene molecules deliver oxygen molecules to cells, like hemoglobin does in the blood. Sesquiterpenes can also erase or deprogram miswritten codes in the DNA. Sesquiterpenes are thought to be especially effective in fighting cancer because the root problem with a cancer cell is that it contains misinformation, and sesquiterpenes can erase that garbled information. At the same time the oxygen carried by sesquiterpene molecules creates an environment where cancer cells can’t reproduce. Hence, sesquiterpenes deliver cancer cells a double punch-one that disables their coded misbehavior and a second that stops their growth. WOAH.. re-read that one more time.
The American Medical Association (AMA) has said that if they could find an agent that would pass the blood-brain barrier, they would be able to find cures for ailments such as Lou Gehrig’s disease, multiple sclerosis, Alzheimer’s disease, and Parkinson’s disease. Such agents already exist and have been available since Biblical times. The agents, of course, are essential oils-particularly those containing the brain oxygenating molecules of sesquiterpenes.

Properties of Sesquiterpenes:

Sesquiterpenes are heavier than monoterpenes and they tend to appear towards the end of the distillation process. They commonly occur in roots, resins and woods. In general, sesquiterpenes are colorless, are insoluble in water and are more aromatic, less volatile and have higher boiling points than monoterpenes. Sesquiterpenes are non- polar compounds, which oxidize more slowly than monoterpenes.
• Powerful Anti-inflammatory
• Antispasmodic
• Moderate Antimicrobials
• Calming and Soothing to the nervous system

Oils High in Sesquiterpenes:

Black pepper
German chamomile
Clary sage
Clove bud

Phenols are polar compounds (due to the polar hydroxyl group) and have higher
boiling points and is somewhat more water-soluble than alcohols.
Phenols contain a hydroxyl group (-OH) attached to the carbon of a benzene ring, also known as an aromatic ring. The –OH group attachment to the benzene ring makes phenols very weakly acidic and more reactive which possibly creates more irritating compounds.
Okay, again, let’s speak in English.
The 3 main phenols found in essential oils include:
CARVACROL: Oregano (Origanum vulgare), Winter savory (Satureja montana), Wild marjoram (Origanum vulgare), Summer savory (Satureja hortensis), Thymus vulgaris ct. carvacrol, ct. borneol, ct. thymol, and Thymus serpyllum
THYMOL: Thymus vulgaris ct. thymol and ct. borneol, Thymus zygis
EUGENOL: Clove bud and leaf (Syzygium aromaticum syn. Eugenia caryophyllata), Cinnamon leaf (Cinnamomum zeylanicum syn. C. verum), Holy Basil (Ocimum sanctumsyn. O. tenuiflorum)

Properties of oils high in Phenols:
• Analgesic
• Anti-inflammatory
• Strong antibacterial activity
• Strong antifungal
• Great airborne antimicrobials
• Warming
• Supports and enhances immune system
• Potent antibacterial and antifungal treatments of the respiratory and digestive

Oils high in Phenols:
Clove Basil
Cretan or Turkish Oregano Winter savory
Clove Cinnamon


K Davis, exactly what I thought before seeing your post. Glad to see the info in more places though.

It seems that the majority of your post has been plagiarized from the work of Dr. David Stewart, which can be found at this link:

In case of Mercury poisoning, you might want to minerals such as Selenium, which tend to bind with heavy metals and facilitate their excretion.

Essential Oil Safety: A Guide for Health Care Professionals. This book is incredible and breaks down every oil and composition. It is not a reading book, but a reference that if you can wrap your brain around the information it contains you will understand how each oil works and why.

Pouchine Joseph

I use most of these oils. I’ve ordered cinnamon leaf. Clary sage is a wonder. Vetiver and spikenard are good for sleep. I have yet to see results of others. I’m sure they are all doing something. I had over 26 years of mercury poisoning.

CarolJoy Mileti

I was looking for information and you have the very best information that I could fine thank you for this . Do you have any of this published in book form on the sesquiterpenes and the monoterpenes?

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