Terpenoids - Essential Oils 2 Flashcards
(16 cards)
What are common monoterpenes that contain essential oils?
Regular monoterpenes that contain essential oils
* Acyclic (linalool, citronellal)
* Monocyclic (limonene, pulegone)
* Bicyclic (pinenes, thujone)
What are Sesquiterpenes that contain essential oils?
- Many sesquiterpenes are antihistaminic, antiallergic and anti-inflammatory
- eg (-)-a-bisabolol and chamazulene in chamomile, chamazulene also in Achillea
millefolium, Artemisia absinthum, with precursors matricin, achillicin and achillin: - Chamazulene is anti-inflammatory, antioxidant, antimicrobial, antispasmodic, antipyretic and wound healing.
- (-)-a-bisabolol induces apoptosis and inhibited several cytochrome p-450 liver enzymes in vitro.
- Other anti-inflammatory sequiterpenes include: a-caryophyllene=humulene in hops, beta-caryophyllene in clove and sage,
zingiberene in turmeric and ginger.
Sometimes how do we classify essential oils according to functional groups?
Essential oil classification is sometimes done according to functional groups
* Ketones (- one), aldehydes (- al), alcohols (- ol), oxides, phenols, hydrocarbons,
phenolic esters and esters.
- Phenols and alcohols: antimicrobial, phenols are more irritant. Alcohols: tea tree oil, terpinen-4-ol identified as most important antimicrobial compound, cineole detracted from its antifungal activity.
- Aldehydes: mild antimicrobial, calming, anti-inflammatory and antiviral.
- Ketones are more active and toxic than alcohol. They are good for wound healing, and are mucolytic, antibacterial, cholagogue and cholereretic.
- Esters: antispasmodic action.
What are hydrocarbon volatile oils?
Hydrocarbon volatile oils
* Contain only carbon and hydrogen.
* Examples are pinene, limonene, myricene - acyclic monoterpene (nutmeg and lemon),
cadinene - sesquiterpene hydrocarbon (juniper).
* Pinene (Pinus spp., black pepper, thyme), Turpentine oils (volatile oil
distilled from oleoresin) mainly hydrocarbons: rubefacient or liniment for rheumatic disease.
* They are VERY active against bacteria, not against fungi (except dill).
What are the alcohols?
Alcohols: can be acyclic, monocyclic or dicyclic - and name always ends in -ol
* Terpineon-4-ol, alpha-terpineol:
monoterpenes (pine and other coniferous oils)
* Antibacterial and antifungal.
* Menthol (mint), geraniol, linalool,
citronellol, borneol (dicyclic terpene
alcohol) from camphor and
zingiberol (sesquiterpene alcohol)
Tea tree
* Tea tree EO contains terpinen-4-ol, cineole (oxide volatile oil) plus other antiseptic and antifungal constituents.
* Skin disinfectant: activity against a wide range of micro-organism (gram+, gram- bacteria, fungi).
* Skin and mucous membranes, vaginal irritation fungal or other.
* Clinical studies done with tea tree: reduced symptoms of tinea pedis, topically effective in acne, antibacterial mouthwash (reduced methicillin-resistant Staphylococcus aureus
(MRSA)), fungal infections (mouth and skin) and improved healing in recurrent
herpes labialis.
What are the phenol volatile oils?
Phenol volatile oils
* This is where a hydroxyl group is attached to a benzene ring (= Terpene alcohols), most potent and can be toxic.
* Eugenol - a phenylpropanoid (clove)
* Thymol (monoterpene phenol) and carvacrol
* These are antibacterial, antifungal.
- Thyme EO: you find thymol and carvacrol, plus alcohols linalool, geraniol and alpha-terpineol.
- Expectorant, antimicrobial, antihelmintic and antispasmodic.
- It is a dermal and mucous membrane irritant so it should not be used externally, best used in tincture and tea
What are the aldehydes?
Aldehydes - they end with -al
* Terpenoids
* Citral (acyclic) = is a mixture of geranial, neral, citronellal (found in lemon grass, melissa and lemon verbena).
* Phenylpropanoids, no terpene structure (-al group attached to benzene ring).
* Cinnamaldehyde, vanillin (vanilla, benzoin, peru balsams) – (cinnamon, orange oil, lemon and citronella oil).
* Cinnamon oil: carminative and antiseptic. Good to add cinnamon in with hot loemon and honey for a cold!
What are the ketones?
Ketones
* Incorporate carbonyl functional group C=O.
* They can be more active and toxic than alcohol: they are wound healing, mucolytic,
antibacterial, cholagogue and cholereretic.
* Monocyclic terpene ketones examples: menthone, carvone (spearmint), piperitone,
pulegone and diosphenol (buchu).
* Dicyclic ketones: camphor, thujone
* Camphor (Cinnamomum camphora): topically antipruritic, anti infective.
What is Pulegone?
Pulegone
* (+)-pulegone (Mentha pulegium)
* Repels mosquitos and fleas, highly toxic to cats. Used as emmenagogue and possible
abortifacient.
* Large doses of EO can be hepatotoxic, and fatal if taken internally.
What are thujone?
Thujone
* Isomers alpha-thujone and beta-thujone: found in Thuja occ., Artemisia absinthum, Tanacetum vulgare, Salvia officinalis, Achillea millefolium.
* Reversible GABA(A) receptor modulator,
resulting in analeptic (restorative/stimulatory) effect.
* High doses in vivo can lead to convulsions.
* It is antimicrobial, anthelmintic and insecticidal. Do not tend to use it long term.
* Thujone is a ketone and is
neurotoxic and present in
absinthe in small amounts.
* It has antimicrobial, anthelminthic (kills parasites or worms) and insecticidal properties and is contraindicated in pregnancy.
* Ketones are more active and toxic than
alcohols
What are the phenolic ethers?
Phenolic ethers
* Contain an O between C and benzene ring
* An example is anethole (found in aniseed and fennel).
* Safrole - phenylpropanoids (sassafras, and nutmeg), derivatives of safrole – myristicin (nutmeg, black pepper, carrot, parsley, dill).
* Isolated: irritant and toxic.
* Safrole: minor constituent in cocoa, nutmeg, cola.
* Suspected carcinogenic properties.
* Myristicin: toxic in high doses - nausea, delirium and hallucinations.
* Nutmeg: narcotic and intoxicating properties.
* In vivo – amphetamine like effect.
What are the oxide volatile oils?
Oxide volatile oils
* O bridging 2 or more carbons: cineole (Eucalyptus spp., rosemary), ascaridole.
* Cineole (1.8-cineole or eucalyptol):
* Antimicrobial, antifungal, cytotoxic against human cancer cells.
* Expectorant, mucolytic.
* Found in eucalyptus oil: toxic to Haemophilus influenza, H. parainfluenza, Stenotrophomonas maltophilia, Streptococcus pneumonia.
* Eucalyptus oils vary in aroma and quality.
* Oils high in cineole and terpene hydrocarbons are considered the most effective against influenza viruses.
Eucalyptus oil trials
* Antimicrobial against multiple bacteria
* Immune-stimulatory (stimulates white blood cells), anti-inflammatory, antioxidant, analgesic and spasmolytic effects.
* Increased phagocytic activity.
* Inhalation or oral route: beneficial in respiratory problems (bronchitis, asthma, and COAD).
What are the ester volatile oils?
Ester volatile oils
* Two 0s attached to a carbon (lavender, dwarf pine needle, mustard and gaultheria, betula. lavender, roman chamomile and bitter orange).
* Oil of lavender, ester linalyl acetate.
* Most esters are gentle, non-irritant, sedative, antispasmodic.
* Oils in methylsalicylates (a phenol –
found in wintergreen).
Essential oils can contain up to 50 volatile oils!
Citrus oil example
* Aldehydes: neral, geranial (=citral), are antiseptic.
* Esters (flavour): stimulant, carminative, stomachic.
* Hydrocarbon: perillyl alcohol and precursor (+)- limonene (bitter and sweet orange peels):
* Active against cancer cells in vitro, increasing
differentiation, enhancing apoptosis, disabling
protein made by oncogenes.
* Antiviral properties in low concentrations.
* Inducing phase II liver enzymes.
* Dissolve cholesterol-containing gallstones, reduce gastric hyperacidity in GERD, supports peristalsis.
A note on toxicology?
Toxicology
* Essential oils are highly concentrated so very powerful!!!!
* Toxic essential oils include pennyroyal, tansy and parsley so you do not use internally full stop
* History of use as abortifacient. No direct
stimulating action on the uterine muscle, even
found to inhibit uterine contractions. Action due to general poisoning or gastrointestinal
irritation.
* Can lead to contact dermatitis, tea tree oil cases noted. Oxidation increases the likelihood of a reaction.
Essential oils or ‘essence’ slowly evaporate if left exposed. When a drop of oil is placed on blotting paper and a fixed oil is present, what will remain on the paper?
Oily smear
Can you list essemtial oils in their functional groups in alphabetical order?
Essential oils are often classified according to their functional group, listed in alphabetical order: alcohols, aldehydes, esters, hydrocarbons, ketones, oxides, phenols and
phenolic esters .
- ketones are wound healing, mucolytic and choleretic
- tea tree oil is antibacterial and antifungal
- aldehydes are carminative and antiseptic
- methyl salicylates are analgesic (pain relieving) and anti inflammatory
- thymol- antispasmodic and antimicrobial
