Linanool: Linalool one of the terpene alcohols is widely
distributed in the plant kingdom. Linalool has strong effects on the nervous
system and is therefore widely used by aroma therapists and herbologists as a
sedative, spasmolytic and local anaesthetic. It is also used against many skin
complaints, mostly in the form of tea tree oil.
Aldehydes: Aldehydes are a class of highly reactive chemical
compounds that are intermediate between acids and alcohols, containing less
hydrogen than alcohols and less oxygen than acids.
Aldehydes are mostly irritants and can cause skin
irritation in even when diluted. Monoterpene Aldehydes are geranial,
citronellal, citral (which is responsible for the sharp distinctive citric
smell) while Cyclic Aldehydes are also known as aromatic Aldehydes have far more
cloying and sweet smells like Cinnamic Aldehyde and Benzaldehyde, which are
Cyclic Aldehydes, widely used in the perfume industry.
If ingested aldehydes are very irritant to the gastrointestinal tract, causing
nausea and diarrhoea.
For further detail see specific aldehydes:
Ketones: Monoterpenoid Ketones are stable molecules formed by
oxidation of alcohols. Monocyclic Ketones like Pulegone and Thujone are toxic
and should be avoided in any significant volumes in any treatment. Ketones are
expectorant and a respiratory tonic.
Limonene: Limonene has been studied for the anti-tumour effect
noticed in mice. Herbalists often prescribe herbs with this constituent as an
antioxidant and cancer or tumour inhibitor although there is evidence that these
properties are volatile and may be lost as a result of processing of the herb.
Limonene also has antiviral properties.
A phenolic ether found in Fennel, Aniseed and
star anise. Anethol, or anethole is widely used in mouth washes and toothpaste
as a flavouring agent. Anethol is unstable in sunlight or other strong light and
can irritate skin and mucous membrane to the extent that it can cause
Phenolic Ethers: Phenolic ethers on their own are irritant and
toxic Phenylpropane derivatives. Where Phenolic Ethers are present in essential
oils these oils must be used with care and extreme dilutions as even small
amounts of phenolic ethers are toxic.