Technical Information

All pharmaceutical grade eucalyptus oils have to comply with the specifications set out in the various pharmacopoeias. General specifications and limitations are below:

Specifications BP: Eucalyptus Oil

Constituents

Range – Limit  

a(alpha) – pinene

Trace to 9% 

b(beta) – pinene

Less than 1.5% 

a(alpha)- phellandrene

Less than 1.5% 

d(delta) – limonene

Trace to 12% 

1,8-cineole

At least 70%

Camphor

Less than 0.1% 

Sabinene

Less than 0.3% 


Crude (single distilled) eucalyptus oils sometimes do not comply with these specifications.  The main reason is that crude eucalyptus oil can contain isovaleraldehydes which have an unpleasant odour and a cough provoking vapour.  The principal constituent of pharmaceutical grade eucalyptus oils is 1,8-cineole (eucalyptol) which must comprise at least 70% of the contents.

All eucalyptus oils are composed of complex mixtures of volatile organic compounds.

The main group of constituents of eucalyptus oil are monoterpenes.  They have a lower boiling point and are less polar than sesquiterpenes which are the other main group of components of eucalyptus oils.

Monoterpenes and their oxygenated derivatives include alcohols, aldehydes, ethers (oxides), hydrocarbons, aromatic hydrocarbons and phenols.

Sesquiterpenes which have higher boiling points are in the form of alcohols or hydrocarbons in eucalyptus oils.

A brief outline of the major constituents of pharmaceutical BP grade eucalyptus oil, together with their properties and uses follows.

 

1.  1,8-cineole (Eucalyptol)

-   A monocyclic mono terpene ether (oxide). A colourless liquid with a light fresh eucalyptus fragrance and a spicy clean cooling taste
-   Antibacterial, cough suppressant, expectorant, nasal decongestant and a respiratory anti-inflammatory
-   Also a flavour and fragrance and a strong solvent and penetrating oil
-   A pharmaceutical grade eucalyptus oil must contain 70% or more 1,8-cineole

 

2.  a(alpha) – pinene

-   Bicyclic monoterpene hydrocarbon
-   Dry woody, resinous-piney odour used in flavours and perfumery
-   Mildly antibacterial, anti-inflammatory
-   Disinfectant and deodorant
-   A strong natural solvent
-   A pharmaceutical grade eucalyptus oil may contain up to 9% a(alpha)-pinene

 

3.  d(delta) - limonene

-   Monocyclic monoterpene hydrocarbon
-   Odour of orange-citrus 
-   Mildly antibacterial  
-   A strong solvent for removal of oil and grease  
-   Used in cleaning products such as hand cleaners
-   Pure limonene oxidises readily and is a skin and respiratory irritant 
-   Stable as a constituent of eucalyptus oil
-   A pharmaceutical grade eucalyptus oil may contain up to 12% d(delta)-Limonene

 

4.  a(alpha) – terpineol

-   Monocyclic monoterpene alcohol
-   Lilac odour 
-   Strongly anti-bacterial
-   Common ingredient in perfumes, cosmetics and flavours

 

4.  p(para) – cymene

-   Monocyclic monoterpene aromatic hydrocarbon
-   Strong aromatic hydrocarbon odour
-   Good anti-bacterial activity
-   Widely used in soaps and preparations to help overcome undesirable odours

 

6.  Terpinen-4-ol

-   Tricyclic monoterpene alcohol
-   Colourless or pale yellow liquid. 
-   Herbaceous, peppery, woody odour
-   Main constituent tea tree oil
-   Anti-bacterial, anti-fungal and anti-inflammatory

 

7.  Cuminal Aldehyde

-   Colourless to yellowish oil liquid
-   Strong persistent odour
-   Acrid burning taste
-   Strongly anti-bacterial

 

8.  Globulol

-   Tricyclic sesquiterpene alcohol
-   Sweet rose like odour
-   Anti-bacterial

 

9.  p(para) – isoproplyphenol (Australol) Phenol

-   Very strong anti-bacterial

 

10.  Eudesmol

-   Bicyclic sesquiterpene alcohol
-   Mildly anti-bacterial

 

11.  Aromadendrene

-   Tricyclic sesquiterpene hydrocarbon
-   Woody odour.  Boiling point 262 degrees C
-   Some anti-bacterial and anti-fungal activity

For further information on What is Eucalyptus Oil please click here.

 

Eucalyptus Oil - Botany

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Su V, King DJ, Woodrow IE, McFadden GI, Gleadow RM. 2008. Plasmodium falciparum growth is arrested by monoterpenes from eucalyptus oil. Flavour and Fragrance Journal 23, 315-318.

Goodger JQD, Woodrow IE. 2008. Selection gains for essential oil traits using micropropagation of Eucalyptus polybractea. Forest Ecology and Management 255, 3652-3658.

Goodger JQD, Heskes AM, King DJ, Gleadow RM, Woodrow IE. 2008. Micropropagation of Eucalyptus polybractea selected for key essential oil traits. Functional Plant Biology 35, 247-251.

Goodger JQD, Connolly CA, Woodrow IE. 2007. Examination of the consistency of plant traits driving oil yield and quality in short-rotation coppice cultivation of Eucalyptus polybractea. Forest Ecology and Management 250, 196-205.

King DJ, Gleadow RM, Woodrow IE. 2006a. The accumulation of terpenoid oils does not incur a growth cost in Eucalyptus polybractea seedlings. Functional Plant Biology 33, 497-505.

King DJ, Gleadow RM, Woodrow IE. 2006b. Regulation of oil accumulation in single glands of Eucalyptus polybractea. New Phytologist 172, 440-451.

King DJ, Gleadow RM, Woodrow IE. 2004. Terpene deployment in Eucalyptus polybractea; relationships with leaf structure, environmental stresses, and growth. Functional Plant Biology 31, 451-460.