In the fields of medicine and pharmacology the designation “essential oils”
signifies a strong-smelling mix of substances of an oily consistency that are barely
soluble in water and are produced from basic vegetable substances (Teuscher 1997). This terminology corresponds with the definition of the ISO (International
Standard Organisation) describing how they are obtained by steam distillation of plant parts or from the pressing of citrus fruit skins. Normally, an essential oil consists of a large number of chemical components, with possibly up
to 50 individual constituents identified. However, one component may dominate to such an extent that the total characteristic of the oil, its smell, its chemical and physical
characteristics and also its pharmacological effects, are determined by this main component. Essential oils are found in leaves, blossoms and roots, but less so in tree trunks and bark. Typical drugs contain at least 0.1% of essential oils, normally between 1% and 2%, although in some cases up to 20%. The natural, so-called “phytogene” essential oils are often replaced by artificial oils that make it difficult to differentiate between natural and synthetic oils. The ‘phytogene’ oils contain a biological mix of components in which individual monosubstances, such as mint, cineol, trans-anethole, thymol, fenchone, and Dcamphor may dominate and determine the oil’s character.
