Essential Oil: A Concentrated Hydrophobic Liquid

Essential Oil

• Essential oil is a concentrated hydrophobic liquid containing volatile aroma compounds from plants.
• They are usually lipophilic (literally: oil-loving) compounds that usually are not miscible with water. Also, they can be diluted in solvents like pure ethanol and polyethylene glycol.
• They are also known as volatile oils, ethereal oils or aetherole.
• They carry a distinctive scent or essence of the plant.
• They are used in perfumes, cosmetics, soaps, lotions and other products. For flavoring food and drinks and for adding scents to incense and household cleaning products.
• It is used medicinally for skin treatments to remedies for cancer.
• Essential oils are derived from various sections of plants barriers – all spices, juniper etc.

• Families particularly rich in essential oils includes Compositae (Sunflower), Labiataceae/Lamiaceae (mint), Oleaceae, Myrtaceae (eucalyptus all sp.) etc.
• Some best essential oils are lemon oil, cinnamon oil, clary sage, lemongrass oil, lavender oil, tea tree oil, eucalyptus.

Classification of Essential Oils

Essential oils can be divided into 2 groups-

1. Monoterpenes
2. Sequiterpenes

1. Monoterpenes

• They contain 10 Carbon atoms.
• They are built up of 2 isoprene units.
• They are open ring.
• Simple monoterpenes are widely spread.
• They tend to occur as component of majority of essential oils.

Monoterpenes can be further divided into 2 groups. They are:

1. Monocyclic Monoterpenes: e.g. Limnonene, menthol, thymol etc. Menthol is a chief monoterpene compound and source of pipermint oil.

2. Bicyclic Monoterpenes: e.g. α-pinene, β-pinene, camphor etc.

2. Sequiterpenes

• They contain 15 Carbon atoms.
• They consist of 3 isoprene units. 

  

According to the basic Carbon skeleton, they can be further divided into 3 groups. They are-

1. Acyclic sequiterpenes
2. Monocyclic sequiterpenes (Abscisic Acid)
3. Bicyclic sequiterpenes

References:

www.slideshare.net

www.terpenoids.net

www.dictionary.com

Class lecture of Rifat Samad Mam, Assistant Professor, Department of Botany, University of Dhaka