Saturday, 14 August 2010

Aromachemistry - Lavender

The chemical component most associated with Lavender is linalool (a terpene alcohol) which gives lavender its pleasant floral scent and insecticidal properties.  Synthetic linalool is used as an insecticide in the control of fleas and cockroaches so it is hardly suprising that a bunch of lavender is hung upside down in homes to deter insects in an environmentally friendly and safe way.  A bunch of lavender will last a year.  Many plant species produce linalool.  Linalool is also relatively easily synthesised so adulteration by wholesalers with synthetic linalool is a problem if only to ensure an essential oil conforms to the standards of the fragrance trade. 

Linalool is also a good example of stereoisomers found in essential oils.  S-linalool (left) is found in coriander, palmarosa and sweet orange, (having a sweeter floral scent) R-linalool (right) (a floral but more woody scent) is found in Lavender, Laurel and Sweet Basil.

Linalool is used as a scent in 60-80% of perfumed hygiene products and cleaning agents including soaps, detergents, shampoos, and lotions. It is also used as a chemical intermediate. One common product of linalool is Vitamin E.

Lavender has so many uses in aromatherapy.  Recovering cocaine users use lavender mixed with water to heal their nasal passages.

Properties: Akio Nakamura together with colleagues from the University of Tokyo and T. Hasegawa Co., Ltd in Kawasaki, Japan, claim to have demonstrated that inhaling linalool can reduce stress in lab rats. In a study published in The Journal of Agriculture and Food Chemistry , they exposed the animals to stressful conditions and found that those inhaling linalool saw their stress-elevated levels of neutrophils and lymphocytes fall to near-normal levels compared with the controls. Inhaling linalool also reduced the activity of more than 100 genes that "go into overdrive" in stressful situations. The findings could form the basis of new blood tests for identifying fragrances that can soothe stress, the researchers claim

Nakamura, Akio et al.; Fujiwara, S; Matsumoto, I; Abe, K (20 May 2009). "Stress Repression in Restrained Rats by (R)-(−)-Linalool Inhalation and Gene Expression Profiling of Their Whole Blood Cells". The Journal of Agriculture and Food Chemistry (American Chemical Society) 57 (12): 5480–5485. doi:10.1021/jf900420g. PMID 19456160.

Shirley Price Aromatherapy has a brochure 'Getting to know lavender better'.  Much french lavender that is sold and most lavender that finds its way into hygiene products is in fact Lavandin which is a naturally occuring hybrid of spike lavender and true lavender.  All the great pictures of Lavender fields are in fact fields of vigourous Lavendin.  Lavendin is a wonderful home fragrance, for example a few drops can be put on a mat.  The perfume rises when trodden on creating a relaxing atmoshere to come home to.  Lavandin has a relatively small linalool content so finds little use in aromatherapy though it is often sold as Lavender.  Lavendin has a relatively high borneol (40-50%) and camphor (10%) content so like spike lavender must be used with care.


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