General introduction to the genus Lavandula

2015

Lavandula species (Labiatiae, syn. Lamiaceae) are mainly grown for their essential oils, which are used in perfumery, cosmetics, food processing and nowadays also in ‘aromatherapy’ products. The dried flowers have also been used from time immemorial in pillows, sachets etc. for promoting sleep and relaxation. Numerous lavender plants are also sold as ornamental plants for the garden; these include Lavandula latifolia, Lavandula pinnata, Lavandula lanata, Lavandula dentata and Lavandula stoechas and their numerous cultivars.

Lavender oil, distilled from Lavandula angustifolia was used extensively in Victorian times as a perfume and applied in numerous cosmetic products, but now it is used mainly in combination with other essential oils and aromachemicals. This species and numerous hybrids/cultivars, for example, Lavandin ‘grosso’ were originally grown in the South of France, but are now grown virtually round the world. True lavender oil, consisting mainly of linalool and linalyl acetate, has a very variable composition due to the genetic instability of the oil-producing plants and variations due to temperature, water quantity, altitude, fertilizers, time of year, geographic distribution etc. The chemical composition also varies in the numerous hybrids, which produce larger plants with a higher essential oil yield and which are therefore grown more often.

The essential oil of lavender is often adulterated with other oils or some fractions derived from plants containing linalool and linalyl acetate, or with the synthetic components, or the original oil can be acetylated. There is a problem with recognition of such adulterations, although enantiomeric columns have been a useful tool in modern detection.

Aromatherapists consider the oil from Lavandula angustifolia as the most beneficial, together with wild-grown cultivars at high altitude; as yet scientific evidence is lacking for this and all the numerous medicinal claims made, other than for a possible general relaxing effect after inhalation, produced via the Limbic system. Pharmacological studies have shown a relaxation of smooth muscles in vitro using animal tissues, with an initial small contraction exhibited by Lavandula angustifolia; the spasmolytic action was apparently mediated through the secondary messenger cyclic AMP. Studies with animals in vivo have shown a decline in movement after inhalation; in man, there was a slowing down of mental and physical activities. The main components were found in the blood after inhalation and these were also active in their own right when inhaled or massaged into the skin.

Lavandula species have a variable antimicrobial effect; Spike lavender, containing camphor, is the most potent; some species have a moderate antifungal action while the antioxidant activity is very variable. Some species have an acaricidal effect and have low general insecticidal properties. Lavandula has a low toxicity: even the strong undiluted essential oil can be used for some burns, with, anecdotally, beneficial effects on healing, however, cases of allergic airborne contact dermatitis have been reported.

New research on Lavandula species has indicated a wide diversity of applications, for example, the usefulness of Lavandula angustifolia essential oil in the treatment of alopecia.

 

Selections from the book: “Lavender: The genus Lavandula”. Edited by Maria Lis-Balchin. Series “Medicinal and aromatic plants – industrial profiles”. 2002.