LAVENDER

Scientific Name(s):
Botanically, the genus Lavandula can be divided into 5 sub-generic groups.?All the garden and common lavenders belong to the Stoechas and Spica groups.?A number or rare species cultivated in Australia and New Zealand belong to the Pterostachys group.? There are approximately 30 species.?The sub-genus Spica includes L. angustifolia, L. latifolia and L. lanata, all collectively known as lavandin.?True English lavender, L. angustifolia Mill, is the species from which the essential oil used in perfumery is distilled.?This species has also been known by the synonyms L. officinalis Chaix, L. vera DC, and L. spica L.? The synonym L. officinalis indicates that this was the lavender specified for medicinal use.?L. angustifolia is adapted to living in a dry climate and is native to the western half of the mediterranean, reaching altitudes of up to 1800 meters.?It is likely that the Romans or Benedictine monks introduced it to England before the Norman conquest, and it was first recognized as a distinct form of lavender in the twelfth century by the Abbess Hildegard (AD 1098-1180) who lived near Bingen on the Rhine.?It is also recognized as a separate type of lavender by the Welsh physicians of the thirteenth century who knew it as Llafant.?Many garden lavenders are inter-specific hybrids between L. angustifolia and L. latifolia, and these hybrids are collectively known as 'lavandin', with the accepted nomenclature being L. x intermedia Emeric ex Boiseleur.^56? This complex situation results in many incorrect names for lavandin.

Several Lavandula species have been used medicinally, including L. angustifolia Mill. (syn. L. officinalis Chaix. and L. spica L.), L. stoechas, L. dentata, L. latifolia and L. pubescens Decne.

Family: Lamiaceae (formerly Labiatae)?Sub-Family: Nepetoidae, Tribe: Lavanduleae, Genus Lavandula

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Common Name (s):

Aspic, lavandin (usually refers to particular hybrids), lavender, spike lavender, true lavender.

Botany:

Lavender plants are aromatic evergreen sub-shrubs that grow to about 3 feet high. The plants are native to the Mediterranean region. Fresh flowering tops are collected, and the essential oil is distilled or extracted by solvent extraction.¹ The plant has small blue or purple flowers. The narrow leaves are fuzzy and gray when young and turn green as they mature.² Lavender is cultivated extensively for use as a perfume, potpourri and as an ornamental.

Morphology:

Lavenders are herbs and shrubs (Hyptis).?Young stems are often 4-angled with leaves opposite, whorled and simple, with no stipules.?Flowers are bisexual, usually 2-lipped (upper lip with 2 lobes, lower lip with 3 lobes.?Four stamens, in 2 sets (didynamous), with filaments partially fused to petals (epipetalous).?Two partially fused carpels, each with 2 lobes, basal style with 2 lobed stigma.? Fruit 4 nutlets.?Calys usually persistent with 5 fused lobes or 2-lipped.? Infloresence - main stem with flowers in whorls, flowers with or without stalks (infloresence a verticillate spike or raceme, flowers +/- pedicels).? Often with short-stalked epidermal glands containing essential oils.⁵⁶

Distribution:

Most species of lavender are native to the Mediterranean coastal region, but others come from islands in the Atlantic Ocean, tropical north-east Africa (Somalia) and the Indian sub-continent.

History:

Lavender has long found a role in folk medicine. The plant has been used as an antispasmodic, carminative, diuretic and general tonic. Extracts have been used to treat conditions ranging from acne to migraines. ¹ Although the plant has been known to increase bile flow output and flow into the intestine, its greatest value is not in the treatment of biliary conditions.² Lavender has been used quite extensively as an antidiabetic agent in parts of Spain and is included in some commercial herbal antidiabetic preparations.³ Fresh leaves and flowers, as well as the diluted essential oil are applied to the forehead to relieve headaches and to joints to treat rheumatic pain. The vapors of steamed flowers are used as a cold remedy.⁴ Chileans drink the tea to induce or increase menstrual flow.⁵

Lavender is usually administered in the form of an infusion, decoction or oil and is either taken internally or applied topically for relief of neuralgia. Today, lavender oil and extracts are used as pharmaceutical fragrances and in cosmetics. Spike lavender oil is often used in soaps because it is inexpensive but of lower quality than true lavender oil. Lavandin oil, lavender absolute (an extract) and spike lavender oil are used in concentrations of up to 1.2% in perfumes.¹ Small amounts (0.002% to 0.004%) of the oil are used to flavor food.

Lavender's versatility is seen in its various applications as a fragrance in perfumes, bath and shower products, hair care products, toiletry soaps, detergents, typical formulations, synthetic derivatives and production figures.⁶

Lavender flowers contain between 1% to 3% essential oil. ⁷ Lavandin hybrids contain a higher volatile oil content, but its composition is extremely variable. The oil is a complex mixture of more than 150 compounds, the most abundant of which are linaloyl acetate (30% to 55%), linalool (20% to 35%), cineole, camphor, beta-ocimene, limonene, caproic acid, caryophyllene oxide and tannins (5% to 10%).^1,7 However, the relative amounts of these compounds can vary widely between species.^8,9 Perillyl alcohol, a distillate of L. angustifolia has been shown to exert anticancer effects.¹⁰ Several articles on lavender are available, discussing analysis methods,^{11- 13} enantiomeric purity and distinctiveness, ^14-16 variety deviation,^17-20 essential oil quality, ^21,22 GC retention indices,²³ and lavender content in perfumes. ²⁴

Pharmacology:

One report investigated the effects of lavender oil aromatherapy for insomnia and concluded that it is comparable to hypnotics or tranquilizers. ²⁵ Lavender aromatherapy has also been utilized to increase mental capacity and diminish fatigue,²⁶ and to improve mood and perceived levels of anxiety.²⁷ Oils of different lavender species yield different results.²⁸ The German Commission E Monograph lists among lavender's uses, to be helpful for restlessness and difficulties in sleeping.⁷ Lavender EEG studies, which have shown various alpha wave responses to different odors, can be used for psychophysiological response evaluation.³⁰ Spike lavender oil has a spasmolytic effect on animal smooth muscle. These effects are consistent with the pharmacologic activities of many other common volatile oils. In mice, lavender oil exhibits CNS depressant activity, characterized by anticonvulsant activity and a potentiation of chloral hydrate-induced sleep. Another report on aromatherapy finds "exposure time-dependent" decreases in motility in mice after inhalation of lavender fragrance. This helps to confirm folk remedies such as herbal pillow use to facilitate rest or minimize stress in people.²⁹

The infusion and suspension of L. stoechas cause hypoglycemia in normoglycemic rats, reaching maximum activity 30 minutes after administration.³ Further studies with L. dentata and L. latifolia have found the active hypoglycemic components to be partially water soluble. Furthermore, the extracts were not active in rats with alloxan-induced diabetes, indicating the need for intact pancreatic cells for a pharmacologic effect to occur. The active components have not been chemically classified. ³¹

There is little direct evidence to support the use of lavender oil as a choleretic or for the treatment of GI disorders. A Bulgarian report discusses choleretic and cholagogic action of Bulgarian lavender oil. ³² Many volatile oils also may share these common actions. One of lavender's uses listed in the German Commission E Monograph includes helping in functional disorders of the upper abdomen with irritable stomach and intestinal disorders of nervous origin. Its effects are both calming and antiflatulent.⁷

Extracts of lavender are used in Europe as insect repellents. This effect appears to be related to compounds in the volatile oil.³³

A study of percutaneous absorption of lavender oil in massage found that within 5 minutes after application, main constituents of the oil were detected in the blood. After this rapid absorption, most of the lavender oil was excreted within 90 minutes.³⁴

Another report evaluated the role of lavender oil as a bath additive to relieve perineal discomfort after childbirth. When compared with placebo and synthetic oil, analysis of daily discomfort scores show less discomfort between days 3 to 5 with true lavender oil use.³⁵

Herbal research finds perillyl alcohol, a compound distilled from lavender (also found in cherries, mint and celery seeds) to possess anticancer activities.¹⁰ This monoterpene is being tested in clinical trials to study its role in cancer chemoprevention and therapy.^36-37

A variety of mechanisms are proposed to explain perillyl alcohol's chemopreventative and chemotherapeutic effects. One such mechanism is that it promotes "apoptosis," a self-destructing ability the cell has when its DNA is severely damaged. In cancer, these cells lack this self-destructing ability, resulting in abnormal cell growth. ¹⁰ In one report, liver tumor formation was not promoted by perillyl alcohol, but its growth was inhibited by this apoptosis mechanism by enhancing tumor cell loss.³⁸ In another report, the rate of apoptosis was more than 6-fold higher with perillyl alcohol treated pancreatic adenocarcinoma cells than in untreated cells.³⁹

Another proposed mechanism of monoterpenes is inhibition of post-translational isoprenylation of cell growth-regulatory proteins (such as Ras).⁴⁰ Perillyl alcohol has inhibited in vivo prenylation of specific proteins in one report,⁴¹ and has altered RAS protein synthesis and degradation in another. Interfering with these pathways can regulate malignant cell proliferation.⁴² Monoterpene-treated rat mammary tumors have been remodeled and redifferentiated to more benign phenotypes.⁴⁰ Perillyl alcohol treatment resulted in 70% to 99% inhibition of "aberrant hyperproliferation," a late occurring event preceding mammory tumorigenesis in vivo.⁴³

Other cancers where perillyl alcohol has been effective include: murine melanoma growth suppression in vitro and in vivo;⁴⁴ pancreatic carcinoma in hamsters;^45-46 colon carcinogenesis in rats; ⁴⁷ mammary cancer in rats;^40,48 liver tumors in rats; ³⁸ and lung cancer in rats.¹⁰

With such promising results from animal studies, human clinical trials are under way to treat patients with breast, ovarian and prostate cancers. Results are not yet available.¹⁰

Besides anticancer effects, perillyl alcohol has been used orally in rabbits to reduce vein graft intimal hyperplasia. ⁴⁹ It was also found to suppress hepatic HMG-CoA reductase activity, a rate limiting step in cholesterol synthesis, lowering serum cholesterol. ⁵⁰

Toxicology:

Lavender oil exhibited a low order of toxicity when administered subcutaneously to animals. Although lavender absolute has been reported to be a skin sensitizer, no human phototoxicity has been reported. Lavender and lavandin oil have been reported to be nonirritating and nonsensitizing to human skin.¹

However, three reports discuss allergic contact dermatitis from lavender oil and fragrance.^51-53 These examples are few, probably because the oil is used in small quantities in foods and cosmetics and has not been associated with major toxicity during normal use. The German Commission E Monograph lists no known side effects or contraindications.⁷

One report in mice observes an interaction between a 1/60 dilution of lavender oil, and pentobarbital, where sleeping time is increased.⁵⁴

Lavender is an aromatic plant that has been used in herbal medicine for centuries. It has been known to exhibit CNS depressant activity and is used for insomnia or to relieve anxiety and stress. It may also be helpful in GI disorders to reduce sugar and cholesterol levels and aid in grafting surgery. Lately, lavender compound perillyl alcohol is being studied for its promising effects in cancer prevention. Lavender has a low toxicity profile.

Patient Information:

Uses: Therapeutic: Antispasmotic, carminative, antidiabetic agent, restlessness and insect repellant. Nutritional: Food flavoring agent.

May increase or potentiate the CNS depressant effects of sedative-hypnotics.

Side Effects: Allergic contact dermatitis.