Linalool is a monoterpene often found as a major component of essential oils obtained from aromatic plant species, many of which are used in traditional medical systems as hypno-sedatives. Psychopharmacological evaluations of linalool (i.p. and i.c.v.) revealed marked sedative and anticonvulsant central effects in various mouse models. Considering this profile and alleged effects of inhaled lavender essential oil, the purpose of this study was to examine the sedative effects of inhaled linalool in mice. Mice were placed in an inhalation chamber during 60 min, in an atmosphere saturated with 1% or 3% linalool. Immediately after inhalation, animals were evaluated regarding locomotion, barbiturate-induced sleeping time, body temperature and motor coordination (rota-rod test). The 1% and 3% linalool increased (p<0.01) pentobarbital sleeping time and reduced (p<0.01) body temperature. The 3% linalool decreased (p<0.01) locomotion. Motor coordination was not affected. Hence, linalool inhaled for 1h seems to induce sedation without significant impairment in motor abilities, a side effect shared by most psycholeptic drugs.
Linalool is a floral and spicy terpene alcohol. It is found in over 200 plants such as citrus fruits and lavender. Concentrations of linalool above 20 ppb have been shown to give a fruity hoppy aroma to beer. Linalool concentration has been described as an indicator of hoppy flavor and it has been suggested that aiming for a linalool concentration rather than BUs gives better results when looking to make a “hoppy” beer. While this is a nice idea it would require using a GC to measure linalool concentrations in your beer and hence calculate the linalool utilization of your process. This is not really within the means of a brewery which is not pretty sizable. Higher levels of linalool have also been shown to reduce the threshold concentrations of off-notes like diacetyl. Linalool exists in two chiral forms, R- and S-linalool, the R form is a great deal more flavor active.
Linalool’s potential benefits
Why would so many different plants produce linalool? Its anti-microbial properties are protective for the plant and represent a potential therapeutic use in people. Whether it was used as an early antibiotic is unknown, but linalool (often in the form of lavender or peanut stems and leaves) has been used in traditional medicine practices for its sedative and anti-epileptic properties.
Mice exposed to linalool vapors show reduced levels of anxiety and lower depression-like behaviors. In these tests, mice exposed to linalool vapors spend more time in fear-inducing environments, and they’ll continue to work to escape a seemingly hopeless situation. It’s not exactly like testing anxiety and depression in the clinic, but in these well-validated measures, linalool appears to help.
Linalool also makes the immune system more resilient to the destructive effects of stress. Stress causes a shift in the distribution of white blood cells in the body (i.e., the cells of the immune system); the percent of lymphocytes decrease, and neutrophils increase. In rats, linalool prevented this shift, and in doing so, prevented the stress-induced changes in how the rats’ DNA was expressed. Interestingly, the authors reasoned that this protection was mediated by linalool’s ability to activate the body’s parasympathetic response, which is activated when the body is resting and digesting food, thereby fitting with linalool’s anti-anxiety effects.
How does linalool affect the brain?
Studies indicate that linalool’s behavioral effects may largely be mediated by its effects in the brain. One way is through blocking the receptors for the primary excitatory brain chemical, glutamate, which could account for linalool’s potentially anti-epileptic properties in some forms of epilepsy. This terpene also has the ability to enhance the effect of other sedatives, such as pentobarbital.
Additionally, linalool may be muscle-relaxing and have pain-relieving effects through additional distinctive mechanisms. For instance, linalool reduces the signaling strength of acetylcholine, a brain chemical that’s required for muscle contraction and movement. Linalool can have anesthetic-like effects by reducing the excitability of cells in the spinal cord that transmit pain signals to the brain.
Some of linalool’s pain-relieving abilities can be ascribed to its elevation of adenosine levels, an inhibitory brain chemical that is notably blocked by caffeine. Together, this multitude of nervous system targets contribute to its sedative, anxiety-reducing, and pain-relieving benefits.
These effects provide foundational support for linalool’s benefits in pain therapy. In one study, obese patients who underwent gastric banding surgery were either exposed to linalool-rich lavender oil vapor or an unscented control. Only 46% of the patients who inhaled the lavender oil required post-operative opioid medication, compared to 82% of the control group. Further, the morphine needs of those in the lavender group were nearly half that of the control group, together suggesting that linalool can reduce the need for post-surgery opioid-based pain treatment.
Linalool’s potential benefits in Alzheimer’s disease
Perhaps the most exciting therapeutic use for linalool is its emerging potential as a novel Alzheimer’s disease treatment. Alzheimer’s disease is a progressive and currently irreversible disease caused by the buildup of brain plaques and cellular tangles that lead to brain degeneration. This degeneration causes severe memory and cognitive impairment. There are currently no cures for Alzheimer’s disease and current treatment strategies are largely ineffective at recovering function. This has set scientists on a quest to identify techniques that reduce plaques and tangles in an effort to reverse the disease’s course and recover normal brain function.
A promising study published in 2016 points to linalool as a potential Alzheimer’s treatment. In a genetic mouse model of Alzheimer’s disease, linalool reversed many of the behavioral and cognitive impairments associated with the disease. Further, it reduced the number of brain plaques and cellular tangles that define the disease and contribute to brain degeneration.
Linalool still has many hurdles before it makes its way into the clinic. But these Alzheimer’s studies together with previous studies demonstrating benefits in pain, anxiety, and depression point to the importance of continued investigation into the therapeutic benefits of linalool and other terpenes in cannabis.
The chemical composition of many essential oils indicates that they have sedative and hypnotic effects, but there is still a lack of systematic studies on the sedative and hypnotic effects of essential oils. In addition, aromatherapy does not seem to have the side effects of many traditional psychotropic substances, which is clearly worthwhile for further clinical and scientific research. The clinical application of essential oils in aromatherapy has received increasing attention, and detailed studies on the pharmacological activities of inhaled essential oils are increasingly needed.
As insomniacs are usually accompanied by symptoms of depression and anxiety of varying degrees, based on the theory of aromatherapy of Traditional Chinese Medicine, this experiment is to study a Compound Anshen essential oil that is compatible with Lavender essential oil, Sweet Orange essential oil, Sandalwood essential oil and other aromatic medicine essential oils with sedative and hypnotic effects, anti-anxiety and anti-depression effects. To study the sedative and hypnotic effects of Compound Anshen essential oil inhaled and the main chemical components of Compound Anshen essential oil, and to compare and analyze the pharmacodynamics of diazepam, a commonly used drug for insomnia.
The Open field test and Pentobarbital-induced sleep latency and sleep time experiments were used to analyze and compare the sedative and hypnotic effects of inhaling Compound Anshen essential oil and the administration of diazepam on mice. The changes of 5-HT and GABA in mouse brain were analyzed by Elisa. The main volatile constituents of Compound Anshen essential oil were analyzed by gas chromatography-mass spectrometry (GC-MS).
Inhalation of Compound Anshen essential oil can significantly reduce the spontaneous activity of mice, reduce latency of sleeping time and prolong duration of sleeping time. The results of enzyme-linked immunosorbent assay showed that Compound Anshen essential oil can increase the content of 5-HT and GABA in mouse brain. The main volatile chemical constituents of the Compound Anshen essential oil are D-limonene (24.07%), Linalool (21.98%), Linalyl acetate (15.37%), α-Pinene (5.39%), and α-Santalol (4.8%).
The study found that the inhalation of Compound Anshen essential oil has sedative and hypnotic effect. This study provides a theoretical basis for further research and development of the sedative and hypnotic effects of Compound Anshen essential oil based on the theory of aromatherapy.