Linalool, A Common Essential Oil Constituent
Much research has been published on the anti-tumorial effects of essential oils. The research seems to have focused on a few oils with long histories of medicinal use: Frankincense, Myrrh and Lemongrass are examples. Research abstracts are available through Pub Med, at www.pubmed.gov
Linalool, Found in Lavender and Other Oils, Decreases Liver Cell Viability
Linalool has been the subject of numerous studies investigating its anxiolytic (anti-stress) effects. Inhalation of Linalool, extracted from natural essential oils, leads to decreased aggressive behavior, lessens stress response (see Lavender: Nature's Anxiolytic), and improves sleep.
Now, in a study just released in the Journal of Chemico-biological Interactions, researchers at the American University of Beirut focused on a specific natural constituent of many common essential oils: Linalool. Linalool is the 'sweetness' of many oils; Lavender is perhaps the most popular linalool-containing oil, though it is found in many, many species of plants. One of the chemotypes of Thyme essential oil is called c.t. (for 'chemotype) linalool, meaning this particular variety of thyme has a high percentage of the linalool molecule.
Linalool Appears to Kill Cells at a Very Low Concentration
In this study, linalool derived from steam distilled Coriander essential oil was found to decrease the viability of the HepG2 cell line, cells of liver used throughout the world for research. Coriander was chosen as the spice is considered to have important medicinal qualities. Linalool inhibited these problematic liver cells from replicating. A concentration of 0.4 micromole inhibited 50% of the cells from replicating, a concentration of 2 micromol inhibited 100% of the cells from replicating, thereby destroying the cells.
Now we don't claim to be high-tech researchers here, but we did take a bit of chemistry in college. It appears this is an exceptionally small amount of linalool -- 1 mole of Linalool is 154 grams. This appears to be .000308 grams of linalool per liter of solution the cell line was bathed in.
Given that most Lavender species produce an essential oil containing between 30 and 40% linalool, this is astounding. 25 drops of Lavender essential oil delivers in somewhere around .3 grams of linalool. This is easily absorbed when topically applied. Some medical aromatherapists consider Lavender safe to ingest in small amounts as well.
This is the freely available abstract:
Study: Linalool decreases HepG2 viability by inhibiting mitochondrial complexes I and II, increasing reactive oxygen species and decreasing ATP and GSH levels.
Usta J, Kreydiyyeh S, Knio K, Barnabe P, Bou-Moughlabay Y, Dagher S.
Department of Biochemistry, Faculty of Medicine, American University of Beirut, Beirut, Lebanon.
Coriander is used as an appetizer, a common food seasoning in Mediterranean dishes, and a remedy for many ailments. In this study, we tested the biochemical effect of its essential oil components, in particular, linalool, its main component. The oil extract was prepared by hydro-distillation of coriander seeds. The various components were identified by gas chromatography coupled to mass spectroscopy.
The effect of the various oil components on the viability of different cell lines (HepG2, Caco2, NIH3t3, MCF7 and Hek293) was examined using MTT assay. Linalool was the most potent and HepG2 cells the most sensitive. A 50% and 100% decrease in the viability of HepG2 was obtained at 0.4muM and 2muM linalool, respectively. Whereas none of the other components exerted a significant effect at concentrations lower than 50muM, myrcene and nerolidol, the structural analogs of linalool, were more potent at 100muM than the other components decreasing HepG2 viability to 26%.
The biochemical effect of linalool on mitochondria isolated from HepG2 showed a concentration-dependent inhibition in complexes I and II activities of the respiratory chain, and a time-dependent decrease in ATP level. In addition, a time-dependent decrease in glutathione (GSH) level and in the reduction of nitroblue tetrazolium was obtained, indicating increase in reactive oxygen species (ROS) generation. Pretreatment with the antioxidants: N-acetyl cysteine (2mM), Trolox (100muM) and different flavonoids (50muM) were partially protective against the linalool-induced cell death; the most effective response was that of rutin and apigenin which restored 91% of HepG2 viability.
We hereby report a decrease in cell viability of HepG2 cells by linalool and identify the mitochondria as one possible target for its site of action, inhibiting complexes I and II and decreasing ATP. In addition, linalool increased ROS generation and decreased GSH level.
We will be looking into this particular study further and will report more information when available on The Ananda Apothecary website. In the meantime, we'll keep using essential oils like we had been, happy to graced by the possibility of another profound health effect!*