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Thujone

Dateline: 09/20/99

By Alan Bruzel

In the late 19th century, the alcoholic intoxicant absinthe claimed among its devotees such talented writers and artists as Charles Baudelaire, Vincent van Gogh, Arthur Rimbaud, Henri de Toulouse-Lautrec, and Oscar Wilde. If their rapture with this libation crossed the line from epicurism into addiction, then what ingredient floating in the emerald-green liqueur was responsible?

Absinthe was an alcoholic extract of several herbs, including wormwood (Artemisia absinthium). Supplementary flavorings were added, but wormwood provided the astringency. The marketed concoction was bitter enough to require mixing with sugar and dilution with water.

At a concentration of about seventy-five percent ethanol, absinthe allowed its many plant-derived organic compounds to remain soluble. Addition of a more polar solvent (water) drove some of these compounds out of solution, resulting in a cloudy, yellowish-white liquid.

One of these organic compounds is thujone, a bicyclic terpene with an odor reminiscent of the structurally similar menthol.

Thujone	Menthol

Thujone takes its name from the eastern white cedar, Thuja occidentalis; cedarleaf oil contains approximately 60% thujone. Thujone is also found in other plants. The essential oil from sage (Salvia officinalis) is approximately 40% thujone, from tansy (Tanacetum vulgare) approximately 80% thujone, and from wormwood approximately 40% thujone. Plants manufacture this bitter terpene not to provide zing to the distillates of Homo sapiens, but to repel encroaching vegetation and insect pests. Wormwood has been used for millennia as a vermifuge.

The final chapter has not been written concerning which component of absinthe conferred its peculiar intoxicating (and toxic) properties. Those who wish to incriminate thujone point to its abundance in wormwood, its structural similarity to a portion of the tetrahydrocannabinol molecule (the active principle of marijuana, Cannabis sativa), and its limited solubility (which would allow accumulation to toxic levels over an absinthe drinker's lifetime).

Others are less convinced of thujone's culpability. They point to the relatively low amount of thujone ingested per drink (about two milligrams), thujone's inability to bind productively to the cannabinoid receptor, the lack of knowledge concerning the deleterious effects of other herbal constituents in absinthe, and, of course, the havoc wreaked by sustained intake of any high percentage alcoholic product.

Recommended Web resources for additional information:

Absinthe
History, paraphernalia, and notoriety surrounding this intoxicant. From About.com's Cocktails Guide.

Absinthe FAQ
Chemistry, preparation, and notable users of this alcoholic beverage. From Matthew John Baggott.

Absinthe & Thujone
Molecule of the Month from Karl Harrison, University of Oxford.

Summary of Data for Chemical Selection: Alpha-Thujone
This "Generally Recognized as Safe" material is being re-examined. From the National Toxicology Program, US Department of Health and Human Services.

Thujone
Report includes diagram depicting thujone's structural relationship to tetrahydrocannabinol. From Thomas Prisinzano, Virginia Commonwealth University.

Thujone: Molecule of the Day
Information from Rebekah Spencer, Oregon State University.

Wormwood: the Gothic Herb
This plant in history, literature, and art. From Alice Day, Gothic Gardening.

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