thujone

Thujone is a ketone and a monoterpene that occurs naturally in two diastereomeric forms: (−)-α-thujone and (+)-β-thujone. It has a menthol odor. Though it is best known as a chemical compound in the spirit absinthe, absinthe contains only small quantities of thujone, so thujone is unlikely to be responsible for absinthe's alleged psychedelic effects. Thujone acts on GABA and 5-HT3 receptors in the brain. In many countries, the amount of thujone allowed in food or drink products is regulated. Thujone, as a component of several essential oils, is also used in perfumery.
In addition to the naturally occurring (−)-α-thujone and (+)-β-thujone, two other enantiomeric forms are possible: (+)-α-thujone and (−)-β-thujone.