Nootkatone

What is Nootkatone?

If you have ever smelled a real grapefruit and wondered what exactly makes it smell like grapefruit and not orange or lemon, the answer is mostly nootkatone. A sesquiterpene ketone with the formula C15H22O, nootkatone is the dominant odour compound in grapefruit peel oil and the molecule responsible for the characteristic bitter, dry, citrus-woody character that distinguishes Citrus paradisi from every other citrus fruit.

In cannabis, nootkatone is a trace-level compound found on extended lab panels. When present, it adds a faint grapefruit-woody dimension to a strain's aroma profile. Its molecular weight (218 g/mol) is larger than most monoterpenes, so it evaporates slowly and tends to come through in the lingering base note rather than the immediate top note.

Aroma and flavor

Nootkatone carries a scent profile described as grapefruit, woody, dry. Terpenes like this one shape both how a cannabis flower smells and much of its perceived character.

Commonly associated effects

In cannabis products, Nootkatone is commonly associated with the following qualities. These reflect general research and community reports, not guaranteed or medical outcomes.

Named for an Alaskan tree

Nootkatone takes its name from the Alaskan yellow cedar, Callitropsis nootkatensis, named in turn for Nootka Sound on Vancouver Island where European botanists first encountered the tree. The cedar's heartwood oil is extremely rich in nootkatone, and the compound was first isolated and identified from this source in the 1960s. The same molecule was later found in grapefruit peel, where it exists at just a few parts per million, barely detectable by weight but unmistakable to the nose because (+)-nootkatone, the grapefruit-smelling form, can be smelled at under 1 part per million in water (about 0.8 ppm).

From flavour to insect repellent

Nootkatone's aroma sensitivity has attracted considerable industrial interest. The flavour industry uses it to give beverages and confectionery authentic grapefruit character at very low dosages. More unusually, the U.S. EPA registered nootkatone in 2020 as a biopesticide active ingredient for repelling ticks, mosquitoes, and fleas. It occurs naturally in Alaskan yellow cedar and grapefruit peel, but only in tiny total amounts, so commercial supplies are made from valencene (a more abundant sesquiterpene) or by biofermentation. Unlike synthetic repellents, it is considered low-risk and is GRAS (Generally Recognized As Safe) for food use. Seeing a cannabis terpene also listed on an insect-repellent label is a reminder of how broadly terpene chemistry extends.

Frequently asked questions