Nootkatone is the signature grapefruit-like sesquiterpene ketone best known for helping define grapefruit aroma and for its unusually strong insect-repellent literature. Compared with many essential-oil constituents, it has a deeper evidence base: identity data are solid, official EPA registration exists for insecticide and repellent use, and multiple preclinical papers describe anti-inflammatory, antioxidant, and vector-control mechanisms. The evidence is still dominated by animal, cellular, and insect studies rather than human therapeutic trials, so AromaForge should present nootkatone as a well-studied grapefruit marker with regulatory and mechanistic interest, not as a medical ingredient.
Chemical identity and composition
PubChem identifies nootkatone as C15H22O and lists the named compound under the (+)-nootkatone stereochemical entry. In practice, the compound is widely described as a characteristic grapefruit constituent and also occurs in Alaska yellow cedar and some sesquiterpene-rich rhizome oils.
Aroma and practical use
- Use the recorded grapefruit, citrus peel, dry woody, bitter fresh, clean descriptors to explore a blend's scent character; perceived strength also depends on the other ingredients.
- Read the route, preparation and experimental context before using a study finding to choose an oil.
Reported benefits and effects
Findings retain their study context. An animal or laboratory result describes that experiment.
A 2025 Current Biology paper reported that nootkatone acted as both a spatial/contact mosquito repellent and an insecticide, with evidence that it potentiates GABA-mediated signaling and disrupts synaptic transmission in mosquitoes.
This is one of the strongest current constituent-level papers because it moves beyond simple repellency screening into a defined modern mode-of-action discussion.
This reference does not establish a therapeutic result or a safe use level for a custom oil blend.
A 2020 mouse inflammation study found that nootkatone reduced paw edema, leukocyte recruitment, vascular permeability, MPO activity, IL-1beta, and TNF-alpha across acute and chronic inflammation models.
This supports the recurring preclinical pattern that nootkatone is studied as an inflammation-modulating sesquiterpene rather than only as a flavor constituent.
This experimental finding does not establish benefit, dose or safety in people using this blend.
A 2021 Free Radical Biology and Medicine study reported that nootkatone inhibited iNOS, COX-2, reactive oxygen species, and pro-inflammatory cytokines while increasing antioxidant enzymes including NQO1 and HO-1 in neuroinflammation models.
This is a stronger mechanistic paper than many natural-product screens because it included inhibitor and knockdown work around NQO1 and AMPK-related signaling.
This experimental finding does not establish benefit, dose or safety in people using this blend.
A 2018 mouse study found that nootkatone pretreatment reduced diesel-exhaust-particle-induced airway resistance, inflammatory infiltration, oxidative stress, DNA damage, apoptosis, and NF-kB activation.
This adds organ-system breadth to the preclinical record, though it still should not be presented as human respiratory efficacy.
This experimental finding does not establish benefit, dose or safety in people using this blend.
EPA announced on August 10, 2020 that nootkatone had been registered for use in insecticides and insect repellents, citing studies showing formulated products may repel and kill ticks, mosquitoes, and other biting pests.
This is the clearest official regulatory framing for nootkatone and materially differentiates it from most archive constituents.
The source assessment applies to its specified exposure and preparation; this entry is not an unrestricted-use clearance.
Use concerns and concentration limits
Sensitization concernNot flagged
Not flagged in the current model. This is not proof of absence or unrestricted safety.
Phototoxicity concernNot flagged
Not flagged in the current model. This is not proof of absence or unrestricted safety.
Oxidation concernNot flagged
Not flagged in the current model. This is not proof of absence or unrestricted safety.
Penetration enhancementNot flagged
Not flagged in the current model. This is not proof of absence or unrestricted safety.
No numeric constituent-specific use limit is available here. Missing is not an unrestricted-use clearance.
EPA's August 10, 2020 registration announcement places nootkatone in an unusual category for aroma constituents because it has explicit federal review context for insecticide and repellent use.
The source assessment applies to its specified exposure and preparation; this entry is not an unrestricted-use clearance.
No direct public citation is attached to this entry.
Most efficacy-style findings verified in this pass were from insect, cell, or animal studies rather than human therapeutic trials, so wellness or disease language should stay non-medical.
This experimental finding does not establish benefit, dose or safety in people using this blend.
No direct public citation is attached to this entry.
The accessible literature supports low-to-modest concern framing in ordinary fragrance or flavor context, but this pass did not validate a current standalone human cosmetic sensitization threshold document for nootkatone.
This reference does not establish a therapeutic result or a safe use level for a custom oil blend.
No direct public citation is attached to this entry.
Constituents it may interact with
These are research candidates recorded in the interaction matrix. They do not add a proven-amplification bonus to the score.
EugenolAmplification candidate
Candidate in the research matrix. A coefficient alone does not establish amplification at the dose, route or goal of your blend; no proven amplification is inferred from this row.
in vitro · effect
No source citation attached.
Read Eugenol report →octanalAmplification candidate
Candidate in the research matrix. A coefficient alone does not establish amplification at the dose, route or goal of your blend; no proven amplification is inferred from this row.
aroma science · whole_oil
No source citation attached.
Read octanal report →How the effects were investigated
gaba_gated_chloride_channel_modulation_in_insects
Recent insect studies report that nootkatone modulates insect GABAergic signaling, with 2022 and 2025 papers linking its toxicity and repellency to disruption of synaptic transmission and Rdl-associated GABA channel effects.
This reference does not establish a therapeutic result or a safe use level for a custom oil blend.
nfkb_and_proinflammatory_cytokine_suppression
Several preclinical studies report that nootkatone suppresses NF-kB-linked inflammatory signaling and lowers markers such as TNF-alpha, IL-1beta, MPO, or oxidative stress outputs in mouse and cell models.
This experimental finding does not establish benefit, dose or safety in people using this blend.
nqo1_ampk_nrf2_linked_antioxidant_signaling
A 2021 neuroinflammation paper specifically implicated NQO1, AMPK, and Nrf2-associated pathways in nootkatone's anti-inflammatory and antioxidant effects in LPS-stimulated microglia and mice.
This experimental finding does not establish benefit, dose or safety in people using this blend.
What this report cannot establish
- A reported constituent percentage does not establish an effective human therapeutic dose or the amount absorbed into the body.
- The presence of a constituent does not guarantee a clinical benefit, rash treatment or sleep improvement from a custom blend.
- An unflagged concern or missing use limit does not establish safety for ingestion, inhalation, skin exposure or a particular person.
- A candidate constituent interaction does not establish that two oils amplify one another at the selected proportions.
- Constituent descriptors alone do not establish a precise top, heart or base lifetime in a finished blend.
Known data gaps (7)
- This pass did not verify a strong human clinical efficacy literature for isolated nootkatone.
- The identity record is strong, but stereochemical and supplier CAS usage can vary across databases and commercial references.
- Most mechanism and benefit-oriented evidence remains preclinical or insect-focused rather than consumer-use clinical data.
- IFRA Standard 185 (Amendment 40) does not set a numeric maximum-use percentage for nootkatone; it instead requires fragrance-grade material to meet a purity specification (>=98%, melting point >=32C), based on Expert Panel review finding no sensitization in humans tested with high-purity material.
- No constituent-specific numeric dermal reference is available here.
- Some findings do not record an explicit exposure route; consult the linked study before applying them to a use.
- Interaction candidates lack an attached source citation and remain unqualified.