CONSTITUENT REPORT
indole
Indole is a small bicyclic nitrogen heterocycle that shows up in the AromaForge archive mostly as a trace but high-impact floral-signature constituent rather than a bulk oil component. Live evidence strongly supports its identity, odor character, presence in floral materials such as jasmine and orange blossom contexts, and its use in fragrance science. Separate biological literature also shows that indole functions as a microbial signaling molecule and can activate the human aryl hydrocarbon receptor in experimental systems, but those findings are context-specific and do not justify consumer-facing medical claims.
Chemical identity and composition
PubChem and NIST identify indole as C8H7N with IUPAC name 1H-indole. It is chemically simple but olfactorily disproportionate: trade and sensory references consistently describe a strong fecal or animalic profile at high concentration that turns floral on dilution. In the current archive, neroli Tunisia explicitly lists indole at 0.21%, and an accessible jasmine extraction paper identifies indole among the compounds responsible for the high diffusivity of jasmine fragrance.
Aroma and practical use
- Use the recorded animalic, fecal at concentration, floral on dilution, jasmine-like 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 2015 Sci Rep study reported that indole functions as a human-AHR selective agonist and suggested a role in inter-kingdom signaling between enteric microflora and the immune system.
This is mechanistically important but should not be treated as evidence of a consumer health effect from aromatic exposure.
This experimental finding does not establish benefit, dose or safety in people using this blend.
A 2007 BMC Microbiology study found that indole decreased E. coli biofilms through SdiA-linked signaling, repressed motility-associated behavior, and changed biofilm architecture from scattered towers to flatter colonies.
This is strong support for indole as a bona fide signaling molecule in microbial systems, but it is not a therapeutic finding.
This experimental finding does not establish benefit, dose or safety in people using this blend.
A 2012 jasmine extraction paper identified indole among the compounds responsible for the high diffusivity of jasmine fragrance in liquid CO2 extracts.
This is one of the most relevant archive-facing findings because it directly supports indole's floral-signature role in perfumery materials.
This reference does not establish a therapeutic result or a safe use level for a custom oil blend.
A 2022 honey aroma study identified indole as the compound responsible for a fecal descriptor in certain floral honeys and measured a detection threshold of 64 micrograms per kilogram in honey.
This is useful sensory evidence because it captures the dual identity of indole as both a low-threshold off-note and a naturally floral-derived odorant.
This reference does not establish a therapeutic result or a safe use level for a custom oil blend.
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.
A recorded constituent reference, not a recommended oil dilution. Product category, source applicability and all contributing oils must be checked before use.
recorded reference · RIFM fragrance ingredient safety assessment, indole, CAS 120-72-9 (Food Chem Toxicol 144:111693, 2020), Table 1: maximum acceptable concentration for Category 5 (products applied to face and body using the hands, primarily leave-on) = 0.10%, based on non-reactive Dermal Sensitization Threshold (900 micrograms/cm2); current 95th-percentile use concentration (0.0040%) is well below thisA formal RIFM fragrance ingredient safety assessment for indole was published in 2020, indicating that a modern fragrance-safety dossier exists for this molecule.
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.
Trade and sensory references consistently emphasize that indole is intensely animalic or fecal at higher concentration and more floral only at low dilution, which matters for practical handling and formulation context.
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.
The accessible biology literature for indole is largely microbial, receptor-level, or systems-biology research rather than evidence for topical or inhaled wellness outcomes.
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.
Methyl anthranilateAmplification 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 Methyl anthranilate report →How the effects were investigated
human_ahr_agonism
A 2015 Sci Rep paper identified indole as a human-AHR selective agonist and proposed that microbiota-derived indole may contribute to host-microbe signaling at the gastrointestinal mucosal interface.
This experimental finding does not establish benefit, dose or safety in people using this blend.
bacterial_biofilm_signaling_via_sdia
Biofilm papers in E. coli describe indole as an extracellular and interspecies signaling molecule that changes biofilm formation through SdiA-linked regulation and motility effects.
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 (5)
- Most accessible indole biology papers are mechanistic or microbial and are not directly translatable to aromatic use claims.
- Archive occurrence is likely undercounted because many floral oil data sheets focus only on larger peaks even when indole is olfactorily important.
- The RIFM DST-based maximum acceptable concentration used here (0.10%, Category 5: face/body leave-on via hands) is a non-reactive dermal sensitization threshold benchmark, not a formal IFRA Standard restriction (indole has no dedicated IFRA Standard as of this pass); other RIFM product categories permit different percentages (e.g. 0.021% axillae, 0.39% fine fragrance, 2.7% household).
- 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.