indole
LowScientific/Technical
Definition
Meaning
A white crystalline organic compound, C8H7N, with a complex bicyclic structure consisting of a benzene ring fused to a pyrrole ring, produced in the intestines by bacterial decomposition of tryptophan and found naturally in plants such as jasmine and orange blossoms.
The term also refers to the parent compound and its many derivatives, which form a large class of heterocyclic compounds. These derivatives are fundamental structures in many biologically active molecules, including pharmaceuticals (e.g., certain cancer drugs), alkaloids (e.g., strychnine), dyes, and fragrances.
Linguistics
Semantic Notes
In chemistry and biochemistry, 'indole' almost exclusively denotes the chemical compound or its class. In perfumery, it refers specifically to the aromatic compound used in fragrances, which can have a floral scent at low concentrations but an unpleasant fecal odor at high concentrations.
Dialectal Variation
British vs American Usage
Differences
No significant differences in meaning or spelling. Pronunciations differ slightly (see IPA).
Connotations
None beyond the technical or olfactory contexts.
Frequency
Equally rare in general discourse but equally common in relevant scientific fields in both regions.
Vocabulary
Collocations
Grammar
Valency Patterns
[Compound] is an indole derivative.[Compound] contains the indole ring system.The [process] produces indole.Indole is [adjective].Vocabulary
Synonyms
Neutral
Weak
Usage
Context Usage
Business
Extremely rare. Might appear in contexts of pharmaceutical, fragrance, or chemical manufacturing.
Academic
Predominant usage. Common in research papers, textbooks, and lectures in organic chemistry, biochemistry, pharmacology, and perfumery.
Everyday
Virtually never used.
Technical
The primary domain of use. Specific to chemical synthesis, analytical reports, and industrial specifications.
Examples
By Part of Speech
verb
British English
- The bacteria can indolise tryptophan.
- The strain was tested for its ability to indole.
American English
- The bacteria can indolize tryptophan.
- The strain was tested for its ability to produce indole.
adjective
British English
- The indolic structure is crucial for activity.
- They studied indolic metabolism.
American English
- The indole structure is crucial for activity.
- They studied indole metabolism.
Examples
By CEFR Level
- Indole is a chemical found in some flowers.
- Some perfumes use a substance called indole.
- The characteristic smell of jasmine is partly due to indole.
- Researchers are studying new indole-based medicines.
- The indole nucleus serves as a privileged scaffold in medicinal chemistry for designing serotonin receptor modulators.
- Gas chromatography confirmed the presence of several volatile indole derivatives in the bacterial culture supernatant.
Learning
Memory Aids
Mnemonic
Think of INDOLE as the INside DOLphin's scent? No! Better: IN a molecule, a benzene ring and a pyrrOLE ring join to form INDOLE.
Conceptual Metaphor
A BUILDING BLOCK or SCAFFOLD (for more complex molecules like drugs and fragrances).
Watch out
Common Pitfalls
Translation Traps (for Russian speakers)
- The Russian term 'индол' is a direct cognate, but its pronunciation and technical specificity must be matched. Do not confuse with 'индолентный' (indolent/lazy), which is unrelated.
Common Mistakes
- Mispronouncing as /ɪnˈdoʊl/ (stress on second syllable).
- Using it as a countable noun in non-technical contexts.
- Confusing it with 'indolent' due to similar spelling.
Practice
Quiz
In which field is the term 'indole' MOST frequently used?
FAQ
Frequently Asked Questions
Pure indole can be an irritant and should be handled with standard laboratory precautions. Its derivatives have a vast range of effects, from therapeutic to toxic.
This is a common olfactory phenomenon. At very low concentrations, indole contributes a floral, jasmine-like note. At higher concentrations, its odor is perceived as fecal or nauseating.
It's a biochemical test used to identify bacteria, particularly E. coli, based on their ability to produce indole from tryptophan using the enzyme tryptophanase.
Yes, trace amounts occur naturally in foods like broccoli, cauliflower, and meats, resulting from the breakdown of the amino acid tryptophan.