skatole

Skatole, also known as 3-methylindole, is an aromatic heterocyclic compound with the chemical formula C9H9N. It is typically a colorless to pale yellow oily liquid and is notable for its very strong, fecal odor at low concentrations. Its odor is a defining characteristic and makes skatole a key contributor to the smell of feces and decaying organic matter.

Natural occurrence and formation: Skatole is produced by bacterial degradation of the amino acid tryptophan in the gastrointestinal tract and in decomposing organic matter. It occurs in feces, manure, and other decaying materials and can be detected in trace amounts in various animal tissues and environmental samples. In the environment and in food-related contexts, skatole is often studied as an odorant and as a marker of microbial activity.

Chemical structure and properties: Skatole belongs to the indole family, featuring a benzene ring fused to a pyrrole ring with a methyl substituent at the 3-position. The molecule is relatively nonpolar and has limited water solubility, with the bulk of it being soluble in organic solvents. It is volatile enough to contribute to odors at low concentrations and can be analyzed by standard odor and analytical techniques such as gas chromatography–mass spectrometry.

Uses and significance: In perfumery and flavor science, skatole is used in very small amounts to impart animalic or musky notes, though its strong and unpleasant odor requires careful handling and precise dosing. It is also relevant in studies of spoilage, environmental odor, and gut microbiology as a distinctive odor compound.

Etymology and safety: The name skatole derives from the Greek skatos, meaning feces. Handling should follow standard chemical safety practices; inhalation and dermal exposure should be minimized due to irritation risk and odor impact.