Skatole

Skatole or 3-methylindole is an organic compound belonging to the indole family. It occurs naturally in and, in high concentrations, is the primary odor of feces. In low concentrations, it has a flowery smell and is found in several flowers and essential oils, including those of orange blossoms, jasmine, and Ziziphus mauritiana.

It is used as a fragrance and fixative in many perfumes and as an aroma compound. Its name derives from the Greek root skato-, meaning "feces".  Skatole was discovered in 1877 by the German physician Ludwig Brieger (1849–1919).

Biosynthesis, chemical synthesis, and reactions
Skatole is derived from the amino acid tryptophan in the mammalian digestive tract.  Tryptophan is converted to indoleacetic acid, which decarboxylates to give the methylindole.
 
Skatole can be synthesized via the Fischer indole synthesis. 

It gives a violet color upon treatment with potassium ferrocyanide.

Insect attractant

Skatole is one of many compounds that are attractive to males of various species of orchid bees, which apparently gather the chemical to synthesize pheromones; it is commonly used as bait for these bees for study. It is also known for being an attractant for the Tasmanian grass grub beetle (Aphodius tasmaniae).

Skatole has been shown to be an attractant to gravid mosquitoes in both field and laboratory conditions.  Because this compound is present in feces, it is found in combined sewage overflows (CSO) as streams and lakes containing CSO water have untreated human and industrial waste.  Knowledge of this attractant makes CSO sites of particular interest when studying mosquito-borne diseases such as West Nile virus.

Animal studies
Skatole has been shown to cause pulmonary edema in goats, sheep, rats, and some strains of mice. It appears to selectively target club cells, which are the major site of cytochrome P450 enzymes in the lungs. These enzymes convert skatole to a reactive intermediate, 3-methyleneindolenine, which damages cells by forming protein adducts (see fog fever). 

With the testicular steroid androstenone, skatole is regarded as a principal determinant of boar taint. 

It contributes to bad breath.

Application
Skatole is the starting material in the synthesis of atiprosin.

See also
 Indole
 1-Methylindole
 2-Methylindole (methylketol)
 5-Methylindole
 7-Methylindole
 Cadaverine

References

External links
 What's that smell?

Category:Methyl indoles
Category:Foul-smelling chemicals
Category:Perfume ingredients