An indole is an organic heterocyclic compound with a bicyclic structure having a nitrogen-composed pyyrole ring fused to a benzene ring; any product that contains these indolic structures is considered an indole. The compound is aromatic and solid at room temperature, and it has many applications in the fragrance industry, and increasingly, the pharmaceutical industry. Indoles are primarily produced within the human body as a byproduct of the degradation process of the amino acid, tryptophan. It is processed and usually found to accumulate in human feces, and at high concentrations, indoles possess a strong, unpleasant fecal odor. Surprisingly, at very low concentrations, they have a pleasant, flowery smell and are used often as a constituent in flower scents, like orange blossom.
Indoles are important precursors for other substances made within the human body and are, therefore, researched and used in lifestyle and medical applications. The compound was officially discovered in 1866 by a scientist working with the properties of zinc dust who reduced oxindole from the zinc dust into an indole. After the discovery, indoles became important constituents of the textile industry, and as more research was conducted, the larger role that indoles played within the human body system was realized. The indolic nucleus in substances like tryptophan and auxin has led to a better understanding of their mechanism within the body.
The complex chemical structure of indoles make them stabilizing to protein structure. Any structure that contains the compound or its derivative can help an enzyme or protein form into its correct structure or even help to correct the structure. One of the proposed methods of this action is that indoles readily form hydrogen bonds, which are essential for protein formation. Proteins that contain the rings associated with indolic structure stand up to heat and chemical manipulation better than proteins without the rings. Many of the indoles that are harvested today come from coal tar, where it is found in one of its most stable states.
Indole alkaloids are a group of specific chemicals that are found in many plants around the world including snakeroot and periwinkle. One indole derivative, indole-3-carbinol, is found abundantly in cruciferous vegetables like broccoli, cauliflower, and cabbage. The properties of this indole derivative are anti-carcinogenic, antioxidant, and anti-artherogenic. These effects have been well-proven in randomized controlled studies. More research will reveal the many applications that this derivative and others like it will have in the treatment of lifestyle diseases.