Indoles and their derivatives are well-known as an important class of heterocyclic compounds, their core being a near-ubiquitous component of biologically active natural products, widespread in different species of plants, animals, and marine organisms. The indole is also well-known as one of the most important scaffolds for drug discovery, capable of serving as ligand for a diverse array of receptors. Indoles is used in textile dyes, perfumes, in agriculture and veterinary medicine. Relatively new areas are dietary supplements and nutraceuticals.