Indole is an organic compound that is both aromatic and heterocyclic, with a chemical formula of C8H7N. Its structure is comprised of a fused five-membered pyrrole ring and a six-membered benzene ring, resulting in a bicyclic configuration.

Indole, which acts as a signal molecule between cells, plays a role in regulating several bacterial physiological processes, such as spore formation, plasmid stability, drug resistance, biofilm creation, and virulence.

Indole, known as Benzopyrrole, is a heterocyclic organic compound present in flower oils like jasmine and orange blossom, coal tar, and fecal matter. Its applications include use in perfumery, production of tryptophan, an essential amino acid, and indoleacetic acid (heteroauxin), a hormone that stimulates root development in plant cuttings.

Indoles are heterocyclic ring systems that have been extensively studied due to their numerous applications in various pathophysiological conditions including cancer, microbial and viral infections, inflammation, depression, migraine, emesis, hypertension, among others.

The involvement of the lone pair of nitrogen in the resonance of the aromatic bicyclic structure gives indole a weak basic character, making it one of the versatile scaffolds in medicinal chemistry.