Indole-2-carboxylic acid ethyl ester is a reagent involved in the preparation of: CRTH2 receptor antagonists, acetolactate synthase inhibitors, p38 MAP kinase inhibitors, cannabinoid CB1 receptor antagonists, and an anticancer agent against leukemia K562 cells.

Indole-3-acryloylglycine (IAG) is an indole derivative typically found in human urine. Analyzing the levels of IAG is useful for the diagnostic of certain disorders like Hartnup disease. It can also be used as a reagent for chemical synthesis.

Indole-3-carbinol is an inhibitor of carcinogenesis at the initiation stage. However, it enhances carcinogenesis at the post-initiation stage. Indole-3-carbinol induces cell cycle arrest and additionally blocks cyclin-dependent kinase 6 expression. It has been shown to suppress cell adhesion and migration in vitro.

Indole-3-Carboxylic acid is used to prepare antitumor agents and amino acid derivatives. Additionally, it can be used to synthesize serotonin 5-HT4 and 5-Ht6 receptor antagonists, Very Late Antigen-4 (VLA-4) antagonists, and potential agents against Alzheimer's disease.

Indole-3-carboxylic acid methyl ester is useful in the preparation of: nitric oxide synthase inhibitors, RNA polymerase II inhibitors, Very Late Antigen-4 (VLA-4) inhibitors, serotonin 5-HT4 inhibitors, and protein kinase C alpha inhibitors.

Indole-3-propanol is a reagent used for chemical synthesis. It has been used in the synthesis of h5-HT1D receptor agonists.

3-(3-Indolyl)-2-oxopropanoic acid, 3-Indolylpyruvic acid

Indole-4-carboxylic acid is a reagent used in chemical synthesis. An indole with several applications it has been used in the synthesis of histamine H3 antagonists and hydroxamic acids inhibitors, along with HIV protease inhibitors and SARS-CoV 3CL proinhibitors. Outside of pharmaceutical applications Indole-4-carboxylic acid can form a copolymer.

Indole-5-carboxaldehyde is a reagent that has been used in the synthesis of various pharmaceuticals, such as anti-inflammatory drugs and HIV-protease inhibitors, along with NMDA receptor antagonists. In other applications it can be used to synthesize para-para stilbenophanes.