Recent Progress of Bioactivities, Mechanisms of Action, Total Synthesis, Structural Modifications and Structure-activity Relationships of Indole Derivatives: A Review

Indole (2,3-benzopyrrole) containing a pyrrolyl ring possesses the characteristic of electron-rich aromatic compounds. Indole occurs in the oil of jasmine and cloves and coal tar. Additionally, it is also present as a putrefaction product from animals' intestines. Notably, indole and its derivatives exhibit a wide range of biological properties, such as anti-Alzheimer's disease, anti-cancer, anti-bacterial, anti-inflammatory, anti-human immunodeficiency virus (HIV), anti-diabetic, anti-tuberculosis, anti-oxidant, anti-coronavirus, and antifungal activities. In this mini-review, recent advances in biological activities, mechanisms of action, total synthesis, structural modifications, and structure-activity relationships of indole and its derivatives from 2018 to 2020 are described. We hope the present paper can pave the way for future design, development, and application of indole derivatives as potent drugs.