Anti-Tumor Activity of Indole: A Review

Abstract: Generally, heterocyclic compounds are included in a large class of pharmacologically active compounds. The indole scaffold in this category is widely distributed in nature and present in many active compounds, especially anti-cancer agents. Due to its unique physicochemical and biological properties, the indole platform has been considered a favorable scaffold in anti-cancer drug design and development. Various indole compounds (synthetic, semisynthetic, and natural) show remarkable anti-proliferative activity. According to the recent literature, this review describes the role of indole scaffolds as anti-cancer agents. Indole was reported to induce anti-tumor activity through multiple mechanisms, for example, Epidermal Growth Factor Receptors (EGFR), histone deacetylase (HDAC), kinase, DNA-topoisomerases, and tubulin inhibition. The current review focuses on some indole compounds with amazing effects against different types of cancers as there are too many FDA-approved drugs, for example, osimertinib, alectinib, and anlotinib in NSCLC treatment, panobinostat in multiple myeloma, midostaurin in acute myeloid leukemia treatment, etc. Moreover, several compounds are still in clinical trials to treat different cancer types. Additionally, there are some oxindole derivatives with potent inhibition against different types of tumors, such as ovarian cancer, colorectal cancer, and prostate cancer. Different series of oxindoles are promising and recommended for further studies due to their remarkable inhibition of tumor cells. Accordingly, the collection of data on a pharmacologically significant motif might aid researchers in further employing indoles in developing novel anti-cancer drugs with potentially fewer side effects and higher potency against this rapidly spreading disease.