Kaur M, Mehta V, Abdullah Wani A, Arora S, Bharatam PV, Sharon A, Singh S, Kumar R. Synthesis of
1,4-dihydropyrazolo[4,3-b]indoles via intramolecular C(sp
2)-N bond formation involving nitrene insertion, DFT study and their anticancer assessment.
Bioorg Chem 2021;
114:105114. [PMID:
34243073 DOI:
10.1016/j.bioorg.2021.105114]
[Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Revised: 06/17/2021] [Accepted: 06/18/2021] [Indexed: 11/19/2022]
Abstract
We herein report a new synthetic route for a series of unreported 1,4-dihydropyrazolo[4,3-b]indoles (6-8) via deoxygenation of o-nitrophenyl-substituted N-aryl pyrazoles and subsequent intramolecular (sp2)-N bond formation under microwave irradiation expedite modified Cadogan condition. This method allows access to NH-free as well as N-substituted fused indoles. DFT study and controlled experiments highlighted the role of nitrene insertion as one of the plausible reaction mechanisms. Furthermore, the target compounds exhibited cytotoxicity at low micromolar concentration against lung (A549), colon (HCT-116), and breast (MDA-MB-231, and MCF-7) cancer cell lines, induced the ROS generation and altered the mitochondrial membrane potential of highly aggressive MDA-MB-231 cells. Further investigations revealed that these compounds were selective Topo I (6h) or Topo II (7a, 7b) inhibitors.
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