Design, Synthesis, and Evaluation of Novel Indole Hybrid Chalcones and Their Antiproliferative and Antioxidant Activity

The synthesis, anticancer, and antioxidant activities of a series of indole-derived hybrid chalcones are reported here. First, using the well-known Claisen–Schmidt condensation method, a set of 29 chalcones has been designed, synthesized, and consequently characterized. Subsequently, screening for the antiproliferative activity of the synthesized hybrid chalcones was performed on five cancer cell lines (HCT116, HeLa, Jurkat, MDA-MB-231, and MCF7) and two non-cancer cell lines (MCF-10A and Bj-5ta). Chalcone 18c, bearing 1-methoxyindole and catechol structural features, exhibited selective activity against cancer cell lines with IC(50) values of 8.0 ± 1.4 µM (Jurkat) and 18.2 ± 2.9 µM (HCT116) and showed no toxicity to non-cancer cells. Furthermore, antioxidant activity was evaluated using three different methods. The in vitro studies of radical scavenging activity utilizing DPPH radicals as well as the FRAP method demonstrated the strong activity of catechol derivatives 18a–c. According to the ABTS radical scavenging assay, the 3-methoxy-4-hydroxy-substituted chalcones 19a–c were slightly more favorable. In general, a series of 3,4-dihydroxychalcone derivatives showed properties as a lead compound for both antioxidant and antiproliferative activity.