Anticancer Activity–Structure Relationship of Quinolinone-Core Compounds: An Overall Review

Quinolinone/quinoline is one of the most unique structures in the discovery of heterocycles that have attracted much attention in the field of medicinal chemistry. The basic scaffold of fused quinoline derivatives is of great interest to medicinal chemists since large road maps of the gene and protein expression can be used to classify cancers or predict responses to certain types of treatments targeting the level of both transcription and translation and the level of enzyme activity. These specific regulations may open the door for the discovery of new drug candidates including anticancer targets. This review provides a comprehensive description of various quinolinone derivatives, especially by concentrating on compounds containing benzimidazole rings. Quinolone moieties are experimentally proven anticancer pharmacophores which may further enhance their activity due to various functional groups, mostly the electron-withdrawing groups such as fluoro, chloro, nitro, amino, and carbonyl groups that showed stronger activity than those with electron-donating groups such as methyl and methoxy groups. The presence of an electron-withdrawing or electron-donating group at the quinolone ring influences the redox properties affecting DNA synthesis. Structural motifs attributed to noteworthy inhibitory results are identified and highlighted to encourage further research and drug development. This work aims to help researchers in discovering more powerful, active, and less toxic quinoline-based anticancer drugs and developing new vision in the search for their rational design.