Novel benzylidene benzofuranone analogues as potential anticancer agents: design, synthesis and in vitro evaluation based on CDK2 inhibition assays

The classical anticancer agents do not have their efficacy on inhibiting the G2 phase of the cell cycle. There are a very few reports available on drugs that work at G2 phase. Flavopiridol is one such drug candidate. In the current study, we sought to make analogues of flavopiridol. Still, the conditions used during their synthesis were unfavourable for the formation of flavopiridol and led to the generation of benzofuranones. In the present work, a new series of benzylidene benzofuranones were designed, synthesized and evaluated for their antioxidant, anti-colorectal cancer activity. Molecular docking, MMGBSA and molecular dynamics studies were conducted to assess their binding affinity at the active site of CDK2. Based on the cytotoxicity exhibited by test compounds, the compound NISOA4 (from isopropyl series) was further selected for mechanistic anticancer studies on HCT 116 cell lines. The compound selected was evaluated by comet assay, DNA fragmentation assay, cell cycle analysis, apoptosis detection by annexin FITC, semi-quantitative RTPCR based gene expression studies and FRET assay on the target CDK2/Cyclin A. Compound NISOA4 exhibited marked olive moments in comet assay studies. The apoptotic DNA fragmentation for compound NISOA4 demonstrated a marked change in the DNA fragmentation. The compound exhibited cell cycle arrest at G2/M phase at both the test concentrations. Apoptosis induction was observed at both the test concentrations and the compound was found to be a potent proapoptotic agent. It exhibited marked inhibition for the CDK2 gene expression and did not show any effect on CyclinA gene expression. However, the compound NISOA4 along with other analogues showed appreciable inhibition for the CDK2/Cyclin A target enzyme.